SynFlash user manual v2.0
Contents
1. data in Green 7 Slate button connect other side of button to pin ground Blue 8 LED ON logic out high when white LEDs are on Purple To wire your own serial cable Head start hint a popular computer uses serial cables with DIN8 connectors Snip off one end and you are halfway done 9 pin Dsub Din8 2 serial out 4 Orange 3 serial in 6 Green or purple 4 attn 3 Red or yellow 5 gnd 1 Black 6 A jumper 7 together SynFlash DIN 8 jack www syncheck com user manual pg 122. a full video frame If there is an intervening vertical blanking interval such as between fields of an interlaced video frame see box on the next page each flash pip event is unbroken for its full duration it does not turn off for the vertical blanking time between fields When interlaced video signals are in use the Field switch selects which video field a flash pip shall begin on Our switch is labeled F1 F2 on some units or Lower Upper SynFlash operation is identical regardless of the label There is much confusion about which video fields are lower upper odd even field one field two We must leave it to the user to determine which setting is appropriate When interlaced images of www syncheck com SynFlash and interlaced video Let us first consider NTSC Rather than thinking of NTSC video as 29 97 frames per second we prefer to think of it as 59 94 fields per second If a flash rate of 10 is selected there will be one flash pip for every 20 fields 10 frames of video Assuming the field switch is set to F1 the white LEDs and audible pip will turn on at the beginning of line 21 near the start of field 1 and remain continuous through the end of line 525 the end of field 2 The LEDs will remain lit during the entire portion of active video of both fields as well as during the vertical interval separating field 1 and field 2 If the field switch is set to F2 the LEDs will light at the begin
3. at least one completely white frame When using SynFlash in manual mode it is generally possible to release the switch after only one flash pip particularly with slower flash pip speeds however we recommend that you allow at least two or three flash pips or more Additional flash pips will be convenient later on when measuring with Syncheck Also it is possible that the mechanical noise of the mode switch itself may be recorded by your microphone and later mistaken as the start of a pip giving a false synchronization error By using several flash pips instead of relying on the first and only one ambiguity is eliminated An external pushbutton may be connected to SynFlash s DIN8 jack between pin 7 and pin 1 SynFlash ground When operating in Manual mode the pushbutton will trigger flash pips exactly as the mode select switch does Both are active The external pushbutton input is ignored at all other times You can connect directly to the supplied DIN8 cable or build your own With our cable connect the pushbutton between the black ground and blue wires We have included one other function of Manual mode we call Flashlight If you have no reference connected to SynFlash the field switch allows SynFlash to function as a flashlight Because the white LEDs draw considerable battery power some of the remaining circuitry including the microprocessor is placed into a low power sleep mode Unfortunately we must occasionally wake up the pr
4. camera The best advice we can give about shooting SynFlash s white LEDs with your camera is to shoot them as tightly and fully framed as possible It will make no difference whatsoever if the LEDs are in focus or not in fact a wildly out of focus shot may actually work best Strive for full frames of whiteout within a black or very dark image The closer you come to achieving a perfect white black image the easier it will be to use Syncheck later Syncheck sees large changes from dark to light as marker flashes thus bright objects or reflections in your image may reduce Syncheck s ability to see the flashes Sometimes a simple adjustment of the playback monitor s brightness or contrast controls will allow perfect results but a bit of practice shooting and measuring BEFORE you are in the field will be wise As noted attention to how you shoot SynFlash will be rewarded later Try to eliminate everything except SynFlash s LEDs from your video frame The easiest way is to bring SynFlash and your lens face to face using SynFlash s case to block everything else It is often helpful to iris down and or insert a neutral density filter to darken your image SynFlash will work with the camera s automatic gain on or off as long as you take care that the LED flashes primarily dominate the image Because automatic gain tends to clip the brightness of the flashes and raise gain in between it is better to turn off automatic gain In day
