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ClickRepair 3.9 & ClickRepairRT 1.3 User`s Manual

1. Pause within a few seconds of hearing a problem will still give the Opportunity to go back and attempt to fix it manually Method Simple versus Wavelet It is clear from the interface that there are more methods available x2 and x3 These more com plex methods are the subject Chapter 10 and should not be used initially Simple means that each channel is processed as a single data stream of sound samples taken at the given sampling rate This is the simplest and most efficient choice and in some cases it is per fectly adequate even beneficial However there can be significant advantages from splitting the sional into two streams separating the high and low frequency components by selecting the Wavelet method The theory of wavelets permits this to be combined with lossless down aT sampling so that each of the two filtered streams is down sampled to one half of the given sam pling rate As a result of the down sampling processing the two streams is only a little slower than processing one unless the repair rate is high I already explained in Chapter 4 that wavelets are not equivalent to conventional filtering coupled with conventional re sampling Rather the theory allows for perfect reconstruction of the data stream if no repairs are made in the wavelet streams For records in good condition this exceeds 99 5 of the file The question arises which method to use Here are some observations
2. Reset default behaviours Reset Gefault window location and size Reset default behaviour for all dialogs Reset other defaults Cance OK Language ClickRepair has a choice of three languages in the user interface English French and German If your computer is set to French or German as language of choice the program should automati cally use that language from the first time it is used To change the language in use use the drop down list in the preferences dialog The French translations were kindly provided by Michel Poulain the German translations by Willy Kunz Both are long time users of the application Sound Buffer Length Versions of ClickRepair previous to 3 8 had a set buffer length of 524 288 samples approximately 12 seconds at 44 1kHz In the new versions the choice of a longer buffer is intended to make it more convenient to experiments with and re process selected portions of the file while they are still resident in computer memory RAM The extra memory requirements are significant and choosing the longest buffer length 2097152 samples may cause Out of Memory dialogs on some systems Because the necessary memory allocations are made as the file is opened it is only possible to change these settings while no file is open Language is the only preference that may be set for ClickRepairRT 53 Log Files Logging may be turned on at any time using the preferences dialog At the st
3. 20 most detailed View at 1 1 then View at 2 1 up to View at 256 1 The viewing scale also de termines how many sound samples are displayed per pixel across the display window As the scale increases the fraction of the sound buffer which is displayed increases The indicator of the sound bar changes to show this becoming progressively wider For manual inspection and adjustment of repairs it is advisable to use the most detailed scale 1 1 Menus On all platforms there are six menus with menu items as given here e File Batch Setup Breakpoints File Dialogs Open Start Pause Abort e Edit Undo Fix Accept e Settings Default LP Default Brass Default Percussion Default Mono Default 78 Import Ex port saved settings if any Custom Sound Play Stop Off faster Removed Noise In Original Out Repaired Loop Mixer Set tings e View from 1 1 to 265 1 e Help Registration Website Keyboard Shortcuts On Mac OS X the Application menu has the items e Quit ClickRepaitr e About ClickRepair e Preferences On other platforms these three appear as extra items on the File and Help menus Even if you ate using the in window controls buttons etc and or keyboard shortcuts most of the time the menus serve to provide extra information where there is insufficient room for this on screen For example the Edit gt Accept item changes to Edit gt Accept Fix a
4. it is possible to process directly from it It has been explained already that ClickRepair makes no changes to any part of an audio file except for the sound data itself Therefore files processed directly from CD will be saved with the same headers and file extension as were passed in by operating system You will be able to open these new files with any program which is able to deal with the original file directly If you want to test this drag one of the tracks from the CD to the desktop using the Finder This will copy it Now attempt to open it with your Audio Editor or other application If it works for the origi nal it should work for the file produced by ClickRepait 18 5 User Interface Basics Visual Interface Once you have tried the program I recommend making some experiments setting the Automatic slider to Off or at least to a small number This will cause the program to stop before making any repair whose length is greater than the chosen maximum enabling manual intervention w a 3 Y O gt 4 gt In the figure here the program stopped because 42 consecutive samples in the left channel are pro posed for repair more than the Automatic setting of 30 The features of the user interface may now be seen Notice that e The Start button reads Resume because processing has paused e There are two views displayed the top one long and narrow Each shows the left and righ
5. version does sound a great deal better than the badly damaged original 45 A Genuine Pop ii tA se f A T fA 4 My w a T n A te pa 4 gt i gt Here is a different kind of example the automatic detection and repair of a pop that goes unde tected using the normal wavelet algorithm even at a sensitivity of 90 Clearly there is a significant pop in the right channel bottom trace and the fact that the automatically detected and generated repair has no red rectangle is due to the fact that there is no associated click This is despite the fact that a click has been detected in the left channel upper trace Using previous versions of ClickRe pair this pop could only be repaired by finding and treating it manually a very tedious and time consuming process Manual repairs are the subject of the next chapter since there are times when this is the only effective remedy available Time reversed Processing A number of users have noted that with certain types of audio material for which false detection is a difficult problem the situation can be much improved by reversing the audio file so that it plays backwards processing the reversed file with ClickRepair then reversing the new file to make it play forwards again The underlying reason is simple some percussive sounds have a sharp attack and relatively slower decay and when played backwards that becomes a slow attack with a
6. working at a lower sample rate than 44 1 kHz is obviously counter productive since the CD rate is an absolute bare minimum for high quality sound reproduction and resampling is not a recommended extra procedure Some comments on special techniques for Shellac records may be found at the end of Chapter 9 Given 88 2 kHz or 96 kHz data the actual processing is performed on two parallel data streams each at half the sample rate using wavelets to perform exact reconstruction re sampling This means that the output file will exactly match the input file sample by sample except for those samples which are repaired The technique is in no way equivalent to using normal audio software to down sample the original 96 kHz file to 48 kHz After that process up sampling to 96 kHz can not restore what was lost in the down sampling Wavelets are a method of data analysis which combines frequency and time information in a sophisti cated way This differs from Fourier analysis which treats signals in blocks transforming each block of samples which are organised sequentially in time in to a block of the same length which is organ ised sequentially by frequency content In the form used by ClickRepair a wavelet transform takes an incoming data stream and separates it into two streams containing the high and low frequency com ponents with the extra property that each stream is sampled at half of the original rate The magic of the transforms employe
7. 1400 samples on display here the relative levels appear to be constant although they are in fact changing slowly It is necessary to change the horizontal scale to a higher value in order to see the dynamics more clearly Tnt en A few oe O 7 G Significant damage will often benefit from manual adjustment This is the subject of the next chapter but to make this clear here is the result of making a much longer repair in the left channel 40 The bump is taken out of that channel and the relative level difference is reduced making for a better overall result Shellac Records Much of what is in this manual applies to material sourced from any record vinyl or shellac In this section I make a few brief comments on the challenges posed by the older shellac records The introduction of vinyl records coincided more or less with the introduction of full frequency range recording Most shellac records were designed to play at 78 rpm or thereabout and their frequency range was restricted to about 8 kHz because of technical limitations Equalization schemes varied although a common feature was the reduction of bass frequencies to limit groove excursion Details may be found in various places for example at www rfwilmut clara net The granular nature of the shellac recording material means that hiss is still quite prominent even after applying the proper equalization which will lift the bass relative to the treble
8. 483 647 bytes for AIFF files the limit is 2 147 483 647 audio samples For 24 bit stereo this amounts to about 12GB At tempts to open longer files will result in an error dialog For stereo files in 32 bit 96kHz resolution 2GB is a little over 46 minutes At a resolution of 24 96 it is about 62 minutes at a resolution of 16 44 1kHz it is over 3 hours Some Windows Audio Editors can open longer WAV files using proprietary file formats and or meta data files ClickRepair is not able to handle these special file formats 15 ClickRepair has one other dialog related to file length issues shown here It is a warning that the file leneth given in the header disagrees with the actual physical file length on disk This alert is pro vided for information only in most cases it will not affect the use of the file either by ClickRe pair or by other audio editing programs Warnin inconsistent file lenoth header see manual 9 Dont show again Ox In more detail e Provided that the file is at least as long as the sum of its required chunks this error will not affect processing and there will be no problem in proceeding e If the file is incomplete this warning will be followed by the larger error alert above with the number of missing bytes stated Processing will not be possible in this case e ClickRepair does not change these or any other headers even if they are inconsistent Sample Sizes The sound data used for
9. a Normal or Gaussian statistical distribution Crackle is a complete misfit because the propor tion of outlying data does not fall off in the assumed manner De crackling concentrates on removing the outliers leaving a file which should be much more responsive to de hissing There are many other recipes which could be suggested For example if the record was played at 45 rpm an audio editor can be used to change the sample rate to 76 4 kHz without resampling ClickRepair will operate on this file differently applying an extra level of wavelet decomposition see the section on Sample Rates in Chapter 4 But because the audio was not resampled it is the identical data set which is being treated I have found that this technique may improve de clicking but degrade de crackling because the detection algorithm is working at half the sample rate The main point is that restoration of old recordings is as much an art as a science a considerable amount of experiment and critical listening will be required to achieve good results The only firm recommendation I can make is to do the initial de clicking on the original data set before any equalization and or resampling For example 500Hz will move to 867Hz when changing from 45 rpm to 78 rpm 42 10 More Advanced Methods The methods described in Chapters 6 and 9 were the basis of ClickRepair 2 and they remain the core of ClickRepair 3 Not only that their operation is u
10. as when the program was last shut down Reset Default Window Location and Size erases this per sistent information and resets the window immediately but only after the OK button is clicked The information will not be reset again until the Preferences dialog is again invoked Reset Default Behaviour for all Dialogs refers to the fact some of the dialogs have a Don t Show Again button This is to prevent such dialogs becoming annoying once you understand the flow of program use If you wish to see any of these dialogs again check this box and select OK Reset other defaults resets all check boxes and radio buttons not associated with the Detection amp Review control group 55 14 Other Features Behaviour of Buttons The Main Controls group consists of five buttons but some buttons have more than one func tion This has already been mentioned indirectly in relation to the Open button which became the Start button then alternatively the Pause and Resume button Other buttons with multi ple use are the Fix button which can alternate with Undo and the Play button which can alternate with Stop These buttons can be operated using fixed keyboard shortcuts as described earlier but they never receive the keyboard input focus and cannot be clicked using the spacebar or any other normal method for the particular platform By contrast the
