From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.lang.hm (unknown [66.167.227.145]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 5F1413B2A4; Fri, 27 Mar 2020 15:12:28 -0400 (EDT) Received: from dlang-laptop.LAN (dlang-laptop.LAN [10.2.0.162]) by mail.lang.hm (Postfix) with ESMTP id 64BE3AD9C3; Fri, 27 Mar 2020 12:12:27 -0700 (PDT) Date: Fri, 27 Mar 2020 12:12:27 -0700 (PDT) From: David Lang X-X-Sender: dlang@dlang-laptop To: "David P. Reed" cc: Dave Taht , Make-Wifi-fast , Anthony Minessale II , Cake List , Ken Rice , cerowrt-devel , bloat In-Reply-To: <1585335604.839628636@apps.rackspace.com> Message-ID: References: <1585335604.839628636@apps.rackspace.com> User-Agent: Alpine 2.21.1 (DEB 209 2017-03-23) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Subject: Re: [Bloat] [Cake] mo bettah open source multi-party videoconferncing in an age of bloated uplinks? X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Mar 2020 19:12:28 -0000 On Fri, 27 Mar 2020, David P. Reed wrote: > > Congestion control for real-time video is quite different than for streaming. Streaming really is dealt with by a big enough (multi-second) buffering, and can in principle work great over TCP (if debloated). > > UDP congestion control MUST be end-to-end and done in the application layer, which is usually outside the OS kernel. This makes it tricky, because you end up with latency variation due to eh OS's process scheduler that is on the order of magnitude of the real-time requirements for air-to-air or light-to-light response (meaning the physical transition from sound or picture to and from the transducer). at some level this is correct, but if the link is clogged with TCP packets, it doesn't matter what your UDP application attempts to do, so installing cake to keep individual links from being too congested will allow your UDP application have a chance to operate. David Lang