[Bug 16611] Are reverse domain names sufficient for capability detection ?

https://www.w3.org/Bugs/Public/show_bug.cgi?id=16611

--- Comment #2 from David Dorwin <ddorwin@google.com> 2012-06-22 19:04:59 UTC ---
(In reply to comment #1)
> I assume from the current issue description that this would cover concepts such
> as domain support and embedded licenses? Would it allow things like querying
> whether the UA is a member of a given domain?

The key system string is targeted at determining the presence of a specific
system and telling the UA to use it. The intent is to allow an application to
make quick synchronous decisions on the type of license to request and possibly
which content stream to provide. In this way, the application can avoid
providing content and licenses that the UA cannot use.

It seems reasonable to expect that specific versions or even sub-products of a
key system might need to be identified. These might even indicate a "level" of
robustness.

The key system string does not provide any assurances of capabilities, so the
server and CDM are responsible for actual enforcement via their message
exchange. The key system string in generateKeyRequest() might indicate to the
CDM some configuration class (to be used in preparing the message), but
specific requirements should be specified in the license provided to addKey().

The question is whether this is sufficient. For example, does the application
need to be able to determine current platform state and not just CDM
capabilities. I don't think key system is appropriate for current state because
at least some states likely cannot be determined synchronously. Also, the
strings used for canPlayType() and generateKeyRequest() should probably be
identical, so using strings to perform detailed capability queries in
canPlayType() should probably be avoided.

To answer your question, I think querying for a given domain should either be
done within the key exchange flow or using some TBD mechanism. Support for
embedded licenses (with the assumption that one would exist if supported) might
fall under "robustness level" identification.

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Received on Friday, 22 June 2012 19:05:02 UTC