[Galene] Re: SVC support

[Dave Taht <dave.taht@gmail.com>]

On Wed, May 12, 2021 at 8:19 AM Juliusz Chroboczek <jch@irif.fr> wrote:
>
> 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.

This is a really, really promising sounding technique!

> 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.

Currently. As both these are open source they can certainly be
improved. I haven't
hacked on firefox in quite some time... I can reach out to some contacts in the
mozilla organization and/or is there a good mailing list to join?

> 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.

Have you reported it?

>
> -- Juliusz
> _______________________________________________
> Galene mailing list -- galene@lists.galene.org
> To unsubscribe send an email to galene-leave@lists.galene.org



-- 
Latest Podcast:
https://www.linkedin.com/feed/update/urn:li:activity:6791014284936785920/

Dave Täht CTO, TekLibre, LLC