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Re: Screen sharing and device pixel ratio

From: Harald Alvestrand <harald@alvestrand.no>
Date: Mon, 14 Dec 2015 10:58:00 +0100
To: public-media-capture@w3.org
Message-ID: <566E92A8.5060704@alvestrand.no>
Den 11. des. 2015 03:14, skrev Mathieu Hofman:
> In this case this isn't an aspect ratio issue, the pixels are still square, they just have higher density.
> But I agree it fits the same reasoning, the transport shouldn't know about transforms necessary on the pixels, it should just deal with "simple" pixels.
> 
> Now for the density, as an application I might still like to access the non-scaled stream locally, so I'd like a knob saying give me physical pixels, or give me logical pixels.
> Maybe logical pixels should be the default? This is a breaking change with existing implementations.
> 

I see logical pixels as a hack that was introduced in order to avoid
having to retrofit applications that made unwise assumptions about the
relationship of pixels to screen size; I'd prefer that we not perpetuate
the lunacy that they cause.

I could see adapting the "scaleResolutionDownBy" control that exists on
RTCRtpEncodingParameters to screenshare capture, so that people who
wanted the sender to reduce the pixel count could get what they want -
but I would strongly prefer to keep the idea that "one pixel has one
color" (a "logical pixel" in a factor-of-2 scaled screen has four
colors, probably different).

Harald
Received on Monday, 14 December 2015 09:58:36 UTC

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