5. SynFlash Signal reference generator for Syncheck User manual firmware v2 0 NOTE Firmware version 2 0 may be installed in any unmodified SynFlash unit Contents l Introduction Page 2 2 Shooting SynFlash with your camera Page 2 3 Auto Flash mode Page 4 4 Flash pip repetition speed Frames per Flash Page 4 5 Flash pip duration and interlaced signals Page 5 6 Manual Mode Page 7 7 Sleep Mode Page 8 8 Care and feeding Page 8 9 Firmware upgrade Page 8 10 Why are different flash speeds available Page 9 11 Specifications and pinout Page 12 FCC Compliance This device adheres to part 15 of the FCC Standards for test equipment as defined by paragraph 15 3 dd in particular paragraph 15 103 c Operation is subject to the following two conditions 1 This device may not cause harmful interference and 2 this device must accept any interference received including interference that may cause undesired operation Changes or modifications not expressly approved by Pharoah Editorial Inc could void the user s authority to operate the equipment SynF lash conforms to the following standards EN55103 1 Electromagnetic emission EN55103 2 Electromagnetic immunity EN61000 4 3 RF Immunity EN61000 4 8 Magnetic field Some components used in SynFlash may contain lead www syncheck com user manual pg 1 Introduction Install a fresh 9 volt battery and insert SynFlash into its rubber boot The flexible rubber boot is pulled
6. alf of them every other one are stretched to fill more than one frame of video One source frame becomes two video fields The next frame from our 24fps source is copied into three fields of the 30fps video 1 frame of original becomes 1 5 frames of new This alternation of one frame into 2 fields with the next frame into 3 fields is called 2 3 pull up Chart 1 below will help reveal how each second of the original 24 frames is distributed into 60 fields 30 frames of new video Chart 1 includes two possible versions of this process first where the first original frame is copied to two fields and the other where the first original frame is copied to three fields Both are equally likely Ignore the blue areas for the moment Chart 1 30 24 conversion with 5 frames per flash Let us look at how SynFlash s flash pips fit into this process If we had chosen a SynFlash speed of 5 fpf for the sake of discussion only since such a rate is not available on SynFlash where its white LEDs would flash every fifth frame the chart s blue areas show that some flashes would be converted into only two fields while others would be converted into 3 fields Two noteworthy things would happen to our flashes First some of them would be two fields long and some would be three fields long Inconsistent lengths of our new frames would not matter because Syncheck ignores the length of each flash but the timing between the start of each frame would be unavoidabl
7. d flash pips provides a reference point for manual correction For instance 30fps video using a flash pip speed of 10fpf results in skipped flash pips every 5 3 seconds By watching and listening a rough correction may be manually estimated and applied Once a rough amount of error correction has been applied thus bringing the remaining error to within the limits of your Syncheck 4 or 16 frames depending on model final measurements and adjustments can be made using Syncheck in the traditional way Some users may find it easier to look for the presence of a single flash pip instead of looking for space in an ever repeating pattern You may place SynFlash into a manually triggered mode of operation see next section much like an electronic clapper stick so that an operator can trigger single flash pips on demand As long as a reference signal is connected to SynFlash all flash pips will always be correctly synchronized to it www syncheck com user manual pg 6 Manual Mode For manual clapper stick type of operation the mode select switch or an externally connected button switch via the DIN8 jack can be used to trigger one or more flash pips As long as a valid reference signal is connected flash pips will be synchronized properly to it There are three ways you may enter Manual mode To enter Manual mode from Auto flash mode press and hold the mode select switch Within a couple of seconds SynFlash will enter Manual Mo
