[MPlayer-users] Issue capturing w/ v4l2

Jindrich Makovicka makovick at kmlinux.fjfi.cvut.cz
Mon Sep 1 09:10:54 CEST 2003

rbtq7ol02 at sneakemail.com wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> I'm having some issues with capturing with v4l2.  I suspect it's not setting the video format on the card correctly when it starts capture.  I first noticed the problem with mencoder, but it can be demonstrated easily enough with mplayer as well.  I built a fresh copy from CVS to make sure the problem wasn't already fixed.  The commands and output for three runs of mplayer appear at the end of this message.  The first and third runs use v4l2.  The second run uses v4l1, and the second and third run (and any following captures) are correct.  For now, it looks like this can be worked around by running mplayer w/ v4l1 and vo null at boot time (I've yet to make up a script for that).  I'm using Gentoo linux with kernel 2.6.0-test4-mm3.  The frames grabbed are at:
> http://chshrcat.homelinux.net/~chshrcat/01c.png
> http://chshrcat.homelinux.net/~chshrcat/02c.png
> http://chshrcat.homelinux.net/~chshrcat/03c.png
> I'll also take a look at the src, but I don't know mplayer internals or v4l at all, so it's unlikely at best that I can find the problem myself.
> Thanks in advance for any help anyone can offer on this.

Please, use normid=1 instead of norm=NTSC for v4l2. "1" is the norm ID 
you can see in the output (supported norms: 0 = PAL; 1 = NTSC; 2 = 
SECAM; 3 = PAL-Nc; 4 = PAL-M; 5 = PAL-N; 6 = NTSC-JP; 7 = PAL-60). It's 
mentioned in the manual.

Jindrich Makovicka

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