Subject: Re: RTP and CTI

From: fm-listproc <[email-masked]>
Date: Mon, 3 Jul 2000 14:09:36 -0400 (EDT)

> > It depends on your application to a large degree. The implementations I
> > know are PC-based, handling a small number of streams. If your system has
> > to process a very large number of streams, the trade-off is somewhat
> > different. 
> > 

Speaking as an ex-designer of soundboards, my personal recollection is
that getting data to/from the host across the PCI bus accounts for more
latency than processing RTP.  When Microsoft went from ACM to DirectSound,
the total delay to Netmeeting dropped from 120+ ms to 30 ms.  Since PCI is
not a synchronous bus, there cannot be any guarantee when there is
contention for the PCI BUS.  RTP'ing an audio stream on the fast
processors of today creates very little delay.  I'd worry about a good
CODEC driver first. 

Now, if you want to make a custom ASIC which does everything in hardware,
nothing is stopping you.  Personally, considering that the RTP debate is
far from over (who needs RTP overhead for point to point comms ?), I would
not spend any time implementing RTP in hardware.

-=Francois=-