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

Re: maxHeight and maxWidth

From: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
Date: Thu, 18 Feb 2016 07:19:04 +0000
To: Peter Thatcher <pthatcher@google.com>
CC: Jan-Ivar Bruaroey <jib@mozilla.com>, "public-webrtc@w3.org" <public-webrtc@w3.org>
Message-ID: <1447FA0C20ED5147A1AA0EF02890A64B3749853A@ESESSMB209.ericsson.se>
On 17/02/16 21:16, Peter Thatcher wrote:
>
>
> On Wed, Feb 17, 2016 at 10:36 AM, Stefan Håkansson LK
> <stefan.lk.hakansson@ericsson.com
> <mailto:stefan.lk.hakansson@ericsson.com>> wrote:
>
>     On 17/02/16 18:47, Jan-Ivar Bruaroey 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?
>
>     I think it was Cullen who at a call once said that he was fine with the
>     UA removing data, but not inventing. That has stuck with me since, so it
>     would be OK to downscale resolution (or frame rate) to meet what the app
>     wants, but not the other way around.
>
>
> If upscaling is not allowed, then I it's impossible to meet a
> requirement of "must be exactly 90 pixels in height".

I'm not sure I follow. If the camera can capture in 360, and the UA 
downscale by 4 the result is 90?

Just to be 100% clear: upscaling is of course allowed when rendering, 
playing a 90 pixel video track in a 200 pixel video element would lead 
to upscaling (and reading element.height would return 200 while reading 
element.videoHeight would return 90).

>
>     But I agree, the spec is not clear on what should be done.
>
>      >
>      > See my other post right now about discovery and arbitrary scaling
>     being
>      > mutually exclusive.
>      >
>      > .: Jan-Ivar :.
>      >
>
>
Received on Thursday, 18 February 2016 07:19:58 UTC

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