[vorbis-dev] Flushing audio

[Eric Ross]

On Fri, 12 Sep 2003, Michael Smith wrote:
> Using full VBR (i.e. non-managed modes) will drastically reduce the latency, 
> but it'll still be high. If you need to do this, you may have to write your 
> own vorbis encoder (but it depends on just what latency you can tolerate - 10 
> ms? 50 ms? 100 ms? 500 ms? Vorbis won't do 10 ms, 50 ms would be very 
> marginal and probably not possible, 100 ms or more should be fine if you take 
> appropriate care.)

100ms is ok. I've done some informal tests, and the audio have some delay 
(100ms or so), but it's pretty tolerable, and it's almost the same amount 
of delay i get with other applications.

> You'd also find that the ogg layer has a lot of overhead if you do it like 
> this (one packet per page), so you'd want to do it differently anyway (see, 
> for example, the vorbis-over-RTP drafts).

When i started looking at vorbis (3 days ago), i didnt understand how to 
use vorbis with out ogg. I mean, my plan was getting the audio, encode it 
using vorbis and just sending using udp in small packets. After looking 
for some time at the examples, i just reused the code to put the vorbis 
stream inside a ogg stream and then sending the ogg pages over udp. I'd 
really like to just bypass ogg, get the plain encoded data, and send it
using a very light framing layer, but i still dont how to do that (the 
vorbis part)

> You might also be able to get away with it (again, this depends: you haven't 
> given much detail, so I can't say for sure) by just ensuring you always write 
> blocks of audio of some minimum size (for VBR modes, this size needn't be all 
> that large. It depends on sampling rate, so give more details if you want 
> recommendations on this), and using a low-latency encapsulation layer (i.e. 
> probably not ogg).

Im using a sample rate of 8000, quality 0.0 and mono audio, just to ensure 
that im using the minimal bandwidth.

Eric.


-- 
The names of their development products, visual this, visual that, almost 
makes one think that you can create software just by looking at your computer

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