[mediacapture-main] Conflicting information about OverconstrainedError.constraint

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

== Conflicting information about OverconstrainedError.constraint ==
[7.4 Error 
names](http://w3c.github.io/mediacapture-main/getusermedia.html#error-names)
 says:

> Name | Description | Note
> ---------|-----------------|-------
> OverconstrainedError | One of the mandatory Constraints could not be
 satisfied. | The constraint attribute is set to the name of the 
constraint *that caused the error*

while [10.2.1 
getUserMedia](http://w3c.github.io/mediacapture-main/getusermedia.html#dom-mediadevices-getusermedia)
 says:
> If *finalSet* is the empty set, let constraint be any required 
constraint whose fitness distance was infinity for all settings 
dictionaries examined while executing the **SelectSettings** algorithm

This is not the same thing. For example, if the following fails with 
`OverconstrainedError`:

    { width: { min: 1280 }, frameRate: { min: 60 }, facingMode: { 
exact: "user" } }

then it's because there are no resolutions at or above 1280 pixels 
wide that *also* do 60Hz *and* face the user, even though there may be
 plenty of 1280x720+ resolutions, 60Hz modes, and cameras that face 
the user.

The first definition fails because there is no single "constraint that
 caused the error".

The second definition works, except it returns "", because none of the
 three constraints have infinite fitness distance from *all* the 
settings dictionaries.

I need to know which one to implement.

See https://github.com/w3c/mediacapture-main/issues/248

Received on Friday, 18 September 2015 05:02:09 UTC