TRoublEsHooTIng HDMI WITH 840Hxl
Contents
1. HDMI sources could send more colors than the human eye can discern This would eliminate any potential color banding artifacts that could be seen when there are not enough colors to properly display certain images Maximum Colors 30 bit 1 073 Billion Colors 36 bit 68 771 Billion Colors 48 bit 281 5 Trillion Colors Calculating HDMI Bandwidth Since all HDMI products are hardware limited to a maximum bandwidth it is important to know how to calculate the bandwidth of source signals to make sure all downstream devices are compatible There are many factors that determine bandwidth like Resolution Refresh Rate and Color Depth The first thing to determine is the pixel clock of the desired resolution Pixel Clock is the number of pixels being sent every second by the source Pixel Clock Total_Horizontal_Pixels Total_Vertical_Pixels Refresh_Rate Common Pixel Clocks 1080p amp G6OHz approximately 154MHz TO80p e24Hz approximately 74 275MHz 1080i amp e6OHz approximately 74 275MHz 20p 60Hz approximately 74 275MHz Once the Pixel Clock is determined the bandwidth can be calculated with the following formula Bandwidth Pixel_Clock bit_depth_per_color 2 Common Bandwidth Calculations 720p 1080i amp e60Hz Pixel Clock 74 275MHz 36bit Color Depth Data Rate 74 275 12 2 1 039Gbps 48bit Color Depth Data Rate 74 275 16 2 1 336Gbps 1080p 24 Pixel Clock 74 275MHz 24bit Colo2. active pixels alone were enough to describe a resolution because you were referring to an existing standard that was followed by the industry Resolutions like 1024x768 and 1600x1200 are in this category Every monitor that supported 1024x768 XGA supported the exact same previously defined standard version of XGA Also every computer when you choose 1024x768 as your output resolution outputted the same standardized version of XGA This made all devices instinctively compatible with each other Today with the rapid acceleration toward High Definition and widescreen display devices standardization has been pushed aside and reliance toward communication between the display and source has become necessary Figure 1 Make Up of a Computer Resolution Horizontal Only IY Total Pixels Back Porch Front Porch lt gt lt us a ACTIVE VIDEO Looking above at Figure 1 you will see that a resolution is certainly more complicated than only active pixels Every resolution has these set of parameters all of which are needed to achieve a perfect image Through EDID a display is able to show the source all of these numbers in the detailed timing section lt can be displayed by what we call a mode line This is an example of a mode line for 1024x768 Detailed timing 1 1024x768p at 60Hz 4 3 Mode line 1024x768 65 000 1024 1048 1184 1344 768 771 777 806 hsync vsync 6 KRAMER ELECTRONICS Ltd e TROUBLESHOOTING HDM
3. claim to be 1920x1080 monitors they all support a different version of 1920x1080 Now it is clear that describing active pixels alone is not specific enough to define a resolution Display manufacturers are able to get away with this because each of their specific timings is completely described in the EDID of that monitor When a computer is connected directly to any of these monitors the mode line is read by the PC and the PC modifies its output to comply with that display Appendix 2 Color Depth What is Color Depth Every HDMI signal has a color depth associated with it Color depth basically defines how many different colors can be represented by that HDMI signal A normal HDMI signal has a color depth of 8 bits per color This may also be referred to as 24 bit color 8 bits per color x 3 colors RGB The number of bits refers to the amount of binary digits used to determine the maximum number of colors that can be rendered For example the maximum number of colors for 24 bit color would be 11111111111111111111111 1 binary 224 16777216 16 7 million different colors Color depth is very important in HDMI signals because the more colors you send the higher the bandwidth of your HDMI signal KRAMER ELECTRONICS Ltd e TROUBLESHOOTING HDMI WITH 840HXL 7 Deep Color HDMI 1 3 introduced something called Deep Color which adds color depths of 30 bit 36 bit and 48 bit into the HDMI standard These higher color depths were added so
4. see that now with even more selections we are able to become more accurate in our sample measurements It seems the sampling rate is now for the moment the limiting factor to making this digital signal better KRAMER ELECTRONICS Ltd KRAMER ELECTRONICS USA INC 3 Am VeOlamo St HEADQUARTERS TECH SUPPORT AFTER 6PM EST Jerusalem Israel 95463 96 Route 173 West Suite 1 Tel 888 275 6311 Tel 972 732650200 Hampton NJ 08827 E mail info kramerus com Fax 972 2 653 5369 Tel 908 735 0018 Web www kramermatrix com E mail info kramerel com 888 275 6311 Web www kramerelectronics com Fax 908 735 0515 2012 Kramer Electronics Ltd All Rights reserved Reproduction in whole or in part without written permission is prohibited
5. Crosshatch Blue 17 AB i i 19 see 2 27 22 MII 23 ug 25 IEE gt E 27 E Square White Dot Alternate Pixels White HScroll White VScroll Multiburst Vertical Split Horizontal Split Red Ramp Green Ramp Blue Ramp Bounce 4 Line Border Window Moving Ball Output Settings Signal Mode H D HDMI DVI HDCP HDCP Color Space CS vuv Yuv RGB 444 422 Color Depth DC 24 Bit 30 Bit 36 Bit AUTO Audio Sample ASF 44 48 s 6 KHZ KHZ KHZ KHZ Audio Bit ASD 16 Bit 20 Bit 24 Bit ga 176 KHZ As described here the 840Hxl is much more than a simple pattern generator it is a tool that when used properly can assist to narrow down issues in HDMI systems By having one source that can toggle all of these options it is simple to single out individual issues in an HDMI system What really makes this box unigue is its ability to react to the EDID of the device it is connected to This will allow the generator to behave less like the generators we are used to and more like a real world source KRAMER ELECTRONICS Ltd e TROUBLESHOOTING HDMI WITH 840HXL Appendices Appendix 1 Resolutions If you re like me when you mention a computer resolution it is simply described using its viewable or active pixels such as 1920x1080 However as you could have guessed there is more going on in a computer signal other than the number of active pixels being sent See Figure 1 In the past the
6. I WITH 840HXL Beginning with 65 000 which is the Pixel Clock for this resolution we then have four numbers that describe horizontal timing four numbers that describe vertical timing and finally the polarity of the sync pulses themselves Remember if displaying XGA is your goal then this mode line communication through EDID is overkill because every display and computer supports this XGA mode line Knowing that the standardization problem exists mostly in widescreen resolutions let s look at an example revolving around 1920x1080 These mode lines were read from the EDID s of the VGA inputs of different 1080p monitors LG LCD Detailed timing 1 1920x108Q0p at 60Hz 16 9 Modeline 1920x1080 148 500 1920 2008 2092 2200 1080 1084 1089 1125 hsync vsync Westinghouse LCD Native preferred timing 1920x1080p at 6OHz 16 9 Modeline 1920x1080 138 500 1920 1968 2000 2080 1080 1082 1087 1111 hsync vsync Samsung LCD Native preferred timing 1920x1080p at 6OHz 16 8 Modeline 1920x1080 138 500 1920 1968 2000 2080 1080 1083 1088 1111 hsync vsync Panasonic Plasma Detailed timing 1 1920x1080p at 60Hz Modeline 1920x1080 148 500 1920 2008 2052 2200 1080 1084 1089 1125 hsync vsync Vizio LCD Native preferred timing 1920x1080p at 60Hz Modeline 1920x1080 136 500 1920 1952 1984 2048 1080 1081 1084 1111 hsync vsync You can clearly see that while all these monitors
7. Ltd e TROUBLESHOOTING HDMI WITH 840HXL Example 1 Bit Depth 1 Potential Values of Each Sample O or 1 On the left diagram below you can see the original analog signal along with where the sampling points are The right hand diagram shows the resulting digital representation of that signal with a Bit Depth of 1 bit Since the bit depth is so low each sampling point must be either a O or a 1 For samples 2 4 6 and 8 you can see that we are forced to round up to 1 resulting in a digital signal that looks nothing like the original analog one Example 2 Bit Depth 2 Potential Values of Each Sample OO O1 10 11 On the left diagram below you can see the original analog signal along with where the sampling points are The right hand diagram shows the resulting digital representation of that signal with a Bit Depth of 2 bits KRAMER ELECTRONICS Ltd e TROUBLESHOOTING HDMI WITH 840HXL 11 Now that we have more values to choose from we don t have to round up quite as much for samples 2 4 6 and 8 This results in a digital signal that is starting to look more and more like its analog cousin Example 3 Bit Depth 3 Potential Values of Each Sample OOO 001 010 011 100 101 110 111 On the left diagram below you can see the original analog signal along with where the sampling points are The right hand diagram shows the resulting digital representation of that signal with a Bit Depth of 3 bits Again you can
