Scalable Video codec : SVC

[Ju Ju]

I'm pointing you a very interesting article about SVC if you are interested in this subject :

http://www.nojitter.com/post/240168352/implementing-svc-in-webrtc

You will learn VP8 support temporal scalability and H264 spatial scalability, natively.

Lorenzo what do you think of his proposal ?

● Recodes regular incoming VP8 video streams from the browser into VP8 SVC
● Reduces the bandwidth of the video streams using SVC

● Create a group video conferencing canvas by mixing and regulating video streams.
● Monitor each client's parameters, its channel and screen resolution (desktop or mobile), and automatically "thin out" the mixed group video conference before sending it on to the WebRTC browser, which results in a normal VP8 stream with the desired characteristics. It could be done effectively by coding server streams into a VP8 SVC and applying SVC to the video stream.

J-

[Ju Ju]

Besides question for lorenzo :

What will do janus if we enable VP9 support in videoroom and enable VP9 SVC in chrome  ?

https://webrtchacks.com/chrome-vp9-svc/

Currently VP9 SVC is enabled in standard Chrome for screensharing only. However, VP9 SVC support for any encoded stream (at least since M57) can be enabled with a field trial command line parameter:

chrome --force-fieldtrials=WebRTC-SupportVP9SVC/EnabledByFlag_2SL3TL

If you do that, Chrome will SVC encode every VP9 stream it sends.  With the above setting, the VP9 encoder will produce 2 spatial layers (with size and size/2) and 3 temporal layers (at FPS, FPS/2 and FPS/4) and no quality layers.

J-

[Lorenzo Miniero]

We're not going to add video transcoding to Janus. If you need that, you should either write a new plugin or use the RTP forwarding to let something else transcode for you (gstreamer, ffmpeg, others).

L.

[Lorenzo Miniero]

Looks interesting but haven't played with that yet, and not sure when I'll find the time to.

L.

[Julien Godier]

Hello lorenzo

i m not talking about transcoding at all !

I m talking about a SFU which can handle information of layer in the VP9 codec

"Each RTP packet carrying a VP9 stream contains data from only one layer frame. Each packet also starts with a VP9 Payload Description. This payload description provides hints to the SFU about the layer frame dependencies and scalability structure."

Meedoz SFU is supporting this feature (what the article explain)

Do you plan to add this in janus ?

Julien

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[Lorenzo Miniero]

As I said, an interesting approach I know about, but no idea on when I'll play with this. We currently have other properties and are busy on other projects.

L.

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[Ju Ju]

ok I understand. it is a good point you already have a look on this.

Did you try this already ? https://github.com/medooze/sfu (A future proof, experimental WebRTC VP9 SVC SFU.)