title: ffmpeg hangs when run in background
body: <p>If I run ffmpeg as follows:</p>
  
  <pre><code>ffmpeg -i H264-media-4.264 4.avi
  </code></pre>
  
  <p>It works OK (i.e. 4.avi created OK). However, if I try to run it in background:</p>
  
  <pre><code>ffmpeg -i H264-media-4.264 4.avi &amp;
  </code></pre>
  
  <p>it hangs! (and 4.avi never created)
  Any Idea?</p>
  
  <hr>
  
  <p>Note: The problem is an isolation of of similar problem in python when trying to run it as subprocess and there it hanged as well: ff.py includes </p>
  
  <pre><code>ps = subprocess.Popen(ffmpeg_list, stderr=subprocess.STDOUT,stdout = subprocess.PIPE)
  </code></pre>
  
  <p>and running <code>./ff.py</code> runs OK, <code>./ff.py &amp;</code> hangs too.</p>
  
  <ul>
  <li>System: CentOS 6.6</li>
  <li>ffmpeg: 0.10.2</li>
  </ul>
  
  <p>Results from successful run:</p>
  
  <pre><code> ffmpeg version 0.10.2 Copyright (c) 2000-2012 the FFmpeg developers
   built on Mar 20 2012 04:34:50 with gcc 4.4.6 20110731 (Red Hat 4.4.6-3)
    configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man --enable-shared --enable-runtime-cpudetect --enable-gpl --enable-version3 --enable-postproc --enable-avfilter --enable-pthreads --enable-x11grab --enable-vdpau --disable-avisynth --enable-frei0r --enable-libopencv --enable-libdc1394 --enable-libdirac --enable-libgsm --enable-libmp3lame --enable-libnut --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --extra-cflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -fPIC' --disable-stripping
    libavutil      51. 35.100 / 51. 35.100
    libavcodec     53. 61.100 / 53. 61.100
    libavformat    53. 32.100 / 53. 32.100
    libavdevice    53.  4.100 / 53.  4.100
    libavfilter     2. 61.100 /  2. 61.100
    libswscale      2.  1.100 /  2.  1.100
    libswresample   0.  6.100 /  0.  6.100
    libpostproc    52.  0.100 / 52.  0.100
  [h264 @ 0x24eac00] max_analyze_duration 5000000 reached at 5000000
  [h264 @ 0x24eac00] Estimating duration from bitrate, this may be inaccurate
  Input #0, h264, from 'H264-media-4.264':
    Duration: N/A, bitrate: N/A
      Stream #0:0: Video: h264 (Baseline), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 25 fps, 25 tbr, 1200k tbn, 50 tbc
  [buffer @ 0x24efa60] w:640 h:480 pixfmt:yuv420p tb:1/1000000 sar:1/1 sws_param:
  [mpeg4 @ 0x24eb540] removing common factors from framerate
  Output #0, avi, to '4.avi':
    Metadata:
      ISFT            : Lavf53.32.100
      Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 25 tbn, 25 tbc
  Stream mapping:
    Stream #0:0 -&gt; #0:0 (h264 -&gt; mpeg4)
  Press [q] to stop, [?] for help
  frame= 2324 fps=477 q=31.0 Lsize=    2603kB time=00:01:32.96 bitrate= 229.4kbits/s    
  video:2542kB audio:0kB global headers:0kB muxing overhead 2.409572%
  </code></pre>
  
  <p>Results from hanged run:</p>
  
  <pre><code>ffmpeg version 0.10.2 Copyright (c) 2000-2012 the FFmpeg developers
    built on Mar 20 2012 04:34:50 with gcc 4.4.6 20110731 (Red Hat 4.4.6-3)
    configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man --enable-shared --enable-runtime-cpudetect --enable-gpl --enable-version3 --enable-postproc --enable-avfilter --enable-pthreads --enable-x11grab --enable-vdpau --disable-avisynth --enable-frei0r --enable-libopencv --enable-libdc1394 --enable-libdirac --enable-libgsm --enable-libmp3lame --enable-libnut --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --extra-cflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -fPIC' --disable-stripping
    libavutil      51. 35.100 / 51. 35.100
    libavcodec     53. 61.100 / 53. 61.100
    libavformat    53. 32.100 / 53. 32.100
    libavdevice    53.  4.100 / 53.  4.100
    libavfilter     2. 61.100 /  2. 61.100
    libswscale      2.  1.100 /  2.  1.100
    libswresample   0.  6.100 /  0.  6.100
    libpostproc    52.  0.100 / 52.  0.100
  
  
  [5]+  Stopped                 ffmpeg -i H264-media-4.264 4.avi
  </code></pre>