[Bug 17470] Provide specific guidance on when generateKeyRequest should be called

https://www.w3.org/Bugs/Public/show_bug.cgi?id=17470

--- Comment #6 from Joe Steele <steele@adobe.com> 2012-09-05 15:43:38 UTC ---
(In reply to comment #5)
> (In reply to comment #4)
> > I would like to reopen this issue. I am concerned about the cases where being
> > able to preload keys would significantly impact the user experience. 
> > 
> > Consider this scenario -- 
> > The user browses to a video distributor using a domain key model for
> > determining entitlements. If the user has not yet acquired the appropriate keys
> > and there is no additional user interaction required, they could be acquired
> > while the user is browsing the video selection rather than waiting until the
> > user selects a video and tries to play. This would result in a better user
> > experience in cases where the key acquisition takes a perceptible amount of
> > time (i.e. over 1 sec).
> 
> This sounds similar to the use case mentioned in Comment 1. I think what you
> want to do is possible with the new OO APIs.
> 
> > Given that loading is required to begin, how can we achieve this? Could the
> > MediaKeys object be instantiated independent of an HTMLMediaElement?
> 
> Yes, in the OO APIs. You just can't assign the MediaKeys to the
> HTMLMediaElement until loading has started.

It would be good if an example of this use case was somewhere in the document.
It is not clear now that this would work. This use case could invalidate Step 1
of the createSession algorithm, as there would be no obvious mime-type to pass
in to createSession. We could allow null to be passed (currently this would
trigger an error), or we could define a special mime-type for this use case
(e.g. "undefined") or we could specify that the CDM must ignore it.

In the use case I am thinking of -- the standalone MediaKeys instance would
never be attached to an HTMLMediaElement. It would be released after it had
been used for pre-loading keys.

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Received on Wednesday, 5 September 2012 15:43:43 UTC