From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: mail.toke.dk; spf=pass (mailfrom) smtp.mailfrom=irif.fr (client-ip=2001:660:3301:8000::1:2; helo=korolev.univ-paris7.fr; envelope-from=jch@irif.fr; receiver=) Received: from korolev.univ-paris7.fr (korolev.univ-paris7.fr [IPv6:2001:660:3301:8000::1:2]) by mail.toke.dk (Postfix) with ESMTPS id 31B40849875 for ; Wed, 12 May 2021 17:19:37 +0200 (CEST) Received: from mailhub.math.univ-paris-diderot.fr (mailhub.math.univ-paris-diderot.fr [81.194.30.253]) by korolev.univ-paris7.fr (8.14.4/8.14.4/relay1/82085) with ESMTP id 14CFJaJr011672 for ; Wed, 12 May 2021 17:19:36 +0200 Received: from mailhub.math.univ-paris-diderot.fr (localhost [127.0.0.1]) by mailhub.math.univ-paris-diderot.fr (Postfix) with ESMTP id E43A8DB1CC for ; Wed, 12 May 2021 17:19:36 +0200 (CEST) X-Virus-Scanned: amavisd-new at math.univ-paris-diderot.fr Received: from mailhub.math.univ-paris-diderot.fr ([127.0.0.1]) by mailhub.math.univ-paris-diderot.fr (mailhub.math.univ-paris-diderot.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id FXrrAK4u7UP4 for ; Wed, 12 May 2021 17:19:34 +0200 (CEST) Received: from pirx.irif.fr (unknown [78.194.40.74]) (Authenticated sender: jch) by mailhub.math.univ-paris-diderot.fr (Postfix) with ESMTPSA id DA9E8DB1C9 for ; Wed, 12 May 2021 17:19:34 +0200 (CEST) Date: Wed, 12 May 2021 17:19:34 +0200 Message-ID: <87r1icnfnd.wl-jch@irif.fr> From: Juliusz Chroboczek To: galene@lists.galene.org User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/28.0 Mule/6.0 MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (korolev.univ-paris7.fr [194.254.61.138]); Wed, 12 May 2021 17:19:36 +0200 (CEST) X-Miltered: at korolev with ID 609BF208.001 by Joe's j-chkmail (http : // j-chkmail dot ensmp dot fr)! X-j-chkmail-Enveloppe: 609BF208.001 from mailhub.math.univ-paris-diderot.fr/mailhub.math.univ-paris-diderot.fr/null/mailhub.math.univ-paris-diderot.fr/ X-j-chkmail-Score: MSGID : 609BF208.001 on korolev.univ-paris7.fr : j-chkmail score : . : R=. U=. O=. B=0.000 -> S=0.000 X-j-chkmail-Status: Ham Message-ID-Hash: FZRIOUO5WRRHFMK7RAX4FPG73DZYBWFD X-Message-ID-Hash: FZRIOUO5WRRHFMK7RAX4FPG73DZYBWFD X-MailFrom: jch@irif.fr X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.4 Precedence: list Subject: [Galene] SVC support List-Id: =?utf-8?q?Gal=C3=A8ne_videoconferencing_server_discussion_list?= Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Hi, I've just pushed the code for Scalable Video Coding (SVC) to the branch "svc" of the github repository; be aware that I will be rebasing this branch. It's currently running on galene.org port 8444 (but not port 8443, which is running stable 0.3.5). SVC is a technique where a single video stream is "layered": frames are labelled with information about whether they can be dropped, and the server can reduce the bitrate sent to a client. The advantage of SVC over simulcast is that switching layers is a much more lightweight operation: switching simulcast streams requires a keyframe, while switching scalable layers can happen a few times per packet. SVC requires no support on the receiver side -- it's the sender who does the layering, the receiver receives a perfectly banal video stream. Sending a scalable stream is controlled by the simulcast switch, due to some limitations in both Chrome/Chromium and Firefox, so you cannot have SVC without simulcast. Which is a waste, but what can I do. You can test by enabling simulcast then testing the "stats.html" page; the layer chosen for each down track is indicated before the bitrate. Temporal scalability (reducing the framerate) is supported for both VP8 and VP9; unfortunately, I wasn't able to test the VP9 support, since my version of Chromium immediately crashes when you request a VP9 simulcast stream. Spacial scalability (reducing the resolution) should be doable for VP9, but the point is somewhat moot until Chromium fix their bug. -- Juliusz