8. TROUBLESHOOTING HDMI WITH 840HXKL By Tom Kopin CTS ISF C AUGUST 2012 m m m m m m m m m KRAMER WHITE PAPER WWW KRAMERELECTRONICS COM TABLE OF CONTENTS COLORDEPR THR tu ad anda haan FFA WYD ese Ohi tee ee eee tele YO A Ud GAA COLORSPACE sorat UL GR a ath gn GG Dd O AY AN OU YN dn Ad ood ABM DMI eiere iegareni pern neroksi sia be dndedain nage geen cada FN OND dae diene FAR EENE DEERE DAFEN FC NA ANO WOW ssa coins dd a YF EU RF Guten i A amen dd CG RS GT Y Rema anes 1 AUDIG SAMPLING EFEREQUEN GY dn WR NT YN y da FY CG OL GAY Gu FY YY Ny od AUDIO BIT DEPTH isiad RODD ATI DR DORF UO LLD DE GU RD DEU bade DU LI FdA hae nies FC CONTROL SOF TW AF E ea du UG LEE h RAOR YDA AU GU GY Dd GRADD SUMMAR ai A dL aW ante dM a RyL o CO ARG dio Aina ODID n DOG O DDd WN AG APPENDIX 1 RESOLUTIONS I FY UY GE DDUG pes FFF ODd Fd YD CE Erbyn WEFR APPENDIX 2 COLOR DER Rrr rna WE Gyd Yd DG GG GA dd YDY gy A Ynyd EPER APPENBIX3 ALIDIO SAMPLNG FREGUENGY seit ai iu ui gm I YRR seus EE dares APPENDIX4 AUIDIO BIT DEPTH nien inp innat ein E KENE UNERA AERE EREE See RG Ed o NA NR EXAMP CE uo Y OY RD eae DR NY Aue ae eee ee A O Salen a do RA o Overview The 840HXxl is a new Pattern Generator by Kramer Electronics The 840OHxl replaces the 840H in the Kramer Line The 84OH was a simple pattern generator that allowed you to choose a pre defined resolution and then sent a number of diffe
9. lution you like based on a set of detailed timing numbers The last space is called Output Native Resolution which reads the detailed mode line of the Native Resolution of the display s EDID and sets its output to exactly what the display is looking for This feature makes our pattern generator much less like a generator and more like a computer graphics card with the ability to adapt to anything you plug into it In today s world of non standard resolutions and every display manufacturer doing something a little different having a generator that can adapt to the EDID of any display is imperative See Appendix 1 for more details on Resolutions and EDID HDCP The 840Hxl has another very powerful feature the ability to turn HDCP On and Off We all know HDCP is the 4 letter word that we love to hate It quietly adds that extra level of complexity to our HDMI signals which can sometimes be the difference between getting a picture or not Testing for HDCP compliance can be hard because it usually reguires switching sources For example when I want to test with an HDCP compliant source will use the Blu Ray player and when I want to test a non compliant source will use my PC Even though this method works well problems arise when the Blu Ray doesn t work It is difficult to know if the problem is actually HDCP Color Space Color Depth or something else Using the 840HXxl to toggle HDCP on and off is very important because with one bu
10. ly doing is telling the generator whether you would like to output audio or not Based on experience I can tell you that when certain DVI monitors receive embedded audio they do not know what to do with it and crash showing no picture at all and others will just ignore the audio and show the video DVI is in guotations because the fact that a display has a DVI connector does not always mean it does not support audio Some manufactures will use a DVI connector just for the locking mechanism while the EDID provides audio support The 840Hxl has 3 settings for this feature HDMI Which will output embedded audio with the set Audio Sampling Frequency and Audio Bit Depth Selected DVI Which will output a digital video signal without embedded audio Auto When in Auto Mode the 840HXxl will use the EDID of the downstream device to determine whether to send audio or not lt will only send out what the destination supports The 840Hx will output 2 channel PCM audio when audio is being embedded Now let us take a look at the audio capabilities of the 840HXl KRAMER ELECTRONICS Ltd e TROUBLESHOOTING HDMI WITH 840HXL 3 Audio Sampling Frequency PCM Audio Pulse Code Modulation PCM Audio is a method of digitally representing an analog audio signal lt uses both a Sampling Freguency and Bit depth to convert a continuous analog voltage into a series of 1 s and O s Audio Sampling Freguency The audio sampling freguency is defi
