[Ffmpeg-devel] Streaming from camera segfaults on Ubuntu Dapper

Timo Rantalaiho Timo.Rantalaiho
Tue Oct 24 17:12:45 CEST 2006

Hello Luca,

On Sun, 22 Oct 2006, Luca Abeni wrote:
> Since this segfault might involve the v4l2 input format, I am interested
> in the bugreport. Can you provide a backtrace, as indicated at
> http://ffmpeg.mplayerhq.hu/bugreports.html ?

Do you mean the gdb output that I posted earlier:


> Also, I just committed a more strict check on some parameters returned
> by the v4l2 driver... Can you do a "svn update" and repeat the test?

Yes, and now the behaviour changed! There is a more verbose
error message "The v4l2 frame is 460800 bytes, but 115200 bytes are

thrantal at toro:~/downloads/ffmpeg$  ./ffmpeg -r 5 -s 320x240 -y -an -vd
+/dev/video /tmp/out.asf
FFmpeg version SVN-r6624, Copyright (c) 2000-2006 Fabrice Bellard, et al.
  libavutil version: 49.0.1
  libavcodec version: 51.21.0
  libavformat version: 50.6.0
  built on Oct 23 2006 16:09:39, gcc: 4.0.3 (Ubuntu 4.0.3-1ubuntu5)
[video4linux2 @ 0x834f360][4]Capabilities: 5000001
Input #0, video4linux2, from '':
  Duration: N/A, bitrate: N/A
  Stream #0.0: Video: rawvideo, yuv420p, 320x240, 4608 kb/s,  5.00 fps(r)
Output #0, asf, to '/tmp/out.asf':
  Stream #0.0: Video: msmpeg4, yuv420p, 320x240, q=2-31, 200 kb/s,  5.00 fps(c)
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop encoding
The v4l2 frame is 460800 bytes, but 115200 bytes are expected
frame=    0 q=0.0 Lsize=       0kB time=10000000000.0 bitrate=   0.0kbits/s
video:0kB audio:0kB global headers:0kB muxing overhead inf%

Then ffmpeg exits instantly, with exit code 0.

Best wishes,


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