I came to the conclusion that on mobile phones, WebRTC video is not yet usable. Even with just audio on a cellular network, call quality started deteriorating after a few minutes on every platform that I tried. Video without a WiFi signal was hopeless.
I discussed this with an WebRTC expert, and the problems are partly with WebRTC, partly with how mobile operators shape their data traffic.
Also all platform implementations that were considered the best of the breed were bought by mobile chat companies (both SnapChat and OK Hello did acquisitions on this front)
What I've been wondering is if Apple gets any QoS concessions from the carriers for Facetime, because it usually works pretty well on 4G. Not sure if Facetime's quality is due to robust error correction, or because they've been able to wrangle special QCI/bearer status for Facetime data.
> mobile phones, WebRTC video is not yet usable
Once VoLTE + Video becomes common (eg, Verizon Advanced Calling), then it'll be interesting to see the impact on video-call quality, and whether V/VoLTE sessions can be established with the other end of a SIP trunk, and hence (browser) WebRTC from there.
However, ORTC does seek to improve with simulcast/SVC, and attributes of ORTC will merge into WebRTC as well, ultimately providing more hooks, finer-grained control and better instrumentation/visibility to the upper layers.
All that said, you can do acceptable quality WebRTC voice and video over 4G LTE today. But you do need a rock solid signal and be prepared to with a fully charged battery if you are not plugged in.
Simulcast/SVC, for example, are irrelevant outside of multiway video. And you can already do simulcast with WebRTC.
The WebRTC protocol itself is defined in RTCWEB at the IETF and based on the existing RTP and RTCP transports, and SCTP transport layer. I don't think you'll be able to do better.
I actually spent several days last summer evaluating and developing prototypes on top of platform APIs (e.g. TokBox, Sinch) and tested the call quality in several different situations (moving from WiFi to 3G, dropping and regaining signal during the call, call behavior while moving in public transport etc.)
I described my experience and conclusion, hoping to spark informed discussion of the topic. Your comment didn't add any information to it.