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• How Much H.264 In Each Encoder ?

  8 septembre 2010, par Multimedia Mike — General

  Thanks to my recent experiments with code coverage tools, I have a powerful new — admittedly somewhat specious — method of comparing programs. For example, I am certain that I have read on more than one occasion that Apple’s H.264 encoder sucks compared to x264 due, at least in part, to the Apple encoder’s alleged inability to exercise all of H.264′s features. I wonder how to test that claim ?

  Experiment
  Use code coverage tools to determine which H.264 encoder uses the most features.

  Assumptions

  • Movie trailers hosted by Apple will all be encoded with the same settings using Apple’s encoder.
  • Similarly, Yahoo’s movie trailers will be encoded with consistent settings using an unknown encoder.
  • Encoding a video using FFmpeg’s libx264-slow setting will necessarily throw a bunch of H.264′s features into the mix (I really don’t think this assumption holds much water, but I also don’t know what “standard” x264 settings are).

  Methodology

  • Grab a random Apple-hosted 1080p movie trailer and random Yahoo-hosted 1080p movie trailer from Dave’s Trailer Page.
  • Use libx264/FFmpeg with the ‘slow’ preset to encode Big Buck Bunny 1080p from raw PNG files.
  • Build FFmpeg with code coverage enabled.
  • Decode each file to raw YUV, ignore audio decoding, generate code coverage statistics using gcovr, reset stats after each run by deleting *.gcda files.

  Results

  • x264 1080p video : 9968 / 134203 lines
  • Apple 1080p trailer : 9968 / 134203 lines
  • Yahoo 1080p trailer : 9914 / 134203 lines

  I also ran this old x264-encoded file (ImperishableNightStage6Low.mp4) through the same test. It demonstrated the most code coverage with 10671 / 134203 lines.

  Conclusions
  Conclusions ? Ha ! Go ahead and jump all over this test. I’m already fairly confident that it’s impossible (or maybe just very difficult) to build a single H.264-encoded video that exercises every feature that FFmpeg’s decoder supports. For example, is it possible for a file to use both CABAC and CAVLC entropy methods ? If it’s possible, does any current encoder do that ?

• Revision 36780 : On n’a plus besoin du pipeline body_prive puisque l’on passe par le cron ...

  31 mars 2010, par kent1@… — Log

  On n’a plus besoin du pipeline body_prive puisque l’on passe par le cron On détermine mieux le chemin des fichiers de saveauto pour le pipeline "mes_fichiers_a_sauver"

• FFMPEG : Invalid Pixel Format String -1 when converting MP3 to SWF

  22 janvier 2013, par James Riley

  I'm having an issue with FFMPEG - receiving an error when trying to convert an MP3 into an SWF. The full output contains :

  $ ffmpeg -i track1.mp3 -y -ar '44100' -ab '96k' 'sample.swf'
  
      FFmpeg version SVN-r26402, Copyright (c) 2000-2011 the FFmpeg developers
  
      configuration: --enable-libmp3lame --enable-libvorbis --enable-shared --disable-mmx
  
      libavutil     50.36. 0 / 50.36. 0
  
      libavcore      0.16. 1 /  0.16. 1
  
      libavcodec    52.108. 0 / 52.108. 0
  
      libavformat   52.93. 0 / 52.93. 0
  
      libavdevice   52. 2. 3 / 52. 2. 3
  
      libavfilter    1.74. 0 /  1.74. 0
  
      libswscale     0.12. 0 /  0.12. 0
  
      Input #0, nsv, from 'track1.mp3':
  
       Metadata:
  
         encoder         : Lavf52.93.0
  
         artist          : Test
  
         title           : Track02
  
         album           : Mixtape
  
         disc            : 1/1
  
         genre           : Acoustic
  
         date            : 2013
  
         track           : 2/2
  
         album_artist    : Test
  
         Duration: 00:00:00.00, start: 0.000000, bitrate: -2147483 kb/s
  
         Stream #0.0: Video: [216][195]2[138] / 0x8A32C3D8, 44318x50468, 24 fps, 24 tbr, 24 tbn, 24 tbc
  
         Stream #0.1: Audio: h[228][146][142] / 0x8E92E468, 0 channels
  
      [buffer @ 0x175cd00] Invalid pixel format string '-1'
  
      Error opening filters!

  I'm aware the FFmpeg version here is old, but the issue is only occuring for one of the MP3s I am testing here. I have many others that are working just fine.

  What can be causing this issue and what steps can I take to resolve this ?

  From what I understand, the pixel format relates to the video output, yet in this case, the SWF is only to be used for audio. I've tested this on a newer version of FFmpeg and the issue isn't occuring - I certainly plan to upgrade FFmpeg on the test server I'm using, but would like to get to the bottom of why this is happening and try to get this particular MP3 converting, where its currently failing despite many others not having the same issue.

  Thanks for any help !