From: Juliusz Chroboczek <jch@irif.fr> To: galene@lists.galene.org Subject: [Galene] SVC support Date: Wed, 12 May 2021 17:19:34 +0200 [thread overview] Message-ID: <87r1icnfnd.wl-jch@irif.fr> (raw) 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
next reply other threads:[~2021-05-12 15:19 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-12 15:19 Juliusz Chroboczek [this message] 2021-05-12 15:41 ` [Galene] " Dave Taht 2021-05-12 16:26 ` Juliusz Chroboczek 2021-05-12 16:35 ` Juliusz Chroboczek
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