[Ffmpeg-devel] [bugs] grabbing v4l2 -> buffer underflow ; packet too large ; pcm_s16le vs mp2

[Michael Niedermayer]

Hi

On Thu, Feb 23, 2006 at 06:10:04PM +0000, Dieter wrote:
> [ beware, there are multiple issues here ]
> 
> With some assistance from Luca (thanks again) I now have
> ffmpeg grabbing video from v4l2.  At least it *says* it is.
> 
> But CPU usage is 100% if outputting DV.  So I'm afraid it
> will be dropping frames or such.
> 
> Added some -m flags to gcc and now it sometimes is
> 2-4% idle but still usually 100% busy.
> 
> And the resulting DV file is garbage.  The video is complete noise,
> there is audio, but with a lot of noise.
> 
> Tried outputting mpeg instead, and got a bunch of complaints
> about buffer underflow and packet too large:
> 
> FFmpeg version CVS, Copyright (c) 2000-2004 Fabrice Bellard
>   configuration:  --prefix=/app --disable-bktr --disable-ffserver --disable-ffplay --disable-audio-beos --disable-v4l --enabl
> e-memalign-hack --enable-gpl --disable-network --disable-strip --enable-a52 --extra-cflags=-DHAVE_LRINTF -mcpu=athlon-4 -msse
> 2 -msse3 
>   libavutil version: 49.0.0
>   libavcodec version: 51.7.0
>   libavformat version: 50.3.0
>   built on Feb 23 2006 13:53:26, gcc: 3.3.5 20050117 (prerelease) (SUSE Linux)
> [video4linux2 @ 0x82d1518][4]Capabilities: 5010015
> Device Init(720 480 842093913)
> Device Init(720 480 1345466932)
> Device Init(720 480 1448695129)
> Frame Format: 1448695129
> Number of buffers: 27
> Input #0, video4linux2, from '':
>   Duration: N/A, bitrate: N/A
>   Stream #0.0, 1/1000000, 29.97 fps(r): Video: rawvideo, yuv422, 640x480, 1001/30000, 147308 kb/s
> Input #1, audio_device, from '':
>   Duration: N/A, bitrate: N/A
>   Stream #1.0, 1/1000000: Audio: pcm_s16le, 48000 Hz, stereo, 1536 kb/s
> Output #0, mpeg, to '/video/2006_02_23_chan10ntsc_t1_1min_test_audioargs_2_ffmpeg.mpeg':

dont mux to mpeg-ps, its not a good choice for anything realtime and not a
good choice for for non-standard codecs 
(anything except mpeg*,aac,mp1/2/3, ac3, h.26*)

mans, any flames or improvements for our mpeg-ps (de)muxer? so its fast but
still compliant or supports all video & audio codecs, for example raw?

[...]
-- 
Michael