8. de The red M LED will light all others will extinguish The green lock LED is independent if SynFlash is locked to your reference it will remain lit You may also enter Manual mode directly at power on by holding the mode switch down before turning on SynFlash SynFlash will enter Manual mode silently and without a flash The third way to enter Manual mode is to turn on SynFlash without a reference signal connected You must power cycle turn off wait two to three seconds turn on to return to Auto flash mode Once in Manual mode SynFlash waits until you press the mode select switch When pressed Synflash will output one or more flash pips As long as you hold the switch flash pips will repeat If you entered Manual mode from Auto flash mode by holding the Mode switch the speed of repetition will be the same as when you were in auto flash mode If the recalled rate is invalid for some reason a default 1 per second rate is used As long as a valid reference signal is connected the flash pips are placed precisely with the reference s active video lines just as they are during Auto flash mode With interlaced reference signals the field switch determines field placement just as in Auto flash mode If a reference is not connected the speed of flash pip repetition is predetermined and the length of the flash pips are extended to about 75 milliseconds a length that guarantees a video camera running at any usual video standard will record
9. e corrector With a reference signal connected turn on SynFlash It should very quickly lock onto your reference signal and begin operation in auto flash mode Once locked flash pips occur at the default speed of one per second If your reference frame rate is a common video rate one of the three frame rate LEDs 24 25 30 should light as per the chart below A flickering lock green LED indicates a frame rate related to NTSC video 23 976 29 97 or 59 94 has been detected Except for a flickering lock LED operation and behavior is identical FPS 24 25 30 1080i 1080p sf 720p SD LED LED LED Lock LED 23 976 e xt J J 740 A e xV 25 0 e N N n 29 97 e xk N 4 NTSC 30 0 e e J N 47 952 e xt N 48 0 e e J 50 0 V V J 59 94 e zt J 4 N 60 0 e e N N N e continuous LED 3 flickering LED other frame rates may also be possible During auto mode operation the white LEDs will flash with a simultaneous audible pip We call these flash pips Each flash pip is one video frame in duration When locked to progressive signals flash pip duration is 2 video frames SynFlash always powers up with flash pip repetition speed of l per second locked to the reference signal The repetition speed of flash pips is selectable whenever the unit is in auto flash mode via the MODE switch There are 5 speeds available including stopped Discussion
10. ectronic device static discharge of sufficient intensity may overcome the built in protections Take care to prevent static discharge into the unit particularly into external DIN 8 plug connections In static prone environments you should always discharge yourself by touching one of the connected BNC jacks or any metal ground point first SynFlash is not waterproof The audio transducer is not guaranteed against water damage If you anticipate use in the rain it is possible to cover the acoustic transducer holes with a material such as SaatiTech s BO25Hyphobe www saatitech com This is a mesh material that will affect acoustic output somewhat but will not allow casual water penetration An easier way to prevent rain damage is to operate SynFlash within a clear plastic bag We also suggest that you use the supplied rubber boot to retard weather entry into the DIN 8 jack and battery compartment Keep a fresh battery handy SynFlash will drain your battery if left on or accidentally turned on during storage or travel Full battery voltage provides brighter flashes and louder pips Firmware Upgrade Windows is required for firmware upgrade Mac is not supported for firmware upgrade at this time You may download an executable file from our website and connect SynFlash to a PC using the cable supplied or suitable equivalent If you do not have a DB9 serial connection you may use a USB to serial converter Not all work however Belkin F5U109 d
11. lieve it is better to use one of the faster rates and then roughly average the readings When measuring the converted picture with Syncheck you will see the offset value change with each flash pip The amount of change from one flash pip to the next will stay within a range of one full frame An average offset error somewhere in the middle of the error range is probably the best compromise Why do we not recommend one flash per second We prefer to avoid the possibility that our single frame flash will either be dropped or doubled depending on the direction of the conversion We also believe more flashes per second are a better indicator of what is actually occurring www syncheck com user manual pg 11 Specifications Video reference black burst composite sync and composite video SD Standards 625PAL and 525NTSC 625SECAM is untested but should work Tri level sync most progressive or segmented scan Frame rate between 24 and 60 720P24 25 30 is not supported unless segmented scan Flash audio pip rate 12 10 8 frames per flash pip 1 per second manual trigger Acoustic output 2 9 3 1 KHz 90db at 1 foot Audio output approx 2V p p Battery 9V standard alkaline Weight 1 1b Pin out of auxiliary 8 pin DIN connector Typical serial cable 1 Ground Black 2 9V diode isolated from battery Brown 3 PC Serial atn Red 4 PC Serial data out Orange 5 Audio line out unbalanced 120 ohm Yellow 6 PC Serial