11. check box Automatic scaling is restored once you resume processing or you can re select the check box To magnify the display move the slider down which reduces the display peak level This might seem counter intuitive but is a consequence of showing the peak level ClickRepair scales the display window automatically usually the most convenient scheme To reveal as much detail as possible damage is not included in setting the level Peak levels are displayed in deci bels dB just above and below the sliders The sliders also move down as the peak level falls Infor mation about sample sizes and peak levels was given in the Sample Sizes section in Chapter 4 Gen erally there is no need to worry about these controls Small clicks in a quiet passage might be quite disturbing yet the same clicks in a loud passage might not be noticed This is intuittve when the dis play is scaled automatically and the click might even extend off the display in red The horizontal scale used in the display window is controlled by the View menu and also by a small horizontal slider visible in the central strip of the display window whenever processing is paused You can use either for changing the scale but only when processing is paused The effect of increasing the ratio is that more samples are displayed across the display window at the expense of having a less detailed view The scales progress in powers of 2 starting with the
12. delays are extremely variable processed data is not sent to the sound system directly rather to a second buffer which then feeds the sound system If this buffer emp ties then the sound is broken up as if the computer were stuttering The algorithms use techniques from advanced digital signal processing theory and can be extremely taxing on processing power I have attempted to make the coding as efficient as possible but the algo rithms have been chosen for their effecttveness more than their speed Turning the sound off may be 23 the only viable setting with slower processors in which case it is still possible to play the contents of the buffer from time to time because the repairs have already been made The upshot of all this latency is that if you hear a click or other undesirable artifact it will already be about 1 2 seconds in the past by the time you can click Pause and the program can respond Since the main sound buffer the buffer displayed in the sound bar is longer than this the click is still accessible for repair In order to go back and fix the problem you will therefore have to navi gate back as described later It would be more convenient to go automatically to the exact point at which the problem was actually heard in response to clicking the Pause button This would involve much tighter synchronization of the processing loop with the user interface resulting in a significant d
13. e The exact reconstruction algorithm means that a repair to just one sample of an underlying stream is spread over a minimum of four samples in the output stream The implies that a bigger fraction of the original samples will be changed e On the other hand wavelet processing will smooth small defects so the actual modifications made to a smaller number of samples in a single stream are likely to carry at least as much energy as in the modifications made by the wavelet algorithm e The pitch protection and merge algorithms see later are able to use a longer time scale on a down sampled stream which is beneficial To further assist in understanding the differences here are two pictures showing Simple top and Wavelet bottom both at the default sensitivity of 50 in automatic operation on the same glitch J ai paregees tO Tie d e t sbe View at ll A Clearly the wavelet method is better at these settings although the Simple method does achieve an almost identical result if the sensitivity is increased to 60 The problem is that the higher sensitivity will almost certainly increase the number of false detections J aii ia ae T 4 t gre View af 11l f gt Here are some recommendations e For records in only moderate condition and for shellac 78 records Wavelet is a must e Pitch Protection works better in Wavelet mode although it is available in Simple mode e For records in very good conditi
14. file This was done automatically because Pause on com pletion of processing is selected in the preferences The two check boxes at the lower right of the Breakpoints dialog are linked to the corresponding check boxes in the Preferences dialog se lecting or de selecting these check boxes in the one dialog will carry over to the other and also add or remove this final breakpoint The breakpoint dialog will open automatically if Stop at Markers is selected in the preferences otherwise it may be invoked from the File menu item Break points once the file is open 1 00 000 Breakpoint 1 3 30 000 Breakpoint 2 6 00 000 Breakpoint 3 6 20 960 on completion of processing Stop at markers M on completion of processing In using these breakpoints remember that the Abort button can be used to restart processing from the beginning of the file A consequence of having Pause on completion of processing as a marker is that processing can be restarted before the file is closed Breakpoints may be inserted dur ing or after processing This can be useful if it is already too late to go back simply insert a marker and then restart processing from the beginning Remember too that with sound output turned off processing is very fast when using the latest dual and multi core computers Resetting Defaults Normally ClickRepair re opens with the window in the same location and at the same size
15. file in turn Also if you try to organise the files so that an output file will over write its input file this will generate an error dialog and the file will not be added Note that there will be no confirmation dialogs asking permission to overwrite existing files It is possible to lose existing files if you choose to replace them in this way when batch processing Note also that the new files are created as soon as the files are added to the Batch Setup dialog Moving these files before processing is complete will cause unpredictable errors Individual detection and repair settings are provided for each file in the batch Controls for these settings appear next to each file name There is insufficient room to label the check box and radio buttons which correspond in left to right order to those appearing across the bottom of the main ClickRepair window Note that the drop down list has access to and displays any custom settings which you have saved he ws 4 gt to ah uP ta t gt 5 9 ni ndi s 4 gt to a ie To remove files from the batch simply click on the name of a file in the Batch Setup dialog The corresponding line will he highlighted as shown here and the Remove File button will be en 51 abled to allow removal For removal the shift key may be used to extend a selection multiple ran dom selection is not supported Processing When you are completely satisfied with the batch
16. format mos A owed AIFF WAVE AIFC File length Ox Channels fi A owed Sample size 7 Allowed 16 or 24 Sample rate ii A owed 96000 manmanm e The file uses something other than 16 24 or 32 bit integer sample type or 32 bit normalized float Sample types not supported include 8 bit integer and float formats other than 32 bit nor malized e The file uses some form of compression Note that WAVE files can use various compression formats whereas AIFF files are uncompressed Other file types MP3 AAC are also unac ceptable Uncompressed sound files are huge about 10MB for each minute of CD quality data It follows that most but not all of the file is the sound data itself This is the only part of the file to which ClickRepair will make any changes In particular e All chunks which occur before the sound data are copied to the new file verbatim e All data which occurs after the sound data is copied verbatim without any format checking e File name extensions are copied from the input file so as not to change file associations e On Mac OS X the file type and creator which is used by the Finder in determining file associa tions are also copied File Lengths The maximum file length acceptable to ClickRepair depends on the file format and is determined by the standard formats for WAV and AIFF files together with what may be indexed using 32 bit integers For WAV files the maximum length is about 2GB actually 2 147
17. only way to change an existing named setting is to save the new values with the same name After the confirmation dialog the old values will be replaced by the new ones The settings menu is disabled while a file is being processed The custom settings may also be saved to a file using the Export item on the menu which will result in a dialog allowing the file to be named and its location chosen Previously saved files may be opening using the Import item and the settings they contain will be added to any existing cus tom settings Deciding on Appropriate Settings A uset wrote to me as follows I ran an experiment whereby I processed the same track using different values of the DeClick slider 10 20 30 35 40 50 and the default 60 The program reported the number of fixes at the various settings The number of fixes increases dramatically as the slider setting increases but that should not be a surprise Aurally I found that at 30 a few isolated faint clicks remained but at 35 even these were gone My untrained ear seems to detect however that as the slider setting in creases the music becomes very subtly duller and less bright Therefore I m thinking of adopting the strategy of using the lowest setting that removes all audible clicks Is this a valid approach Can I use the same setting for the same music genre or should I re calibrate for each album track This may indeed be a good strategy but beware
18. possibly followed by a low pass filter to further reduce the treble On the other hand most vinyl records play at 33 rpm and have a frequency range from subsonic to 20 kHz or more Hiss is reduced to a low level by a combination of the smoother vinyl material together with RIAA or similar pre emphasis which extends to 20dB at the top and 20dB at the extreme bass again to limit groove excursions The phono stage of a typical amplifier boosts the bass and reduces the high frequencies according to the RIAA standard This implies that hiss which is already lower because of the vinyl material is reduced to an acceptable level and should require no further treatment Given a shellac recording the first challenge for many people is to find a suitable turntable and car tridge with which to capture it It is essential to have a stylus with the larger tip radius required for shellac records but it is not essential to have a turntable which will play at 78 rpm The former problem can often be overcome by purchasing a second stylus for an existing cartridge the latter problem can be circumvented by recording at 45 rpm and using an audio editor to re sample The same audio editor will be required to apply the necessary equalization and other operations In fact I have an older turntable which will play at 78 rpm but prefer the lower noise levels of a later turntable which only plays at 33 and 45 rpm If the original record was designed to play at
19. settings click Send to ClickRepair which will dismiss the dialog and cause the Open button to change to Start The Automatic slider will be set to All although the previous setting will be saved If you do not alter this setting during processing of the batch it will be restored on completion Processing will not start automatically you must click the Start button to commence Before you do you might like to review the Sound output settings If you don t want to run in fully auto matic mode change the Automatic slider setting If you click the Abort button during batch processing the action will apply only to the file cur rently being processed If the action is confirmed the window title will change to show the next file in the batch the Pause button will change back to Start and processing will be suspended You must click Start to continue You may also choose to abort files before processing begins until the list of files is exhausted and in this way abort all or part of a batch 52 13 The Preferences Dialog Preferences Using the Preferences menu item on Mac OS X or clicking the Preferences button on Win dows brings up the dialog shown here Preferences MW Append cr to file names IW Save in same folder cr Stop at markers TA Beep Pause om completion of processing Produce log file Choose language English m
20. two channels are made independently However since the source material is mono the final file should reflect this fact There are a number of possibilities e Audition the left and right tracks separately and choose the one which is better One wall of the groove is often less damaged than the other e A variation of the above splice together sections of the tracks to provide the final mono cut This can be very time consuming but can produce good results e Merge the two channels to produce a single mono track which is written to both channels of the stereo format file 38 A problem for all of these techniques is one of normalization It is nearly always the case that the two channels of data even if they are highly correlated as they should be are at different record ing levels I have shown an example of this above Each of the processes involved in capturing the record to a sound file can contribute to this lack of equalization The Stereo gt Mono option in ClickRepair performs a merge of the two channels to provide a mono signal option 3 in the above list The same data is written to both channels of the output file The merge automatically and dynamically adjusts the channel contributions to the mix the idea behind options 1 and 2 An outline of how it works is as follows e The left and right hand channels are processed independently in order to extract the maximum amount of information e The tw
21. wav type 1 and normalized 32 bit float aifc type 132 wav type 3 Be aware however that internal processing is 25 bit integer in all cases The output file will automatically be in the same format as the input file The signal from the turntable equipment itself is totally unsuitable for conversion to a normal digital CD This is because records are produced with a heavy emphasis on the high frequencies and de emphasis on the low frequencies and must be played back through a suitable equalizer This equalizer de emphasizes the high frequencies and re emphasizes the low frequencies This is the reason why a good quality vinyl LP has relatively little hiss equally it is the reason why hum and rumble can be difficult problems to deal with For shellac 78 records I recommend some careful research one place to start is Roger Wilmut s page www tfwilmut clara net The most likely choice is to connect the turntable equipment to the phono input of your music system and capture the output from auxiliary out sockets into the computer In addition there are other solutions for sound input such as purchasing a dedicated preamplifier or a USB sound card system ClickRepair is not an application for capturing and editing sound files There are many possibilities for that depending on the platform and your budget If you already have some files which have been captured and burned to CD see below Recommended
