On Sun, 2 Nov 2003, Laurent Pinchart wrote:

> >     tccat | mplayer -vo yuv4mpeg | head -1
> 
> YUV4MPEG2 W720 H576 F25000000:1000000 Ip A0:0
> 
> Is that valid ? Note that I don't get the error on the first frame, but on 
> frame 15:

        If you really do have a progressive stream it's valid.  Otherwise
        the interlace tag 'Ip' is wrong.  It should be either It (top
        field first) or 'Ib' (bottom field first).   Most DVDs that I 
        have looked at are 'It' while DV (from a analog->DV capture) is
        always Ib (bottom first).

        The 'A' tag isn't right but that's usually not a problem because
        0:0 means unknown and most tools will use a (hopefully correct)
        default.   You may want to explicitly set a pixel aspect though
        (either 10:11 for NTSC or 59:54 for PAL, assuming a 4:3 movie -
        for 16:9 movies the values are of course different).  

>    INFO: [yuvscaler] yuvscaler 1.6.1.90 (10-02-2003) is a general scaling 
> utility for yuv frames
>    INFO: [yuvscaler] (C) 2001-2003 Xavier Biquard <[EMAIL PROTECTED]>, 
> yuvscaler -h for help, or man yuvscaler
>    INFO: [yuvscaler] SVCD output format requested in PAL/SECAM norm
>    INFO: [yuvscaler] input:   frame size:  720x576 pixels (622080 bytes)
>    INFO: [yuvscaler] input:   frame rate:  25/1 fps (~25.000000)
>    INFO: [yuvscaler] input:    interlace:  none/progressive
>    INFO: [yuvscaler] input: sample aspect ratio:  ?:?
>    INFO: [yuvscaler] from 720x576, take 720x576+0+0, 
> NOT_INTERLACED/PROGRESSIVE

        Yep - yuvscaler saw the "progressive" tag and logged that for
        you.   

>    INFO: [yuvscaler] scale to 480x576, 480x576 being displayed
>    INFO: [yuvscaler] Scaling uses the RESAMPLE algorithm,
>    INFO: [yuvscaler] frame rate: 25.000 fps
>    INFO: [yuvscaler] Scaling ratio for width is 3 to 2
>    INFO: [yuvscaler] and is 1 to 1 for height
>    INFO: [yuvscaler] Specific downscaling routing number 6
>    INFO: [yuvscaler] output:   frame size:  480x576 pixels (414720 bytes)
>    INFO: [yuvscaler] output:   frame rate:  25/1 fps (~25.000000)
>    INFO: [yuvscaler] output:    interlace:  none/progressive
>    INFO: [yuvscaler] output: sample aspect ratio:  ?:?
>    INFO: [yuvscaler] Frame number 0
>    INFO: [yuvscaler] Frame number 1
> [...]
>    INFO: [yuvscaler] Frame number 12
>    INFO: [yuvscaler] Frame number 13
>    INFO: [yuvscaler] Frame number 14
>    INFO: [yuvscaler] Couldn't read FRAME header: bad header magic!
> **ERROR: [yuvscaler] Couldn't read frame number 15!

        That means yuvscaler did not see the line "FRAME\n" when it
        expected it.

        To me that suggests that mplayer corrupted the output.  Are
        you running a current version of mplayer?   I think that
        some changes were made a little while ago in the yuv4mpeg area
        (on the other hand I may have confused mplayer and ffmpeg - I
        know the yuv4mpeg logic in ffmpeg was recently fixed and does
        a better job now).

        Next thing to try is dump the mplayer -vo yuv4mpeg output to
        a file (not all of it of course - just the first 20 frames or
        so) and find the 15 or 16th 'FRAME' word.   That's not too hard
        because the frame size is known (720x576*3/2).

        Good Luck.

        Cheers,
        Steven Schultz



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