[Speex-dev] different output for opt/non-opt on win32 platform

Jean-Marc Valin Jean-Marc.Valin at USherbrooke.ca
Thu Jan 6 10:53:37 PST 2005

> i was wondering whether speex frames could be made "independent",

If you tweak the encoder, you can probably do that... except that you'll
multiply the bit-rate by about 3.

> as in if some packets are lost, there is no need for re-transmission of
> these frames (for VoIP app, i see concealment is provided in speex) to decode 
> future frames . from the draft RFC for speex, I don't see space
> reserved for state info.

Read the draft and manual carefully. Speex does provide a way to recover
from packet loss (without retransmission). The frame that follows the
lost frame won't be exact, but it can still be decoded (and Speex
accounts for all that).

> if Speex's decoder's state memory is small enough, it could be sent 
> from encoder to the decoder.

There ain't no such thing as a free lunch. Of course the decoder state
is large.

> or there are other
> mechanisms in place to deal with the lost packet problem?

Yes, just read the doc, and optionally look at the --packet-loss option
in speexdec, which simulates loss of packets.


Jean-Marc Valin <Jean-Marc.Valin at USherbrooke.ca>
Universite de Sherbrooke

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