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• Http Live Streaming - Segmenting mp3 on Linux

  14 mai 2012, par krisbulman

  I simply want to segment an mp3 for HTTP Live Streaming in any linux distro (preferably CentOS) for the purpose of audio streaming to an iOS app.

  Out of the linux segmenters, I can get the following to compile in CentOS.

  1. http://wiki.andy-chu.com/doku.php?id=http_live_streaming (not sure last time this was updated)

  2. m3u8-segmenter on github (updated months ago)

  3. https://github.com/carsonmcdonald/HTTP-Live-Video-Stream-Segmenter-and-Distributor [ruby wrappers + c] (last updated 2 years ago, and a v2 branch 9 months old)

  In order to prep the file for segmenting, here is the ffmpeg conversion string to generate a valid ts file :

  $ ffmpeg -er 4 -i input.mp3 -f mpegts -acodec libmp3lame -ar 22050 -ab 32k -vn output.ts

  Each of the segmenters require various input switches, all quite simple, and all crash out with a seg fault. #2 actually does some segmenting, but faults after 56 segments every time. I've tried various mp3s with the same results. The issue queues for 2 & 3 are full, with no responses in months of the same issues.

  Others must be doing this in a live production environment that isn't running OSX.. what are your methods ?

• PHP ffmpeg fetch metadata missing title, author, comment, artist

  19 avril 2012, par chrismacp

  I've been trying to fetch remote mp3 (and other format) meta data using the php5-ffmpeg extension.

  It is working although I am always missing the title, author, comment, artist details.

  I've been scouring the web for an answer but not found any solution.

  I did find this patch http://cvs.pld-linux.org/cgi-bin/viewvc.cgi/cvs/packages/php-ffmpeg/tests-metadata-api.patch which I thought may solve the problem, but I've been unable to compile php-ffmpeg even without the patch so haven't been able to work out if it will fix the problem.

  It seems this extension was abandoned a couple of years ago so I'm not holding out much hope of getting this working.

  Does anyone have any ideas of how to get remote meta data from audio video files using other tools ?

  I am thinking of just parsing the output of ffmpeg itelf using the '-i' option as this does return the correct meta data. Just a bit wary of calling exec in PHP for security reasons.

• Theora puts incorrect PTS presentation time on video with held frames

  17 mars 2012, par hexatron

  I have a problem with the packet PTS/DTS on OGG Theora videos with held frames.
  Theora tries to be clever about held frames by omitting duplicate frames
  and using the packet PTS/DTS (they are equal) to skip the held frame time.

  For example, a 2-second-long 10 fps video with frames
  
    A A A A A A A A A A B C D E F G G G G G
  
  should encode with PTS (the frame start) as (note the encoder adds some dup frames)
  
      A 0.0
  
      A 0.1
  
      B 1.0
  
      C 1.1
  
      D 1.2
  
      E 1.3
  
      F 1.4
  
      G 1.5
  
      G 1.9
  
  But libtheora (and ffmpeg) put an incorrect time stamp on frame B
  
  (the first frame following a the dup frames)
  
      B 0.6
  
  This causes video to hiccup on the mislabeled frame.
  
  
  
  My crude fix for this is to use
  
      current frame PTS =  (next frame PTS time) - (one frame time)
  
  and
  
      last frame PTS = duration - (one frame time)

  (I tried submitting a bug report for theora at xiph.org, as the theora site recommends, but could not figure out how to register for a login. I also noticed the reports were several years old, so decided to document this behavior here)