[Bug 26207] Provide a way to check system capabilities required for UHD playback

https://www.w3.org/Bugs/Public/show_bug.cgi?id=26207

Bob Lund <b.lund@cablelabs.com> changed:

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--- Comment #4 from Bob Lund <b.lund@cablelabs.com> ---

(In reply to David Dorwin from comment #3)
> (In reply to Jerry Smith from comment #1)
> UHD might be a use case, but I don't think this feature request is more
> general and the summary should reflect this.

As you and Mark point out, this feature could be more generally applicable but
gets into checking for media capabilities beyond content protection and output
protection. General media capability checking wouldn't be defined by EME.

EME should focus on the content protection related checks.

> 
> My initial thoughts:
> 
> #1 is simple and perhaps the short-term solution (it's already defined)
> while the other options are explored.
> 
> #2 may be the best way to provide answers to robustness questions. The
> server/application knows what types of licenses it supports, so why not let
> it ask the CDM directly. Anything else requires the application and UA to
> translate robustness requirements to text and text to robustness
> capabilities, respectively. This model is also consistent with
> getUsableKeyIds().
> 
> However, this may not always be sufficient since licenses don't normally
> specify the types of media (audio vs. video) or codec(s) to be used with
> each key. Without such information, applications might get false positives
> or negatives.
> 
> Also, it's unclear how this would work since licenses are usually issued
> after a license request and the license may depend on information from the
> device, which is not possible with such a simple query. There may be room
> for improvement here, but it's something to keep in mind.
> 
> #3 - There is a general lack of powerful capability detection for
> HTMLMediaElement, most of which is unrelated to robustness. I think that
> should be solved in general outside of EME. I believe this needs to be
> solved for unprotected content and there are a lot of stakeholders and
> interested parties that may not be participating in the EME specification.
> 
> Such a discussion will either solve the robustness problem or provide a
> model EME can build on. While such a querying API might be easily
> extensible, the robustness-media type mapping seems like something that may
> not fit well on a generic solution. Also, output protection might be the
> only capability for which detection may require a noticeable delay on
> subsequent calls. Such a delay could make the querying capability less
> useful since the goal is to start fetching the right media streams as
> quickly as possible.
> 
> I do not think standardizing labels for proprietary robustness mechanisms
> makes sense, at least without corresponding standardization of related
> aspects of the license. It seems difficult to come up with a consistent
> vocabulary that will work across key systems without excluding some valid
> scenarios. Content providers define their needs in the license, which is
> what makes #2 attractive.

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Received on Tuesday, 22 July 2014 15:10:41 UTC