W3C home > Mailing lists > Public > public-media-capture@w3.org > August 2012

Re: MediaStreams and state changes

From: Stefan Hakansson LK <stefan.lk.hakansson@ericsson.com>
Date: Tue, 7 Aug 2012 09:59:53 +0200
Message-ID: <5020CAF9.7020601@ericsson.com>
To: Travis Leithead <travis.leithead@microsoft.com>
CC: "public-media-capture@w3.org" <public-media-capture@w3.org>
On 08/06/2012 07:29 PM, Travis Leithead wrote:
>> From: Stefan Hakansson LK
>> [mailto:stefan.lk.hakansson@ericsson.com] If we isolate this down
>> to resolution of video, I had this idea of that the consumer would
>> hint to the producer the size, and the producer could adapt. Say
>> you have a MediaStream connected to a video element, the
>> width/height of the video element could be used to change the
>> resolution produced by the camera - the browser knows has all facts
>> about the consumer and controls the producer. Similarly a record
>> function would have to provide width/size. If there are several
>> consumers (e.g. two local video elements, or one video element
>> along with a recording) the browser could determine the best
>> compromise (which probably is to catch video with the highest
>> resolution consumed).
>> This idea could easily be extended over a PeerConnection. If the
>> video is consumed on the other side of the PeerConnection the
>> width/height could be signaled back to the sending browser, and
>> used as input to how that browser handles the camera.
>> The advantage would be that the naive author would just have to set
>> up the size of the video element to fit the intended layout, and
>> the rest would be automatic.
>> However, one feedback has been that this should not 'just happen',
>> the app should be in control. So perhaps it is not a good idea.
> Frankly, making things like this automatic seems like trouble--we
> might get it right for some set of scenarios, and other scenarios
> will consider this behavior a "bug". I'd strongly recommend leaving
> the control (at least with questions like resolution) up to the
> application.
>> But if the application controls the resolution, is there really a
>> benefit if the app receiving a MediaStream from a PeerConnection
>> can ask (using some local API) for a specific resolution? Could
>> this not just as well be signaled back to the sending app, that
>> uses (a variant of) the API proposed by Travis to change the
>> resolution produced by the camera.
> If I understood you correctly, are you saying that: since the
> application can control the resolution, then having
> PeerConnection-based resolution-change-request API is unnecessary? If
> so, then I agree.
Yes, that is what I meant.
Received on Tuesday, 7 August 2012 08:00:20 UTC

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