comments on AVD 2253 from Raleigh

Paul E. Jones paulej at PACKETIZER.COM
Wed Sep 25 23:55:30 EDT 2002


Roni,

The current definition, which was drafted by Terry Anderson, is pretty clear
that multiple payload streams must carry data from a single "source", I
believe.  Have a look at AVD 2257.

Paul

----- Original Message -----
From: "Even, Roni" <roni.even at polycom.co.il>
To: "'Paul E. Jones'" <paulej at packetizer.com>; "Even, Roni"
<roni.even at polycom.co.il>; <ITU-SG16 at echo.jf.INTEL.COM>
Cc: "Martin Euchner" <Martin.Euchner at icn.siemens.de>
Sent: Wednesday, September 18, 2002 4:06 AM
Subject: RE: comments on AVD 2253 from Raleigh


> Paul,
>
> I think that the requirement were to prevent audio and video in the same
> stream on one side and to allow for multiple video or audio in the same
> stream to be compatible with SIP capabilities and not only for MOIP. So I
> think that there should be a text saying that in multiple streams we do
not
> recommend audio and video in the same stream and to be able to specify the
> packetization scheme for the multiple streams.
> Roni
>
> > -----Original Message-----
> > From: Paul E. Jones [mailto:paulej at packetizer.com]
> > Sent: Tuesday, September 17, 2002 7:52 PM
> > To: Even, Roni; ITU-SG16 at echo.jf.INTEL.COM
> > Cc: Martin Euchner
> > Subject: Re: comments on AVD 2253 from Raleigh
> >
> >
> > Roni,
> >
> > ,
> > > I have some concerns about the changes proposed in this AVD.
> > >
> > > 1. The AVD adds a new data type called multiplepayloadstream that is
> > > intended to allow more then one payload in a stream.
> > According to the
> > ASN.1
> > > you can have different media types in the same logical
> > channel which is
> > not
> > > a good practice and would break a lot of implementations.
> >
> > We already have precedence for this, such as RFC 2833.  In
> > addition, this
> > feature would only be used if both sides advertise the
> > capabilities, so I do
> > not expect to see anything break.
> >
> > > 2. The data type in H.245 open logical channel describe the
> > media type but
> > > do not specify the RTP payload format used. There are cases
> > were there is
> > > more then one way to build the RTP stream for example in
> > H.263. In the OLC
> > > in H2250LogicalChannelParameters there is a RTPPayloadType
> > parameter that
> > > describe the RTP payload. If the AVD is used to describe
> > multiple streams
> > > there is no way to specify the packetization scheme used.
> >
> > This might be true.  Would it be possible to add those parameters as
> > necessary in the future?  At the moment, the only use for
> > this capability at
> > the moment is for modem over IP, wherein every payload that
> > will be used is
> > understood based solely on the capability, I believe--
> > perhaps I'm wrong.
> > In any case, the important thing is to know whether the
> > syntax precludes the
> > specification of additional parameters.
> >
> > > 3. I think that the editor of H.235 will look to see if the
> > proposed AVD
> > > allows to specify and change a key for each payload that
> > can be used in
> > the
> > > logical channel. I am not an expert on H.235
> >
> > Most definitely.. I would certainly welcome comments and
> > input in the area
> > of security.
> >
> > Paul
> >
> >
>

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