FYI There is done some job in 3GPP SA-4 to impose requirements on jitterbuffer behavior for the same reasons that you describe. The current approach is to put limitations on both late loss and excess delay caused by the jitterbuffer. The issue is not settled yet but the intended outcome will be a set of requirements that a jitterbuffer should comply with. Ingemar > -----Original Message----- > From: Arne Lie [mailto:arne.lie@xxxxxxxxxxxx] > Sent: den 12 september 2006 12:58 > To: 'Lars Eggert'; Magnus Westerlund (KI/EAB) > Cc: dccp@xxxxxxxx > Subject: SV: SV: DCCP voice quality experiments > > OK, I understand the motivation of being play-out buffer > usage independant. However, due to the strict > delay-constraints for VoIP, playout-buffer size must also be > highly restricted, which should give less differences among > the different implementations. > One exeption could of course be the advanced ones that slows > down playout speed (and adjust pitch) in the case of playout > buffer draining. > - arne > > > -----Opprinnelig melding----- > > Fra: Lars Eggert [mailto:lars.eggert@xxxxxxxxxxxxx] > > Sendt: 12. september 2006 11:50 > > Til: Magnus Westerlund > > Kopi: dccp@xxxxxxxx > > Emne: Re: SV: DCCP voice quality experiments > > > > On Sep 12, 2006, at 11:29, Magnus Westerlund wrote: > > > I think Arne meant to actually do subjective evaluations. > > > > Ah. That's what I meant by "additional work" :-) > > > > > The issue I see with this is that the quality you get will > > be heavily > > > dependent on the jitter-buffer implementation and error > concealment > > > implemented in the player. Using a streaming player or something > > > similar for these subjective measurements would be > > providing results > > > that are ignoring a couple of important factor, like delay. > > > > Right. We wanted to exclude these factors and focus (only) on the > > impact of the transport protocol on voice quality, which is why we > > used the described dynamic-programming approach to compute > an optimal > > playout strategy offline. > > > > Lars > > -- > > Lars Eggert NEC Network > > Laboratories > > > > > > > > >
