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• How to optimize ffmpeg w/ x264 for multiple bitrate output files

  10 octobre 2013, par Jonesy

  The goal is to create multiple output files that differ only in bitrate from a single source file. The solutions for this that were documented worked, but had inefficiencies. The solution that I discovered to be most efficient was not documented anywhere that I could see. I am posting it here for review and asking if others know of additional optimizations that can be made.

  Source file       MPEG-2 Video (Letterboxed) 1920x1080 @>10Mbps
  
                    MPEG-1 Audio @ 384Kbps
  
  Destiation files  H264 Video 720x400 @ multiple bitrates
  
                    AAC Audio @ 128Kbps
  
  Machine           Multi-core Processor

  The video quality at each bitrate is important so we are running in 2-Pass mode with the 'medium' preset

  VIDEO_OPTIONS_P2 = -vcodec libx264 -preset medium -profile:v main -g 72 -keyint_min 24 -vf scale=720:-1,crop=720:400

  The first approach was to encode them all in parallel processes

  ffmpeg -y -i $INPUT_FILE $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 250k -threads auto -f mp4 out-250.mp4 &
  ffmpeg -y -i $INPUT_FILE $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 500k -threads auto -f mp4 out-500.mp4 &
  ffmpeg -y -i $INPUT_FILE $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 700k -threads auto -f mp4 out-700.mp4 &
  

  The obvious inefficiencies are that the source file is read, decoded, scaled, and cropped identically for each process. How can we do this once and then feed the encoders with the result ?

  The hope was that generating all the encodes in a single ffmpeg command would optimize-out the duplicate steps.

  ffmpeg -y -i $INPUT_FILE \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 250k -threads auto -f mp4 out-250.mp4 \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 500k -threads auto -f mp4 out-500.mp4 \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 700k -threads auto -f mp4 out-700.mp4

  However, the encoding time was nearly identical to the previous multi-process approach. This leads me to believe that all the steps are again being performed in duplicate.

  To force ffmpeg to read, decode, and scale only once, I put those steps in one ffmpeg process and piped the result into another ffmpeg process that performed the encoding. This improved the overall processing time by 15%-20%.

  INPUT_STREAM="ffmpeg -i $INPUT_FILE -vf scale=720:-1,crop=720:400 -threads auto -f yuv4mpegpipe -"
  
  
  
  $INPUT_STREAM | ffmpeg -y -f yuv4mpegpipe -i - \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 250k -threads auto out-250.mp4 \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 500k -threads auto out-500.mp4 \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 700k -threads auto out-700.mp4

  Does anyone see potential problems with doing it this way, or know of a better method ?

• Revision 74038 : On corrige le bug de glob pour SPIP 2. Depuis SPIP 2, la majorité des ...

  30 juin 2013, par teddy.spip@… — Log

  On corrige le bug de glob pour SPIP 2. Depuis SPIP 2, la majorité des sites installe leurs plugins dans le répertoire ’plugins/auto’. Avec l’ancien code, on avait une erreur pour le foreach.
  Cette correction va permettre aussi de lister les paquets.xml propre à SPIP 3. On prioritise en prenant le paquet.xml sinon plugin.xml. Si un plugin est compatible Spip 2 ET Spip 3, en toute logique si on a paquet.xml et plugin.xml, la compat est indiquée dans les deux xml.
  Je monte en version juste pour historique de la modif de ce commit.

• ffmpeg terminates without any output

  11 septembre 2012, par Khan

  I am using ffmpeg to convert a video file to mp4. here is my code

      echo "converting ".basename($src)." --- to --- ".basename($dest).".mp4...<br />";
  
  $command = FFMPEG.&#39; -i &#39; . $src . &#39; -sameq -strict -2 -vcodec libx264 -ar 22050 -y &#39; . $dest.&#39;.mp4 2>&amp;1&#39;;   //
  
  echo $command.&#39;<br />&#39;;
  
  
  
  exec($command,$output,$status);
  
  echo &#39;<pre>&#39;,join(&#39;<br />&#39;,$output),&#39;</pre><br />&#39;;
  
  
  
  if($status == 0) {              // Success
  
      echo &#39;Successfully converted to MP4!<br />&#39;;
  
  } else {
  
      echo $status."<br />failed<br />";
  
  } 

  The code works fine on my localhost (Windows 7 + wamp).. But on live server , only $command is echoed.. and script is terminated. The output file is generated but it is only 4.5MB (it should be around 17 MB) and not complete... and sometime I get the following output..

      ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers  built on Sep 10 2012 00:38:24 with gcc 4.1.2 20080704 (Red Hat 4.1.2-52)  configuration: --prefix=/home/one01qsc/local --extra-cflags='-L/home/one01qsc/local/lib/ -I /home/one01qsc/local/include/' --extra-ldflags='-L/home/one01qsc/local/lib/ -Wl,-rpath,/home/one01qsc/local/lib/' --enable-libmp3lame --enable-libvorbis --enable-shared --disable-yasm --enable-libtheora --enable-libx264 --enable-gpl
  
    libavutil      51. 54.100 / 51. 54.100
  
    libavcodec     54. 23.100 / 54. 23.100
  
    libavformat    54.  6.100 / 54.  6.100
  
    libavdevice    54.  0.100 / 54.  0.100
  
    libavfilter     2. 77.100 /  2. 77.100
  
    libswscale      2.  1.100 /  2.  1.100
  
    libswresample   0. 15.100 /  0. 15.100
  
    libpostproc    52.  0.100 / 52.  0.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/one01qsc/public_html/temp/pending/1455-testing-mobidick.mov':
  
    Metadata:
  
      major_brand     : qt
  
      minor_version   : 537199360
  
      compatible_brands: qt
  
      creation_time   : 2012-09-08 16:00:41
  
    Duration: 00:00:23.13, start: 0.490000, bitrate: 6028 kb/s
  
      Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 5331 kb/s, 29.97 fps, 29.97 tbr, 60k tbn, 59.94 tbc
  
      Metadata:
  
        creation_time   : 2012-09-08 16:00:41
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:1: Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, s16, 192 kb/s
  
      Metadata:
  
        creation_time   : 2012-09-08 16:00:41
  
        handler_name    : Apple Alias Data Handler
  
  [buffer @ 0x2405ce0] w:1920 h:1080 pixfmt:yuv420p tb:1/60000 sar:0/1 sws_param:flags=2
  
  [buffersink @ 0x2429ec0] No opaque field provided
  
  [aformat @ 0x23fa560] auto-inserting filter 'auto-inserted resampler 0' between the filter 'src' and the filter 'aformat'
  
  [aresample @ 0x2402e60] chl:stereo fmt:s16 r:44100Hz -> chl:stereo fmt:flt r:22050Hz
  
  [libx264 @ 0x24288e0] using cpu capabilities: none!
  
  [libx264 @ 0x24288e0] profile High, level 4.0
  
  [libx264 @ 0x24288e0] 264 - core 128 - H.264/MPEG-4 AVC codec - Copyleft 2003-2012 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=24 lookahead_threads=4 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to '/home/one01qsc/public_html/temp/1455-testing-mobidick.mp4':
  
    Metadata:
  
      major_brand     : qt
  
      minor_version   : 537199360
  
      compatible_brands: qt
  
      creation_time   : 2012-09-08 16:00:41
  
      encoder         : Lavf54.6.100
  
      Stream #0:0: Video: h264 (![0][0][0] / 0x0021), yuv420p, 1920x1080, q=-1--1, 30k tbn, 29.97 tbc
  
      Metadata:
  
        creation_time   : 2012-09-08 16:00:41
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:1: Audio: aac (@[0][0][0] / 0x0040), 22050 Hz, stereo, flt, 128 kb/s
  
      Metadata:
  
        creation_time   : 2012-09-08 16:00:41
  
        handler_name    : Apple Alias Data Handler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 -> libx264)
  
    Stream #0:1 -> #0:1 (aac -> aac)
  
  Press [q] to stop, [?] for help
  
  frame=   18 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=   0.0kbits/s

  the value printed for $status is 137 in this case.

  Any help is really appreciated.