Re: [siprec] Multiplexing different participants' streams on the same port
"Parthasarathi R (partr)" <partr@cisco.com> Wed, 30 March 2011 16:54 UTC
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Thread-Topic: [siprec] Multiplexing different participants' streams on the same port
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From: "Parthasarathi R (partr)" <partr@cisco.com>
To: "Elwell, John" <john.elwell@siemens-enterprise.com>, Hadriel Kaplan <HKaplan@acmepacket.com>, "Paul Kyzivat (pkyzivat)" <pkyzivat@cisco.com>
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Cc: siprec@ietf.org, Leon Portman <Leon.Portman@nice.com>
Subject: Re: [siprec] Multiplexing different participants' streams on the same port
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John/Hadriel, Please read inline. Thanks Partha -----Original Message----- From: siprec-bounces@ietf.org [mailto:siprec-bounces@ietf.org] On Behalf Of Elwell, John Sent: Wednesday, March 30, 2011 8:33 PM To: Hadriel Kaplan; Paul Kyzivat (pkyzivat) Cc: siprec@ietf.org; Leon Portman Subject: Re: [siprec] Multiplexing different participants' streams on the same port (this time as individual) It occurs to me that if you just indicate, say, audio in the m-line and a given codec, middleboxes doing call admission control might make some assumptions about bandwidth and assume just a single stream at the rate concerned. <partha> IMO, This problem will be solved in case bandwidth attribute under the single stream is populated properly. If it is the problem, then the problem is outside the scope of SIPREC. </partha> Putting several such streams over the same path, from different participants, might cause problems. Any opinions? John > -----Original Message----- > From: siprec-bounces@ietf.org > [mailto:siprec-bounces@ietf.org] On Behalf Of Hadriel Kaplan > Sent: 30 March 2011 13:58 > To: Paul Kyzivat > Cc: siprec@ietf.org; Leon Portman > Subject: Re: [siprec] Multiplexing different participants' > streams on the same port > > > In practice we see all kinds of things in the RTCP cname, often > unrelated to signaling info. > But you can't rely on it anyway, since you can't rely on there being > any RTCP. > > Furthermore, although I've (shockingly) seen some devices indicate > SSRC in SDP per RFC 5576, it's rare... <partha> May take time to adopt..As less RTP MUX in single stream implementation may be one of the reason. </partha> which means you won't know the > SSRC at call setup time, so it won't be available to send in metadata > at that time, requiring an update. > <partha> I guess that it is possible to populate SSRC while offer is sent out and it is implementation specific </partha> > I humbly suggest that UDP port numbers are not in short supply, and > using one per stream is both simple and effective. <partha> may not always the case. There are nightmare with multiple m-lines passing through some middle boxes </partha?> > > -hadriel > > > On Mar 29, 2011, at 6:13 PM, Paul Kyzivat wrote: > > > On 3/29/2011 6:05 PM, Charles Eckel (eckelcu) wrote: > >> Typically they appear in RTCP only, and not in SIP or SDP. > > > > I understand that. > > > > I'm just wondering what is done by typical sip devices that > handle both > > media and signaling - e.g. phones and gateways. Presumably > *something* > > is put in for the cname. But I suspect that layering will > result in the > > media layer doing its own thing without knowledge of what > sort of names > > are being used in the signaling layer. > > > > If so, just reporting the cname in the metadata might not > provide any > > benefit if it can't be correlated with some signaling name. > > > > Thanks, > > Paul > > > > The RTCP > >> identify the mapping of CNAME to SSRC. In the SDP, you can > specify the > >> SSRC for a media stream as described in RFC 5576 - > Source-Specific Media > >> Attributes in the Session Description Protocol (SDP). I am > not sure if > >> there are many existing implementations that do this. > >> > >> Cheers, > >> Charles > >> > >>> -----Original Message----- > >>> From: Paul Kyzivat (pkyzivat) > >>> Sent: Tuesday, March 29, 2011 11:41 PM > >>> To: Charles Eckel (eckelcu) > >>> Cc: Leon Portman; Parthasarathi R (partr); siprec@ietf.org > >>> Subject: Re: [siprec] Multiplexing different > participants' streams on > >> the same port > >>> > >>> Charles, > >>> > >>> *In practice* how are cnames set for sip calls? > >>> I'm assuming they are something canned and unrelated to > the signaling > >>> identity. > >>> > >>> Thanks, > >>> Paul > >>> > >>> On 3/29/2011 10:20 AM, Charles Eckel (eckelcu) wrote: > >>>> For the format and value of the CNAME, I suggest having a look at > >>>> "Guidelines for Choosing RTP Control Protocol (RTCP) > Canonical Names > >>>> (CNAMEs)", draft-ietf-avt-rtp-cnames-05. > >>>> If the SIP AOR is meant to be the AOR registered by the > participant, > >>>> this is almost certainly going to be something different. > >>>> The participant AOR is per participant. The CNAME is per media > >> stream. > >>>> > >>>> Cheers, > >>>> Charles > >>>> > >>>>> -----Original Message----- > >>>>> From: Paul Kyzivat (pkyzivat) > >>>>> Sent: Tuesday, March 29, 2011 2:23 PM > >>>>> To: Leon Portman > >>>>> Cc: Parthasarathi R (partr); Charles Eckel (eckelcu); > >> siprec@ietf.org > >>>>> Subject: Re: [siprec] Multiplexing different > participants' streams > >> on > >>>> the same port > >>>>> > >>>>> > >>>>> > >>>>> On 3/29/2011 7:21 AM, Leon Portman wrote: > >>>>>> I like it. > >>>>>> > >>>>>> Quick question. In metadata we are using "<aor>" > attribute but in > >>>> SDP, it is "CNAME"? Can we use the > >>>>> same? > >>>>> > >>>>> Charles knows more than I about RTP. AFAIK CNAME is an > essentially > >>>>> arbitrary string that is assigned by the media source. > (Are their > >>>>> constraints on its length or format?) Perhaps it could > be formatted > >> as > >>>> a > >>>>> sip AOR, perhaps not. Even if it *could*, in practice > *will* it be? > >>>> ISTM > >>>>> it would not be wise to count on these being the same. > >>>>> > >>>>> We should probably allow participants to specify their cname as > >> well > >>>> as > >>>>> their AOR. This may get complicated if the same > participant ends up > >>>> with > >>>>> differing media streams it sends. > >>>>> > >>>>> I also wonder if the SRC will always know the CNAMEs of the > >> streams. I > >>>>> suspect we can't count on that. > >>>>> > >>>>> Thanks, > >>>>> Paul > >>>>> > >>>>>> Leon > >>>>>> > >>>>>> > >>>>>> > >>>>>> -----Original Message----- > >>>>>> From: siprec-bounces@ietf.org > [mailto:siprec-bounces@ietf.org] On > >>>> Behalf Of Parthasarathi R (partr) > >>>>>> Sent: Monday, March 28, 2011 10:42 AM > >>>>>> To: Charles Eckel (eckelcu); Paul Kyzivat (pkyzivat); > >>>> siprec@ietf.org > >>>>>> Subject: Re: [siprec] Multiplexing different > participants' streams > >>>> on the same port > >>>>>> > >>>>>> Charles, > >>>>>> > >>>>>> IMO, the current metadata model helps to address RTP > MUX streams > >> as > >>>> well. In terms of model, > >>>>> multiple participants (P1, P2, P3) metadata block points to the > >> single > >>>> stream (S1) and stream block > >>>>> contains SSRC& CSRC information. IOW, SIPREC model > abstract RTP > >> MUX > >>>> stream within media stream block. > >>>>> Please let me know in case you feel that model does not > address