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[whatwg] Scripted <video> query proposal

From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 22 Aug 2008 14:46:09 +1200
Message-ID: <11e306600808211946s495f89bcne19a3e42cea997a2@mail.gmail.com>
On Fri, Aug 22, 2008 at 1:56 PM, Tim Starling <tstarling at wikimedia.org>wrote:

> interface HTMLMediaElement {
>    ...
>    boolean supportsType(in DOMString type);
>    ...
> }
> The supportsType() method must return false if the user agent is sure it
> cannot support the given type, and true if the user agent either can
> support the given type, or cannot determine whether it can support the
> given type.

Wouldn't it be better to return three possible values: "yes", "no" and
"don't know"?

Any browser that supports integration with an extensible framework like
GStreamer, Quicktime or Direct Show is going to have a hard time ever
reporting "false". Apparently there was a conversation today in #theora that
you might have seen whcih explains why this is so, at least for GStreamer.

With a three-value return, at least Firefox with both Ogg Theora and
Quicktime support could return "yes" for Ogg and "maybe" for other types.
But I think Safari is going to have to return "maybe" all the time ---
except perhaps for codecs built into Quicktime. That doesn't help you.

It still seems to me that the best approach would be to try to play the
stream using <video>, catch the error if that fails and then instantiate
fallback. This is really what the media frameworks want you to do; the
browser is just the meat in the sandwich.

"He was pierced for our transgressions, he was crushed for our iniquities;
the punishment that brought us peace was upon him, and by his wounds we are
healed. We all, like sheep, have gone astray, each of us has turned to his
own way; and the LORD has laid on him the iniquity of us all." [Isaiah
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