> Now, you could do a lot of work to parse the SDP locally, figure out exactly what changed, send just that difference to the other side, and have it be smart e

> Now, you could do a lot of work to parse the SDP locally, figure out exactly what changed, send just that difference to the other side, and have it be smart enough to patch its local idea of the current SDP with that difference to feed into JSEP, test it on every possible browser, make it robust to future changes in the SDP the browser will generate, etc. I work with WebRTC outside a browser context, and we signal calls with simpler datastructures and generate the SDP right near the WebRTC Api. Our SFU doesn't ever see an SDP, because SDP is a big messy format around simpler parts --- it's easier to just communicate the simpler parts, and marshal into SDP at the API border. Even for 1:1 calls, we signal the parts, and then both ends generate the SDP to feed to WebRTC. IMHO, you're going to have to test your generated SDPs everywhere anyway, regardless of if clients or servers generate them. Well managed compression would certainly help reduce SDP size in transit, but reduce, reuse, recompress in that order.