[FFmpeg-user] FFMpeg: Webcam capture not fast enough. Ffmpeg dies half way (Linux)

[Raghu Ram]

Hi Paul,

No Problem. Is there any extra information you need. If it helps, I am
working on Lenovo Laptop, with Chicony webcam.

Can you please tell me how to change the pixel format?

Thanks.

On Wed, Aug 21, 2013 at 2:14 PM, Paul B Mahol <onemda at gmail.com> wrote:

> On 8/21/13, Raghu Ram <iamanonymouscoward at gmail.com> wrote:
> > Hi All,
> >
> > I am trying to capture webcam output through FFMpeg (on linux inside a
> > virtual machine). here is the detailed question.  The capture is not
> > proceeding beyond 10 seconds. Can you please help.
> >
> > The command I used is:
> >
> > $ ffmpeg -y  -f video4linux2 -r 20 -s 160x120 -i /dev/video0 -acodec
> > libfaac -ab 128k  /tmp/web.avi
> >
> > The most important message I am getting is:
> >
> > *[video4linux2,v4l2 @ 0x9e43fa0] The v4l2 frame is 46448 bytes, but
> 153600
> > bytes are expected*
> > Information on the google for this error is scarce. I am going nuts over
> > this problem. Please help.
>
> I have same problem, it appears error appear less frequently if I
> change pixel format.
>
> Sorry for not debuging this more.
>
> >
> > Ps: Also asked at
> >
> http://stackoverflow.com/questions/18305086/ffmpeg-webcam-capture-not-fast-enough-ffmpeg-dies-half-way-linux
> >
> > *Complete message from ffmpeg:*
> >
> > ffmpeg version N-55159-gf118b41 Copyright (c) 2000-2013 the FFmpeg
> > developers
> >   built on Aug 18 2013 09:09:13 with gcc 4.6 (Ubuntu/Linaro
> 4.6.3-1ubuntu5)
> >   configuration: --enable-libass --prefix=/opt/ffmpeg --enable-debug
> > --enable-libfreetype
> >   libavutil      52. 40.100 / 52. 40.100
> >   libavcodec     55. 19.100 / 55. 19.100
> >   libavformat    55. 12.102 / 55. 12.102
> >   libavdevice    55.  3.100 / 55.  3.100
> >   libavfilter     3. 82.100 /  3. 82.100
> >   libswscale      2.  4.100 /  2.  4.100
> >   libswresample   0. 17.103 /  0. 17.103
> > [video4linux2,v4l2 @ 0x9e43fa0] The V4L2 driver changed the video from
> > 160x120 to 320x240
> > [video4linux2,v4l2 @ 0x9e43fa0] The driver changed the time per frame
> > from 1/20 to 1/15
> > Input #0, video4linux2,v4l2, from '/dev/video0':
> >   Duration: N/A, start: 6424.338678, bitrate: 18432 kb/s
> >     Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422,
> > 320x240, 18432 kb/s, 15 fps, 15 tbr, 1000k tbn, 1000k tbc
> > Codec AVOption ab (set bitrate (in bits/s)) specified for output file
> > #0 (/tmp/web.avi) has not been used for any stream. The most likely
> > reason is either wrong type (e.g. a video option with no video
> > streams) or that it is a private option of some encoder which was not
> > actually used for any stream.
> > Output #0, avi, to '/tmp/web.avi':
> >   Metadata:
> >     ISFT            : Lavf55.12.102
> >     Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 320x240,
> > q=2-31, 200 kb/s, 20 tbn, 20 tbc
> > Stream mapping:
> >   Stream #0:0 -> #0:0 (rawvideo -> mpeg4)
> > Press [q] to stop, [?] for help
> > [video4linux2,v4l2 @ 0x9e43fa0] The v4l2 frame is 46448 bytes, but
> > 153600 bytes are expected
> > /dev/video0: Invalid data found when processing input
> > frame=   29 fps= 14 q=3.5 Lsize=      87kB time=00:00:01.45 bitrate=
> > 490.0kbits/s
> > video:80kB audio:0kB subtitle:0 global headers:0kB muxing overhead
> > 7.760075%
> > [video4linux2,v4l2 @ 0x9e43fa0] Some buffers are still owned by the
> > caller on close.
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> > ffmpeg-user at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-user
> >
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