tunkeat
2005-Jan-06 07:45 UTC
[Speex-dev] different output for opt/non-opt on win32 platform
hi,> > how big is this "Speex's memory"? > > No problem, as long as you decode the stream in order. > > > I am thinking perhaps naively: at > > the encoder side, is it possible to get the states for the decoder > > from the encoder's memory without doing the actual decoding? > > In theory, you could, but I don't see what you'd gain there.i was wondering whether speex frames could be made "independent", 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. if Speex's decoder's state memory is small enough, it could be sent from encoder to the decoder. at the decoder, when each frame is received, the decoder's state could be initialised and decoding could be performed using the transmitted state. possible? or is it already enforced? or there are other mechanisms in place to deal with the lost packet problem? TIA, tk
Jean-Marc Valin
2005-Jan-06 10:56 UTC
[Speex-dev] different output for opt/non-opt on win32 platform
> 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 -- Jean-Marc Valin <Jean-Marc.Valin@USherbrooke.ca> Universite de Sherbrooke
hi, I am currently trying out speex version of 1.1.6 FIXED_POINT. noticed there's a 64 bit integer being used in the long term prediction. any chance of using a 32 bit integer without incurring some major side-effects? cheers, tk