11. ned as the number of measurements taken on the X axis of an audio signal per unit of time usually per second During the conversion from analog audio a higher sampling rate will result in a more comprehensive recording especially in the higher freguencies of the original signal The Nyguist theorem states that the minimum sampling freguency must be at least 2x as high as the maximum frequency of the audio being recorded The human ear can hear frequencies up to 2OkHz which is why CD s chose a sampling freguency of 44 1kHz slightly higher than 2x the ability of the human ear The 840HXl allows you to output audio in 6 common sampling rates 44kHz 48kHz 88kHz 96kHz 176kHz 192kHz There is also an Auto Mode which will set the Sampling Freguency base on the EDID of the downstream device See Appendix 3 for examples of Sampling Freguency Audio Bit Depth Bit Depth for Audio is essentially the number of binary digits used to represent each audio sample on the Y axis very similar to Color Depth in video The greater the bit depth of your Digital Audio the more accurate your measurements will be resulting in higher dynamic range The 840Hxl allows you to choose between 3 different Bit Depths for the audio output gt 16bit 20bit 24bit It also has an Auto mode which will select the Audio Bit Depth based on the EDID of the downstream device See Appendix 4 for examples on Audio Bit Depth 4 KRAMER ELECTRONICS L
12. r Depth Data Rate 74 275 8 2 742 75Mbps 36bit Color Depth Data Rate 74 275 12 2 1 039Gbps 48bit Color Depth Data Rate 74 275 16 2 1 336Gbps 1080p 60z Pixel Clock 154MHz 24bit Color Depth Data Rate 154 8 2 1 540Gbps 36bit Color Depth Data Rate 154 12 2 2 156Gbps 48bit Color Depth Data Rate 154 16 2 2 772Gbps 8 KRAMER ELECTRONICS Ltd e TROUBLESHOOTING HDMI WITH 840HXL Appendix 3 Audio Sampling Frequency The frequency of the original analog audio is 2 units in all examples Also in the digital representations sufficient bit depth is assumed In the example below on the left the analog audio signal will be sampled at a rate of 2 which is below the Nyquist Rate The image on the right is a representation of your digital signal based on this sampling rate In this case because am below the Nyquist Rate much of in the audio information is lost in this case ALL In the example below on the left the analog audio signal will be sampled at a rate of 4 which is at the Nyquist Rate The image on the right is a representation of your digital signal based on this sampling rate In this case because am at the Nyquist Rate the basic shape of the original sine wave is still intact It may not be as smooth as the analog wave but all the highs and lows are accounted for KRAMER ELECTRONICS Ltd e TROUBLESHOOTING HDMI WITH 840HXL 9 In the last example below on
13. rent HDMI test patterns The new 840Hxl can be used not only as a pattern generator but as a true HDMI troubleshooting device Via the front panel or through PC software the 840Hx gives the user the ability to control the pattern being outputted the resolution of the HDMI signal whether HDCP is on or off the color depth and the color space of the video output The 840HXl provides full audio support allowing the user to change the sampling freguency and bit depth Combine all these features together into a single generator and you have a powerful product that can be used to determine where the problems are in HDMI environments Read below for a description of each of these features and how they could help Resolutions Like most signal generators the 84OHxl has a predefined list of selectable output resolutions These resolutions include gt 640x480 60Hz 1360x7680e60Hz 1280x1024 75Hz 720x460 60Hz 1440x900 60Hz 1920x1080 60Hz 800x amp 000e60OHz 1400x1050 60Hz 1920x1200 60Hz 1024x768 60Hz 1280x1024 60Hz 720x480i 60Hz 1280x720 60Hz 1680x1050 60Hz 1920x1080i 60Hz KRAMER ELECTRONICS Ltd e TROUBLESHOOTING HDMI WITH 840HXL 1 This is great however with EDID becoming more and more popular having a predefined bank of resolutions will not always work in every situation For this reason we added 8 more resolution spaces Seven of these spaces are user defined and will allow you to create any reso
14. t output Deep Color will be Blu Ray players or Media Players for the most part See Appendix 2 for more details on Color Depth Color Space HDMI is capable of supporting 2 main color spaces RGB and YUV aka YCbCr Different sources will output different color spaces depending on the type of source and also depending on the EDID of the downstream device RGB color space sends a full value of all three primary colors Red Green and Blue and is completely un compressed In YUV color space black and white information is being sent over the Y channel and the chrominance or color is being sent over the U and V channels The 840HxI has the ability of outputting these two different color spaces in 3 different forms RGB The standard color space of HDMI and DVI Common sources of this color space include PO s YUV 4 4 4 YUV YCbCr color space in which the Y Cb and Cr are all weighted equally and is also un compressed YUV 4 2 2 YUV YCbCr color space in which the Cb and Cr carry half the weight as the Y signal 4 2 2 uses a mathematical compression technique in which weights of colors are calculated based on the color accuracy of the human eye to optimize picture while reducing overall bandwidth Auto In this mode the color space being outputted will be selected based on the EDID of the downstream device HDMI DVI One option on the 840HXl is switching between an HDMI and DVI signal mode What you are basical
