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Re: What does a track contain?

From: Luis Lopez <lulop@kurento.com>
Date: Wed, 24 Feb 2016 17:38:08 +0100
Cc: Martin Thomson <martin.thomson@gmail.com>, "public-media-capture@w3.org" <public-media-capture@w3.org>
Message-Id: <8CE42E0B-4F54-4FF3-9518-305A85D20E63@kurento.com>
To: Peter Thatcher <pthatcher@google.com>
To the best of my knowledge, Chrome <video> honors alpha channel but the rest of browsers don't. Hence that approach might work only in Chrome. Just as a workaround, I think that the only standard way of applying alpha transparency is using some kind of infrastructure where decoding could take place and the alpha mixing can be performed. There tools for that (e.g https://www.youtube.com/watch?v=WRmzzblZGDo)


El 24/02/2016, a las 17:28, Peter Thatcher <pthatcher@google.com> escribió:

> I don't know enough about <video> to know the answer to this:  if it has an alpha channel in it, and it's rendered on top of other web elements, is it supposed to render such that you potentially see through the video to the other web elements below?  In other words, could I use a <video> to make a video of a translucent ghost fly around a web page?  Is that the kind of thing we're going for here?   canvas -> track -> <video> -> ghost?
> On Wed, Feb 24, 2016 at 8:20 AM, Martin Thomson <martin.thomson@gmail.com> wrote:
> On 24 February 2016 at 08:13, Peter Thatcher <pthatcher@google.com> wrote:
> > What do you mean "throughout the media pipeline"?  Do you expect a track
> > sent through a PeerConnection to have the alpha channel intact when it comes
> > out the remote side?
> Well, we know that RTP video is generally incapable of handling alpha
> channels, so no.  Unless and until we find a codec that supports an
> alpha channel (APNG perhaps).
> But the simple example of <canvas> piped to <video> presents something
> of a challenge.

Received on Thursday, 25 February 2016 08:33:07 UTC

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