Re: [rtcweb] [tsvwg] Diffserv QoS for Video
"Paul E. Jones" <paulej@packetizer.com> Wed, 11 May 2016 03:31 UTC
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From: "Paul E. Jones" <paulej@packetizer.com>
To: Harald Alvestrand <harald@alvestrand.no>, Ruediger.Geib@telekom.de
Date: Wed, 11 May 2016 03:31:34 +0000
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Subject: Re: [rtcweb] [tsvwg] Diffserv QoS for Video
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Yeah, that's a good point. Let's not go down the path of re-opening a new round of changes that would require yet another LC and more time. Paul ------ Original Message ------ From: "Harald Alvestrand" <harald@alvestrand.no> To: Ruediger.Geib@telekom.de; paulej@packetizer.com Cc: rtcweb@ietf.org; tsvwg@ietf.org Sent: 5/10/2016 3:35:42 AM Subject: Re: [tsvwg] Diffserv QoS for Video >FTR: I don't see such an agreement at all. > >On the contrary, my perception is that people want the ability to >deliver audio with a lower loss probability and lower delay probability >than video - it's more important to the conversation, and there are >fewer things the recipient can do to hide the losses. If the sender >chose to send them on separate flows, they shold have different DSCP >markings. > >I believe this is what draft-ietf-tsvwg-rtcweb-qos-15 section 5 states, >and I believe that this is what TSVWG has declared consensus on and >wrote in the document that passed WG last call and is currently in >"waiting for writeup" state. > >Changing this determination would, at minimum, require reopening the WG >Last Call. >And I'd object. > >Harald > > >Den 10. mai 2016 08:56, skrev Ruediger.Geib@telekom.de: >> Hi Paul, >> >> I think we agree, that audio and video frames, if both are part of >>the same (interactive) media flow should be transported by the same >>PHB [PJ] or the same queue [RG]. The latter is ensured, if the same >>PHB is picked for audio and video. To me the text of the draft so far >>doesn't express that both audio and video are supposed to use an >>"Interactive Video..." PHB, if both are present. I'd prefer to have >>text with a non binding standard requirement saying >> >> However, if the application wishes to send both interactive >> video and audio, it is RECOMMENDED to transport audio >> and video packets by the same per hop behavior. For example, >> audio and video packets would both be marked as AF42 or >> AF43. >> >> I don't insist on descriptive text proposing to transport audio by an >>AF4 PHB offering a lower drop ratio than that used to transport video. >>My audio/video experts support this and I'm pretty sure, that also >>Cisco representatives mentioned that audio quality ranks above video >>quality in telepresence sessions. >> >> Regards, >> >> Ruediger >> >> >> -----Ursprüngliche Nachricht----- >> Von: Paul E. Jones [mailto:paulej@packetizer.com] >> Gesendet: Montag, 9. Mai 2016 21:03 >> An: Geib, Rüdiger >> Cc: brian.e.carpenter@gmail.com; david.black@emc.com; tsvwg@ietf.org; >>rtcweb@ietf.org >> Betreff: Re: AW: [tsvwg] Diffserv QoS for Video >> >> Ruediger, >> >> Perhaps an example might be helpful. How about I add this text for >>illustrative purposes? >> >> To illustrate the use of the above table, let us assume the >> application assigns a priority of "medium" to audio and video >> flows. Given that assumption, if the application wishes to send >> only audio then packets would be marked EF. However, if the >> application wishes to send both interactive video and audio, >> then audio and video packets would both be marked as AF42 or >> AF43. The intent is to ensure that when both audio and video >> are being sent together that they receive similar per-hop >> behavior. >> >> This doesn't get into the preference for AF42 vs. AF43. If it were >>me, I'd mark all audio as AF42 and only key video frames as AF42. All >>predictive frames would be sent with an AF43 marking. I might even >>take it a step further and classify all audio as "high". However, >>I've seen a tremendous amount of debate on this before, so I'd prefer >>to not go too far in dictating audio markings vs. video. I do think >>most people generally agree about at least ensuring the class is the >>same, otherwise the wildly different PHB introduces skew between A/V >>packet arrival, thus inflating the size of buffers managing the A/V >>streams. However, we do not want to dictate that audio should be >>treated significantly better than audio. For deaf users, for example, >>the audio really isn't important at all. That is perhaps an extreme >>example, but it nonetheless highlights why we should be cautious about >>exactly what we normatively mandate. >> >> Paul >> >> ------ Original Message ------ >> From: Ruediger.Geib@telekom.de >> To: paulej@packetizer.com >> Cc: brian.e.carpenter@gmail.com; david.black@emc.com; tsvwg@ietf.org; >>rtcweb@ietf.org >> Sent: 5/9/2016 3:34:25 AM >> Subject: AW: [tsvwg] Diffserv QoS for Video >> >>> Hi Paul, >>> >>> I've talked with audio/video experts of Deutsche Telekom and they >>>too >>> favored what you recommend below: transport audio and video by the >>>same >>> queue. Your statement below however stops there and the draft text >>> doesn't clarify the issue: >>> >>> If there's interactive video with audio, then they both should be >>> marked for the same PHB which is: >>> - EF ? >>> - AF4? Like AF41 Audio, AF42 Video (AF43 in addition, if P or B >>>frames >>> are to receive a lower priority / >>> higher drop precedence PHB)? >>> >>> I personally prefer AF4 if audio and video are to be transported in >>>the >>> same queue. >>> >>> I'd also ask for the draft text to be clear about the issue when to >>> mark audio by the EF PHB. My understanding after reading your >>>statement >>> below is: Audio marked EF if there's no video flow only. >>> >>> ... >>> BC>Finally, why is audio not also subdivided into interactive and >>> BC>non-interactive? As far as I can see, both are logically >>>possible. >>> >>> [PJ] For WebRTC, audio alone is "interactive" in nature (which is >>> why it's marked EF). However, if one is sending audio and video >>> it makes sense to mark them both same way to get the same PHB and >>> hopefully have them queued in the same buffers along the path. >>> Sending audio as EF and possibly having a PHB that results in >>> packets arriving much faster than corresponding video packets >>> marked as AF42 is not at all helpful for applications that have >>> to synchronize the audio and video flows. >>> ... >>> >>> Paul >>> >>> >>> Regards, >>> >>> Ruediger >>> >>
- [rtcweb] Diffserv QoS for Video Black, David
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Brian E Carpenter
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Bernard Aboba
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Brian E Carpenter
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Bernard Aboba
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Brian E Carpenter
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Stefan Håkansson LK
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Paul E. Jones
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Ruediger.Geib
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Paul E. Jones
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Ruediger.Geib
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Harald Alvestrand
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Ruediger.Geib
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Romascanu, Dan (Dan)
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Paul E. Jones
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Black, David
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Brian E Carpenter
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Ruediger.Geib
- Re: [rtcweb] [tsvwg] Diffserv QoS for Video Cullen Jennings (fluffy)