Framerate knob for simulcast

[stefhak]

The discussion at TPAC concluded that we need a knob to control framerate per stream when simulcast is used.

[aboba]

How about this?

partial dictionary RTCRtpEncodingParameters {
unsigned long maxFramerate;
};

maxFramerate of type unsigned long
The maximum framerate to use for this encoding.

A remaining question: how is the receiver's maximum framerate determined? This could be codec-specific, because a device might support hardware decoding for one codec, but not another.

Since not all codecs include a max-fr SDP parameter (e.g. VP8 does, but H.264 does not), this value cannot be determined from SDP for all codecs.

Do this imply that we need to add maxFramerate as a generic codec capability in RTCRtpCodecCapability? Today, all we have is mimeType.

[elagerway]

This issue has been flagged for discussion at the interim on Thursday, Slides placeholder: https://docs.google.com/presentation/d/1qfaxn8GMplm__s_ejMq6C3atA_pBnGXsjmAkKNIh3Ds/edit#slide=id.gf7328a83a_1_27

[aboba]

At the interim, I believe that consensus was to leave maxFramerate in the spec, and not put in another framerate knob. If so, this issue can be closed.