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@packetizer.com] Sent: Tuesday, September 17, 2002 7:52 PM To: Even, Roni; ITU-SG16@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.
- 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.
- 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.
- 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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv@lists.intel.com