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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 ?

• ffmpeg error when I changed the server

  5 octobre 2012, par NewPHP

  I am changing someone's working site "video.net"(an example) from one server to another.
  But I am getting an error like :

  Warning : require_once(ffmpeg/movie.php) [function.require-once] : failed to open stream : No such file or directory in /store/websites/dvb/video.net/642/include/config.php on line 7.

  Fatal error : require_once() [function.require] : Failed opening required 'ffmpeg/movie.php' (include_path='. :/usr/share/pear :/usr/share/php') in /store/websites/dvb/video.net/642/include/config.php on line 7

  The error lines are below.

    function __autoload ($className)
  
    {
  
        $className = explode("_", $className);
  
        $className = implode("/", $className);
  
        require_once ("{$className}.php");
  
     }

  I haven't used ffmpeg before. Also I am new to it. Do you guys have any idea, what do I want to check ? I hope this is probably some installation error or something like that.

  Thanks !

• How to parse RTP H264 packet using FFMpeg [closed]

  9 novembre 2012, par TMMDev

  I am new to this forum,
  i hope someone can help me with my problem.

  I need to convert RTP H264 packets using FFMpeg to BMP files, i have achieved the following until now :

  -Reading H264 file and convert it to BMP files using FFMpeg.

  -Receiving raw RTP H264 packets.

  I would really appreciate if someone can help me decode RTP H264 packets using FFMpeg,
  i have done lots of searchs over the internet, and found the following solutions :

  • libavformat using rtp_h264.c, i could not download the library anywhere, although the file is there, but no way to use it without downloading the library, can someone please provide a download link and an example if possible ?

  • live555 using H264VideoRTPSource, after downloading the library, i did not understand how to use this code, should i instantiate the class ? or inhert it ? is there an example over the internet on using H264VideoRTPSource ?

  Is there any other way to do it WITHOUT reading all the standards (RFC3984 and RFC6184)

  Thank you.