title: Ffmpeg performance issue when transcoding to webm
body: <p>I have recently updated ffmpeg from version 2.0.2 to the most recent release 2.7. I installed it using the same building configuration as the old version and the same codecs version (libvpx and h264). When I tried to transcode an mp4 video to webm, I found out that the speed of the new version is significantly lower (3 times) than the old one. I run this on two identical 8 core machines (Intel(R) Xeon(R) CPU E5-2680 v2 @ 2.80GHz) - OS: Ubuntu 14.04. Below is the command I run: </p>
  
  <pre><code>/usr/local/bin/ffmpeg -i in.mp4 -f webm -vcodec libvpx -b:v 1000K out.webm
  </code></pre>
  
  <p>These are the outputs for the two versions:</p>
  
  <p>v 2.0.2</p>
  
  <pre><code>ffmpeg version 2.0.2 Copyright (c) 2000-2013 the FFmpeg developers
  built on Jan  7 2015 13:51:25 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --disable-ffplay --disable-ffserver --enable-libxvid --enable-gpl --enable-nonfree --enable-pthreads --enable-libmp3lame --enable-libx264 --enable-libfaac --enable-zlib --enable-avfilter --enable-libfreetype --enable-libfdk_aac --enable-libtheora --enable-libvorbis --enable-libvpx --enable-pic --enable-shared  
  libavutil      52. 38.100 / 52. 38.100
  libavcodec     55. 18.102 / 55. 18.102
  libavformat    55. 12.100 / 55. 12.100
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 79.101 /  3. 79.101
  libswscale      2.  3.100 /  2.  3.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  3.100 / 52.  3.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.mp4':
  Metadata:
  major_brand     : isom
  minor_version   : 512
  compatible_brands: isomiso2avc1mp41
  encoder         : Lavf55.12.100
  Duration: 00:00:10.19, start: 0.000000, bitrate: 1724 kb/s
  Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1480 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
  Metadata:
    handler_name    : VideoHandler
  Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 253 kb/s
  Metadata:
    handler_name    : SoundHandler
  [libvpx @ 0x22f3760] v1.3.0
  Output #0, webm, to 'out.webm':
  Metadata:
  major_brand     : isom
  minor_version   : 512
  compatible_brands: isomiso2avc1mp41
  encoder         : Lavf55.12.100
  Stream #0:0(und): Video: vp8 (libvpx), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 1000 kb/s, 1k tbn, 29.97 tbc
  Metadata:
    handler_name    : VideoHandler
  Stream #0:1(und): Audio: vorbis (libvorbis), 44100 Hz, stereo, fltp
  Metadata:
    handler_name    : SoundHandler
  Stream mapping:
  Stream #0:0 -&gt; #0:0 (h264 -&gt; libvpx)
  Stream #0:1 -&gt; #0:1 (aac -&gt; libvorbis)
  Press [q] to stop, [?] for help
  frame=  302 fps= 23 q=0.0 Lsize=    1445kB time=00:00:10.18 bitrate=1161.9kbits/s    
  video:1304kB audio:128kB subtitle:0 global headers:4kB muxing overhead 0.644833%
  </code></pre>
  
  <p>v 2.7</p>
  
  <pre><code>ffmpeg version 2.7 Copyright (c) 2000-2015 the FFmpeg developer built with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
    configuration: --disable-ffplay --disable-ffserver --enable-libxvid --enable-gpl --enable-nonfree --enable-libmp3lame --enable-libx264 --enable-libfaac --enable-zlib --enable-libass --enable-pthreads --enable-avfilter --enable-libfreetype --enable-libfdk_aac --enable-libtheora --enable-libvorbis --enable-libvpx --enable-pic --enable-shared --enable-openssl
    libavutil      54. 27.100 / 54. 27.100
    libavcodec     56. 41.100 / 56. 41.100
    libavformat    56. 36.100 / 56. 36.100
    libavdevice    56.  4.100 / 56.  4.100
    libavfilter     5. 16.101 /  5. 16.101
    libswscale      3.  1.101 /  3.  1.101
    libswresample   1.  2.100 /  1.  2.100
    libpostproc    53.  3.100 / 53.  3.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.mp4':
    Metadata:
      major_brand     : isom
      minor_version   : 512
      compatible_brands: isomiso2avc1mp41
      encoder         : Lavf56.36.100
    Duration: 00:00:10.19, start: 0.000000, bitrate: 1596 kb/s
      Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1480 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc (default)
      Metadata:
        handler_name    : VideoHandler
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
      Metadata:
        handler_name    : SoundHandler
  [libvpx @ 0xfe4640] v1.3.0
  Output #0, webm, to 'out.webm':
    Metadata:
      major_brand     : isom
      minor_version   : 512
      compatible_brands: isomiso2avc1mp41
      encoder         : Lavf56.36.100
      Stream #0:0(und): Video: vp8 (libvpx), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 1000 kb/s, 29.97 fps, 1k tbn, 29.97 tbc (default)
      Metadata:
        handler_name    : VideoHandler
        encoder         : Lavc56.41.100 libvpx
      Stream #0:1(und): Audio: vorbis (libvorbis), 44100 Hz, stereo, fltp (default)
      Metadata:
        handler_name    : SoundHandler
        encoder         : Lavc56.41.100 libvorbis
  Stream mapping:
    Stream #0:0 -&gt; #0:0 (h264 (native) -&gt; vp8 (libvpx))
    Stream #0:1 -&gt; #0:1 (aac (native) -&gt; vorbis (libvorbis))
  Press [q] to stop, [?] for help
  frame=  302 fps=8.3 q=0.0 Lsize=    1410kB time=00:00:10.18 bitrate=1133.4kbits/s    
  video:1274kB audio:123kB subtitle:0kB other streams:0kB global headers:4kB muxing overhead: 0.909304%
  </code></pre>
  
  <p>I tried ffmpeg 2.6.3 and the performance the same as for 2.7. Also it looks like when I transcode webm to mp4 2.7 is 30% faster than webm.</p>
  
  <p>I tried to look if there are building configuration options for the new version but couldn't find anything. </p>
  
  <p>Can anyone suggest a possible reason for the worse speed performance of the new version when transcoding to webm?   </p>