[whatwg] on codecs in a 'video' tag.

Ralph Giles giles at xiph.org
Mon Apr 2 14:40:55 PDT 2007

On Mon, Apr 02, 2007 at 01:55:38PM -0700, Dave Singer wrote:

>    [...]        Does Ogg/Theora have a 'required features' or 
> 'required version' in the bitstream?

Theora doesn't currently have any profiles, and the spec
has no optional decoder features. The only thing that can be
marked explicitly in the header (aside from the normal image
size, framerate, bitrate parameters) is the chroma subsampling.

[now thoroughly off topic]

As spec authors, we're not opposed to adding profiles of some 
sort, flagged either in the metadata, reserved bits, or in the
"tiny" field of the bitstream version number. An obvious first 
example be the VP3-compatible subset currently in common use.

As far as more complex profiles, people have asked us about
that, but we've been reluctant to declare anything without
actual feedback from implementations. If someone does have
a product where they've found a useful dividing point, we'd
like to hear about it. Otherwise we figure people can pick
a resolution and framerate as easily as we can.


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