Re: [rtcweb] An input for discussing congestion control (Fwd: New Version Notification for draft-alvestrand-rtcweb-congestion-00.txt)
Randell Jesup <randell-ietf@jesup.org> Mon, 19 September 2011 13:17 UTC
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Date: Mon, 19 Sep 2011 09:16:03 -0400
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Subject: Re: [rtcweb] An input for discussing congestion control (Fwd: New Version Notification for draft-alvestrand-rtcweb-congestion-00.txt)
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On 9/19/2011 4:29 AM, Henrik Lundin wrote: > Tim, > > The problem that we are trying to attack with the proposal is perhaps > better described as "available bandwidth estimation" rather than > congestion control. I _would_ like to try and separated it from > codecs. The bandwidth estimator should inform the sender of the > current feasible rate between two endpoints, and it should then be up > to the sending client (application, codecs, channel coding, etc) to > figure out a way to stay within that limit, while maintaining an > acceptable quality for the use-case at hand. Right - I think we're in agreement (and Tim is) that this is the best tack to take on the problem - involve the application in figuring out how to meet the bandwidth limits. This part of it will largely be an API specification problem; figuring out how to set up the API to tell the JS app what is available, and the interfaces for responding to that. > > On Mon, Sep 19, 2011 at 10:21 AM, Tim Panton <tim@phonefromhere.com > <mailto:tim@phonefromhere.com>> wrote: > > > I'd like to lurk on any BoF list, if I may, > but I have a feeling that congestion control isn't quite such a > self-contained problem > as forming a BoF list might imply. > > Roughly, my argument is that any modern congestion control for RTC > needs to involve the application > and the codec. > Absolutely agree. > > Here's an example: > I'm in a video conference with 4 other people and I'm > exceeding the available downlink > bandwidth. What I want is that the video degrades (framerate of > quality) without _any_ degradation > of the video. > I'm a little confused by that wording, but I suspect we agree. The app might want ask the senders to cut their framerate or cut their resolution, or cut quality but keep framerate & resolution, or ask the senders to switch to lower-bandwidth parameters unless the VAD decides the person is talking, etc. No one answer is the 'right' one for every app or situation. > I might even want to drop all the video but keep the audio and > screenshare alive. > Exactly. > Conversely if I'm watching an ice hockey game - I'd rather > lose audio quality than frame-rate. > > But in _both_ cases I'd like the app to try and tweak the encoder > params to get within the available bandwidth > before we start injecting delay or dropping frames. > > So my proposal is that the web app is given a chance to get within > the available bandwidth > before the system starts putting hard constraints on the RTP level. > > All of which makes it something we need to discuss in a holistic > fashion with the rest of the API. > -- Randell Jesup randell-ietf@jesup.org
- [rtcweb] An input for discussing congestion contr… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Magnus Westerlund
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Stefan Holmer
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Varun Singh
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Tim Panton
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Varun Singh
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi
- Re: [rtcweb] An input for discussing congestion c… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi
- Re: [rtcweb] An input for discussing congestion c… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Dzonatas Sol
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi
- Re: [rtcweb] An input for discussing congestion c… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Jim Gettys
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Ingemar Johansson S
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Stefan Holmer
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi