MediaStreamTrack.stop() should be async

[sonntag-philipp]

Hello there,

I'm currently working with the mediacapture api in different browsers. While working on the MediaStreamTracks, I've noticed that the stop method doesn't provide a way to get notified when the track is actually stopped by the underlying user agent.

This can cause issues in platforms, where a camera can only be opened once by the browser api.

My proposal for a solution would be to make the .stop() method async by returning a promise.
The promise should be resolved when the user agent made sure, that the media track is stopped.

The described method in the RFC.

[fippo]

does that require an API change or should the user agent ensure pending closes are done before attempting to open a device?

[sonntag-philipp]

Yes, I think it would require an api change as the method signature of MediaStreamTrack.stop() would change to return a promise.
Anyway, this wouldn't affect existing uses of the method. They could just ignore the return value.

[guidou]

I agree that returning a promise would be useful and allow more flexibility for implementation.

[alvestrand]

Changing the API does not seem like a good option, given that this is a rather old and stable spec by now.
Moving it to mediacapture-extensions in order to figure out how to solve the problem.