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Re: [EME] To what extent should EME support usage rules?

From: Joe Steele <steele@adobe.com>
Date: Tue, 20 May 2014 16:55:10 +0000
To: "Maruyama, Shinya" <Shinya.Maruyama@jp.sony.com>, David Dorwin <ddorwin@google.com>, Adrian Bateman <adrianba@microsoft.com>, "Niels Thorwirth" <nthorwirth@verimatrix.com>
CC: "public-html-media@w3.org" <public-html-media@w3.org>
Message-ID: <9C0B21AE-C814-4018-94C8-7792F575F8B2@adobe.com>
Adobe could support a start time for some keys. However not all keys would have a start time until they had been started.

The name “usableKeyIds” would need to change of course. Maybe “availableKeyIds”?

In this case the “status” of a key would start to look more like X.509 certificate status: (http://en.wikipedia.org/wiki/Certification_path_validation_algorithm)
  * valid
  * valid but usage limited (aka downscaling)
  * invalid because validity period has not started
  * invalid because validity period has expired
  * invalid because revoked
  * invalid for DRM-specific reason
  * unknown (can’t tell without trying to use it)

Not sure how many of these are common. However I think applications could use this for testing and debugging so it could be useful especially for interop testing. 
I am in favor of more information, but this could complicate things quite a bit for CDM implementors. I would like to hear feedback from some of them.

David, Adrian, Niels — any comments on this?


On May 14, 2014, at 7:40 PM, Maruyama, Shinya <Shinya.Maruyama@jp.sony.com> wrote:

> I agree with your point.
> From your viewpoint, I wonder if start time would be useful for application to know a key is not available yet because start time is future time.
> You opinion?
> - Shinya
> From: Joe Steele [mailto:steele@adobe.com] 
> Sent: Thursday, May 15, 2014 6:11 AM
> To: Maruyama, Shinya
> Cc: public-html-media@w3.org
> Subject: Re: [EME] To what extent should EME support usage rules?
> There are a couple of additional usage rules that have been mentioned.
> There has been discussion of usage rules around output protection (e.g. HDCP). This used to be represented via an error code, but that has gone away at this point. 
> There has also been discussion around output downscaling in bug 25092.
> My opinion is that the application only needs to know about things that might be impacting playback. 
> For example:
> * When a key is no longer available because it has expired. What type of expiration occurred and the exact times makes less sense to me. 
> * When playback has stopped because output protection has been violated. Again the type of OP failure makes less sense to me. 
> * When playback has degraded for some reason (e.g. OP failure). 
> There are lots of other usage rules (geolocation, domain membership, etc.) but I think most of these can be invisible to the application and handle on the server side. Do you have a specific policy in mind that we do not have?
> Joe
> On May 13, 2014, at 12:07 AM, Maruyama, Shinya <Shinya.Maruyama@jp.sony.com> wrote:
> Now expiration time is the only usage rule EME API supports by Bug 25537.
> Is the expiration time sufficient for the envisioned use cases? or
> Is there still the room to add other parameters?
> For instance, in case of rental video, start time and period after first use are used in general.
> In this case, constructing UI only by expiration date might be confusing to users because end time shortens after first use implicitly.
> As to start time, it might be useful if video is upcoming movie; i.e. start time is future time.
> Honestly, I’m not sure what is the criteria to decide which usage rules are common concept in EME world.
> Any opinion?
> Thanks,
> Shinya

Received on Tuesday, 20 May 2014 16:55:40 UTC

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