[theora] Encoding vorbis with theora

Stuart Fisher stuart.fisher at fig7.com
Sun Jan 16 07:35:17 PST 2011

Hi Ernie,

I was thinking about similar issues some time ago. I'd been writing some code to playback theora clips.

The way I see it is that a player has to assume the audio track is always a continuous audio stream. The video track, on the other hand, doesn't have to be. The reason is that in order to playback the clip you need to have synchronisation between the audio and video. The audio stream provides that synchronisation (the player uses the audio clock to determine when video frames should be displayed). So in other words I think you need to encode the audio as a continuous stream (i.e. just encode silence between the sections of audio).

That's the way I figured it out in my mind, but I wonder if there is a defnitive explanation somewhere of how theora encoders and decoders should handle discontinuity in the timeline.


  ----- Original Message ----- 
  From: Ernie Lyon 
  To: theora at xiph.org 
  Sent: Sunday, January 16, 2011 2:50 PM
  Subject: [theora] Encoding vorbis with theora

  Hey everyone;

  I'm able to encode and mix audio data (in wav format) into theora with vorbis - easy enough. However, my issues comes when I need that audio data to play at certain locations in the video time line.

  I'm encoding the video in a frame by frame basis and am also providing the frame rate by which the encoded frames are to be played. So, to me, it sounds like it shouldn't be very difficult to tell vorbis/theora when to play various audio cuts during play - which is why I've been pulling my hair out trying to dig through docs and forums in search of how to do this.

  Any help would be fantastic! 



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