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Capture 4ch PAL video through tvp5158

Ning Xin
Prodigy 60 points
Other Parts Discussed in Thread: TVP5158

The tvp5158 4ch loopback demo is written for NTSC video input. How to capture 4ch PAL video? The demo set resolution to 720x526 for PAL, not 720x576.

Another question: What is frame rate of the output of tvp5158 4ch D1 line-interleaved mode. 30fps? Is it possible to output 25fps?

  • 0
    TI__Genius 15310 points

    Hello Ning,

    What do you use for the backend?  DM6467?  The TVP5158 has auto switch enable by default so it should automatic switch to PAL when you connect PAL input.  You just have to reconfigure the backend to PAL for display.

    The TVP5158 output 30fps and it is not possible to output 25fps.  The backend has to do frame drop if you want to output 25fps.

    Regards,

    Viet

  • 0 in reply to Viet Dinh
    TI__Expert 6120 points

    Hello Ning,

    The TVP5158 does not support frame rate conversion.

    If the input for a particular video channel is NTSC, the corresponding output frame rate will be 30fps.

    If the input for a particular video channel is PAL, the corresponding output frame rate will be 25fps.

    The frame rate of the super-frame is not important.

    Regards,

    Jim

  • 0 in reply to Viet Dinh
    Prodigy 60 points

    The tvp5158 is connected to DM6467. The following is my understanding, please fix me:

    The total pixel of the standard NTSC is 858x525, and the active video is 720x480.

    The size of the super-frame for 4ch line-interleaved mode is 858x2100, and the active line is 728 pixels.

    The frame rate of the super-frame is always 30fps, no matter the input is NTSC or PAL.

    It is the responsibility of demux to output 720x480@30fps or 720x576@25fps. A output frame may be seperated by two super frames.

    ps: I do not need drop frame. I just want to capture 4ch PAL video.

  • 0 in reply to Ning Xin
    TI__Expert 6120 points

    Hello Ming,

    The TVP5158 output formatter creates super-frames by inserting a 2-line VSYNC into the multiplexed channel data stream at fixed arbitrary time intervals.

    The default size of the super-frame for 4-Ch D1 is 1704 bytes (720*2 + 8 + 248 + 8) x 2102 lines (4*525 + 2).

    Thus, the default frame rate of the super-frame is 30.2 Hz (108MHz/1704/2102).

    However, the super-frame size information is only needed to configure the video port on the DM6467.

    Once the data is captured is DDR memory, you're left with video channel data that is either NTSC (30 fps) or PAL (25 fps).  The super-frame size and frame-rate is irrelevant at that point.

    If the frame rate of the video channel data and the display interface are different, you'll need to either skip or repeat frames in the backend as required.

    Regards,

    Jim

  • 0 in reply to James Nave
    Prodigy 60 points

    Thank you for your answer.