[whatwg] Scripted <video> query proposal
eric.carlson at apple.com
Fri Aug 22 16:21:05 PDT 2008
On Aug 22, 2008, at 2:36 PM, Robert O'Callahan wrote:
> On Sat, Aug 23, 2008 at 1:46 AM, Eric Carlson
> <eric.carlson at apple.com> wrote:
> On Aug 21, 2008, at 8:56 PM, Robert O'Callahan wrote:
>> Does that actually enumerate all supported codecs? Looking at the
>> Webkit code and the Quicktime docs, it looks like it's just
>> enumerating file/container types.
> Indeed the code enumerates movie importers and just builds a list
> of the MIME types supported by QuickTime, so it can not yet deal
> with a type string with an RFC4281 "codecs" parameter. We are
> working on that requirement, but the current approach is still
> useful because the "codecs" parameter is not yet widely used.
> That will require extensions to Quicktime, right?
> So using your current approach implement Tim's proposed API, we can
> use this to answer "yes" or "no" if the MIME type contains no codec
> string, and if the MIME type does contain a codec string we can
> either answer "no" (if the container is not supported) or "maybe".
> I suppose if Tim's willing to assume that anything supporting the
> Ogg container supports Theora and Vorbis, that's good enough for
> now ... for Quicktime. We'll have to look into whether something
> similar is possible with GStreamer and DirectShow. But I guess even
> if it isn't, a 3-value version of Tim's proposed API is better than
A three state return is an interesting idea, but wouldn't you then
be required to return "maybe" for MIME types that can describe
multiple formats? For example, "video/mpeg" can be used to describe a
video elementary stream, an MPEG-1 system stream, an MPEG-2 program
stream, or an MPEG-2 transport stream. "application/ogg" can include
dirac, flac, theora, vorbis, speex, midi, cmml, png, mng, jng, celt,
pcm, kate, and/or yuv4mpeg. And then there is "video/quicktime"...
I think it makes more sense to leave it as a boolean, where "no"
means the UA does not support the type, and "yes" means that the UA
implements some support for the type but errors can occur during
loading and/or decoding.
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