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Re: [mediacapture-record] Bugs in isTypeSupported() example

From: ddorwin via GitHub <sysbot+gh@w3.org>
Date: Thu, 08 Dec 2016 17:37:59 +0000
To: public-media-capture-logs@w3.org
Message-ID: <issue_comment.created-265803358-1481218676-sysbot+gh@w3.org>
I guess you need to decide on the meaning of a positive response from 
`isTypeSupported()`. Most likely, it should be used to find a value 
that can be successfully used for the `mimeType` member of 
`MediaRecorderOptions`. If so, the API should only allow 
sufficiently-specific types.

`canPlayType()` may not be a good guide, especially since it can 
return three values vs. the Boolean returned by `isTypeSupported()`. 
Note that `"maybe"` really just means the user agent can't not play it
 (it is not "[a type that the user agent knows it cannot 
render](https://html.spec.whatwg.org/multipage/embedded-content.html#dom-navigator-canplaytype)").
 Since `isTypeSupported()` returns a Boolean (and because `"maybe"` 
has been confusing), it should be more certain when returning a 
positive result (e.g., "the user agent is confident that the type 
represents a media resource that it can" record).

Note: `canPlayType()` enables the application to walk a tree. (Is WebM
 supported? If so, is WebM with VP9 supported? If so, is WebM with VP9
 and OPUS supported?...) In this case, checking just the container 
might be useful in determining all capabilities. However, for the 
purposes of determining whether a specific stream can be played, that 
is unnecessary.

-- 
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Received on Thursday, 8 December 2016 17:38:07 UTC

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