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Re: maxHeight and maxWidth

From: Peter Thatcher <pthatcher@google.com>
Date: Wed, 17 Feb 2016 11:36:13 -0800
Message-ID: <CAJrXDUEF36rE0J1ds+X0jj4u9Wyxv3DfVvTt_M0KMqCDhaEvpA@mail.gmail.com>
To: Jan-Ivar Bruaroey <jib@mozilla.com>
Cc: "public-webrtc@w3.org" <public-webrtc@w3.org>
On Wed, Feb 17, 2016 at 9:45 AM, Jan-Ivar Bruaroey <jib@mozilla.com> wrote:

> On 2/17/16 12:36 PM, Peter Thatcher wrote:
> The original thread was about both screencasts and rotating cameras, and
> I've mostly been focusing on the screencasting case (trying to figure that
> out before moving on to rotation).
> But, actually, I have a question for you about getUserMedia:
> If I specify an exact height of 90 pixels (min and max are 90) and the
> camera can't open that small, what will an implementation of getUserMedia
> be expected to do?  Will it scale the camera's input in order to get that
> exact height, or will it just say "nope"?  Or is it implementation
> dependent?
> I believe Chrome will rescale it to whatever you want, whereas Firefox
> will fail with OverconstrainedError, reflecting the fact that no camera on
> the machine has a native 160x90 mode. Both are to spec btw, but which one
> honors the intent of the spec?
​So the only way on Firefox to get a video track that outputs less than 91
pixels in height (perhaps to put into a MediaRecorder to record a small
video) is to open a bigger video track, open a PeerConnection, create an
RtpSender, set the maxHeight to 90, hook that PeerConnection into another
PeerConnection, create an RtpReceiver, and then use the track of that

Or I guess you could do something like render to a canvas, do the scale in
there, and then use the canvas as source of the track.

Both seem crazy.

> See my other post right now about discovery and arbitrary scaling being
> mutually exclusive.
> .: Jan-Ivar :.
Received on Wednesday, 17 February 2016 19:37:21 UTC

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