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• Use opencv to encode into flv, playable by flash player

  13 février 2012, par Hemang Shah

  I've compiled ffmpeg with libx264 using configure options given at 1.

  This results in the following codecs being available in ffmpeg :

  $ ffmpeg -codecs | grep "264\|flv"
  
  ffmpeg version 0.10 Copyright (c) 2000-2012 the FFmpeg developers
  
  built on Feb 10 2012 13:54:15 with gcc 4.6.1
  
  configuration: --enable-gpl --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264 --enable-nonfree --enable-postproc --enable-version3 --enable-x11grab
  
  libavutil      51. 34.101 / 51. 34.101
  
  libavcodec     53. 60.100 / 53. 60.100
  
  libavformat    53. 31.100 / 53. 31.100
  
  libavdevice    53.  4.100 / 53.  4.100
  
  libavfilter     2. 60.100 /  2. 60.100
  
  libswscale      2.  1.100 /  2.  1.100
  
  libswresample   0.  6.100 /  0.  6.100
  
  libpostproc    52.  0.100 / 52.  0.100
  
  DEVSD  flv             Flash Video (FLV) / Sorenson Spark / Sorenson H.263
  
  D V D  h264            H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  
  D V D  h264_vdpau      H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (VDPAU acceleration)
  
  EV    libx264         libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  
  EV    libx264rgb      libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 RGB

  After this, I compiled opencv. Here is partial cmake result :

  --   Video I/O:
  
  --     DC1394 1.x:                 NO
  
  --     DC1394 2.x:                 NO
  
  --     FFMPEG:                     YES
  
  --       codec:                    YES
  
  --       format:                   YES
  
  --       util:                     YES
  
  --       swscale:                  YES
  
  --       gentoo-style:             YES
  
  --     GStreamer:                  YES
  
  --     UniCap:                     NO
  
  --     PvAPI:                      NO
  
  --     V4L/V4L2:                   /1
  
  --     Xine:                       NO

  Now, using opencv's VideoWriter, I tried to encode into flv with the following FOURCC codes :
  FLV1, X264

  While the FLV1 results in a video file not playable by flash player, but playabe by vlc ; X264 produces no results at all.
  Here is the console output for X264, resulting in a 0 byte file.

  Output #0, flv, to 'd.flv' :
  Stream #0.0 : Video : [0][0][0][0] / 0x0000, yuv420p, 320x240, q=2-31, 4915 kb/s, 90k tbn, 24 tbc

  Do you see anything amiss or incorrect ?
  thanks,

• Run ffmpeg without outputting configuration information ?

  28 mars 2014, par Matt Joiner

  I'm invoking ffmpeg with subprocess.Popen, and trying to capture the stderr output and write it to logging.

  args = ['ffmpeg', '-i', path]
  
  if start:
  
      args += ['-ss', start]
  
  if end:
  
      args += ['-t', end]
  
  args += [
  
      '-vcodec', 'copy',
  
      '-acodec', 'copy',
  
      '-scodec', 'copy',
  
      '-f', 'mpegts',
  
      '-y', '/dev/stdout']
  
  self.child = subprocess.Popen(
  
      args,
  
      stdin=open(os.devnull, 'rb'),
  
      stdout=subprocess.PIPE,
  
      stderr=subprocess.PIPE)

  ffmpeg generates a lot of configuration information like the following :

  FFmpeg version 0.6.2-4:0.6.2-1ubuntu1,
  Copyright (c) 2000-2010 the Libav
  developers built on Mar 22 2011
  15:55:04 with gcc 4.5.2
  configuration :
  —extra-version=4:0.6.2-1ubuntu1 —prefix=/usr —enable-avfilter —enable-avfilter-lavf —enable-vdpau —enable-bzlib —enable-libgsm —enable-libschroedinger —enable-libspeex —enable-libtheora —enable-libvorbis —enable-pthreads —enable-zlib —enable-libvpx —disable-stripping —enable-runtime-cpudetect —enable-vaapi —enable-gpl —enable-postproc —enable-swscale —enable-x11grab —enable-libdc1394 —enable-shared —disable-static WARNING : library configuration
  mismatch libavutil configuration :
  —extra-version=4:0.6.2-1ubuntu2 —prefix=/usr —enable-avfilter —enable-avfilter-lavf —enable-vdpau —enable-bzlib —enable-libdirac —enable-libgsm —enable-libopenjpeg —enable-libschroedinger —enable-libspeex —enable-libtheora —enable-libvorbis —enable-pthreads —enable-zlib —enable-libvpx —disable-stripping —enable-runtime-cpudetect —enable-vaapi —enable-libopenjpeg —enable-gpl —enable-postproc —enable-swscale —enable-x11grab —enable-libfaad —enable-libdirac —enable-libfaad —enable-libmp3lame —enable-librtmp —enable-libx264 —enable-libxvid —enable-libdc1394 —enable-shared —disable-static libavcodec configuration :
  —extra-version=4:0.6.2-1ubuntu2 —prefix=/usr —enable-avfilter —enable-avfilter-lavf —enable-vdpau —enable-bzlib —enable-libdirac —enable-libgsm —enable-libopenjpeg —enable-libschroedinger —enable-libspeex —enable-libtheora —enable-libvorbis —enable-pthreads —enable-zlib —enable-libvpx —disable-stripping —enable-runtime-cpudetect —enable-vaapi —enable-libopenjpeg —enable-gpl —enable-postproc —enable-swscale —enable-x11grab —enable-libfaad —enable-libdirac —enable-libfaad —enable-libmp3lame —enable-librtmp —enable-libx264 —enable-libxvid —enable-libdc1394 —enable-shared —disable-static libavutil 50.15. 1 / 50.15. 1
  libavcodec 52.72. 2 / 52.72. 2
  libavformat 52.64. 2 / 52.64. 2
  libavdevice 52. 2. 0 / 52. 2. 0
  libavfilter 1.19. 0 / 1.19. 0
  libswscale 0.11. 0 / 0.11. 0
  libpostproc 51. 2. 0 / 51. 2. 0

