Mediasoup – WebRTC Video Conferencing - Hackdot

Re:Mediasoup – WebRTC Video Conferencing by manthideaal on Friday April 03, 2020 @08:51AM (#22768664)

In order to send a datagram to multiple IP the first, and naive idea, one can think of is to change the datagram protocol to allow for multiple destination. Today, 2020, is the right time. I am thinking about platforms that have hundred or thousand of simultaneous receiving ends, so that the branching point occurs near the destination. Again, googling this proposal is not new (1) RFC 1770, category informational.

Edited: It seem that RtcDataChannel can be used with SFU, example LiveSwitch in 2018, but they don't use multiple destination datagrams (3)

More on similar proposal (2).

(1) IPv4 Option for Sender Directed Multi-Destination Delivery. The Selective Directed Broadcast Mode (SDBM) is an integral part of the U.S. Army standard for tactical data communication networks as defined in MIL-STD-188-220().

(2) https://www.researchgate.net/publication/238663190_IPv4_Opti...

(3) https://www.frozenmountain.com/developers/blog/archive/indus...

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Re:Mediasoup – WebRTC Video Conferencing by manthideaal on Friday April 03, 2020 @09:22AM (#22768876)

Each receiver sending feedback does not prevent the server for using datagrams with multiple destinations. I can see that each peer use a different resolution and bitrate but that is another layer, is like sending information at several resolutions and each peer selecting the best one.

Edited: I must learn something about multicast in IPv6, the idea seems interesting.

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Re:Mediasoup – WebRTC Video Conferencing by ibc on Friday April 03, 2020 @09:31AM (#22768942)

> is like sending information at several resolutions and each peer selecting the best one.

Well, no. This is not about sending all video layers to all receivers and let them choose which one to render. Not al all.

The purpose of video simulcast/SVC is the opposite: make the SFU decide (based on estimated per receiver bandwidth or whatever) which video layers to deliver to each receiver, so a HQ video of 8 mbps does not break your Internet downlink (you just receive the lowest video layer which is 1 mbps, for example).

And more important: no, the server can not send the same UDP datagram (the same RTP packet) to all receivers. The server needs a different RTP sequence number count and a different SRTP encryption keys with each receiver.

I'm afraid this is not so easy as you say, not at all.

BTW: Do you want to say something about mediasoup? or just about your stuff?

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Re:Mediasoup – WebRTC Video Conferencing by manthideaal on Friday April 03, 2020 @10:25AM (#22769419)

Thanks for all the info. I think that mediasoup is a very good SFU. I wish you the best and I hope mediasoup SFU to become a crucial tool for rtc.

Edited: In a recent article (1) it seems that multicast is better than SFU in webrtc. In the PhD. Thesis (2) a hybrid model is used: Hybrid multicast-unicast video streaming over heterogenous cellular networks.

(1)https://ieeexplore.ieee.org/document/8811590 (2) https://summit.sfu.ca/item/16802

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