W3C home > Mailing lists > Public > public-webrtc@w3.org > February 2016

Re: maxHeight and maxWidth

From: Jan-Ivar Bruaroey <jib@mozilla.com>
Date: Wed, 17 Feb 2016 15:15:17 -0500
To: Peter Thatcher <pthatcher@google.com>
Cc: "public-webrtc@w3.org" <public-webrtc@w3.org>
Message-ID: <56C4D4D5.8070802@mozilla.com>
On 2/17/16 2:36 PM, Peter Thatcher wrote:
> On Wed, Feb 17, 2016 at 9:45 AM, Jan-Ivar Bruaroey <jib@mozilla.com 
> <mailto: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 RtpReceiver?
>
> 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.

Peter, I agree that seems crazy. Can you perhaps elaborate a bit on your 
use-case that requires this 160x90 video stream locally?

.: Jan-Ivar :.
Received on Wednesday, 17 February 2016 20:15:49 UTC

This archive was generated by hypermail 2.3.1 : Monday, 23 October 2017 15:19:47 UTC