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

Maciej Stachowiak mjs at apple.com
Sat Jul 11 17:08:15 PDT 2009

On Jul 11, 2009, at 3:34 PM, 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.

Thanks for doing the research. We'd appreciate bug reports on any  
Safari/WebKit behavior that seems incorrect, and I'll certainly ask  
the Apple folks who work on this to study the matter. Our life is a  
little harder than Mozilla's since we use a separate media framework  
and support an open-ended set of codecs. But still, we'd like to get  
this right.

I think you are probably right that the "maybe"/"probably" distinction  
is not currently reliable and likely not relied on in practice. What  
we do seem to have is some reliance on the answer being one of "maybe"  
or "probably" as indication of a positive result. I don't know the  
extent of such reliance but I suspect it will be worse before we can  
design, implement and ship a thorough redesign.

One possibility is to consider canPlayType a lost cause as far as  
having a really great API, and add a cleaner and better defined API in  
parallel. But I'm not sure the improvement would be worth the cost.  
Depends on the specifics.

  - Maciej

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