theora - Jan 2011 - 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!

-- 
-Ernie
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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.

Stuart

  ----- 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! 


  -- 
  -Ernie



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