Hi kind developers, I need select soon the best freeware VOIP codec, I see that all competitors are using iLBC because of the separate packets management. How speex behave in case of packets drop? Why other choice all iLBC? Thank you for any kind answer. Best regards. ------------------------------------- Roberto Della Pasqua Http: www.dellapasqua.com Email/Msn: roberto@dellapasqua.com Aol/Yahoo: DellaPasquaR Icq: 164672275 ------------------------------------- This e-mail and any attachment contain information which is privileged and confidential and is intended for the addressee only. If you have received this message but you are not the intended addressee, be advised that you are not authorized to read, copy or use this email or any attachment. If you have received this email in error, please destroy it and notify the sender by return email. Thank you. -------------------------------------
> I need select soon the best freeware VOIP codec, I see that all competitors > are using iLBC because of the separate packets management.Me wrote: The more I think about it, the more I think independent frames are a bad idea. When network conditions get really bad, I think it will always be a better idea to send redundant information than to try making the frames independent. Just think about a case where you have 30% packet loss. What will perform the best between iLBC at 15 kbps and Speex at 8 kbps where each frame is transmitted twice (so 9% effective loss)? I think this paper should be a good read on the topic: http://www.icassp2004.com/Papers/viewpapers.asp?papernum=3280 Of course, I still believe it's a good thing to minimize (not eliminate) dependency between frames whenever it doesn't affect quality/bitrate too much.> How speex behave in case of packets drop?If you want to see for yourself how Speex performs with packet loss, all you need to do is to encode a file with speexenc with the sampling rate and bitrate you want and then decode it with "speexdec --packet-loss N myfile.spx", where N is the percentage of packet loss.> Why other choice all iLBC?No all others choose iLBC, and I suppose that part of the reason is with marketing. Speex is not developed by a company, so nobody is getting paid to convince people to use it. Also note that Speex includes a lot more than iLBC in the "free package". Speex also does wideband, acoustic echo cancellation, noise cancellation, jitter buffering, while you have to pay GIPS for all these features. The Speex license is of course also open-source, which is not the case of iLBC (even though they don't charge, it is not open-source). Jean-Marc -- Jean-Marc Valin <Jean-Marc.Valin@USherbrooke.ca> Universit? de Sherbrooke
Roberto Della Pasqua wrote:>Hi kind developers, > >I need select soon the best freeware VOIP codec, I see that all competitors >are using iLBC because of the separate packets management. > >How speex behave in case of packets drop? >Why other choice all iLBC? > >Thank you for any kind answer. > >I think Jean-Marc is right about the relative merit of a good 8kbps codec with FEC versus iLBC at about twice that bit rate. iLBC sounds no better than a good 8kbps codec. However, I'd like to address the "all competitors" part. Skype has used the non-free wideband iLBC as a specific choice. However, most other systems either don't support iLBC, or throw it in as an extra because they have the ROM space, and it costs them nothing. I don't see anyone taking up iLBC as a strategic choice in the way they so, say, G.729. I think so far iLBC has been a commercial failure. I assume Skype didn't need to pay much. Regards, Steve