No success capturing RGBs from a VCR Scart output with OSSC

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  • #44844
    flp437
    Participant

    I had tried to use the OSSC to capture from a Panasonic VHS Combo VCR that do output RGB 576i via a Scart plug. Theoretical consumer video equipment do output RGB as RGBs via Scart( 3 RGB separate signals and a full composite with Hs and Vs all mixed in one additional channel- 4 ch. total).

    According to OSSC specs it does apparently support video in RGBS ( Composite video, luma or composite sync could be used as a sync source in RGBS mode). Also, as far as I know the HSYNC frequency is around 15.6 kHz in Scart RGB so again within the specs supported by the OSSC.

    Initially it did seem to work as when the VCR did output the initial menus in RGB the OSSC reported AV1:RGBS 625i 15,62 kHz 50.00 Hz and I did get an excellent menu image in the capture software ( virtualdub). The card for transferring the hdmi signal to the pc has been a Magewell Pro Hdmi pcie .
    However as soon as I put the tape running the OSSC was unable to maintain sync and goes mad trying to scan different resolutions and frequencies without success – no sync. in this situation the Magewell receives no signal.
    I tried to play around with Sync opt. but had no luck so far.

    So my questions is the is there any type of conflict in between the Scart rgb specs from consumer video equipment and OSSC /AV1 RGBS specs ? Is it necessary to change any specific setting in the OSSC to get sync going on. Is there any type of know incompatibility in these context?
    Thanks for any help about this subject

    #44857
    BuckoA51
    Keymaster

    I’m not aware of any VHS player that converts VHS to RGB internally, are you certain of this? My guess is that it’s dropping back to composite video during playback.

    The other possibility is that you simply need a time base corrector to deal with the peculiarities of VHS. OSSC was never designed with this kind of signal in mind and isn’t by any stretch a good fit for this task.

    #44864
    flp437
    Participant

    “I’m not aware of any VHS player that converts VHS to RGB internally, are you certain of this? My guess is that it’s dropping back to composite video during playback”

    Yes it does convert to RGB internally. Panasonic VCR/DVD combo´s do have the particularity that they provide the signal in all outputs doesn´t matter if you are playing a VHS tape or a DVD. This one DMR ES-35V does output composite, svideo, component and RGB through scart ( component/component progressive and rgb have to be selected in menu it cannot output both simultaneous). The same goes for audio it does outputs audio via optical output simultaneous with the RCA outputs, even for VHS.

    The OSSC works fine with the YUV component from this Panasonic combo and I was trying to do a proof of concept with the RGB output.

    I can use the RGB output from the DMR-35 in the scart input of another combo DMR EH65 / DMR 765 and get an HDMI output selecting RGB input in the menus with good results.

    It doesn’t seem a TBC problem to me, even if I needed a tbc I should be able to see an image with problems eventually but see some sort of output. However the OSSC as soon as tape playback begins losses Sync completely, could it be that it changes H or V frequency and it goes out the OSSC range ?

    #44991
    BuckoA51
    Keymaster

    try increasing both H-PLL coast values to at least 4?

    #45011
    flp437
    Participant

    Problem Solved, but not as I was expecting.
    The Panasonic is not really outputing RGB from the scart when running VHS, I was wrong, it does however output RGB when running a DVD.
    So it outputs RGB for menus but as soon as VHS begins playing it fallback probably to composite video that is also present in the scart, however if it´s a DVD it remains outputing RGB.
    By the way the OSSC works fine with the RGB signal from the Panasonic combo. The combo however does output YUV component even with VHS and it does work also fine with the OSSC.
    Situation identified and closed

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