Simulcast Layers

mediasoup libraries
1

Hi,
I was trying to generate 4 layers for simulcast as described in mediasoup :: RTP Parameters and Capabilities with “Simulcast with 4 streams and 3 temporal layers using RID”.
However, I could never get r3 stream. Max spatial layers are 3. Streams generated for r0,r1 and r2.
I have made appropriate settings too for maxBitrate, scaleResolutionDownBy for stream enoodings. Starting resolution is 1280x720 and then scales down.

{ rid: 'r0', scaleResolutionDownBy: 8, maxBitrate: 100000, scalabilityMode: 'S1T3' },
{ rid: 'r1', scaleResolutionDownBy: 4, maxBitrate: 200000, scalabilityMode: 'S1T3' },
{ rid: 'r2', scaleResolutionDownBy: 2, maxBitrate: 700000, scalabilityMode: 'S1T3' }, 
{ rid: 'r3', scaleResolutionDownBy: 1, maxBitrate: 2500000,	scalabilityMode: 'S1T3' }

image

I have also set maxIncomingBitrate in config.js for a value of 5000000 to honor bitrate arrangements.
Also I have experimented a lot but ended up creating only 3 or less layers never more.
For the snippet provided I could get r0 : 160x90, r1 : 320x180, r2 : 640x360 so never 1280x720 by checking into chrome://webrtc-internals
Am I missing anything here to generate more than 3 layers ?
Thanks in advance.

2

Chrome just generates up to 3 streams in simulcast.

1 Like
3

So is it true to consider that “mediasoup v3 can handle unlimited spatial and temporal layers” (referred from the docs) but there isn’t a browser (I have tested on chrome, firefox, opera, edge, avg) to generate more than 3 layers ?

4

Yes, it’s true.

2 Likes
5

Thanks. Much appreciated