  Prior to finally outputting the stuff I'd like to log :

  Seems stream 0 codec frame rate
  differs from container frame rate :
  47.95 (66893/1395) -> 23.98 (66893/2790) At least one output file
  must be specified

  Is there an option to prevent this excessive output ? Should I be doing it differently ?

• How do I improve the quality of a video produced from still PNG images ?

  9 avril 2012, par cormullion

  I'm trying to create a video from a few hundred PNG images. The PNG images look OK to me, e.g. here are two in MacOS X Preview :

  

  They're about 1200 pixels square, 16 bit RGB, no transparency.

  But my attempt to make a few hundred of these into a video is encountering the following problem - nearly every frame has this yellow corruption (artefacts ?), that sort of blocky flickery stuff you see on poor quality videos :

  

  The ffmpeg command I'm using is something like this :

  ffmpeg -f image2 -i /tmp/image-%07d.png -vcodec mpeg4 -vb 20M -r 20 poincare.mov

  I've tried changing a few parameters, but I probably changed the wrong ones. Any idea which parameters I should be changing, and to what value ?

  Console output is :

   ffmpeg -f image2 -i /tmp/image-%07d.png -vcodec mpeg4 -vb 30M -r 30 poincare.mov
  
      FFmpeg version UNKNOWN, Copyright (c) 2000-2010 the FFmpeg developers
  
      built on Nov  9 2010 12:20:29 with gcc 4.2.1 (Apple Inc. build 5664)
  
      configuration: --prefix=/Users/worth/OtherApps/ffmpeg/ffmpeg/../local/x86_64 --enable-static --enable-shared --enable-gpl --enable-version3 --enable-libmp3lame --enable-pthreads --enable-libvorbis --enable-libx264 --enable-libxvid --enable-libspeex --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-libvpx --enable-memalign-hack --disable-debug --disable-stripping --arch=x86_64
  
    libavutil     50.33. 0 / 50.33. 0
  
    libavcore      0.12. 0 /  0.12. 0
  
    libavcodec    52.94. 3 / 52.94. 3
  
    libavformat   52.84. 0 / 52.84. 0
  
    libavdevice   52. 2. 2 / 52. 2. 2
  
    libavfilter    1.59. 0 /  1.59. 0
  
    libswscale     0.12. 0 /  0.12. 0
  
      Input #0, image2, from '/tmp/image-%07d.png':
  
    Duration: 00:08:55.44, start: 0.000000, bitrate: N/A
  
      Stream #0.0: Video: png, rgb48be, 1200x1198, 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  File 'poincare.mov' already exists. Overwrite ? [y/N] y
  
  [buffer @ 0x101301ae0] w:1200 h:1198 pixfmt:rgb48be
  
  [ffsink @ 0x101301d50] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'out'
  
  [scale @ 0x101302090] w:1200 h:1198 fmt:rgb48be -> w:1200 h:1198 fmt:yuv420p flags:0xa0000004
  
  Output #0, mov, to 'poincare.mov':
  
    Metadata:
  
      encoder         : Lavf52.84.0
  
      Stream #0.0: Video: mpeg4, yuv420p, 1200x1198, q=2-31, 30000 kb/s, 30 tbn, 30 tbc
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press [q] to stop encoding
  
  frame=13386 fps= 27 q=2.0 Lsize=  536132kB time=535.43 bitrate=8202.7kbits/s    
  
  video:535981kB audio:0kB global headers:0kB muxing overhead 0.028261%