22. 80 rpm resampling is required in either case In an earlier chapter I mentioned that the minimum useful sampling rate for a vinyl record was 44 1 kHz This is because the highest theoretically available frequency is one half of the sampling rate known as the Nyquist frequency limit But if the source material is limited to about 10 kHz then those comments no longer apply In addition a 78 rpm record played at 45 rpm and captured at 44 1 kHz is effectively sampled at 76 4 kHz This means that there are many possibilities for how to proceed One suggestion is as follows e Run the file through ClickRepair without resampling or equalization possibly merging to mono Merging will remove quite a lot of vertical low frequency noise 41 e Resample and equalize Remember that if you captured using an audio system which applies RIAA equalization then after resampling the RIAA turn over and cut off frequencies will have shifted accordingly whereas the corresponding 78 rpm frequencies will only now be correct e Run the file through ClickRepair again particularly to take advantage of de crackling If the file is still stereo apply the merge at this time e After all this the remaining hiss will be continuous and possibly obtrusive but should be suitable for the application of de hissing and or further equalization as desired An important point to note is that most de hissing algorithms rest on the assumption that the noise has
23. ClickRepair 3 9 amp ClickRepaitRT 1 3 www kagi com clickrepair for Java enabled platforms User s Manual Brian Davies clickrepain Akagi COM Preamble Please Read I began to write this software in 2004 I had started to transfer my LP collection to CD and had every thing I needed Or so I thought until I decided that it might be nice to remove the clicks and cracks from my recordings without doing too much damage to the music My search for suitable software if I wanted to do a half decent job at an affordable price was frustrating So began this project If you find ClckRepair useful please help by posting information to news and discussion groups and rat ings feedback on the site where you found it This way the circle of users will increase and I shall feel en couraged to devote the time and effort required to maintain and improve the software ClickRepair and ClickRepairRT are written in Java a system which allows the same application to run on different platforms Mac OS X Windows Linux The Windows installer is produced using Inno Setup 5 by Jordan Rus sell The manual is produced using Apple s Pages application typeset in Garamond and exported as PDE I wish to thank those users who have contributed to the design of the Interface I owe a particular debt to Michel Poulain and Willy Kunz who spent many hours working on the French and German translations and also pro vided much feedba
24. Order of Processing After capturing the sound to file you may want to perform some or all of the following e Remove subsonic and low frequency noise e Remove the clicks and crackle e Reduce continuous noise such as hiss gt DeNoiseLF part of the DeNoise package on my website is designed for this purpose 13 e Separate the tracks of the record into distinct sound files so they can be navigated on the CD e Fade the beginning and end of each track before burning the CD All of the processes except for click and crackle removal will require other software Hiss and rumble reduction may be carried out using the DeNoise and DeNoiseLF applications which may be found on the ClickRepair website general editing functions such as audio capture separat ing and fading tracks etc will require an audio editing program Some users have questioned the order recommended here given that there are other commercially available packages which recommend general noise reduction as the first step The reasons for re moving the clicks and crackle first when using ClickRepair are simple e If left in large clicks can significantly upset any continuous noise reduction process e Clicks and crackle are partially removed by filtering leaving them audible but harder to find e ClickRepair is highly non linear whereas most digital audio processing is linear The most obvious way in which ClickRepair is non linear is that i
25. a single click followed by a shift click is not used as a selection mechanism for sound playback This differs from a common behaviour pattern of many programs but it avoids ambiguity in the meaning of a single click Note that if a double click is too slow it will be treated as two single clicks There is a small blue indicator in the central strip of the sound bar that will track the sound as it is played During this time the button will display Stop Notice that if sound output is off the processed sound is played as the default option If you want to play back the original sound or the removed noise select the appropriate radio buttons The shortcut for both Play and Stop is the spacebar The Loop check box results in an end less loop until either you choose either to stop or to resume processing You may change the radio buttons while listening but don t forget that there is a lag before it affects the sound being heard Having heard where the problem is click at that point and play the surrounding samples Further refinement is made by using the left or right arrow keys to scroll the display coupled with replaying the suspect passage 33 Undoing Repairs in the Sound Buffer Once you have navigated to the desired location in the sound buffer it may be that a repair was already made which does not seem to be acceptable The first step should be to undo this repair which will reveal the
26. ackle e The Automatic slider sets the extent to which repairs are fully automatic e The Pitch Protection check box turns on an algorithm which avoids periodic false repairs to the hard edge of high energy pitched sound such as brass instruments and some voice e The Method radio buttons give a choice of single or dual stream wavelet processing e The Stereo radio button is for normal stereo LP records Do not select Stereo gt Mono before reading Chapter 9 e The drop down list provides the convenience of saving and recalling combinations of settings It should be evident that there are a multitude of parameters which affect the processes of detection and repair and it is tempting to allow these to be adjustable This would be counter productive with out complete technical documentation of the mathematical algorithms and the factors which affect their operation in the hands of a technically expert user During testing and development of the pro gram it became clear that less would be better than more moreover I have read reviews of some audio repair software which complain about a plethora of obscure settings So there are very few user defined settings This chapter explains each of the settings in turn and also how groups of settings may be saved with custom names and then reloaded for reuse First however it is important to understand that most of the detection parameters are dynamically generated by
27. agnifying the difference Therefore the maximum signal to noise ratio attainable on a standard CD is about 87 dB 14 1 2 bits quite adequate for capturing a record provided that the transfer is not made at too 16 low a level But if the transfer is made at a level which never peaks for example above 12dB 2 bits of the available digital data is unused and 12dB of the available signal to noise capacity is discarded Internal processing uses 25 bit integer representation regardless of whether the data files are 16 24 or 32 bit integer or floating Capturing and processing in 24 bit format give greater flexibility for editing the audio even if the data is finally truncated to 16 bit for burning CDs indeed this is the format widely used by professions for audio editing and production usually at 96 kHz as well Note moreover that the resolution and dynamic range of audio captured as 16 bit data is not im proved by subsequent conversion to 24 or 32 bit formats for this it is necessary to perform the analogue to digital conversion using hardware which provides 24 bit Sample Rates As mentioned previously ClickRepair is designed to work with audio files at sample rates of 44 1 kHz CD and 48 kHz DAT Simply put click removal involves modeling the musical signal as accurately as possible and one critical factor in the process is the relation of the sample rate to the actual time scales For full frequency range material
28. ame folder When the second option is selected the Select folder button will be enabled It may be used to change the output folder if the currently displayed choice is not the desired destination Only fold ers will be displayed in this dialog since we are not yet to the point of choosing files Navigate to and select the desired output folder and click Select All these settings are saved from one ses sion to the next Note that the file dialogs used for batch setup are not the standard file dialogs provided by the operat ing system rather they are Java Swing components and have somewhat different behaviour The choice of destination may not be changed once files have been added to the batch 50 Assembling a Batch Once you ate ready to add files click the Add Files button in the Batch Setup dialog or drag and drop files into the dialog window in the highlighted area Clicking the Add Files button will bring up another file dialog this time permitting only files to be selected Select one or more files and then click the Select button The files will be added to the dialog as shown here To extend the selection in the file dialog use the shift key Random mul tiple selection may be made using the Apple key on Macintosh the Control key on Windows IIJ PEGG If you choose files which cannot be processed by ClickRepair then an error dialog will appear for each such
29. are set from the single DeClick slider and normal de crackling is still available in conjunction with these methods To gain some understanding of the different outcomes of these methods I revisit the example shown in Chapter 6 comparing Simple and Wavelet repair methods The two pictures here are at the same sensitivity but now using Wavelet x2 above and then Wavelet x3 below View a 11 9 After examining a number of repairs made on this particular file I decided to use Wavelet x2 rather than Wavelet because the results seemed a little better both by visual inspection and on listening I rejected x3 because it seemed to introduce extra processing of the audio without any extra benefit but with an increased risk of degradation However it must be said that I could not hear any extra degradation with this particular file Caution Each new layer of processing adds new possibilities for false detection making careful experimentation and listening even more important when choosing between the available options Flattening of Manual Repairs anual adjustment o ese repairs results in them bein attene o a normal wavelet repair Manual adjustment of th p lt them being flattened t l let rep That is to say there is no mechanism for manually constructing one of these multi layered re pairs If processing stops because a repair exceeds the Automatic setting or if you
30. art of each logged session a file dialog will appear to allow the log file name and location to be chosen Clicking the Cancel button in this dialog will turn logging off It may also be turned off at any time using the preferences dialog The log files are plain text for easy use They record the file names settings and times taken Files and Processing The Append cr to File Names check box determines the default behaviour for how the output file is named and where it is saved in relation to the input file The default appended string cr may be changed by typing a new choice in its place Remember e If the same name is used for both input and output files they cannot be in the same folder e The default locations for each are the folders last used for input and output e When batch processing the save options are controlled directly from the Batch Setup dialog The Save in same folder cr checkbox determines the folder to which the new file is saved by default that is the way the save dialog is initially displayed If this check box is selected the dialog will be set to save the output file in the same folder as the input file with cr appended If this check box is not selected then the dialog will be set to the same folder as the last output file with or without an appendage The Beep and Pause on completion of processing check boxes allows you to enable or disable the wa
31. ase do they should buy their own license Seqgstration Code key to continue using it i eee oe 4 ar LALA ai Port hate When purchasing the key you will be asked for your name minimum six characters This informa tion is encoded into the license key and you will need it again in precisely the same form to regis ter the program Note that it is not case sensitive John Brown JOHN BROWN and john brown are equivalent The information should be emailed automatically by Kagi to the email address you gave once the transaction is approved Access to Registration Information Immediately after registering ClickRepair the About box will appear as shown below Notice that there is print button if you have a printer I recommend printing the information immediately Otherwise write it down and keep it in a safe place The information will also remain available by choosing About ClickRepair in the menus 1 In fact on the first couple of launches after registering the About Box can only be dismissed either by us ing the Print button or by waiting for 10 seconds ClickRepair 2 4 Build 38a Brian Davies 2004 2008 Registered to Bian Davies KANEK 88 2 2 oe XHEK 8 ee Print java version 1 5 0_13 by Anole inc OK Users may also access the information via the Registration item on the Help Menu The re sulting dialog is shown below The example is for a French user whose nam
