Re: Constraints 2014

On 3/26/14 4:31 AM, Harald Alvestrand wrote:
> On 03/26/2014 02:18 AM, Jan-Ivar Bruaroey wrote:
>> Sure, that is certainly doable, if people prefer, or we could perhaps 
>> do videoSourceId and audioSourceId? Things don't seem to overlap much 
>> otherwise.
>
> If they don't overlap, to me that's an argument for keeping each in 
> its own bag.
> If they overlap, to me that's an argument for keeping each in its own 
> bag; separation of concerns.

First of all, I'm delighted we're discussing what I consider mostly 
naming, e.g. video::sourceId vs. videoSourceId, frameRate vs. maybe 
video::rate - I don't hold a strong opinion, but I'm curious.

> It seems hard to find an argument that would convince me that mixing 
> audio and video constraints into one bag is a good idea :-)
>
> (this is about how we pass the bag/bags to gUM. That's separate from 
> the question of whether having different type definitions for the two 
> is a great idea or not.)

Let me play devil's advocate then: A camera and a mic - light and sound 
- are so similar - rather than complements - that their properties don't 
deserve separation by TYPE, and we must use bags to keep their otherwise 
ambiguous settings apart?

If we had, say, transport properties - like bandwidth - then I would see 
why. Bits are bits. But we don't. That's over in PeerConnection.

I actually had things broken down in an earlier draft (below), but typed.

.: Jan-Ivar :.

(EARLIER DRAFT USING AUDIO & VIDEO GROUPS)

dictionary MediaStreamOptions {
     (boolean or VideoTrackConstraints) video = false;
     (boolean or AudioTrackConstraints) audio = false;
     DOMString peerIdentity;
};

dictionary Constraints {
     sequence<DOMString> require; // names of required constraints, if any
     sequence<DOMString> prefer;  // names of preferred constraints, if any
};

dictionary VideoTrackConstraints : Constraints {
     ConstrainLong width;
     ConstrainLong height;
     ConstrainDouble aspectRatio;
     ConstrainDouble frameRate;
     ConstrainVideoFacingMode facingMode;
     // Dictionary may be extended through gUM-specific IANA registry.
};

dictionary AudioTrackConstraints : Constraints {
     ConstrainDouble volume;
     ConstrainLong sampleRate;
     ConstrainLong sampleSize;
     boolean echoCancelation;
     // Dictionary may be extended through gUM-specific IANA registry.
};

interface VideoStreamTrack : MediaStreamTrack {
     VideoTrackConstraints getInherentCapabilities();
     VideoTrackConstraints snapshotCurrentSettings();
     void applyConstraints(VideoTrackConstraints settings,
                           VoidFunction successCallback,
                           ConstraintErrorCallback errorCallback);
};

interface AudioStreamTrack : MediaStreamTrack {
     AudioTrackConstraints getInherentCapabilities();
     AudioTrackConstraints snapshotCurrentSettings();
     void applyConstraints(AudioTrackConstraints settings,
                           VoidFunction successCallback,
                           ConstraintErrorCallback errorCallback);
};