We don't transcode audio/video on the server. Each stream is processed and muxed by the client. The server is merely relaying rtp packets and tagging them with a given ssrc per peer. The client does the rest of the work.
The bulk of the user-space time on the SFU is spent doing encryption (xalsa/dtls). We also avoid memory allocations in the hot paths, using fixed-size ring buffers as much as possible.
The bulk of the user-space time on the SFU is spent doing encryption (xalsa/dtls). We also avoid memory allocations in the hot paths, using fixed-size ring buffers as much as possible.
Additionally, we coalesce sends using sendmmsg, to reduce syscalls in the write path: (http://man7.org/linux/man-pages/man2/sendmmsg.2.html)
I posted some about the specs here: https://news.ycombinator.com/item?id=17954163