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Re: MediaStreams and canPlayType

From: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
Date: Fri, 17 Oct 2014 11:56:50 +0000
To: Harald Alvestrand <harald@alvestrand.no>, "public-media-capture@w3.org" <public-media-capture@w3.org>
Message-ID: <1447FA0C20ED5147A1AA0EF02890A64B1D089775@ESESSMB209.ericsson.se>
On 17/10/14 13:15, Harald Alvestrand wrote:
> A MediaStream is a control surface for what the browser does with media.
> The concept of a "type" is totally foreign to the concept of a
> MediaStream; if the MediaStream(track) can be created, the browser can
> play it - it was created by the very same browser!
> Wherever the MediaStream converts into something that can be passed over
> the network, types are of relevance: MediaStreamRecorder, <video> tag
> rendering to canvas, WebAudio rendering to audio buffers,
> PeerConnections rendering to RTP - and at the corresponding interfaces
> for incoming, the media type is also of relevance.
> But this needs to be functions that belong on that interface, not on the
> MediaStream.

Yes, and I was only talking about the media-element.canPlayType, nothing 
on MediaStream(Track).


> MediaStreams are abstractions that live in the browser. The browser can
> always do it.
> On 10/17/2014 10:48 AM, Stefan Håkansson LK wrote:
>> I recently came across a WebRTC site that used video.canPlayType to
>> check up front if the endpoint was compatible with their service or not.
>> Our document says nothing about this, and I think it should (but I'm not
>> sure what it should say).
>> Off the top of my head there are a couple of paths we could follow:
>> #1: state that canPlayType is unsuitable to check compatibility with
>> MediaStreams of a certain format and that it can be assumed that
>> anything the PeerConnection can negotiate can be played (as well as of
>> course any strictly locally generated media). The follow up question is
>> of course how you check if the PeerConnection will be able to decode
>> your network streams without doing a call set up with negotiation, I
>> guess there the answer would be to use createOffer and parse the SDP.
>> #2: Define strings (mime-types?) that can be used with canPlayType to
>> see if the video element can play the MediaStream format in question.
>> Should we do something about this, and if so, #1, #2 or something else?
>> Stefan

Received on Friday, 17 October 2014 11:57:17 UTC

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