12. light and depending on camera lens opening size it may also be helpful to fashion a rough hood from a piece of cardboard or stiff paper with a hole large enough for SynFlash to protrude through The cardboard can be brought into contact with the lens hood blocking ALL light except that from SynFlash Such a hood is simple cheap and highly effective www syncheck com user manual pg 2 You must record audio pips from SynFlash at the same time you shoot its flashes Turn off automatic sound gain if possible Because SynFlash pips are very short automatic gain will almost always increase ambient useless noise levels Another tip hold your microphone close to SynFlash s audio transducer A distance of a couple of inches will work in all but the noisiest of environments In noisy environments you will benefit by getting the microphone as close as possible www syncheck com user manual pg 3 Auto flash mode Connect a video reference signal to one of SynFlash s BNC connectors before turning it on The BNC connectors form a simple loop through with negligible load SynFlash does not terminate the connection and you may loop the reference signal to another device or terminate it with a 75 ohm terminator Usually a terminator is not required but proper termination is always best practice The reference signal needs to be reasonably stable SynFlash will probably not reliably lock to a consumer VHS deck for example because it lacks a timebas
13. n 3ms a short enough delay to be insignificant for our purposes When recording SynFlash we highly recommend that you place your microphone quite close to SynFlash s transducer to reduce time delay caused by sound propagation through air as well as to reduce the effects of noise and reverberation from the space you are recording in Because sound travels through air at roughly 1 millisecond per foot the distance between your microphone and SynFlash can make a small but measurable sync error By placing your microphone within a few inches of SynFlash both potential problems are greatly reduced You may choose to use SynFlash s line level output instead of a microphone pickup This signal a replica of the transducer s output is available on pin 5 of the DIN8 connector In practice a microphone is often more practical and more relevant Also the crystal transducer cannot be disabled Large audio video synchronization error times like those encountered from remote television broadcasts can easily exceed the measurement parameters of our companion Syncheck products SynFlash supports two additional methods that can help you in such cases As you have probably noticed most of our flash pip patterns are very regular with some silent breaks SynFlash uses a pattern of 12 regularly spaced flash pips followed by 4 skipped flash pips Earlier firmware created 14 flash pips followed by 2 skipped flash pips The space during skippe
14. ning of line 283 near the start of field 2 and extinguish half way through line 263 of the following frame The exact line numbers when SynFlash turns on and off are probably unimportant to you as long as it is understood that a camera WILL NOT see any light from SynFlash except during the intended two video fields With interlaced PAL signals the LEDs will turn on starting with line 23 field switch set to F2 or 336 field switch set to F1 and extinguish half way through line 623 switch set to F2 or the end of line 310 switch set to F1 As with NTSC the exact line numbers are relatively unimportant as long as it is understood that a camera WILL NOT see any light from SynFlash during any portion of frames other than the intended one user manual pg 5 SynFlash are properly reproduced accurate Syncheck measurements can be made no matter how the Field switch is set If you do not know which setting is best we suggest setting it to F2 Upper for PAL or F1 Lower for all others Flash pip duration with progressive formats is 2 frames starting with active video in the first frame and ending with active video in the second frame This is a limitation of the current hardware design Audible pips are turned on and off exactly with the white LEDs SynFlash s transducer contains a piezoelectric crystal speaker It has a relatively short startup time such that the time between LED turn on and first detectible sound emission is less tha
