[h323forum] Re: Codec negotiation question

[Paul E. Jones]

Paul,

Do you mean RFC 2508?

In any case, Robert's point is indeed valid.  This is where having a
specialize GW that multiplexes the RTP streams for delivery over the
long-haul is something practical.

Perhaps we could take that up as a work item with SG16? It would be
reasonable to specify how such an Gateway might function in order to trunk a
large number of active calls over long distance.  Anyone interested in such
a work item?

Paul

----- Original Message -----
From: "Paul Long" <plong at packetizer.com>
To: <h323forum at mail.imtc.org>
Sent: Monday, December 16, 2002 7:49 PM
Subject: [h323forum] Re: Codec negotiation question


> Robert,
>
> Excellent point. I hadn't thought of that. I wonder what happened to
> cRTP. Anybody know? That would sure help.
>
> Paul
>
> >
> > On Mon, 16 Dec 2002 12:53:34 -0500
> > "Paul Long" <plong at packetizer.com> wrote:
> >
> > > I know lots of folks would like a means of expressing exact
> > > packetization, but isn't the solution trivial? All you need is a
> small
> > > FIFO and a few lines of code to re-packetize according to any
> internal
> > > requirements. Just write incoming frames regardless of size, e.g.,
> > > 30fpp, to the FIFO, and read whatever size frames you want, e.g.,
> 80fpp
> > > from the FIFO (only read if there are at least X fpp in the FIFO).
> >
> > DSP hardware is not the only reason for wanting to have the remote
> > endpoint send larger packets. We have many clients on long haul
> internet
> > links (300ms+ ping times), often with a slow tail circuit (ISDN or
> even
> > modem) and you REALLY want the other end to send more than one G.723.1
> > frame per packet to reduce the significant overhead that there is in
> the
> > RTP.
> >
> >
> >
> > > > It is unfortunate but true that there is no way of expressing a
> > > minimum
> > > > acceptable number of frames per packet.
> > > >
> > > > Regards,
> > > > Chris
> > > >
> > > > Paul Long wrote:
> > > > > Davide,
> > > > >
> > > > > There is nothing in the standard that requires the acceptance
> of an
> > > OLC
> > > > > or precludes terminating the call for any reason whatsoever so
> both
> > > EPs
> > > > > are technically compliant.
> > > > >
> > > > > Packetization in TCS and OLC expresses the _maximum_ frames per
> > > packet,
> > > > > but several vendors don't understand this simple concept and
> > > continue
> > > > > to produce products that expect an exact packetization. There
> is a
> > > good
> > > > > chance that that is why EP A is rejecting the OLC. It wants the
> > > channel
> > > > > opened at exactly 80fpp, although there is no way to express
> this
> > > in
> > > > > H.323. IMO, if this is the reason, that product is broken.
> > > > >
> > > > > Paul
> > > > >
> > > > >
> > > > >>Hi all,
> > > > >>
> > > > >>I have a question about a codec negotiation.
> > > > >>During H.245 negotiation, endpoint A (master) exports g711A-law
> > > with
> > > > >
> > > > > packetization 80, endpoint B (slave) exports g711A-law with
> > > > > packetization 30. After that, endpoint A opens a channel with
> > > > > packetization = 20 ms. Endpoint B acknoledges the OLC and tries
> to
> > > open
> > > > > a channel with packetization = 30 ms.
> > > > >
> > > > >>Here Endpoint A rejects the OLC and the call is disengaged.
> > > > >>
> > > > >>Does anybody can tell me which endpoint dosn't behave according
> to
> > > > >
> > > > > the H323 standard?
> > > > >
> > > > >>Thank you in advance.
> > > > >>
> > > > >>Davide
> > > > >
> > > > >
> > > > > ---
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> > > >
> > > > --
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> >
> > ----------
> > Robert Jongbloed                        Equivalence Pty. Ltd.
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