[Bug 21855] Avoid network traffic and duplicate sessions for the same key(s)

https://www.w3.org/Bugs/Public/show_bug.cgi?id=21855

--- Comment #6 from David Dorwin <ddorwin@google.com> ---
I like that the UA is not involved in deciding whether Initialization Data is
duplicate. I think that is an important requirement for any solution to this
issue.

Some of the downsides I see are:
 * Calling createSession() for every needkey event could result in a
continually growing set of MediaKeySession objects (and related resource
usage), which serve no purpose, as, for example, the player adaptively switches
among streams.
 * The CDM-specific behavior may/will likely lead to potentially inconsistent
behavior across implementations and require apps to deal with the worst case
implementation in apps.

Sharing underlying session/keys among MediaKeySession objects raises some
interesting questions. Are all such objects treated as identical? If not, what
is the expected behavior?
  - Can update() & close() be called on any of them?
  - Which MediaKeySession objects will receive keymessage events (i.e. for
renewal)? What about keyerror events?
  - When something like renewal happens and a session transitions (on a
keymessage) from Ready to Pending, do all MediaKeySession objects transition
(with the corresponding event)?

Similarly, as mentioned in
https://www.w3.org/Bugs/Public/show_bug.cgi?id=17750#c5, the sharing of
underlying sessions/keys complicates close(). We can address this by
eliminating close() or defining it in a compatible way, but we need to resolve
these issues together.

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Received on Tuesday, 30 July 2013 00:57:53 UTC