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

Simon Pieters simonp at opera.com
Tue Jul 28 01:26:45 PDT 2009

On Tue, 28 Jul 2009 02:39:46 +0200, Andrew Scherkus <scherkus at google.com>  

>> On Sun, 12 Jul 2009, Philip Jägenstedt wrote:
>> >
>> > Not that I except this discussion to go anywhere, but out of  
>> curiosity I
>> > checked how Firefox/Safari/Chrome actually implement canPlayType:
>> >
>> > http://wiki.whatwg.org/wiki/Video_type_parameters#Browser_Support
>> >
>> > Firefox is conservative and honest (except maybe for "audio/wav;
>> > codecs=0", what could you do with the RIFF DATA chunk?) Safari gets
>> > maybe/probably backwards compared to what the spec suggests. Chrome
>> > seems to ignore the codecs parameter, claiming "probably" even for  
>> bogus
>> > codecs. Authors obviously can't trust the distinction between "maybe"
>> > and "probably" to any extent.
>> That certainly is unfortunate.
> Thanks for calling us out :)
> We've addressed this in our latest builds.  We now fall somewhere between
> Firefox and Safari in terms of conservativeness and honesty.
> We still give bogus codecs a "maybe" if the container is supported, since
> that seems to be what the spec suggests.

That doesn't match my reading of the spec...

The spec says

"The canPlayType(type) method must return the empty string if type is a  
type that the user agent knows it cannot render;"


"A type that the user agent knows it cannot render is one that describes a  
resource that the user agent definitely does not support, for example  
because it doesn't recognize the container type, or it doesn't support the  
listed codecs."

> A "probably" is only for both a
> container and codec match.

Simon Pieters
Opera Software

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