it. > >>>>>> > >>>>>> In case of metadata format, multiple "participant" > elements have > >>>> send element with single stream > >>>>> element. The stream element has a label attribute which > points to > >> the > >>>> m-line which contains "ssrc" > >>>>> attribute with CNAME parameter. I attached the example for your > >>>> reference and The example is the one > >>>>> of the way to represent RTP-MUX stream in the metadata format. > >> Please > >>>> let me know the issues with this > >>>>> format and example. > >>>>>> > >>>>>> I agree with Paul and you that we need to understand > how RTP mux > >>>> stream will be standardized but > >>>>> IMO, it is not the limiting factor for SIPREC as of now. > >>>>>> > >>>>>> Thanks > >>>>>> Partha > >>>>>> > >>>>>> -----Original Message----- > >>>>>> From: siprec-bounces@ietf.org > [mailto:siprec-bounces@ietf.org] On > >>>> Behalf Of Charles Eckel (eckelcu) > >>>>>> Sent: Friday, March 18, 2011 8:40 PM > >>>>>> To: Paul Kyzivat (pkyzivat); siprec@ietf.org > >>>>>> Subject: Re: [siprec] Multiplexing different > participants' streams > >>>> on thesame port > >>>>>> > >>>>>> I agree with the comment regarding CLUE, so let me > take a simpler > >>>> example, and audio mixer. This > >>>>> mixer may mix the audio from multiple participants. > >>>>>> > >>>>>> Participant 1 (P1) > >>>>>> Participant 2 (P2) > >>>>>> Participant 3 (P3) > >>>>>> > >>>>>> P1 sends audio stream with SSRC-P1 > >>>>>> P2 sends audio stream with SSCR-P2 > >>>>>> P2 sends audio stream with SSCR-P3 > >>>>>> > >>>>>> MixerA(Ma) > >>>>>> > >>>>>> Ma sends mixed audio stream with SSRC SSRC-Ma and CSRC > >>>>>> SSRC-P1/SSRC-P2/SSRC-P3 as part of the CS. > >>>>>> The SRC sends this stream to the SRS for recording. I > suspect it > >>>> might change the SSRC to be SSRC- > >>>>> SRC but maintain the CSRC information identifying P1/P2/P3. > >>>>>> I expect this would be modeled as a single stream with 3 > >>>> participants P1, P2, P3. The mapping of P1 > >>>>> to SSRC-P1 is captured in the RTCP data sent by SRC to > SRS. In this > >>>> case, there is no need to anything > >>>>> in the metadata. > >>>>>> However, if the CSRCs are not propagated all the way > to the SRS, > >>>> then perhaps participant info would > >>>>> need to be communicated via the metadata. > >>>>>> > >>>>>> Note, I do not pretend to have this all figured out; > rather, I am > >>>> putting out some ideas to see if > >>>>> this gels with what others have in mind. > >>>>>> > >>>>>> Cheers, > >>>>>> Charles > >>>>>> > >>>>>>> -----Original Message----- > >>>>>>> From: siprec-bounces@ietf.org > [mailto:siprec-bounces@ietf.org] On > >>>>>> Behalf Of Paul Kyzivat (pkyzivat) > >>>>>>> Sent: Friday, March 18, 2011 5:38 AM > >>>>>>> To: siprec@ietf.org > >>>>>>> Subject: Re: [siprec] Multiplexing different participants' > >> streams > >>>> on > >>>>>> the same port > >>>>>>> > >>>>>>> I don't know if this is a good idea or not. But if we want to > >>>> consider > >>>>>> > >>>>>>> it, then we should probably enter into some > discussion with CLUE, > >>>> to > >>>>>> see > >>>>>>> if there is any commonality. > >>>>>>> > >>>>>>> Over in CLUE, this mixing of multiple streams over one RTP > >> session > >>>> has > >>>>>> > >>>>>>> been brought up because it is a technique used in existing > >>>> proprietary > >>>>>> > >>>>>>> products. But the CLUE wg isn't yet to a point where > it is ready > >> to > >>>>>>> decide if this will be a requirement. And the AVT people have > >>>> strong > >>>>>>> opinions on what is/isn't appropriate. > >>>>>>> > >>>>>>> Thanks, > >>>>>>> Paul > >>>>>>> > >>>>>>> On 3/18/2011 4:11 AM, Elwell, John wrote: > >>>>>>>> Something