32. atch mainly in the left hand channel It is clear that there is a sig nificant bump between the two repairs which were made automatically This is witnessed by the fact that the peak levels displayed by the two vertical sliders suddenly differ by 10dB 39 en f ee Jian fA a v t F gt E v ay A mene Me t u T Tmp t n amp few oe 0 z As before the black traces show the repaired audio signal with repairs indicated by red rectangles above and below However the level difference has been taken into account when making the merge The information about this is displayed in green as follows e The light green shading indicates the relative normalizations applied for the merge It shows that the right hand channel was amplified considerably while the left hand channel was reduced The range of this indication is from 6dB to 6dB In the example shown the left channel is reduced by about 1 5dB the right channel is increased by about 2dB to achieve the final mix e There is a second signal trace in dark green which shows the merged and normalized signal cor related with each channel individually Where the traces coincide it overwrites the black trace e Looking at the dark green traces we see that these adjustments lead to a considerable improve ment in the final result Because greater weight has been given to the right channel the bump has been reduced e Over the
33. ay ac 37 cording to which the peak levels differ by about 1dB In fact I examined this file quite carefully and found that the level difference was 1 4dB over the entire transfer OR fA A ipa For mono records I strongly recommend that the capture is done in stereo to a stereo file Click Repair will automatically process the file as a stereo file There is provision to merge the resulting output as explained below but the file format will remain stereo This method gives much better results for mono recordings both vinyl and shellac Even if the signal has been pre mixed to mono if the file has two channels of data it is a stereo file and will be processed as stereo by ClickRepair Note however that if the two channels contain identical sound data then only one is actually processed internally In summary e Better noise reduction may be achieved by capturing and processing mono material in stereo e The file format for a CD is stereo even if the source material is a mono record Users of previous versions of ClickRepair will notice that the Mono and Shellac check boxes have disappeared In fact both were associated with pre mixing the incoming signal to mono With ClickRepair 2 the only way to process a single channel is to use a sound file with only one channel The Stereo gt Mono Option Stereo files of mono records are processed in stereo decisions on click detection and repair in the
34. bad sample can trigger a click detection but samples which are less obviously outliers will be analyzed as small groups several consecutive samples which are moderately out of line may trigger detection It is impossible to choose a sensitivity which will see all clicks removed no matter how small with no false detections The default values have been chosen to work well on many types of music which have been captured from records that are in a reasonable state of repait e Much of the time lower settings will remove all audible clicks e It may be possible to increase the sensitivity without doing significant damage but this is not rec ommended unless there is a need e If the sensitivity is set too high sudden changes in musical content may cause false detection leading to increased incidence of undesirable false repairs e If the sensitivity is set too low there is increased probability of not detecting audible clicks The bottom line is that the selection of the sensitivity is a trade off between click removal and mu sical degradation The final decision will be governed by a number of factors including e The degree of damage older records may benefit from settings of 60 80 or more e Type of music some vocals are particularly difficult and may need settings of 30 40 or less e Percussive music could be even more difficult and might need even lower settings The de click algorithm is iterative place
35. be closed using the close button box in the title bar unlike dialogs 10 The exception is that Swing dialogs are used for assembling batch jobs because of some limitations im posed by native dialogs 11 The symptom is a message saying that the selected file cannot be found the name of the selected file hav ing been corrupted as it was communicated to ClickRepait 56 Keyboard Operation Nearly all the menu items have menu shortcut keys and may be selected in this way In addition the buttons in the Main Controls control group may be operated by various shortcut keys without the command or control key these may be viewed by choosing Keyboard Shortcuts see Chap ter 5 for details This makes for speedy operation but it also enables mistakes to be made more speedily so beware In the main window the tab key cycles the keyboard focus around the objects in the Detection and Review group once an object has the focus it may be operated in the normal manner the space bar is equivalent to clicking a check box or radio button while the left and right arrow keys operate the sliders As mentioned earlier the selection point for manual repairs may be manipulated using the arrow keys Here is a list of these keyboard shortcuts e The left and right arrow keys move the currently selected edge of a repair one sample at a time e Holding down the shift key while using left and right arrow keys moves the re
36. beatles cr aiff If the option is de selected the save dialog will suggest that the output file have the same name as the input file and ClickRepair will refuse to save it in the same folder with the suggested name Each time you choose an input file the dialog will go back to the folder previously selected and in most cases to the previously selected file in that folder Each time you choose a location for an out put file it will go back to the previously chosen folder either for input or output depending again on a choice which may be set in the Preferences Of course you are free to make changes in the dialogs themselves After the files are open the window title will change to indicate the file name total length the sam pling rate and the bit size The Open button will change to a Start button Click Start to be gin 11 HA ime 2 28000 1 4207 u70 wtest en amp teow oo 4 e gt 4 Progress in Automatic Mode With the default settings processing will continue unabated A short segment of the file 524 288 samples about 12 seconds is resident in computer memory RAM at any given time as new sound samples are read in repaired samples are written out to make room for them In this manual this data cache is called the sound buffer You can observe the state of this buffer in the upper display there is also a progress indicator bar in the lower display For more informat
37. buttons in dialogs may be operated in the default manner by first using the tab key to bring the desired button into focus then clicking the space bar Abort Button The Abort button does just that it results in the output file being deleted since it would not be readable The immediate response is to pause processing and display a dialog asking for confirma tion of the action If you want to stop processing but still finish copying the input file to the out put file move the DeClick and DeCrackle sliders to Off and wait for processing to finish File Dialogs Java has two types of File Dialogs native dialogs as provided by the underlying operating system and Swing dialogs that are provided by the Java Virtual Machine Java run time system Normally there is no need to worry about this and ClickRepair will choose native dialogs whenever possible A small number of users have been plagued by random bugs in the native dialogs as provided by the Java run time both on Apple Mac and Windows system The File Dialogs item on the File menu provides a work around in such situations since the problem is not in the ClickRepair code itself Another work around is to use drag and drop for file selection although this places some limitations on the destination of the new file Note that the Shortcuts window is not a dialog Its OK button cannot be focussed and the window can
38. ck Table of Contents Introduction Basics Important Warnings Organisation of Manual Recommendations Further Information Installation and Registration Apple Mac OS X Microsoft Windows Registration Access to Registration Information Quick Start Initial Interface Basic Controls Choosing Files Progress in Automatic Mode Producing and Organising Files File Requirements Recommended Order of Processing Notes about File Structure File Lengths Sample Sixes Sample Rates Reading from CDs User Interface Basics Visual Interface The Sound Bar The Display Window The Scale Controls Menus Keyboard Shortcuts NN A VN NN A SC Sf N N N 10 10 10 11 t2 13 13 13 14 15 16 17 18 19 19 19 20 20 Zi ZZ Making a Repair Audio Monitoring Sound Latency The Progress Indicator Detection and Repair Settings The DeChck Control The DeCrackle Control The Automatic Control Method Simple versus Wavelet Pitch Protection Possible conflict between DeCrackle and Pitch Protection Saving and Recalling Settings Deciding on Appropriate Settings Audio Monitoring and the Sound Buffer Java Sound Output settings The Sound Bar Listening to the Sound Buffer Undoing Repairs in the Sound Buffer The Last Buffer Using ClickRepaitRT Audio Input and Output Using a Sound Input Jack Limitations and Differences Processing Mono Records File Formats The Stereo gt Mono Option Viewing Merge Details Shellac Records Mo
39. clicked the application starts to process incoming audio and the but ClickRepairRT 1 0 Registered to Brian Davies Sound Input Sound Output Java Sound Master Gain 5 0 dB Out j In Built in Input 44 100kHz 1 Main controls _ lt lt DeClick gt gt Start gt A viable alternative which by passes the inbuilt audio system entirely is to purchase a USB audio interface for example the inexpensive Griffin iMic 35 ton changes to Stop It is important to note that the pop up menus for selecting sound input and sound output may only be changed while ClickRepairRT is not processing so do not press Start yet Rather select the sound input and output source and sample rate from the pop up menus Then connect and start an audio source and temporarily mute the audio output Sound Input Sound Output gt L3 i T DOGUE 5 O ME P Master Gain 5 0 dB Main controls Out _ _ in Stoo lt lt DeClkk gt gt Nice ve Now press Start to process the incoming audio The level input indicator should show that audio is being recetved by the application and also indicate the input level It should only go near the right hand end of the scale indicated by red on the loudest passages and should never go off scale beyond OdB at any time This can not be adjusted within ClickRepairRT itse
40. d and repaired even though the attack of the xylophone gets through unscathed A new setting Default Percussion has been added to indicate the likely use of reverse mode Reverse processing is available in all of the wavelet modes as well Its operation is also independent of the Pitch Protection and Stereo gt Mono merge options and it can be used in conjunction with any or all of those features Note however that for the new Default Percussion setting I have chosen Simple mode since these default settings are meant to be a starting point for indi vidual experimentation 47 11 Manually Adjusting a Repair There are a number of reasons for manual intervention even though this can be painfully slow compared with automatic mode They include e ClickRepair may have missed a significant click or thump and you may have to locate it manually e ClickRepair may have found a click but under or over estimated its extent e Record damage can be very severe ranging from a major scratch that extends across many tracks to even worse scenarios and may need individual attention to remove a residual thump Using the Mouse Assuming you have the program stopped with the offending samples firmly in view in the display window you can initiate or adjust a repair using the mouse e To choose the start of the repair selection left click at the desired position e To choose the end of the repair selection rig
41. d here is that when the two streams are subsequently merged the reconstruc tion is exact This is just as well since the high and low frequency separation does not have a steep cut off Wavelets are used in other components of ClickRepair as described in later chapters The maximum allowed sample rate is 192 kHz which triggers an extra layer of wavelet decomposti tion and reconstitution In this case no repairs are made to the high frequency stream since it con tains no perceptible audio information Nevertheless the original data is preserved exactly 4 Effectively 24 bit audio because of the requirements for perfect wavelet reconstruction 17 Reading from CDs Some users may have previously captured records and and burnt them to CD and now wish to de click them Obviously it would be convenient to process such files directly from the CD without first extracting the tracks The sound data on a standard CD is 16 bit stereo sampled at the rate of 44 1 kHz The physical format of the data is such that it has to be ripped to recover a valid computer sound file On Mac OS X each track on a CD is presented by the Finder as a file of type AIFC whose encoding is of type sowt This is a standard file type and since the operating system is doing the ripping the data can be read directly by ClickRepair Of course data cannot be written back to the CD but since ClickRepair will not edit the original file
