Re: [rtcweb] AVPF vs AVP

Hi, 

>Again, the word is MUST for video. I think that systems that 
>will interwork with RTCWEB systems will support AVPF since 
>they will need to support current video codecs. I do not see 
>RTCWEB systems interwork with systems that support only H.261 
>or even H.263, so I assume that the interworking will be with 
>systems that also use AVPF for video.
>  
>As for CLUE, we can discuss it in CLUE if relevant at all. It 
>may be relevant only for the video capture that should be 
>used for interworking with non CLUE systems.

Correct. 

Again, if we *mandate* the anyone involved in a session (CLUE session or something else) supports AVPF, we can use AVPF in the m= line.

Regards,

Christer

> > -----Original Message-----
> > From: Christer Holmberg [mailto:christer.holmberg@ericsson.com]
> > Sent: Friday, September 16, 2011 8:51 AM
> > To: Roni Even; Magnus Westerlund
> > Cc: rtcweb@ietf.org
> > Subject: RE: [rtcweb] AVPF vs AVP
> > 
> > 
> > Hi,
> > 
> > >I can agree that if you are doing video call you must send AVPF 
> > >regardless if you are talking with this type of systems 
> that you call 
> > >"not legacy" or systems that you call "legacy".
> > >This must be a MUST in the text otherwise the so called 
> "legacy" end 
> > >point will think it is AVP and will not send feedback 
> messages which 
> > >will break video conferencing applications.
> > 
> > If the video conf app *requires* AVPF, you should include 
> AVPF in the 
> > m= line.
> > 
> > The AVP+a=rtcp-fb proposal is an alternative to CapNeg, 
> where there is 
> > "built-in" fallback to AVP in case the answerer does not 
> support AVPF.
> > 
> > And, IF we choose to go forward with this proposal, it 
> should also be 
> > adopted by CLUE.
> > 
> > Regards,
> > 
> > Christer
> > 
> > 
> > 
> > 
> > > > -----Original Message-----
> > > > From: Magnus Westerlund [mailto:magnus.westerlund@ericsson.com]
> > > > Sent: Thursday, September 15, 2011 7:06 PM
> > > > To: Roni Even
> > > > Cc: rtcweb@ietf.org
> > > > Subject: Re: [rtcweb] AVPF vs AVP
> > > >
> > > > On 2011-09-15 16:01, Roni Even wrote:
> > > > > Magnus,
> > > > > I noticed that you claim that all AVPF feedback messages are
> > > > explicitly
> > > > > negotiated, is this a requirement. At least RTCP-SR-REQ is not
> > > > negotiated in
> > > > > SDP.
> > > >
> > > > You are correct, had not actually noticed that. Fortunately
> > > that isn't
> > > > an real issue.
> > > >
> > > > First of all the support of AVPF can still be 
> negotiated with the 
> > > > a=rtcp-fb. Simply the trr-int configuration lets both side show 
> > > > support of AVPF.
> > > >
> > > > Secondly, for the RTCP-SR-REQ if one uses the header 
> extension to 
> > > > deliver the synch data then that is explicitly indicated.
> > > And if you
> > > > ignore or don't understand the request then you simple 
> fall back 
> > > > to normal synchronization procedures with more delay before
> > > completing it.
> > > >
> > > > >
> > > > > As for using AVPF while signaling AVP that will 
> confuse endpoint 
> > > > > that
> > > > so not
> > > > > understand this convention and can support AVPF. They 
> will see 
> > > > > an
> > > > offer with
> > > > > AVP but with parameters that are not part of AVP. They can
> > respond
> > > > with AVP
> > > > > without the AVPF parameter and behave like AVP endpoints
> > > even though
> > > > they
> > > > > support AVPF. This will prevent them from sending 
> AVPF feedback
> > > > messages.
> > > >
> > > > They can still use AVPF timing rules, even if the other
> > > end-point is
> > > > AVP only. They only need to restrict themselves from
> > > sending feedback
> > > > messages.
> > > >
> > > > > This may be a problem for what you call "legacy" video
> > > conferencing
> > > > > endpoint. (I do not like the term legacy here since these are 
> > > > > not
> > > > legacy
> > > > > endpoint but AVP/AVPF compliant EPs
> > > >
> > > > Yes, I agree it is not without issues in that regard.
> > > >
> > > > I would also like to note that if you require AVPF and 
> don't think 
> > > > talking to AVP only end-points then one really should
> > > include the AVPF
> > > > in the m= line to prevent fallback.
> > > >
> > > > >
> > > > > I think that if we are not going to use cap-neg we 
> should make 
> > > > > it historical.
> > > >
> > > > I kind of agree with that also. But if it constantly 
> fails in the 
> > > > market I think we have to recognize that and do something else 
> > > > that works better.
> > > >
> > > > Cheers
> > > >
> > > > Magnus Westerlund
> > > >
> > > >
> > > 
> --------------------------------------------------------------------
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> > > >
> > > 
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