15. ocessor in order to read the switches www syncheck com user manual pg 7 and discover if one of them was changed The processor s wakeup cycle causes a very short wink of the LEDs approximately every second Sleep Mode In order to save battery power further we take advantage of some limited opportunities for SynFlash to enter an extended low power snooze Snooze is entered after approximately two minutes of unattended operation the mode switch was not pressed Snooze is not allowed during Auto flash mode except during no flash operation it is easy to forget that SynFlash is turned on when it is not flashing While snoozing all outputs and LEDs are turned off and the processor enters a low power state You can return to normal operation by holding down the mode key briefly less than 2 seconds usually or with a power cycle Snooze is allowed during all manual mode operations The only indication that SynFlash is snoozing is a very brief flash of the red M LED every two seconds Battery drain is reduced but not eliminated so you should always power off SynFlash when not needed Care and Feeding The protective rubber boot should remain on use unless you need access to the DIN 8 jack We have designed SynFlash to accept normal wear and tear but we will not warrant your unit against careless abuse Switch handles can be broken off with excessive force so take normal care when packing the unit for travel As with any modern el
16. oes NOT work We have tested the FTDI US232B adapter available here http www parallax com detail asp product_id 800 00030 Many others should work You may send the unit to us for firmware upgrade for the cost of shipping www syncheck com user manual pg 8 Why are different flash speeds available If you do not wish to follow the discussion in this section we believe the default rate of one per second is suitable for most purposes Three other flash pips repetition speeds flashes per frame have been chosen for SynFlash to help us identify errors during frame rate conversions If no rate conversion will be required any repetition speed will work as well as any other If you need to shoot at one frame rate and perform some work at another there will be a frame rate conversion involved at one or more points along the work path Syncheck can help spot all errors introduced by the conversion process but we must take care not to introduce errors in our measurements where none actually exist Take the case of converting from 24 fps or 23 976 progressive to 30 fps or 29 97 interlaced as when shooting 24fps film and editing on a system capable only of 30fps display A frame rate conversion is required to stretch those 24 frames into 30 usually via a 2 3 pull up process Remember as you read that each of the 30 new frames is made up of 2 fields There are 60 fields per second When converting the original 24 frames per second h
17. of flash pip repetition speed Frames per Flash It is important to differentiate between two potentially confusing terms Frames per second is abbreviated as fps and refers to the rate of video images Professional video formats run with or near frame rates of 24 25 30 48 rare 50 and 60 fps frames per second We also use the term Frames per flash abbreviated fpf to describe how rapidly SynFlash s flash pips occur FPF is the number of video frames that occur from the beginning of one flash pip to the beginning of the next flash pip You can choose one of several fpf speeds using the Mode selection switch The default fpf speed at power up is dependent on the reference signal s frames per second rate and is equivalent to one flash per second approximately For instance if SynFlash powers up with a PAL www syncheck com user manual pg 4 signal connected SynFlash will automatically begin operation with a flash pip speed of 25 frames per flash This means there will be one flash pip for every 25 video frames which is one flash per second The Mode switch allows you to cycle through available speeds of one per second 8 10 or 12 fpf frames per flash and stopped For example 10 fpf means that a flash pip will occur once every 10 video frames With a PAL reference that will be 5 flash pips every 2 seconds With an NTSC reference that will be 3 flash pips every second approximately Be certain you under
18. on over SynFlash Make certain the rubber boot s swing out foot on the back side is closed flat against the back Place the empty boot in front of you open side up Insert the battery end of SynFlash into the bottom of the boot and lower SynFlash fully into the boot while guiding the boot s thin upper lip across the front of the white LEDs We use both hands Take care not to push the LEDs too hard SynFlash is a companion product to Syncheck intended for use in front of your video camera as part of a complete stage to finish synchronization check of audio and video signals Synflash with Syncheck will allow an accurate study of audio to video synchronization errors at many points along the production path from initial shoot to release Gen locked precisely generated sound and light signals can be recorded by your equipment and checked with Syncheck for accuracy at any time and perhaps at a distant location Use with a video reference signal for precise operation see specifications Shooting SynFlash with your camera We suggest that if you are using a tube type camera you should iris down when SynFlash is aimed directly at your camera SynFlash s white LEDs are rather bright although nowhere near the intensity of regular stage lighting While we do not expect phosphor burn due to SynFlash s LEDs we suggest that you err on the side of caution SynFlash emits bright flashes with audible tones that can be recorded by your