42. e had an accent that was mangled by the Kagi website S bastien was SA c bastien Although the user name may not be changed in a way which disagrees with the license code accented characters are recognized and used by ClickRepair when making this check Note in the example below that the user has entered the correct characters in the ClickRepair registration despite the incorrect Kagi website translation Also upper and lower case letters may be interchanged Registered Name S bastien Registration Code KAXKAX XKXKNH AXKAXK XEXKX Close Save The information in this dialog may be saved into a text document using cut and paste 3 Quick Start Initial Interface On starting ClickRepair the default window has the appearance shown below There are controls that affect the way that damage is detected reviewed and repaired and windows for reviewing and adjusting repairs When the program is started for the first time the defaults are set for automatic processing of vinyl LP stereo records in reasonable condition Default LP as here Initially the display window is blank except for a message that it can be used to drag and drop a file for proc essing s Ue iu en bam D oot Daa Mangs t ar ipae Wre Lepa seen M J al Lu ean taa Basic Controls ClickRepair does not rely on menus for the most important operations just buttons check boxes and sliders The more important functions have keyboard shortcuts which match the menu sh
43. ecord in bad condition there will be many repairs The time required to look for longer term correlation will increase exponentially and processing may become painfully slow e Some records have periodic groove damage caused by stylus mis tracking exactly at the pitch of the sound The results of periodic repair may be an improvement over the original 29 Possible conflict between DeCrackle and Pitch Protection Use of Pitch Protection together with DeCrackle may seriously impair de crackling This can happen on records with a lot of crackle if some of it also has a distinct pitch Whenever you turn on these two options together a warning dialog will show as a reminder of the potential conflict Pitch Protection may impair DeCrackle Don t show again OK In some circumstances if you want to use both options it might be better to de click first with Pitch Protection on with or without de crackling then process the resulting file a second time with DeCrackle set to a suitably low value In other circumstances deploying the two simultane ously may not lead to any problem Only experiment will tell where the balance lies between noise reduction and damage to the music itself Saving and Recalling Settings Settings in the Detection and Review control group may be saved with any chosen name up to 32 characters in length and recalled at a later time using the drop down list in the Detection and Rev
44. epair had in progress Clearly there is a heavy thump which can be seen and heard its reduction requires manual intervention as shown here Since the damage is so extensive it can be difficult to find all of it automatically although it is un likely that ClickRepair will miss it altogether A TT We em 2 st a 4 gt t gt The second figure shows an acceptable restoration which was constructed in each channel by right clicking with the mouse in order to extend the end points The repair and the original dam age were auditioned using the Play button Because of the magnitude of the damage several attempts at repair were auditioned and compared Although this is time consuming hopefully you will not have too much damage of this magnitude to deal with Because so much of the audio data has been lost a repair such as this cannot reconstruct the origi nal sound although it can be a plausible interpolation In the example shown 500 samples have been interpolated about 11 3 milliseconds of sound In fact all but a few of the heavy cracks in this particular record were repaired satisfactorily without manual help but the residual thump shown in this example was on too long a time scale and too smooth for further automatic progress Important the first and last 1024 samples in the sound buffer cannot be repaired manually because the algorithms may require up to 1024 samples on eithe
45. full extent of the underlying damage To undo the repair for review shift click in a red rectangle If the repair still seems reasonable click Fix again Otherwise it may be changed using the mouse and arrow keys This is explained more fully in the next chapter The Last Buffer When the last samples have been processed there is still a full sound buffer that may not have been auditioned and which has not been committed to file An opportunity for review may be set using the preferences there can be a one second warning beep and or an indefinite pause before finalis ing the file The default is for a beep but no pause Press Pause during this time to pause the program in the usual way You can then listen to the contents of the last buffer and also navigate back and make changes if desired On resumption the remainder of the output file will be written and the repair statistics displayed The final statistics pertain to the whole file unlike the progress statistics which are a running aver age for the current contents of the sound buffer 34 8 Using ClickRepairRT The purpose of ClickRepairRT is to enable records to be played via an application which applies the declick algorithms directly to the audio stream Before using ClickRepairRT it would be useful to explore the operation of ClickRepair itself That is why this chapter occurs relatively late If ClickRepair is in trial mode then ClickRepairRT wil
46. ht click e Hither of these actions may be combined with dragging the mouse that is moving the mouse while keeping the button depressed The size of the selected area is limited to 2048 samples Each time you change the selection a new repair will be constructed and displayed in blue e You can clear a selection by left clicking to the right of the selected area or right clicking to the left of the selected area With a one button mouse on a Macintosh click is left click and control click is right click Using the Arrow Keys The arrow keys may be used to refine the selections To understand how this works first notice that one edge of a selection rectangle displays as a darker vertical line and that on changing a selection using the mouse this dark edge tracks the most recent change This is to indicate that that edge may be moved one sample at a time using the left and right arrow keys 48 e To move the selected edge left or right use the left and right arrow keys e Holding down the shift key accelerates the arrow keys by a factor of 10 the selected edge moves 10 samples at a time e To toggle between the right and left selected edges use the up and down arrow keys The first figure previous page displays an example taken from a favorite LP that met with an acci dent I got the program to stop by setting Automatic to 30 and then for the purpose of this pic ture I manually undid the work which ClickR
47. ics in the pro eress bar and to do some investigation using the sound bar to navigate the sound buffer To review any part of the sound buffer simply click on the vertical red line that marks the repair and the display window will show the samples at about that place If the point clicked is not exactly at the repair which will be evident because the blue indicator does not coincide properly with the vertical red line then use the right or left arrow keys to scroll the selection showing in the display 52 First click Pause the sound bar does not respond in automatic mode Finding the damage may require some detective work There are two reasons why just examining the display can be unsatisfactory e Sometimes quite a small glitch can lead to a surprisingly audible click e Sound files are not small so it can be like looking for a needle in a haystack He HHH A mmm Ob Bho HHH H mmmn apompmostopos ai lt EG Listening to the Sound Buffer Once processing has paused the Play button may be clicked to play the selected contents of the sound buffer but only after that selection has been made as indicated by the grey section on the soundbar in the picture above To select just a portion of the soundbar for playback click and drag with the mouse To select the whole of the sound buffer double click As explained above a single click in the soundbar makes the display window scroll for which reason
48. iew control group I call this the settings menu in the following All settings are remembered from one session to the next Note that the settings menu changes from the currently named settings to as soon as manual adjustment are made to any of the settings This is an indication that some settings have changed Velete custom settings Default Brass Save Current settings as Wavelet LP Save Close The settings menu comes with four presets Default LP Default Brass Default Mono Default 78 These are pre programmed and cannot be changed If you have settings which you would like to add to the list select Custom on this list A dialog will appear shown above Simply type in the name for your settings then click Save The current settings will then be saved with the chosen name The Settings dialog may be used to manage the list as follows 30 e To add a set type in the name and click Save e To change a set type in a name which already exists click Save and confirm in the ensuing dialog that you want to update the settings of that name e To remove a set select the unwanted settings in the drop down list click the Delete button and confirm in the ensuing dialog It is important to note that the Settings dialog does not offer any possibility for adjusting the set tings its sole purpose is to save settings which are actually in use and to manage that list The
49. ion on the sound buffer and its use consult Chapter 7 weston amp irra 4 t gt A At the end but only after the repaired file is completely written out a dialog box will appear and statistics will be displayed The program is then ready to process the next file Notice that in the example shown here less than 1 in 1000 of the samples have been changed Information displayed in the progress bar see Chapter 5 for further information Finished click Oper or press O for next ran Don t show again ox As with many of the dialogs there is a Don t show again check box I recommend that you do not turn off these dialogs until you are proficient in use of the program 12 4 Producing and Organising Files File Requirements Before you can repair audio files they must first be captured This is done by playing the record into a suitable sound editing program via a sound card or other analog to digital converter to cap ture the data as a digital stream There are a number of useful resources for learning about this for example www delback co uk Ip cdr htm and www a reny com iexplorer restauration html Both give thorough coverage of the process from connecting the sound equipment to the computer and capturing the recording to preparing and burning the CD The files must be uncompressed mono or stereo in either AIFF or WAVE format Acceptable sample sizes are 16 24 or 32 bit inte ger aiff
50. it my website for information which will be posted when it is available There is no installer for Mac OS X I recommend that you create a folder ClickRepair in your Application folder and keep the applications and the manual in it For easy access drag the Appli cation icons to the dock as well Microsoft Windows Microsoft discontinued Java deployment for Windows some time ago ClickRepair users should download and run the installer CRinstall exe which does not come with a Java run time You will be prompted to install one if necessary The applications have been tested with Java 1 6 on both Windows XP and Windows 7 Shortcuts to the Application and to the Manual are installed in the Windows Start gt Programs menu at Start gt Programs gt ClickRepair Alternative Deployment All Platforms Linux Mac OS X and Windows users can all run the Java Jar files directly To do this download and unpack the Linux version a zip file which will deliver two jar files and this manual pdf These jar files are identical to the jar files included in the Mac or Windows versions but they lack the normal packaging of applications specific to those platforms Double clicking ClickRepairjar or ClickRepairRT yar should launch the applications using the built in Java launcher provided the sys tem is equipped with a modern Java run time Linux users may need to invoke them from the command line or they may respond to double clicking This
51. iversion of processor power to this task The Progress Indicator The program runs without pausing while it is making repairs automatically during which times the progress bar gives useful feedback as follows e The blue bar shows graphically what fraction of the file has been processed so far e The current processing point is displayed in the form minutes seconds milliseconds e Statistics are shown in parentheses They are the average fraction of samples currently in the sound buffer which have been repaired Left and right displayed separately The repair rate depends on numerous factors and there can be no simple rule However I offer the following suggestions when choosing sensitivity settings as described in the next chapter e For a vinyl record repairing more that 1 in 200 samples should be viewed with suspicion al though it might lead to results that are more acceptable e Unless your records are in really good condition it is unlikely that the repair rate will fall below about 1 in 1000 2000 samples e For 78 rpm shellac records anything goes if the result is an improvement in the perceived audio quality Don t expect miracles 24 6 Detection and Repair Settings The Detection and Repair group contains controls with the following functions explanations form the content of this chapter and Chapter 10 e The DeClick and DeCrackle sliders set the sensitivity for detection of clicks and cr
52. l be also be in trial mode There is no mechanism for registering ClickRepairRT other than to register ClickRepair itself after which ClickRepairRT will be automatically registered They are bundled as a pair Audio Input and Output If ClickRepair has already been tried the issue of audio output will have already been sorted out The remaining hurdle is find a suitable set up for audio input The first thing to note is that the output from a turntable pickup must be passed through a pre amplifier to apply the necessary equalization the pre amplifier also brings the level up to that of a line input feed On most com puters a 3 5mm audio input jack can accept audio from either e a microphone this will be for a low level signal typically 5mV e a line input feed this will be for a high level signal typically 500mV If the audio input which is at line level is fed into an input jack set for microphone input severe clipping will occur which cannot be rectified later in the processing chain Getting appropriate set tings depends on the mechanisms provided by the operating system to control the available audio hardware The following section applies only to the use of the audio input and output jacks which employ a built in sound card provided with a particular computer Using a Sound Input Jack The first step is to start the application which gives the window shown below Notice the Start button When this button is