Charles mentioned in another thread triggered me to > >>>> raise > >>>>>> this. > >>>>>>>> > >>>>>>>> We consider different participants in the CS as potentially > >>>>>> producing separate media streams that > >>>>>>> the SRC sends to the SRS, where the SRC can send them mixed or > >>>>>> unmixed. > >>>>>>>> > >>>>>>>> When sending them unmixed, up till now I think we have > >> considered > >>>>>> sending them to separate ports on > >>>>>>> the SRS and identifying them as separate m= lines in the SDP. > >>>> Another > >>>>>> possibility might be to > >>>>>>> multiplex the different streams on the same port and identify > >> them > >>>> by > >>>>>> different SSRC values. I am not > >>>>>>> sure whether this would be a correct use of SSRC, and > I suspect > >> we > >>>>>> would need to check with AVTCORE. > >>>>>>> Recent discussions in other contexts (telepresence, > RTC-Web) have > >>>> also > >>>>>> drawn my attention to such > >>>>>>> possibilities. See also > >>>>>> > https://datatracker.ietf.org/doc/draft-perkins-rtcweb-rtp-usage/. > >>>>>>>> > >>>>>>>> Of course, it would mean that we would have to rethink how we > >>>>>> reference the different streams from > >>>>>>> metadata. > >>>>>>>> > >>>>>>>> I am not necessarily proposing such a change - I just want to > >> make > >>>>>> sure we have given it due > >>>>>>> consideration. > >>>>>>>> > >>>>>>>> John (as individual) > >>>>>>>> > >>>>>>>> > >>>>>>>> _______________________________________________ > >>>>>>>> siprec mailing list > >>>>>>>> siprec@ietf.org > >>>>>>>> https://www.ietf.org/mailman/listinfo/siprec > >>>>>>>> > >>>>>>> _______________________________________________ > >>>>>>> siprec mailing list > >>>>>>> siprec@ietf.org > >>>>>>> https://www.ietf.org/mailman/listinfo/siprec > >>>>>> _______________________________________________ > >>>>>> siprec mailing list > >>>>>> siprec@ietf.org > >>>>>> https://www.ietf.org/mailman/listinfo/siprec > >>>>>> > >>>> > >> > > _______________________________________________ > > siprec mailing list > > siprec@ietf.org > > https://www.ietf.org/mailman/listinfo/siprec > > _______________________________________________ > siprec mailing list > siprec@ietf.org > https://www.ietf.org/mailman/listinfo/siprec > _______________________________________________ siprec mailing list siprec@ietf.org https://www.ietf.org/mailman/listinfo/siprec
- [siprec] Multiplexing different participants' str… Elwell, John
- Re: [siprec] Multiplexing different participants'… Paul Kyzivat
- Re: [siprec] Multiplexing different participants'… Charles Eckel (eckelcu)
- Re: [siprec] Multiplexing different participants'… Parthasarathi R (partr)
- Re: [siprec] Multiplexing different participants'… Leon Portman
- Re: [siprec] Multiplexing different participants'… Elwell, John
- Re: [siprec] Multiplexing different participants'… Paul Kyzivat
- Re: [siprec] Multiplexing different participants'… Paul Kyzivat
- Re: [siprec] Multiplexing different participants'… Charles Eckel (eckelcu)
- Re: [siprec] Multiplexing different participants'… Paul Kyzivat
- Re: [siprec] Multiplexing different participants'… Charles Eckel (eckelcu)
- Re: [siprec] Multiplexing different participants'… Paul Kyzivat
- Re: [siprec] Multiplexing different participants'… Hadriel Kaplan
- Re: [siprec] Multiplexing different participants'… Elwell, John
- Re: [siprec] Multiplexing different participants'… Elwell, John
- Re: [siprec] Multiplexing different participants'… Parthasarathi R (partr)
- Re: [siprec] Multiplexing different participants'… Hadriel Kaplan
- Re: [siprec] Multiplexing different participants'… Henry Lum
- Re: [siprec] Multiplexing different participants'… Paul Kyzivat