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RGB24 Capture problems.. frame clipping/overlapping (see pics)

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  • #1

    RGB24 Capture problems.. frame clipping/overlapping (see pics)

    <body bgcolor="#0099FF" text="#FF0000">
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    Can anyone tell me why I am getting these &quot;breaks&quot; or frame overlaps
    in my captures? Or has anyone else had this problem? These are RGB24 captures
    compresses to MPEG4 in realtime using the &quot;UNSUPPORTED BY MATROX&quot;
    VirtualDub 1.4c.</p>


    <img src="http://208.32.63.242/SB.jpg" width="400" height="398"></p>


    <img src="http://208.32.63.242/SB2.jpg" width="400" height="398"></p>


    <img src="http://208.32.63.242/SB3.jpg" width="400" height="398"></p>


    <img src="http://208.32.63.242/SB4.jpg" width="400" height="398"></p>
    </div>

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  • #2
    Most likely from the CPU overhead causing a timing problem, and no wonder if you're using RGB24.

    RGB24 is mathematically derived from the Marvel's native YUY2 signal. Because of this using RGB24 as your realtime capture signal also means you're encoding the signal twice; once from YUY2 to RGB24 and then again by encoding RGB24 to MPEG-2. Not a good way to reduce CPU overhead.

    By capturing YUY2 and encoding that on the fly you get the signal right off the tree and speed up the process considerably.

    Get the 1.52 video tools & patch them for use with YUY2. In a capture program like AVI_IO or VirtualDUB you will then be presented with YUY2 as an option and can then select MPEG-4 (or PICVideo MJPeg or whatever..) as the compressor with much more confidence that the things will work.

    An added plus is that the full frame data rate with YUY2 is only 20 mb/s for a 704x480 frame. With a 640x480 RGB24 frame that rate is over 27 mb/s. YUY2 is therefore much easier on the drive subsystem even without compression.

    Dr. Mordrid


    ------------------
    Asus P3B-F 6 PCI
    PIII/850
    Gigabyte GA-6R7+ slotkey
    Matrox G400/Flex3D
    Matrox RT-2000
    256 megs RAM
    Promise SuperTrak100 (4 x 60g IBM 75GXP: 240g RAID0)
    AWE64 Gold


    [This message has been edited by Dr Mordrid (edited 20 December 2000).]

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    • #3
      Dr Mordrid,
      thank you very much for your reply... I have this YUY2 hack and I use it in 98SE but after 5 mins.. or even 30 mins I get an illegal operation in RRAPI.DLL.. any ideas on why that is?... so I opted to just use RGB24 and encode that directly to MPEG4, but on my 98OS I can't use my SMP.. so I boot (I have dual boot) into 2000 and can encode into MPEG4 from RGB24 without maxing the cpu and with no or very low reported frame loss... any suggestions? thanks again for your reply.

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