Speex dev - Dec 2006 - Algorithmic Delay

Hi,

I was hoping to get some clarification on the meaning of algorithmic latency in
Speex.

For wideband signals, algorithmic delay is specified to be 34 ms (20 ms is the
frame size and 14 ms is the lookahead).

Does this number (34 ms) account for the double-buffering on the input?

Assuming that the computation time and sound wave propagation time are
negligible, should I expect compressed audio to be ready for network
transmission 34 ms after the sound is created or 54 ms (the algorithmic delay of
34 ms + 20 ms for double-buffering at the ADC)?

Thanks,
Tom

The 34 ms includes everything: frame size, encoder latency/lookahead and
decoder latency/lookahead. It means that "in theory" (everything else
ideal), you could get 34 ms end-to-end latency with the codec. Of
course, in practice, you need to add network latency, soundcard
buffering and the jitter buffer. But those are codec-independent anyway.

	Jean-Marc

Tom Lukasiak a ?crit :
> Hi,
> 
> I was hoping to get some clarification on the meaning of algorithmic
> latency in Speex.
> 
> For wideband signals, algorithmic delay is specified to be 34 ms (20
> ms is the frame size and 14 ms is the lookahead).
> 
> Does this number (34 ms) account for the double-buffering on the
> input?
> 
> Assuming that the computation time and sound wave propagation time
> are negligible, should I expect compressed audio to be ready for
> network transmission 34 ms after the sound is created or 54 ms (the
> algorithmic delay of 34 ms + 20 ms for double-buffering at the ADC)?
> 
> Thanks, Tom
> 
> 
> _______________________________________________ Speex-dev mailing
> list Speex-dev@xiph.org 
> http://lists.xiph.org/mailman/listinfo/speex-dev
> 
>