[speex-dev] Using speex.

Jean-Marc Valin jean-marc.valin at hermes.usherb.ca
Mon May 12 08:53:42 PDT 2003

>    1) Is there any sample implementation using Speex in web conerencing
>       in voice?  To be more specific, in Windows platforms?  (ActiveX? 
>       Java applet implementation?)

Well there's a (non-applet) Java implementation. Otherwise, I don't have
such code, but maybe someone on the list does.

>    2) What is the recomended bandwidth?  4kbs (in one way)?  2 kbs?
>       (The shown samples sound pretty good at 4kbs.)

Well, it all depends on the bandwidth you can afford. 4 kbps is really
the minimal rate. I suggest using more than that if you can afford
(ideally 8, 11 or 15 kbps). If you have even more bandwidth, you can go
wideband (16 kHz) and get much better quality.

>    3) What is the recomended buffer?  1 second or 2 seconds?

Depends on your application, but such a large delay will likely cause
problems in conversations (you it takes twice the delay to hear the
answer to your question).

>    4) What would happen if sound packets are dropped (time shift
>       in different computer clock speeds)?  What if some
>       packet holes have to be filled?  (repeating the previous packet?)

Whenever you need to play a packet that hasn't arrived yet, just call
the decode function (speex_decode) with NULL as the "bits" argument.

>    5) Any otther issues that I should pay attention to?

I guess you'll find out when you get there ;)

>    6) Anybody did it and I can learn from?

Anyone on the list?


Jean-Marc Valin, M.Sc.A.
LABORIUS (http://www.gel.usherb.ca/laborius)
Université de Sherbrooke, Québec, Canada

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