19. sh pip speed of 4 for 24fps or 5 for 30fps would work just as well as our choices of 8 for 24fps and 10 for 30fps There would be twice as many flashes per second and Syncheck can accept the faster rates but if rapid acoustic pips are played in a highly reverberant room with long acoustic decay times there could be trouble distinguishing one pip from the next To reduce the likelihood of this possibility and increase the maximum amount of un ambiguous error that can be measured we have settled on a slower speed of 8fpf For 25fps operation 10 frames per flash will convert to exactly 12 fpf at 30 frames Chart 3 below In cases where only the playback speed is changed such as shooting at 24 fps but speeding up the playback to 25fps it does not matter what flash speed is chosen because no frame conversion is taking place eo RS ES Chart 3 30 25 conversion aid www syncheck com user manual pg 10 If you wish to shoot at 30fps and convert to 25fps a flash speed of 12 is best Another potentially troublesome conversion is between 24 and 25 fps either direction with NO playback speed change 1 second 1 second We suggest using either 8 or 10 fpf in these cases The typical method of converting from 24 to 25 with no time speedup is to repeat one of the 24 frames each second while the typical method of converting from 25 to 24 with no time slowdown is to omit one out of every 25 frames In either of these circumstances we be
20. stand the difference between flames per second fps and frames per flash fpf before proceeding or you may become very confused When detecting a new reference frame rate SynFlash will typically begin operation at a speed of one flash pip per second For instance if 23 976 rate is detected SynFlash will output a flash pip every 24 frames Recall that 23 976 and 24 are operationally identical If a rate of 25 or 50 is detected SynFlash will output a flash pip every 25 or 50 frames respectively which is once per second You may select different flash pip speeds by momentarily pressing the Mode switch Each switch press will cycle to the next fpf setting As long as SynFlash is locked to a video reference you are free to select any of the five possible settings per sec stopped 8 fpf 10fpf and 12fpf If you press and hold the mode switch SynFlash will enter a special gen locked Manual slate mode that uses your most recent fpf selection We will discuss Manual mode in a later section Flash pip duration and interlaced video fields As we have said when SynFlash is locked to your reference signal all flashes and pips are precisely timed turning on and off at specific video line numbers For purposes of discussion we may say that a flash pip has duration of 1 frame but in fact each flash pip s start and end points coincide with active video within each frame Flash pip duration is actually slightly less than
21. y altered at the same time Sometimes there would be 12 fields between flashes other times there would be 13 fields between flashes This would cause half frame chatter in the error reading displayed by Syncheck While technically accurate it would be a variability that over time would average to zero The measurement chatter only serves to confuse our reading Instead we are more interested in whether the overall offset between audio and video has www syncheck com user manual pg 9 been changed in other words is one consistently ahead of the other By selecting a flash rate that will be consistently converted into the new rate we can eliminate the measurement chatter To accomplish this with a 24fps reference signal you can select 8 flashes per frame On Chart 2 below the blue areas show where our flashes occur You can see that 8fpf will convert perfectly into 10 fpf when the 24 frames are converted into 30 Even though some flash frames will be converted into two fields and others into three fields the time between each flash start will be consistent Looking at this from the other direction when working with a 30fps reference you could choose a speed of 10 frames per flash 10 fpf converts evenly to 8 fpf at 24fps In fact it should be possible to convert from 24 to 30 and back to 24 with no measurement chatter at either rate Chart 2 30 24 conversion with 8 frames per flash You might have realized that a fla
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