Should the spec provide guideline on the default degradation preference to use for capture tracks?

w3c / mst-content-hint

This is the specification for the content-hint attribute. This optional hint permits MediaStreamTrack consumers such as PeerConnection or MediaRecorder to encode or process track media with methods more appropriate to the type of content that is being consumed.

https://w3c.github.io/mst-content-hint/

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Should the spec provide guideline on the default degradation preference to use for capture tracks? #60

Open youennf opened 2 weeks ago

youennf commented 2 weeks ago

From https://codepen.io/youennf/pen/JjgaxmQ, it appears that:

Chrome default degradationPreference is maintain-resolution for screen share feeds (and probably maintain-framerate for camera feeds)
Safari default degradationPreference is maintain-framerate for both screen share and camera feeds.
Firefox is probably doing the same as Safari.

While it is always difficult to mandate a particular degradation preference (if screen sharing a movie, maintain-framerate might be better), the spec could provide guidance and suggest some default behaviours for the various track types.

alvestrand commented 2 weeks ago

Strictly speaking, degradation-preference is a sender property, while mst-content-hint is a track property. So a track spec shouldn't want to talk about degradation preference - we have webrtc-pc referencing mediacapture-main, and not the other way around.

We could add a section to the mst-content-hint section on how to deal with tracks that don't have a hint.

youennf commented 2 weeks ago

Well, this spec is defining both content-hint track property and degradationPreference parameter so either we migrate this spec to webrtc-pc and mediacapture-main and do the work in webrtc-pc, or we keep this spec and we do the work here.

https://w3c.github.io/mst-content-hint/#behavior-of-an-rtcpeerconnection is about RTCPeerConnection behaviour when there is an explicit content-hint. It might be worth adding guideline in that section when there is no explicit contentHint.