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[mediacapture-main] Need more attributes in MediaDeviceInfo

From: Iñaki Baz Castillo via GitHub <sysbot+gh@w3.org>
Date: Fri, 14 Apr 2017 13:26:13 +0000
To: public-media-capture@w3.org
Message-ID: <issues.opened-221808833-1492176371-sysbot+gh@w3.org>
ibc has just created a new issue for https://github.com/w3c/mediacapture-main:

== Need more attributes in MediaDeviceInfo ==
Let assume an app in which the user can choose the webcam device in a drop list and get a preview of it. If he selects a front camera, the preview `<video>` element must enable CSS `transform: scaleX(-1);` (mirror effect). If he selects a back/rear camera, no mirror effect must be applied.

This seems to be a very common scenario. But AFAIK it's unfeasible with the current API.

The drop list is filled with `enumerateDevices()` by filtering `device.kind === 'videoinput'`, and (assuming a previous permissions prompt) it can display the `device.label` of the video devices. But from the API point of view, the app has no way to know whether a device in the list is a front or a back camera.

So, the user chooses one, the app gets its `device.deviceId` and calls `getUserMedia()` with `video: { exact: device.deviceId }`. At that point, the app has no way to know whether it must apply the "mirror effect" to the local video or not.

I know about some developers (including me) matching `/(back|rear)/i` to the `device.label`. Hope the API can provide something much better than that. Things would be much easier (or just feasible) if `DeviceMediaInfo` includes more fields such as  `facingMode`. 

I may understand that the proper way to go is by calling `getUserMedia()` with the choosen `deviceId` (as above) and then inspect the retrieved video `MediaStreamTrack.getConstraints()`, which seems to include `facingMode`. However (at least in Firefox which is closer to the spec) `track.getConstraints().facingMode` is an empty object. Is that because `getUserMedia()` was NOT called with a `facingMode` constrain?

If so, the same problem as the above described applies.

Please view or discuss this issue at https://github.com/w3c/mediacapture-main/issues/447 using your GitHub account
Received on Friday, 14 April 2017 13:26:21 UTC

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