[Bug 25923] isTypeSupported should be asynchronous

https://www.w3.org/Bugs/Public/show_bug.cgi?id=25923

--- Comment #35 from David Dorwin <ddorwin@google.com> ---
For any solution where the type support checking mechanism triggers or is only
available after prompting, implementing support for more than one promptable
key system would result in either complex UX or potentially multiple prompts if
the first key system does not support the types the application wants.

For example, if an application requests (supported) key system A, the user may
be prompted, and only after the user accepts would the application find out
that the key system does not support codec foo. The application would then
request (supported) key system B, potentially prompting the user again.

This is a problem for both the original proposal (asynchronous
isTypeSupported(), which would be called multiple times in parallel) and the
proposal in comment #32.

I see two possible solutions to this problem:
1) The application can check for the best case support without prompting for
permissions or download.
 * In other words, the equivalent of the current isTypeSupported() reports the
best case for the user agent implementation not what is actually supported.
 * The application can call this before requesting access to the CDM, which
would trigger the prompt and/or download.
2) Some type of request involving multiple key systems (and probably types)
that allows the user agent to make a reasonable decision.
 * The user agent may not do what the application wants, though, and such
decisions have generally been left to the application.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.

Received on Wednesday, 24 September 2014 18:18:20 UTC