53. layed now in black but there are light red rectangles above and below marking the fact that repairs were made In addition the button itself changes to Undo Cherry Blossoms 6 20 960 44 100kHz 16bit ee eS IST Sr Fe aa T eee ye an SL ey OO ee S TTT STE I 7 x 7 N A ff Nae Ve al Time 0 32 985 View at 1 1 Om Sound Output Noise nO Out Off Loop M Main controls IN Resume Accept Detection amp Review DeClick 50 DeCrackle Off Automatic to 30 Pitch Protection Reverse _ Method Simple Wavelet x2 a Stereo gt Mono a2 The repair may be undone immediately by clicking the Undo button after which the same button which reverts to Fix may be used to reapply it immediately This is the simplest mode for mak ing and or undoing repairs After making a repair click Resume to continue The button will then display Pause until it is clicked again or until processing stops again A shorter alternative to clicking Fix followed by Resume is to use the Accept button it applies the fix and resumes with a single action P PP S Of course if you decide immediately after doing this that it may not have been the best decision it is easy to pause and then use the sound bar to redo that or any other repair provided it is still resident in the sound buffer Information on how to navigate the sound buffer i
54. lf but must be ad justed in the audio subsystem of the computer itself e On Mac OS X these settings can normally be accessed from System Preferences gt Sound Make certain that input is set to Line Input rather than Microphone Finer control may be had from AudioMidiSetup in Applications gt Utilities e On a Windows system there may not be any corresponding choice between microphone and line input Nevertheless it should be possible to set the properties of the input perhaps by turning off the Microphone Boost in an Advanced settings section Depending on the hardware OS combination some experimentation might be needed Once the input has been set undo the mute of the output and adjust the output level This step should be simple since it uses the same methods as ClickRepair Once everything is working the settings will be remembered by ClickRepairRT from one use to the next Limitations and Differences ClickRepairRT 1 0 is limited to sample rates of 96kHz Processing corresponds to the Simple Re verse mode of ClickRepair The single sensitivity slider has no numbers corresponding to the slider in ClickRepair and has fewer steps The default centre setting corresponds to a setting of 30 on the DeClick slider in ClickRepair These simplifications have been made for a number of rea sons e Using simple mode enables the latency to be kept to a minimum approximately 60ms e Simple reverse mode is the least comp
55. log allowing the input file to be selected there will be a second dialog allowing the output file to be named and placed Setting of the sliders and check boxes may be done individually or collectively by using the Set tings menu or the drop down list to access the pre defined and custom settings This is all de scribed in detail in later chapters Choosing Files Before you can go on it is necessary to decide how to organise input and output files ClickRepair operates by opening the input file to be processed as read only together with a second output file to which the repaired audio is written The files must be uncompressed mono or stereo in 16 24 or 32 bit AIFF or WAVE format The output file will be in the same format as the input file More details of file formats are given in the next chapter To choose the files using standard file dialogs click the Open button and choose the input file Once this is done a second dialog will appear for naming the output file The two files may not be the same file This means that either they must reside in different folders directories or they must have different names ClickRepair has two modes controlled by the Append cr check box in the Preferences If this op tion is selected the default the save dialog will assume that you want to use this when naming the output file in relation to the input file i e beatles aiff becomes
56. method of deployment can be useful on Mac or Windows systems if the launch mechanisms that are part of the standard downloads fail to work for some reason There is no package or installer provided for Linux users Registration Each time you start ClickRepair a registration dialog will appear Click Commence trial or Con tinue trial in order to evaluate the program There is a limit of 21 days trial use Evaluation mode imposes no limitations on the features of ClickRepair However you will be reminded of the num ber of days remaining each time you start the program ClickRepairRT also has a 21 day trial period but no registration mechanism It will be registered automatically once ClickRepair is registered a single license suffices for the pair of applications License costs depend on the method of purchase Click the Purchase button or follow the link from the home page www kagi com clickrepair license under the Software tab for further de tails Some users for example residents of many European countries may be charged applicable tax VAT TVA etc at the relevant rate for their state country of residence Tease erher ce etered name ard Doense Code atch may be The program is licensed to an individual user obtained from http jena kaei com chckrepar for US40 Otherwee cormnmerce 21 daw fully fucctoral tr peered If you give it to a friend for evaluation Jeg viered Name ple
57. mp Resume when there is a repair waiting to be made Similarly the Sound output menu items contain more explanation of the four choices which are possible 21 Keyboard Shortcuts A complete list of keyboard shortcuts not to be confused with the usual menu shortcut keys asso ciated with the command control key may be viewed by selecting this item on the Help menu an Keyboard Shortcuts hey Acboe Enter Return Open new file and prepare to start processing Start or Resume processing of currently open file Spacebar Pause processing whee running automaticaly Play of Stop playing selected samples while paused i Apply repairis currently displayed and highlighted Z Undo repairts just made manually Apply repairis and Resume processing Abort processing and delete output file Alt Option Oiselay details of Stereo gt Mono merge while paused OK The resulting window is shown here It is not a modal dialog and may be left open during normal operations for ready reference although it can be rather obtrusive Making a Repair Once a set of samples has been identified for repair the surrounding samples are analyzed for con tent and a repair is constructed In the example shown at the start of this chapter it is evident that the damage should be repaired this is done by clicking the Fix button On doing this the display changes its appearance some what see next figure only the repaired samples are disp
58. nchanged in the new version so for clarity I have left their documentation separate and essentially unchanged In many situations these are the only algorithms that will be needed This chapter describes the two additional algorithms which are the main new feature of ClickRepair 3 and the uses for which they these new algorithms are intended Pops and Bumps Clicks and crackle are usually heard because each individual disturbance lasts for a very short time and is perceived as having a high pitch This is because such disturbance can only be represented using the higher frequencies and hearing depends quite critically on frequency based aural process ing For the same reason clicks will not be perceived if they are masked by sufficiently loud high frequency audio which overlaps in both the frequency and time domains The science of psychoa coustics which is well developed is concerned with understanding which elements present in a given audio stimulus can actually be perceived and which are masked by what is actually being per ceived The problems this raises for the restoration of degraded audio material are immense Some issues which are of relevance for de clicking are e Repairing a click might leave a pop or bump If such a residual artifact is masked by the desirable audio there is no problem If not one problem is seemingly replaced by another e The mechanical or electrical cause of the click might have introduced a pop
59. o channels are merged using dynamically adjusted levels computed via a moving average e The moving average is calculated over a long scale so as not in introduce audible effects All dynamic compression expansion algorithms such as this introduce non linear artifacts which will be heard unless they are kept below auditory perception limits The artifacts produced by the merge algorithm are at a very low level and in the frequency range 0 20Hz e The average level of the merged output is exactly the same as the average of the levels of the incoming channels This means that the louder channel will be reduced the softer one amplified Significant level changes will normally be associated with major damage for example a bad scratch An example is shown below Note the remaining bump in the left hand channel If you intend to process a file more than once perhaps for a subsequent de crackling do not apply the merge option at any of the intermediate stages This way each channel will be processed independently each time Viewing Merge Details It is possible to gain some information on how the merge algorithm is operating as follows e First pause processing e Use the sound bar to navigate for the desired place in the sound buffer e Finally hold down the Option Alt key In response to these actions the display will change as shown in the figure below I have selected a spot where there was a major scr
60. of reducing the sensitivity too much Half removed clicks may sound like pops You should visually examine some of the false repairs which are be ing made they may be insignificant compared with the effect of half removed real damage Since this is a time consuming activity give the settings a name which will remind you of the genre and save them for future use ClickRepair is a program for doing statistical analysis in a situation where there are no black and white answers There is always a trade off between removal of clicks and removal of desirable audio content 31 7 Audio Monitoring and the Sound Buffer Java Sound Output settings Audio monitoring involves sending sound data to a sound data line which has been made available to Java applications The number and functionality of such lines is determined jointly by the operat ing system and the Java run time and is outside the control of ClickRepair Sometimes there is a choice of output lines also these lines often have an associated Master Gain control to set the overall sound output level These features may be accessed from the Mixer Settings item on the Sound menu There is a drop down list which will list all available output mixers together with a Master Gain slider con trol and a button marked Play Test Tone Clicking on this button causes a three second pure tone at A440Hz and maximum allowable amplitude to be sent to the
61. on and if highly pitched sound is not an issue the Simple choice may be the most efficient Note that this check box may not be changed while a file is being processed 28 Pitch Protection ClickRepair makes detection decisions based on quite short term information In fact there are a number of conflicting factors involved in the decision making As a result it is counter productive to have the underlying algorithms look at correlation between repairs separated by more than a few score of samples The problem arises that some music types for example trumpet have the ap pearance of a regular succession of clicks The figure here shows just such an example of solo trumpet The sharp pulses occur with perfect regularity for the duration of a single note the rate at which they occur determines what note we heat y 4 te ra Looking at the figure notice that Default Brass settings are in use this employs Pitch Protec tion Every pulse has been identified as a potential click which would lead to the destruction of the trumpet sound rather than the removal of noise But they have also been identified as due to high energy pitch and no modifications made This is indicated by the use of blue rather than red in the display and in the sound bat Note that this check box may not be changed while a file is being processed When deciding whether or not to use Pitch Protection consider e For a r
62. or bump hardly dis cernible when masked by the click but all too evident once the click is repaired Pressing flaws on records often produce pops and bumps which have no associated click De clicking will not even find these ClickRepair has some methods for helping to address these problems They revolve around a more extensive use of wavelets and are therefore displayed in the interface as extensions of the Wavelet method Specifically e Wavelet x2 uses two levels of wavelet decomposition analysis and repair e Wavelet x3 uses three levels Wavelet x2 x3 These methods add extra layers of wavelet or multi resolution analysis to the existing wavelet method This is seen in the ClickRepair interface the pair of radio buttons Simple Wavelet of ClickRepair 2 has been augmented by two more radio buttons x2 x3 in ClickRepair 3 Repairs 43 made with these new methods are multi layered and there is some indication of this when they are displayed Two colours are used e That part of the repair detected and made in the extra wavelet layers is indicated in orange e That part of the repair made by the standard wavelet de click algorithm is shown in red Notice that the two types of repair may overlap see the examples shown below This is always the case if the longer time scale defect is associated with a detectable click The sensitivity setting for all levels of detection and repair
