[FFmpeg-user] Capturing from DVB-T card

Heiko Baums lists at baums-on-web.de
Thu Dec 22 02:45:08 CET 2011

Am Thu, 22 Dec 2011 01:00:09 +0000 (UTC)
schrieb Carl Eugen Hoyos <cehoyos at ag.or.at>:

> Please try ffmpeg -f v4l2 -standard 3 -channel 1 -i /dev/video0
> (I just found out about "-channel" and I cannot explain its name,
> standard seems slightly clearer...)

-standard 3 doesn't work. I get the message "Unknown standard '3'". But
I can set the video standard with v4l2-ctl.

-channel is indeed the right switch for selecting the video source
(DVB-T, S-Video or Capture). Now I get at least a picture that looks
like a VHS video.

Thanks so far.

Btw., for some reason "ffmpeg ... -channel ..." sets the video source
permanently which isn't done by tvtime, xawtv, mplayer and v4l2-ctl.
That said, after running "ffmpeg ... -channel 1 ..." "v4l2-ctl -I" says
"1 (Composite1: ok)".

And it's maybe a good idea to add the -channel switch to the manpage.

But now I seem to have an a/v-sync issue similar to the one I have with
mencoder and lavc. And the picture quality doesn't seem to be the best
with vcodec=huffyuv or vcodec=rawvideo, it looks at least a bit worse
than with tvtime. But I hadn't had time to look closer at every ffmpeg
option and which options I currently have set in tvtime. So I'll
probably find it out by myself later.

If you have a hint about good settings for good video quality and
avoiding sync issues I'd be glad to hear about it. Otherwise I'll ask
again later if I won't find a solution for the issues by myself.


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