Re: Proposal: One media RTP packet stream (i.e. one SSRC) per RTCRtpSender/RTCRtpReceiver object

They aren’t the same though… only how you configured them produces the same output result.

If you take into account other properties this would be different.

For example, add a mux-id. In the one case they would be different because one sender scenario would be transmitting from different mux-ids and thus be understood to be routed to two different receivers. Versus the other scenario where the sender would share an output mux-id across encodings and be understood by an SFU to be switched into a single receiver as an end result.

Thus they aren’t the same...

-Robin



On April 8, 2016 at 4:26:30 AM, Sergio Garcia Murillo (sergio.garcia.murillo@gmail.com) wrote:

On 07/04/2016 23:05, Peter Thatcher wrote:


On Thu, Apr 7, 2016 at 8:17 AM, Sergio Garcia Murillo <sergio.garcia.murillo@gmail.com> wrote:
Hi Peter,


Also take note that 2, with current propossal can be implemented in two ways, one RTPSender per ssrc (same as my proposal) or all ssrcs in same RTPSender. In order to implement 3 with current proposal it is only possible to do it with several RTPSenders.

​ WebRTC only supports #2, and I think ORTC should only support #2.  You are correct that with the current WebRTC and ORTC APIs, one could accomplish the same thing with one RtpSender or many.  But requiring many is an option that was rejected by the WebRTC WG.  
​  

Do you know what were the objections for rejecting multiple RTPSenders for simulcast (with ssrc-multiplexing over same transport)?
 It is something that needs to be supported anyway by the browser and given that each layer is an independent encoder there should be no performance penalty.

I mean, currently we can do this (in pseudocode)

RTPSender.send({
    encodings: [
        {ssrc:1,pt:100,codec:vp8,},
        {ssrc:2,pt:100,codec:vp8,resolutionScale: 2.0},
    ]
})

or

RTPSender1.send({
    encodings: [
        {ssrc:1,pt:100,codec:vp8,},
    ]
})

RTPSender2.send({
    encodings: [
        {ssrc:2,pt:100,codec:vp8,resolutionScale: 2.0},
    ]
})

Both will produce the same result

Best regards
Sergio