63. or two files in automatic mode with the sound turned on This will serve e As an initial introduction to the application e To ensure that you are properly set up in relation to producing the required files using whatever software you choose for that purpose Subsequent exploration of the features of ClickRepair and the corresponding chapters of this manual may then be made as necessary Further Information The design of ClickRepair is directed toward users who want primarily reliable automatic treat ment of sound files using a stand alone tool I have written ClickRepairRT as an adjunct applica tion after requests from a number of users for a real time processing version of ClickRepair A detailed history of all versions of ClickRepair is on the web site www kagi com clickrepair 2 Installation and Registration Apple Mac OS X Users should download the file ClickRepair dmg Upon double clicking the file it will mount as a volume The contents should be dragged to the desired location on your hard disk most likely the applications folder ClickRepair and ClickRepairRT for Mac OS X require a Java run time and have been tested on Mac OS X 10 3 to Mac OS X 10 7 The latter version Lion does not have Java pre installed but a Java run time is available from Apple you will be prompted to install it the first time you attempt to run a Java application The situation with the upcoming Mac OS X 10 8 is unclear vis
64. ort cut keys Shortcut keys may be displayed in a separate window accessible from the Help menu For example the first step in using the application requires a file to be chosen for processing The alternatives are e Drag and drop drop one or mote files e Select Open from the File menu e Use the menu shortcut key O to make this menu selection e Click the Open button using the mouse e Press the Return key see Chapter 5 for details of how to find these shortcuts Drag and drop is new since ClickRepair 3 6 If only one file is dropped it becomes the input file for immediate processing and the output file a new file with a different name is automatically created The convention for naming this file and the choice of folder where it goes is determined on the basis of the preference settings A dialog will appear showing the full path name of the out Unlike menus this last action is not coupled with using a menu shortcut key A complete list of keyboard shortcuts is given in a later chapter menu shortcuts may be read off directly from the menus 10 put file If more than one file is dropped the Batch Setup dialog is opened and the files are added using the normal rules for batch processing See Chapter 12 for details of how this works If you want complete control over the naming and destination of the output file do not use drag and drop use the Open command After a dia
65. pair 10 samples at a time e The up and down arrow keys move the selected edge to the next or previous unselected edge e When there is no selected repair in the display window the left and right arrow keys are equiva lent to clicking the left and right scroll buttons of the sound bar Mouse Actions Here is a list of mouse actions e Left click defines or moves the beginning of a repair e Right click defines or moves the end of a repair e Left or right click followed by dragging the mouse also defines a repair e Shift click in a light red box undoes the corresponding repair of
66. pause process ing and manually undo a repair it will be presented with the structure intact as in the picture below The Fix button will apply the structured repair Undo will undo it again including its structure But once you make any manual adjustment whatever the repair will revert to a normal wavelet re pair and the original structured repair cannot be recovered 44 sA Pn amp Ar ena 1 gt I illustrate here by showing what happens if the repair above is turned into a normal manual repair by the simple method of moving one edge of the repair by one sample and then back again so that precisely the same set of samples are repaired now using the standard wavelet method fA matan A te ce 4 gt 4 gt T iad g t In this case there is not a lot of difference because the surrounding audio happens to be so nearly periodic Nevertheless the question arises as to which of these two repairs is better There is no definitive answer Either of them represents the result of a statistical analysis to estimate what might have been there Both of these estimates are made blind that is in the absence of any actual knowledge of what has been lost The best one can hope for is that the difference between what might have been and what has been reconstructed are perceptually indistinguishable Given the severity of the damage shown here that is almost certainly not completely true although either
67. r side to make a repair 49 12 Batch Processing To prepare to process a batch of files choose Batch Setup from the File menu This will bring up the dialog shown here Note that this dialog grows in height as more than 4 files are added however the drag and drop area will always be sufficient to display 4 files The maximum number of files which can be added is 256 of which a maximum of 16 will be visible at any one time This is controlled by the vertical scrollbar which will change appearance once there are more than 16 files The display will be slow to update if a lot of files are selected at one time since each file has to be checked and a new skeleton file created Organisation The first thing to decide is how to organise the output files in relation to the input files This is con trolled by two radio buttons and a Select folder button The first option is for each output file to be saved in the same folder as the corresponding input file and named by adding cr to the name of the input file or another string if this has been changed in the Preferences dialog The other radio button allows the output file to be saved to a selected folder the pathway to which is dis played alongside the radio button In this mode the name of the new file will be extended only if this is the selected preference in the Preferences dialog whereas the file name is always extended when saving to the s
68. rds in reason able condition this means that 99 5 or more of the audio is unchanged If the source material is an LP record in good condition captured on good equipment it is quite possible that the 99 5 sounds at least as good as or even better than a typical CD The underlying philosophy of Click Repair is to preserve that 99 5 and use it to find and replace the damage It is indeed surprising how annoying and disturbing a sprinkling of clicks and dust specks can be to the listening experi ence ClickRepair works with mono or stereo sound files up to 32 bits at 192 kHz This includes standard CD and DVD audio formats It is designed to run automatically although there are mechanisms for manual intervention It is also possible to stop at Markers previously inserted by a suitable sound editor ClickRepairRT is a small application bundled with ClickRepair which is a simplified real time version of ClickRepair It accepts input from the sound input stream provided to the Java run time by the computer operating system applies the declick algorithm of ClickRepair and sends the out put to the computer sound output stream via the Java run time It is designed for situations where a dedicated computer is available for insertion into the play back stream Important Warnings While many users report excellent results using automatic processing with appropriate settings please note e Automatic processing may not work well wi
69. re Advanced Methods Pops and Bumps Wavelet x2 x3 Flattening of Manual Repairs 22 23 23 24 25 26 26 27 a 29 30 30 31 32 DZ a2 32 34 34 35 35 35 36 37 37 38 J9 41 43 43 43 44 A Genuine Pop Time reversed Processing Manually Adjusting a Repair Using the Mouse Using the Arrow Keys Batch Processing Organisation Assembling a Batch Processing The Preferences Dialog Preferences Language Sound Buffer Length Log Files Files and Processing Breakpoints and Markers Resetting Defaults Other Features Behaviour of Buttons Abort Button File Dialogs Keyboard Operation Mouse Actions 46 46 48 48 48 50 50 51 52 53 53 53 53 54 54 54 59 56 56 56 56 Df I 1 Introduction Basics ClickRepair is an application for cleaning clicks and crackle from audio files produced by digitizing vinyl LP and shellac 78 records This kind of intermittent noise is typically the result of damage due to scratches dust specks etc It is important to understand the following points e It is impossible to distinguish music from damage with absolute certainty e Repairing damage without a high degree of automation is very time consuming e Filtering the file with a noise filter degrades the musical content whilst merely reducing inter mittent noise such as clicks and crackle ClickRepair is not a noise filter it searches for and repairs localised damage For reco
70. rning beep at the completion of processing and to pause before writing out the final buffer to file if required If you are listening to the audio in real time through a reasonable sound system I recommend turning off the beep Breakpoints and Markers Breakpoints including Markers can be extremely useful allowing the user to choose places in the file where processing is paused so that manual settings adjustments and or manual repairs can be made ClickRepair 3 6 greatly expands this feature over previous versions which only recognised markers placed in the file by selected Audio Editing applications Starting with ClickRepair 3 6 when a file is opened a Breakpoints dialog is available This dialog will pick up any existing markers more importantly it may be used to set arbitrary breakpoints The latter will not be added to the file itself they are remembered only so long as the file remains open The picture here shows three breakpoints that have been added by clicking on the plus button which brings up yet another dialog for that purpose Any of the breakpoints may be removed by 8 Almost certainly a Mac OS application since the MARK chunk was originally defined for AIFF files Al though they can also be used in WAV files the common Windows Audio Editors do not use them 54 simply clicking on them followed by clicking on the minus button In the picture there is a fourth breakpoint set at the end of the
71. s given in a later chapter Audio Monitoring Radio buttons in the Sound Output control group allow you to turn sound output on or off Monitoring particularly with a pair of headphones or reasonable speakers can provide invaluable feedback These buttons may also be controlled from the menus Audio monitoring causes processing to be real time which will be much slower for computers with even moderate processing power when operating on files in reasonably good condition e Selecting Out the default the repaired file will be played as it is processed which is some time after it is read into the sound buffer from file e Selecting In will send the unprocessed data to the audio system which can be useful for A B comparison particularly when used with the Play button detailed instructions are given later e Selecting Noise will enable you to monitor what is being removed by the program There should be no hint of the musical content this would indicate that the settings are too severe causing too many false detections Instruments such as cymbals and brass and certain types of sing ing are among the more difficult music types and may give rise to such problems e The sound can be turned off removing the restriction to real time processing This is the fastest possible mode and the most convenient provided you are confident of the result Sound Latency Given that the computational
72. s where clicks are found are treated at least twice some times more than that Normally there should be no advantage in de clicking the file a second time The DeCrackle Control The detection repair algorithms used for click removal are not particularly attuned to the removal of very short 1 3 sample rapidly repeated small clicks which are usually heard as crackle or buzz not hiss This kind of damage if particularly prevalent with shellac 78 recordings Selecting this option switches on a post process which examines every sample individually and adjusts those which are sufficiently out of line Click removal involves a more collective decision making process making it more likely that small clicks could be overlooked when they are closely spaced Note that e The sensitivity is set by the DeCrackle slider which works in the same way as the DeClick slider 26 e The default values are just suggestions and not meant to replace personal experimentation e Be aware that aggressive de crackling can take the edge off voice cymbals etc This feature should normally be used if click removal seems unable to deal with some forms of crackle However shellac 78 records usually have a great deal of crackle which is why Default 78 has DeCrackle set to 50 All repairs made this way are indicated in the normal manner in the sound bar and display They are distinguished by
73. selected line If the gain is set too high the tone will sound harsh due to clipping If it is set too low the sound output from ClickRepair will be at too low a level I have chosen the default setting of 5dB for the default Java Sound Audio Engine to match what might be expected from typical applications such as Apple QuickTime or Windows Media player To change the settings simply choose something which is suitable then click the OK button The Sound Bar The sound bar shows all the audio data which is still resident in the sound buffer The default leneth of this buffer is 524288 samples for files up to 48kHz about 12 seconds in practice This can be increased by a factor of 2x or 4x to 24 or 48 seconds using the Preferences dialog For files above 48kHz the longest buffer setting may result in Out of Memory messages since all workspaces get doubled or quadrupled in length not just the sound buffer Sound output moreover always remains at the lower sample rate because of limitations with Java sound output Remember that the sound bar represents more than 500 000 samples so a single vertical red line rep resents typically 700 samples and only one has to be repaired for the line to show as red This means that it is possible for the sound bar to show a lot of red areas without there being cause for alarm Equally there may be cause for alarm which is why it is important to observe the statist
