[Speex-dev] Speex questions

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Fri Jun 22 21:38:35 PDT 2007

> 1.- First of all, I want to know if Speex provides a buffer for Jitter..If
> it does, what can I do to use it in my softphone?


> 2.- How does Speex manage the packet loss? (In a general point of view)


> 3.- Is the Delay for this codec low or high? I saw something strange in my
> implementation. I was using constant bit rate, when I set VAD as enabled
> the
> Delay was bigger. You told me by IRC that VAD doesn't have to do with the
> Delay, but it is happening to me. What could it be?

A bug in your code.

> 4.- Another thing you told me by IRC is to pack two frames in one packet to
> reduce the bandwidth consumption. I was packing just one frame per packet
> and it worked. I got audio in both clients but the bandwidth consumption
> wasn't as low as I wanted. Actually my softphone is consuming 3.5
> KBytes/sec
> (Speex+ RTPheader). So, I try to pack two frames per packet but the
> audio is
> too bad. I call the speex_encode_int method before call the
> speex_bits_write
> function. What could be happening with this?

A bug in your code.

> 5.- Finally, I want to know if it's possible to change the bandwidth
> consumption on the fly. I mean, If I use the re-INVITE to change the
> parameters of a session, is it possible to change the parameters of the
> codec and then change the bandwidth consumption too?

You can change the bit-rate on the fly by changing the quality
parameter. You don't need to tell the decoder, it will detect the change


More information about the Speex-dev mailing list