[Bug 17658] need procedure for selection of Key System

https://www.w3.org/Bugs/Public/show_bug.cgi?id=17658

--- Comment #3 from David Dorwin <ddorwin@google.com> 2012-07-09 19:23:01 UTC ---
The application always chooses the key system to use; the media element does
not choose the key system. The only case where the UA "sets" the current key
system is when a <source> element is used to select the source and the selected
element specifies a "keySystem" attribute. Even in this case, though, the key
system to use for a particular source was specified by the application and the
UA is just processing the options.

(In reply to comment #2)
> From specification,
> 
> In step 6 of section 5.1 encrypted block encounted
> It is said if the media element has a selected key system, then use it,
> If not, jump to key presence, there is no key system selection text  in step 9
> Key Presence.
> Step 9 only mentioned 3 choices: 1 key is available, 2 fire needKey event with
> “keySystem”,3 abort resource fetch procedure

"key system" is a variable that is set to null in step 1. Thus, it will be null
in the case you described.

> What’s more, I think before the generateKeyRequest(KeySystem, initData) is
> called, the KeySystem is already
> Selected, and the specification mentioned if KeySystem is null, it will throw a
> SYNTAX_ERROR.
> http://dvcs.w3.org/hg/html-media/raw-file/tip/encrypted-media/encrypted-media.html#dom-generatekeyrequest
> > there are 3, say, is already a challenge).

Yes, the keySystem parameter is required for generateKeyRequest(). Whether this
method has been successfully called before the needkey event is fired may
affect which of the three options for setting the keySystem attribute is used.

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Received on Monday, 9 July 2012 19:23:02 UTC