15. td e TROUBLESHOOTING HDMI WITH 840HXL PC Control Software Using the free PC control software you can easily connect to the 840Hx via USB or RS 232 providing easy access to all the controls described above See a screen shot of the software below It Kramer 840HXL Controller Device Reset About Resolutions Common 1 VGA 640 480 60Hz 2 720 480 60Hz 3 SVGA 800 600 60Hz 4 XGA 1024 768 60Hz 5 1280 720 60Hz 6 1360 768 60Hz 7 1440 900 6OHz 8 SXGA 1400 1050 60Hz 9 SXGA 1280 1024 60Hz 10 WSXGA 1680 1050 60Hz 11 SXGA 1280 1024 75Hz 12 HD 1080 1920 1080 60Hz 13 WUXGA 14 UXGA 1600 1200 60Hz 15 720 490i 60Hz 16 HD 1080 1920 1080i 60Hz Status Of Connected Display HDCP Not supported Type DVI DeepColor Not Supported Load Status HPD Summary User Defined 17 Label 18 Label2 19 Label3 20 Label4 21 Label5 22 Label6 23 Label7 2048x1080 60 B 720x480 60 2 1280x720 60 1920x1080i 60 1440x480i 60 1440x240 60 KA 2880x480i 60 2 24 Output Native Resolution Status Of Output HDCP Signal Type Audio Freq Audio Bit Color Depth ColorSpace No HDCP Auto 48K s 24 bit 24 bit RGB444 Pattems 1 MM 100 Color Bar 2 Wa sH 5 E E a ZZ 9 B Magenta Screen 10 ff 11 White Screen 7596 Color Bar Gray Bar 8 step Red Screen Green Screen Blue Screen Yellow Screen Cyan Screen Gray Bar 16 step RGB Ramp Crosshatch Black Crosshatch Red Crosshatch Green
16. the left the analog audio signal will be sampled at a rate of 8 which is twice the Nyquist Rate The image on the right is a representation of your digital signal based on this sampling rate You can see that the more samples take the more my digital signal start to become like the analog signal These crude examples could be applied in theory to all audio signals Sampling Rates are not the only thing creating your digital waveform Ultimately sampling rates are only telling you where to measure on the X axis Read on to Bit Depth to determine how to measure the Y Axis Appendix 4 Audio Bit Depth Now that we know how to sample an analog signal we need to learn how to create it Audio Bit Depth is the last piece of that puzzle Bit Depth is the value of the analog audio at each sample The greater the bit depth the more binary digits you have to make the reading more accurate 14 bit 2 Potential Values O or 1 22 bit 4 Potential Values OO 01 10 or 11 gt 4bit 16 Potential Values OOOO 1 1 1 1 24 bit 17million Potential Values COOOOOD00000000000000000 111111111111111111111111 Looking at the examples you will see how bit depth alone can play a large part in creating the digital signal To isolate bit depth in the examples the frequency of the original analog signal and the Digital Sampling Rate will be constants Analog Audio Frequency 2 units Digital Sampling Rate 8 10 KRAMER ELECTRONICS
17. tton you can individually isolate the HDCP signal By isolating the HDCP signal you can identify the reason the source isn t working without changing anything else Color Depth HDMI 1 3 introduced something called Deep Color which adds color depths of 30 bit 36 bit and 48 bit into the HDMI standard These color depths are higher than the existing standard of 24 bit color These higher color depths were added so HDMI sources could send more colors than the human eye can discern This would eliminate any potential color banding artifacts that could be seen when there are not enough color shades to properly display certain images One thing to be careful of with Color Depth is how much it affects the total Bandwidth of your HDMI signal If one product or cable in the signal path is not capable of this bandwidth it will result in no picture on the screen Here you can see the differences between different color depths at 1080p60OHz 24bit Color Depth Data Rate 1 540Gbps 36bit Color Depth Data Rate 2 156Gbps 48bit Color Depth Data Rate 2 772Gbps 2 KRAMER ELECTRONICS Ltd e TROUBLESHOOTING HDMI WITH 840HXL With the 840HxL you can toggle the HDMI output between 24 bit 30 bit and 36 bit color depths 48 bit color is currently not implemented in any standard HDMI equipment Color Depth can also be set to Auto which will set the color depth of the output according to the EDID it reads from the downstream device Sources tha
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