Re: [codec] #16: Multicast?

[Koen Vos <[e-mail]>]

Quoting "Raymond (Juin-Hwey) Chen":
> My main point, though, is not in the exact one-way delay value for a  
> codec with a 5 ms frame size, but rather that with a 5 ms frame size  
> you can get a much lower one-way delay than with a 20 ms frame size.

It would be about 15 ms lower - don't know if that counts as "much" :)

Also, note that for a given probability of packets arriving too late  
to be played out, the jitter buffer delay is independent of the frame  
size.


>> - most delay comes from the network and is not codec related, and
>> - one-way delay grows almost linearly with frame size.
>
> Doesn't your last line above contradicts with the second last line?

I meant that approximately:
    one-way delay = codec-independent delay + frame size

("codec algorithmic delay" would be more accurate than "frame size")


>> Afaik, only RTP headers can be compressed between arbitrary Internet
>> end points.  You're still stuck with IP and UDP headers.
>
> I am aware of a header compression technology for VoIP over Cable  
> applications that can compress the header size to a very small  
> fraction of the original size, but it is probably not widely used.

Yes, header compression works between end-points on a cable.  That's  
different from "between arbitrary Internet end points".

best,
koen.