[mediacapture-main] How should applyConstraints deal with constraints from other tracks sharing the same source?

guidou has just created a new issue for https://github.com/w3c/mediacapture-main:

== How should applyConstraints deal with constraints from other tracks sharing the same source? ==
The description of the SelectSettings algorithm (building block for applyConstraints) explains how to filter candidate settings for a given track given the track's basic and advanced constraint sets.
However, I have a few doubts for the case when the track is connected to a source that is shared with other tracks.
More specifically, my main doubt is that, since the constraints for the other tracks should continue to be satisfied, how should those constraints be taken into account?

Say, T1 has constraint sets B1, A11, A12 and A13 applied, and there is T2 which is sharing the same source as T1. 
T2.applyConstraints is invoked with constraint sets B2, A21, A22,and A23.

Step 3 of SelectSettings says:

> For every possible settings dictionary of copy compute its fitness distance, treating bare values of properties as ideal values. Let candidates be the set of settings dictionaries for which the fitness distance is finite.

My first question is what are the "possible settings dictionaries"? Are they all possible dictionaries regardless of their ability to satisfy T1's constraints? Are they only those that satisfy T1's basic constraints? Are they the ones that satisfy T1's basic and advanced? What if some of T1's advanced were ignored during its initialization?

Another question is what role should T1's advanced sets play when resolving T2.applyConstratins.
I assume that T1's basic set must continue to be satisfied, and it is clear what the priority should be for T2's new advanced sets. But, what role should the existing T1 advanced sets play to set the shared source's new configuration?

Please view or discuss this issue at https://github.com/w3c/mediacapture-main/issues/465 using your GitHub account

Received on Friday, 16 June 2017 13:00:25 UTC