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RE: [AVT] Interop issue with H263-1998
Thanks for the background.
Actually I was analyzing an interop issue where one terminal generates H263+ using H263-1998 with no FMTP line, while the other assumes no H263+ annexes are being used and so raises an error on reception of H263+ syntax.
I was trying to understand which of the two terminals is compliant to the RFCs rules, and ... hitted into the problem :(
My conclusion is that it is legitimate to generate H263+ syntax when H263-1998 has been negotiated and no FMTP line has been provided, and that paragraph 8.1.1 of RFC 4629 is inaccurate.
Best regards
Guido
> -----Original Message-----
> From: Even, Roni [mailto:roni.even at polycom.co.il]
> Sent: lunedì 10 settembre 2007 11.09
> To: Franceschini Guido; avt at ietf.org
> Cc: Paltro Pier Carlo
> Subject: RE: [AVT] Interop issue with H263-1998
>
>
> Guido,
> I have to agree that systems that tried to use the payload
> type H263-1998 before RFC 4629 may send any annexes available
> in H.263+, not all of them since that may be not feasible. So
> it was really un-specified before RFC 4629.
>
> The big motivation for RFC 4629 was because the video
> conferencing manufacturers, who were the major users of
> H.263+ were trying to support SIP (Moving from H.263) and ran
> into SDP problems.
>
> When writing the draft, the assumption was that there were no
> real implementations using H.263-1998 but mostly H263 or
> H263-200 with profile and level optional options.
>
> Roni
>
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> A consensus means that everyone agrees to say collectively
> what no one believes individually
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
> > -----Original Message-----
> > From: Franceschini Guido
> [mailto:guido.franceschini at telecomitalia.it]
> > Sent: Tuesday, August 21, 2007 6:49 PM
> > To: avt at ietf.org
> > Cc: Paltro Pier Carlo
> > Subject: [AVT] Interop issue with H263-1998
> >
> > Dear all,
> >
> > I have an issue with the definition of the H263-1998 media type.
> > In the RFC 2429, no optional parameters are defined,
> implying that any
> > valid H263+ stream could be streamed.
> > In the RFC 4629, that obsoletes 2429, various optional
> parameters are
> > specified, which allow specifying the (decoder) support to
> the various
> > annexes.
> >
> > What confuses me is the following statement in RFC 4629,
> concerning H263-
> > 1998
> >
> > Interoperability considerations:
> >
> > These are receiver options; current implementations
> will not send
> > any optional parameters in their SDP. They will ignore the
> > optional parameters and will *** encode the H.263
> stream without any
> > ***
> > of the annexes. Most decoders support at least QCIF
> and CIF fixed
> > resolutions, and they are expected to be available
> almost in every
> > H.263-based video application.
> >
> > Indeed my understanding would be quite different, and I
> would have written
> > instead:
> >
> > These are receiver options; current implementations
> will not send
> > any optional parameters in their SDP. They will ignore the
> > optional parameters and will *** encode the H.263+ stream with
> > possibly all ***
> > of the annexes. Most decoders support at least QCIF
> and CIF fixed
> > resolutions, and they are expected to be available
> almost in every
> > H.263-based video application.
> >
> >
> > Any clarification would be welcomed
> >
> > Best regards
> > Guido Franceschini
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