[theora] Encoding vorbis with theora

Ernie Lyon II fastawdtsi at gmail.com
Sun Jan 16 09:25:27 PST 2011

The "digital silence" is likely what I'm looking for, and from what you mentioned, vorbis having an efficient way of handling that tells me it's *exactly* what I'm looking for.

Now, my use case is a series of images set to a specific frame rate, and now I'm looking to add various bits of audio encoded throughout. Would you consider my theora stream to be "discontinuous?"

Thanks Gregory!


On Jan 16, 2011, at 11:37 AM, Gregory Maxwell <gmaxwell at gmail.com> wrote:

> On Sun, Jan 16, 2011 at 10:35 AM, Stuart Fisher <stuart.fisher at fig7.com> wrote:
>> 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.
> Both Theora and Vorbis are continuous stream types. Kate is an example
> of a discontinuous stream.
> (http://xiph.org/ogg/doc/ogg-multiplex.html)
> Both formats have efficient ways of coding inactivity (digital silence
> in the case of vorbis, no motion in the case of theora), so you should
> just feed them inactivity when you want them to be inactive.

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