[whatwg] Serving up Theora <video> in the real world

Philip Jägenstedt philipj at opera.com
Sat Jul 11 02:38:12 PDT 2009

On Sat, 11 Jul 2009 03:35:22 +0200, Robert O'Callahan  
<robert at ocallahan.org> wrote:

> On Sat, Jul 11, 2009 at 9:37 AM, Philip Jagenstedt  
> <philipj at opera.com>wrote:
>> the point is simply that calling canPlayType without out a codecs list  
>> or
>> with specific codecs, you can learn exactly what is supported and not  
>> out of
>> the container formats and codecs you are interested in, without the  
>> need for
>> the strange "probably"/"maybe"/"" API.
> I think it would be somewhat counterintuitive for  
> canPlayType("video/ogg")
> to return true, but canPlayType("video/ogg; codecs=dirac") to return  
> false.

Well I disagree of course, because having canPlayType("video/ogg") mean  
anything else than "can I demux Ogg streams" is pointless.

Quoting myself from  
(replies from Ian)

On Thu, 13 Nov 2008, Philip Jägenstedt wrote:
> When asking about application/ogg, this could mean 2 things:
>1. "can I demux Ogg streams?"
> 2. "can I demux Ogg streams and decode unknown codecs?"

It's the second (and thus the answer can only ever be "maybe" or "no").


> Unless the codecs parameter is to be made mandatory I think that spec 
> should explicitly make it such that the question asked is 1. In either 
> case we will end up there because 2 is not a meaningful question anduser  
> agents will make untruthful answers in attempts to stay compatiblewith  
> unknown and future content (which might be supported by installingnew  
> codecs in the media framework without upgrading the browser).

Currently the spec says we should interpret canPlayType("video/ogg") as  
"can I demux Ogg streams and decode unknown codecs?", which is a pointless  
question. If we seriously believe that people need the level of control  
provided by the 3-state answer, just let them make several queries to ask  
the precise questions they want to ask.

Philip Jägenstedt
Core Developer
Opera Software

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