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[whatwg] Scripted querying of <video> capabilities

From: Jeremy Doig <jeremydo@google.com>
Date: Thu, 13 Nov 2008 10:52:43 -0800
Message-ID: <35c92870811131052o5f45d6c5hdf0304ed8fd40489@mail.gmail.com>
did this thread go anywhere ?i'm concerned about the "maybe" case - looks
way too much like:
http://en.wikipedia.org/wiki/DShow#Codec_hell

also - when you probe for mime type, do you mean the entire "type" parameter
(including the codecs string) ? for example, there are too many cases where
just passing "video/mp4" would be insufficient. (fragmented index support ?
base/main/high profile ? paff ? cabac ?)

<source src="video.mp4" type="video/mp4; codecs=&quot;avc1.42E01E,
mp4a.40.2&quot;">


On Wed, Oct 15, 2008 at 11:14 PM, Maciej Stachowiak <mjs at apple.com> wrote:

>
> On Oct 15, 2008, at 1:44 AM, Ian Hickson wrote:
>
>
>> On Tue, 14 Oct 2008, Robert O'Callahan wrote:
>>
>>> On Tue, Oct 14, 2008 at 12:13 PM, Maciej Stachowiak <mjs at apple.com>
>>> wrote:
>>>
>>>  While the underlying media frameworks can't necessarily answer, "if I
>>>> give you a file with this MIME type, can you play it?", they can at
>>>> least give a yes/no/maybe answer, which can still be quite helpful,
>>>> since the UA will know it does not need to check some media streams at
>>>> all.
>>>>
>>>
>>> I agree. If the API lets us answer "maybe", there is not much need or
>>> temptation to lie, and we can still return information that could be
>>> useful to scripts.
>>>
>>
>> I have added window.navigator.canPlayType(mimeType). It returns 1, 0, or
>> -1 to represent positive, neutral, and negative responses.
>>
>
> This API would be tempting to treat as a boolean but would of course do
> completely the wrong thing. I think it would be better to either ensure that
> the positive and neutral responses are both values that JS would treat as
> true (for instance make the values true, "maybe" and false), or else make
> all of the return values something self-descriptive and symbolic (for
> instance the strings "yes", "maybe" and "no"). I think 1, 0, -1 are neither
> clear nor likely to be in any way beneficial for perforamnce.
>
> Regards,
> Maciej
>
>
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