[h323forum] Re: Codec negotiation question

Paul E. Jones paulej at PACKETIZER.COM
Tue Dec 17 16:25:33 EST 2002


Denise,

I think that any such scheme should be a candidate for consideration.  There
are a number of such complexities to consider when building such a gateway
for trunking traffic over a long distance.  Defining how to queue packets
for transmission (scheduled, prioritized, FIFO, etc.) is certainly an
important aspect to consider.  There are others and I'd like to see such
discussions progress.

Would you or the company you're consulting with like take an active part in
a standardization activity along these lines?

Paul

----- Original Message -----
From: "Denise Shull" <deniseshull at sbcglobal.net>
To: "'Paul E. Jones'" <paulej at packetizer.com>; "'Paul Long'"
<plong at packetizer.com>; <h323forum at mail.imtc.org>;
<ITU-SG16 at echo.jf.INTEL.COM>
Sent: Tuesday, December 17, 2002 3:55 PM
Subject: RE: [h323forum] Re: Codec negotiation question


> Trying to not 'plug' any company or technology in this arena, however, I
> am doing a consulting project for a company that schedules the packets -
> versus prioritizing them.  They are in beta mode but their tests reveal
> a very effective method for delivering video with greatly reduced
> latency and jitter.
>
> It would be useful to be able to have input from this group both on the
> idea and on their technology specifically.
>
> Regards,
> Denise
>
> Denise K. Shull
> SHULL ADVISORS, LLC
> Strategic Application of Meeting Technologies
> 646-498-6403
> www.videooverip.biz
>
>
>
> -----Original Message-----
> From: Paul E. Jones [mailto:paulej at packetizer.com]
> Sent: Monday, December 16, 2002 8:04 PM
> To: Paul Long; h323forum at mail.imtc.org; ITU-SG16 at echo.jf.INTEL.COM
> Subject: [h323forum] Re: Codec negotiation question
>
> 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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> > > ----------
> > > Robert Jongbloed                        Equivalence Pty. Ltd.
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