74. standard CDs is 16 bit meaning that each sample is a whole number in teger in the range 32768 to 32767 For 24 bit data the range is 8388608 to 8388607 It is im portant when processing CD sound data to adjust the levels so that the loudest passages do not exceed the maximum level saturation renders the audio virtually unusable In ClickRepair audio level is measured relative to this critical saturation level which is labeled OdB A signal which leaves one data bit of headroom has a level of 6dB a signal leaving two bits of headroom has a level of 12dB etc Audio levels are not measured in numbers and fractions rather in decibels dB This is a scale for measuring multiplicative increase and decrease in an additive way a logarithmic scale An audio level of 6dB corresponds to one half the saturation level 12dB corresponds to one quarter 18dB to one eighth etc Note that a signal whose amplitude is reduced by one half has its power reduced by one quarter power is proportional to the square of the amplitude This is why half power is 3dB while half ampli tude is 6dB In the ClickRepair display we are viewing the amplitude In considering what 16 bit audio quality means the following comments may help In a 16 bit number the 16th bit is used to indicate whether the data is positive or negative The lowest bit contains as much quantization error as signal since 100 45 might be recorded as 100 100 55 as 101 m
75. sudden end to the sound The algorithms used in ClickRepair do not see these two in the same way when at tempting the difficult task of detecting clicks among the music ClickRepair 3 has provision for this type of Reverse processing on the fly This saves a great deal of time in situations where reverse processing is of significant advantage The file as a whole will still be processed in a forward direction and audio monitoring retains its normal operation What makes this possible is that the existing algorithms as part of a process of iteration actually treat the file in small overlapping segments each in the forward direction Selecting the Reverse check box causes overlapping segments to be individually processed in the reverse direction without any need to time reverse the entire file 46 Below is a typical false detection and associated false repair made to a file which features a xylo phone The setting is DeClick 20 in Simple mode Since this is not an isolated case but happens repeatedly with this particular file the sound degradation is unacceptable completely altering the sound of the xylophone Clearly for this file automatic de clicking is just not useable with forward processing a A te ro Selecting the Reverse check box only a couple of false detections are made at the DeClick set ting of 20 Even at such a low sensitivity most clicks due to actual record damage are still detecte
76. t chan nel with the left channel over the right which is standard for Audio Editors e There are buttons for other actions particularly Accept and Fix e A horizontal scale slider is now visible this is linked with the View menu The Sound Bar The upper smaller view displays the contents of the sound buffer by default about 12 seconds in length It shows where repairs have been made as vertical red lines and may be used to navigate around and make further changes to samples still in the sound buffer There is also a narrow cen tral strip in which a small blue indicator shows what segment of the sound buffer is being dis played in the lower view The two buttons to the right of the sound bar scroll the samples displayed in the lower view and this is also indicated by movement of the indicator I shall refer to this upper view as the sound bar since it has some similarity with the horizontal scroll bar of a word or image processing program The indicator shows how the samples displayed in the lower view relate to the totality of samples resident in the sound buffer Moreover clicking in the sound bar or in the adjacent right and left shift buttons causes the lower display to scroll 19 The Display Window The lower view is used for examining making and editing repairs I call it the display window although it does more than display sound data and technically it is not a window I
77. t is linked with three scaling controls two vertical sliders and one horizontal slider In the simplest case the samples to be repaired will be found automatically and a repair con structed automatically as in the figure The highlighted samples have been marked for repair the detected bad samples in red the proposed repair in blue Because the channels are processed inde pendently in stereo mode the selection is different between left top and right bottom The central strip of the display window shows the time of the first bad sample and the extent of the proposed repairs When the program is running automatically this central strip serves as a pro gress indicator and displays repair statistics of the sound buffer as processing proceeds Finally when processing is complete it displays useful statistics already seen If the program stops at a marker or is stopped using the Pause button the central strip displays this fact together with the time and the name of the marker if appropriate The Scale Controls To the right of the display window there are two slider controls with a check box in between The sliders control the vertical scaling employed in the display window Normally this is chosen auto matically and is determined by peak levels and indicated by the state of the check box When the check box is selected vertical scaling is automatic Moving the vertical sliders automatically de selects the
78. t will process the same section of the file more than once if clicks are found but it might only process other sections once But ClickRepair is non linear in a more fundamental way which is impossible to describe in a few lines or without the use of advanced mathematics For readers with any knowledge of statistics it relates to the fact that clicks do not fit the pattern of a normal statistical distribution in fact they are a total misfit One other word of warning Before subjecting files to subsequent noise reduction listen to histori cal recordings that have been professionally restored You will find that some of the hiss and other continuous noise is still there This is because such noise cannot be completely removed without inflicting even greater damage in terms of loss of quality and presence of the original signal So tread carefully Notes about File Structure There are many types of sound files They are generally organised in chunks with small header chunks indicating the actual structure and type If you attempt to open a file which ClickRepair is not designed to accept a dialog will appear giving relevant if somewhat technical information An example of such a dialog is shown here The most likely reasons for rejection of a file are 14 ClickRepar cant process this fle oroSiems Cuplayed in red See the manual for further information abost fle handing File header ADowed FORM RIFF tile
79. th some types of music e If you find automatic settings which work well you should save them with names that suggest the music type for which they were satisfactory e Clicks may be detected and removed in manual mode permitting ClickRepair to be used with difficult music types Inevitably this will be quite tedious e Do not delete the original file until you are happy with the quality of the new file e The Quick Start chapter is not a substitute for reading the manual after you have made some initial experiments please take the time to read it e Before purchasing a license key be sure to appraise the usefulness of ClickRepair for your par ticular needs That is the purpose of the trial period Organisation of Manual This manual is organised into the following chapters e Installation and Registration Chapter 2 Quick Start Chapter 3 Producing and Organising Files Chapter 4 User Interface Chapter 5 e Detection and Repair Settings Chapter 6 e Audio Monitoring and the Sound Buffer Chapter 7 Using ClickRepairRT Chapter 8 Processing Mono Records Chapter 9 e More Advanced Methods Chapter 10 Manually Adjusting a Repair Chapter 11 e Batch Processing Chapter 12 e The Preferences Dialog Chapter 13 e Other Features Chapter 14 Recommendations Once you have downloaded and installed the software I recommend that you start the program and use chapter 3 Quick Start to process one
80. the algorithms built in to ClickRe pair and that the two sensitivity sliders in particular provide user input The numbers are an arbitrary percentage A setting of 50 does not mean remove 50 it is just y p 8g 8 J less sensitive than a setting of 60 Moving the slider fully left switches the function Off Usually suitable settings will be found by experimentation For example if you are trying to clean up a rather old record you might find by listening to the output that higher sensitivity gives a more ac ceptable result and by listening to the noise that the music seems unaffected Another record of the same vintage but a different genre may exhibit brief bursts of musical tones in the noise output and you will have a more difficult task in deciding on compromise sensitivity settings I have provided four defaults Default LP Default Brass Default Mono and Default 78 These are intended to serve two purposes e A quick fix for the impatient e A starting point for your own experimentation 25 The DeClick Control The most important parameters for click removal are set through the DeClick slider which de termines the sensitivity for the detection of clicks One of the factors which influences the detection of clicks as opposed to crackle see below is that click detection is made on the basis of looking at short segments of consecutive bad samples One really
81. the use of a lighter red which is useful feedback when treating shellac 78 re cords with relatively high de crackle settings Moreover it is still possible to undo redo repairs made this way although that is not really a practical option Files with a significant amount of crackle may benefit from re processing the output file a second time perhaps with de clicking and pitch protection switched off The Automatic Control This controls the degree of automation When moved fully to the left no repairs will be made without manual supervision when moved fully to the right all repairs will be made automatically The example shown in the previous chapter was at the setting of 30 repairs up to 30 samples in leneth were carried out automatically whereas repairs longer than this cause processing to halt When first using ClickRepair it may be a wise precaution to start with this control set to none This will result in extremely slow progress but will help in checking that the detection settings are chosen so as to maximize the ratio of desirable repairs to undesirable false detections Processing in semi automatic mode will be quicker with the control set to repair 30 60 samples automatically There is a visual indication of the extent of automatic repairs to be seen in the sound bar In the end the aim is to find reasonable settings and then to let the program run in fully or nearly fully automatic mode Clicking
82. utationally intensive allowing for somewhat older comput ers to be used in this role e The listener is less critical of the occasional click when listening live 36 9 Processing Mono Records Like stereo records mono records have a V shaped groove with a left and right hand wall To un derstand the implications for processing of mono records it is useful to consider first how stereo works at least in a simplified way For a stereo record each channel of the audio signal is recorded on just one of the walls The movement of the stylus in response to a signal in just one of the channels is at an angle of 45 to the horizontal and vertical Relative to each other these movements are at 90 Ideally therefore the two signals may be recovered independently of each other Damage to the groove walls can also be quite independent although in practice both walls are often affected but in a different way In addition phono cartridges are mechanical devices subject to mechanical limitations and this en sures that a scratch in one wall will have consequences in both channels When stereo records were introduced they had to be compatible with the existing mono players These had settled on the standard of lateral recording meaning that the signal is recorded as purely horizontal motion Referring to the sketch above if one wall moves down and to the left while the other moves up and to the left the net result is a purel
83. y horizontal movement of the sty lus Conversely if the stylus is moving in response to tracking a mono recording the response measured as movement of the two walls will have the same magnitude and be at 90 to each other Provided that phase conventions are chosen correctly the electrical output which goes to the audio system will be the same in each channel and the record will be heard in mono File Formats Before explaining the implications of this information for the operation of ClickRepair it is essen tial to be clear about the use of the word mono The output from a typical record playing system is stereo regardless of whether the record is stereo or mono When this output is captured to a sound file the file will normally be in stereo format unless the signal is mixed down to mono at that stage and saved as a file with just one channel A mono file has just one channel of recorded data a stereo file has two channels of recorded data This does not depend on the source material both channels might contain identical sound data The figure below shows a small section of a stereo capture of a mono recording The two channels have an obvious high degree of correlation but they are certainly not identical One obvious differ ence is the fact that a small repair has been made in the left channel which was not needed in the right channel Another difference is evident from the scale sliders to the right of the displ

ClickRepair 3.9 & ClickRepairRT 1.3 User`s Manual

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ClickRepair 3.9 &amp; ClickRepairRT 1.3 User`s Manual

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ClickRepair 3.9 & ClickRepairRT 1.3 User`s Manual