[Bug 25218] Allow license management directly via MediaKeySession

https://www.w3.org/Bugs/Public/show_bug.cgi?id=25218

--- Comment #15 from Mark Watson <watsonm@netflix.com> ---
(In reply to Joe Steele from comment #14)
> (In reply to Mark Watson from comment #12)
> > (In reply to David Dorwin from comment #11)
> > > (In reply to Mark Watson from comment #10)
> > I should say that my understanding is that any additional state is really
> > just an optimization. We should assume that a CDM in a 'cold state' can
> > always perform the necessary message exchanges with its server peer to get
> > the content keys needed to decrypt the content. What I understood Joe was
> > asking for was to avoid repeating exchanges every time when they can be done
> > once and the resulting state persisted. The application doesn't even need to
> > know this is happening.
> 
> To say this is just an "optimization" is understating it quite a bit. In the
> same sense, taking a car on a 100mile trip is an optimization over walking.
> Both methods will get you there, but there is a huge difference in
> experience.
> 
> In the case where a web application is using a CDM for the first time, there
> may be bootstrapping keys unique to that origin that need to be downloaded.
> Why unique? Because in our earlier discussions on key sharing it was
> determined that keys should not be shared across origins. 
> 
> If the CDM is using software-based key hiding mechanisms, the bootstrapping
> process is slow. On the order of seconds. This is not a problem when it
> happens once, and can be managed to happen while the application is occupied
> with other things (like displaying video thumbnails for selection) but a
> HUGE problem if it happens on every download. 
> 
> This is the key exchange I do not want to repeat. This key exchange should
> be subject to the same-origin constraints all other CDM communication is. To
> me this implies it must go through the keyrequest/update() mechanism. Or we
> must introduce an alternate mechanism which looks essentially the same, but
> is specific to this purpose.

I certainly agree with not repeating such bootstrap functions unnecessarily.
And I agree it could use the keyrequest / update mechanism to complete it. What
is it in the existing specification that means you have to repeat this part ?

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Received on Wednesday, 30 April 2014 18:06:26 UTC