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

[Paul B Mahol]

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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