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  1. I want to test the CGMS function of one STB, which the CGMS-A data transmit at the line 23/336(NTSC)
    but i can't find one TV support the function
    so please tell me some tv to support the CGMS ,
    thanks guys
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  2. use modern good brand recorder (DVD, HDD etc, brand is important due fact that Sony, Philips etc care about copy protection, Chinese brands or some cheap brands usually don't care about copy protection at all), perhaps PC equipped with capture card will also help (then You can capture VBI and use some dshow filters - Windows is equipped with some video copy protection filters, Linux also can have some helpers to detect and decode CGMS-A status), personally i prefer oscilloscope for CGMS-A testing.
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  3. Member olyteddy's Avatar
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    Use an oscilloscope or waveform monitor to view the presence or absence of the CGMS signal.
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  4. Originally Posted by pandy View Post
    use modern good brand recorder (DVD, HDD etc, brand is important due fact that Sony, Philips etc care about copy protection, Chinese brands or some cheap brands usually don't care about copy protection at all), perhaps PC equipped with capture card will also help (then You can capture VBI and use some dshow filters - Windows is equipped with some video copy protection filters, Linux also can have some helpers to detect and decode CGMS-A status), personally i prefer oscilloscope for CGMS-A testing.
    thanks , i can detect the CGMS-A signal by the oscilloscope, but there are remain two question:
    1.the cgmss-a include the aspect ratio (4:3/16:9/4:3 letter box) display format ,need one tv to support the function
    2.whether the APS is the macrovision(MV)? or the cgms-a contain the MV function ?

    thanks
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  5. Originally Posted by olyteddy View Post
    Use an oscilloscope or waveform monitor to view the presence or absence of the CGMS signal.
    thank you
    the oscilloscope only detect the CGMS signal, but how can test copy-protecion really execute ? and also the aspect ratio display format ?
    thanks
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  6. Originally Posted by yqjykn View Post
    thanks , i can detect the CGMS-A signal by the oscilloscope, but there are remain two question:
    1.the cgmss-a include the aspect ratio (4:3/16:9/4:3 letter box) display format ,need one tv to support the function
    2.whether the APS is the macrovision(MV)? or the cgms-a contain the MV function ?

    thanks
    CGMS-A signal is one thing, information stored inside second - i use scope also to manually decode CGMS-A (14 bits to decode in European version for CGMS-A).
    TV's is a different story - i know that in Europe for sure CGMS-A and WSS (WSS signal is used transmit also CGMS-A data) higher class (i mean more "luxury) TV's (CRTs) support for sure WSS, I can assume that today any decent LCD/PDP TV shall support at least basic aspect ratio signaling transmitted with CGMS-A.

    Macrovision is completely different copy protection system, it imply fake sync pulses and variable levels on some VBI lines, also for NTSC system there is chroma burst split and phase manipulations, also pedestal for video is reduced to increase efficiency for variable video levels on some VBI lines. Not many information about Macrovision is released over this document http://teryx.bobdbob.com/~protius/ls220/BT865macrovision.pdf and few patents that cover detailed aspects how Macrovision is implemented - linked PDF is quite good due description for programming interface which seems to be unified for all silicone products on market (i think this is part of agreement between Macrovision right owner and silicone vendor - interface to use Macrovision seems to be same on all chips worldwide).

    Easiest way to test Macrovision is also with help good, reliable brand recorder (Sony for example), usually they are sensitive and prevent to copy any video protected by Macrovision or by CGMS-A - i think similar to this situation should be also in US.

    http://www.google.com/patents/US4695901
    http://www.google.com/patents/US6516132
    Last edited by pandy; 9th Oct 2012 at 05:02.
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  7. Originally Posted by pandy View Post
    Originally Posted by yqjykn View Post
    thanks , i can detect the CGMS-A signal by the oscilloscope, but there are remain two question:
    1.the cgmss-a include the aspect ratio (4:3/16:9/4:3 letter box) display format ,need one tv to support the function
    2.whether the APS is the macrovision(MV)? or the cgms-a contain the MV function ?

    thanks
    CGMS-A signal is one thing, information stored inside second - i use scope also to manually decode CGMS-A (14 bits to decode in European version for CGMS-A).
    TV's is a different story - i know that in Europe for sure CGMS-A and WSS (WSS signal is used transmit also CGMS-A data) higher class (i mean more "luxury) TV's (CRTs) support for sure WSS, I can assume that today any decent LCD/PDP TV shall support at least basic aspect ratio signaling transmitted with CGMS-A.

