[vorbis-dev] timestamping / latency

[Olaf Matthes]

John Morton wrote:

>The long answer is that it depends on how low you need the latency to be. 
>What's the application you had in mind?
>
We're trying to build a system that allows full-duplex multichannel 
streaming. There will be a version using uncompressed audio and we plan 
to use ogg/vorbis for a second version using compressed audio signals 
(for use with ADSL connections as the minimum bandwidth). The criteria 
to be met are: high audio quality and multichannel support along with 
low latency. So it's not just voice to be transmitted.
We're also working on an echo-cancellation system so the goal is to get 
something like voice over IP but with multiple channels and in much 
better audio quality. Latency should be somewhere around or even below 1 
second.
More information about the project is available here: http://tot.sat.qc.ca/

The most important thing is to get a latency that is somehow 
predictable. With my current code in VBR and a quality setting of 0.4 I 
get everything between 500 ms and 8 seconds depending on the audio 
signal (and thus the bitrate of the stream).

I tested this new CBR feature in the vorbis CVS version and since data 
rates won't drop the latency shouldn't change (I hope). I have to do 
some more tests to find out how stable this is working and whether the 
audio quality matches the quality of a VBR encoded stream. What I found 
so far is that CPU usage is higher than in VBR mode but that's acceptable.

<p>Olaf

<p>--- >8 ----
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