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I'm trying to capture screen by using ffmpeg.

ffmpeg -video_size 1024x768 -framerate 25 -f x11grab -i :0.0+100,200 output.flv

It worked at first, but after I end the first capture by Ctrl + C, second try fails with this error.

ffmpeg version git-2013-08-02-2b9590e Copyright (c) 2000-2013 the FFmpeg developers
  built on Aug  3 2013 01:13:06 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --prefix=/home/ironsand/ffmpeg_build --extra-cflags=-I/home/ironsand/ffmpeg_build/include --extra-ldflags=-L/home/ironsand/ffmpeg_build/lib --bindir=/home/ironsand/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab
  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
  libpostproc    52.  3.100 / 52.  3.100
[x11grab @ 0xb068e60] device: :0.0+100,200 -> display: :0.0 x: 100 y: 200 width: 1024 height: 768
[x11grab @ 0xb068e60] shared memory extension found
X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  140 (MIT-SHM)
  Minor opcode of failed request:  4 (X_ShmGetImage)
  Serial number of failed request:  11
  Current serial number in output stream:  11

I think the stream 11 is still busy by first one, but I don't know how to free it. What should I do to fix this problem? Was that wrong to stop capturing by Ctrl + C?

  • 1
    I'm wondering if killing the program with ^C left a stale lock/resource allocation. Try again, next time stopping ffmpeg by pressing the q key. – ewhac Mar 12 '14 at 18:33
  • Great, It works pretty well now! – ironsand Mar 15 '14 at 4:44

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