    Macrovision is completely different copy protection system, it imply fake sync pulses and variable levels on some VBI lines, also for NTSC system there is chroma burst split and phase manipulations, also pedestal for video is reduced to increase efficiency for variable video levels on some VBI lines. Not many information about Macrovision is released over this document http://teryx.bobdbob.com/~protius/ls220/BT865macrovision.pdf and few patents that cover detailed aspects how Macrovision is implemented - linked PDF is quite good due description for programming interface which seems to be unified for all silicone products on market (i think this is part of agreement between Macrovision right owner and silicone vendor - interface to use Macrovision seems to be same on all chips worldwide).

    Easiest way to test Macrovision is also with help good, reliable brand recorder (Sony for example), usually they are sensitive and prevent to copy any video protected by Macrovision or by CGMS-A - i think similar to this situation should be also in US.

    http://www.google.com/patents/US4695901
    http://www.google.com/patents/US6516132
    thank you very much
    just as you say, if need the Macrovision function ,we may buy the patents or spend much time to design it.
    but i have another question, i want to test the cgms-a of one STB, only watch the cgms data by oscilloscope ?
    you also told me "use modern good brand recorder ", but how test it ? for example, the dvd only display by tv, but it can't copy the active picture from tv , so the cgms-a's copy protection is not tested
    maybe i am confused , sorry
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  8. You don't need to buy any patents (I've provided them only to give You source of information how Macrovision works, if You analyze both patents You should be able to analyze Macrovision signal with scope - normally specification for Macrovision is confidential, also remember that if Your device use Macrovision You need to pay for this Rovi and You need to have special agreement with Rovi which is owner of the Macrovision ACP), both analog copy protection are source copy protection i.e. source (STB, DVD etc.) mark or special bit that source is copy protected (case for CGMS-A) or modify video signal (i.e. signal is intentionally corrupted) in a way that prevent copy device (VCR, DVD recorder etc.) to record such video.

    TV are (they should be) insensitive for both ACP (CGMS-A and Macrovision) - some TV's can be sensitive for Macrovision (some digital TV can be slightly affected by Macrovision) - overall idea behind ACP is that they prevent use recording device but they should be transparent from TV point of view (TV is not recorder but display type device)

    I recommend also use one of recorders (preferably older VCR and modern DVD recorder - can be also PVR that record video to HDD) because this is device that should detect APC (CGMS-A or Macrovision) and prevent You from recording of video signal.
    So from Your perspective trustworthy recorder can be used as a tester for Your source.
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  9. Originally Posted by pandy View Post
    You don't need to buy any patents (I've provided them only to give You source of information how Macrovision works, if You analyze both patents You should be able to analyze Macrovision signal with scope - normally specification for Macrovision is confidential, also remember that if Your device use Macrovision You need to pay for this Rovi and You need to have special agreement with Rovi which is owner of the Macrovision ACP), both analog copy protection are source copy protection i.e. source (STB, DVD etc.) mark or special bit that source is copy protected (case for CGMS-A) or modify video signal (i.e. signal is intentionally corrupted) in a way that prevent copy device (VCR, DVD recorder etc.) to record such video.

    TV are (they should be) insensitive for both ACP (CGMS-A and Macrovision) - some TV's can be sensitive for Macrovision (some digital TV can be slightly affected by Macrovision) - overall idea behind ACP is that they prevent use recording device but they should be transparent from TV point of view (TV is not recorder but display type device)

    I recommend also use one of recorders (preferably older VCR and modern DVD recorder - can be also PVR that record video to HDD) because this is device that should detect APC (CGMS-A or Macrovision) and prevent You from recording of video signal.
    So from Your perspective trustworthy recorder can be used as a tester for Your source.
    thank you very much , maybe i know

    good luck for u
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