RE: DRM Today-based test case for EME

I’m wondering if there’s a reason to special case Clear Key.  If it’s more limited, then perhaps it should be separate from multi-DRM, and could for now stay in sync with updates from Chromium.

Whether Clear Key is included in the common tests or not, it seems desirable to have the infrastructure needed to test each supported keySystem.  Looping through the tests for each keySystem doesn’t sound too difficult, but we’d also want to clearly annotate results so that they are identified (and grouped?) by the keySystem tested.  I’m not sure how this last part would be accomplished, since the harness seems to discover test files and run them in sequence.  Do others know?

Jerry

From: David Dorwin [mailto:ddorwin@google.com]
Sent: Wednesday, July 20, 2016 3:12 PM
To: Mark Watson <watsonm@netflix.com>
Cc: Greg Rutz <G.Rutz@cablelabs.com>; Matthew Wolenetz <wolenetz@google.com> (wolenetz@google.com) <wolenetz@google.com>; Jerry Smith (WPT) <jdsmith@microsoft.com>; Philippe Le Hegaret (plh@w3.org) <plh@w3.org>; Francois Daoust <fd@w3.org>; public-hme-editors@w3.org; Iraj Sodagar <irajs@microsoft.com>; John Simmons <johnsim@microsoft.com>; Paul Cotton <Paul.Cotton@microsoft.com>; Sukhmal Kommidi <skommidi@netflix.com>
Subject: Re: DRM Today-based test case for EME

The abstraction Greg describes makes sense, at least to my rough understanding. Greg, would we vary the test configurations or are all configurations always present and just a way of isolating the logic for each key system?

In case there is any uncertainty, I want to emphasize that most of the "Google clearkey tests" are really just EME API tests that happen to use Clear Key. (The reason they use Clear Key (and WebM) has is related to the fact that they are Blink layout tests that run inside a subset of the code, pass in Chromium, and not depend on external servers.) Most interact with at least a portion of the Clear Key CDM implementation, meaning the behavior and results depend in part on the Clear Key implementation. This is similar to how most media tests are also testing a specific pipeline/decoder. There are some tests that explicitly test Clear Key behavior defined in https://w3c.github.io/encrypted-media/#clear-key, and we should ensure these are labeled "clearkey" in the path. Everything else should probably be converted to general tests.

Mark, my concern is that using Clear Key, which is almost certainly simpler than any other system, could paper over API design, etc. issues for other systems. In practice, I don't think this should be an issue since Edge doesn't implement Clear Key. (Thus, I also think we should err on the side of excluding Clear Key for now.)

For full coverage, all supported combinations would be executed (something I discussed<https://lists.w3.org/Archives/Public/public-hme-editors/2016Jun/0100.html> earlier<https://lists.w3.org/Archives/Public/public-hme-editors/2016Jun/0104.html>). It would be nice if we could get results for the general tests run on each key system (and type), but we'd need to create some infrastructure.

David



On Wed, Jul 20, 2016 at 1:17 PM, Mark Watson <watsonm@netflix.com<mailto:watsonm@netflix.com>> wrote:
Greg - this makes sense and it would be easy to take the drmtoday test we have written and make a new clearkey version of that by enhancing the utils and the config as you describe.

However, we already have a clearkey version of that test in the Google directory (which uses its own utils). So, doing what you say would increase the commonality / consistency between the tests, but it wouldn't get us more tests.

David - the clearkey results are useful information for the implementation report. Again, as with tests based on polyfills, they validate the API design, implementability and specification. These are factors in the decision as well as the current state of commercially useful features in commercial browsers. We are in the unusual situation of not being able to just wait until implementations have matured, so this is going to be an unusual decision.

...Mark

On Wed, Jul 20, 2016 at 1:05 PM, Greg Rutz <G.Rutz@cablelabs.com<mailto:G.Rutz@cablelabs.com>> wrote:
For (B), I wasn’t suggesting that there be two different tests in one file, I was suggesting that we put operations like license requests into utils files that would perform either DRMToday or ClearKey license requests.  For DRMToday, the implementation in these utils files would make the request to the actual DRMToday license server.  For ClearKey, the implementation would likely return a response message that is placed into the test configuration JSON (drmconfig.json in the example test created by Sukhmal).  The JSON config file can help configure both the key system and the desired license response message that we need in order to properly execute the test.

G

On 7/20/16, 1:30 PM, "Mark Watson" <watsonm@netflix.com<mailto:watsonm@netflix.com>> wrote:

So, what we have right now is:
(1) A large number of ClearKey-only tests in a "Google" folder, and
(2) One of those tests (basic playback) migrated to DRM Today, in the root folder

There are two approaches:
(A) Keep ClearKey and DRM tests separate: move the "Google" tests into the root or a "clearkey" folder, continue making new DRMToday versions of each of those ClearKey tests
(B) Make the DRMToday test also support ClearKey, continue making new ClearKey+DRMToday versions of each of the Google tests and, eventually, drop the Google folder

For (B), we need to run two tests in one file, which requires some care with async tests and there's been comments that we should not have multiple tests in one file.

Opinions ?

...Mark





On Wed, Jul 20, 2016 at 11:27 AM, Greg Rutz <G.Rutz@cablelabs.com<mailto:G.Rutz@cablelabs.com>> wrote:
I think the test utilities should be designed to be as DRM-independent as possible.  This would allow us to run any of the test cases that apply to ClearKey simply by providing a DRMConfig and test content that indicates use of ClearKey.  I apologize that I have not been following the EME spec progression that much over the last 12-18 months, but I recall there not being a ton of differences between ClearKey support and other DRMs as I implemented it in dash.js.

For test cases that are valid for ClearKey, the test case would simply execute multiple times on the UA under test — once with ClearKey content and one or more additional times for the “real” DRMs that are to be tested on that UA.  No sense in maintaining separate test code if we don’t have to.

G

On 7/20/16, 10:34 AM, "Mark Watson" <watsonm@netflix.com<mailto:watsonm@netflix.com>> wrote:

Question: should we expand this test case to cover ClearKey ? Or will we rely on the tests in the Google folder for ClearKey ?

If the latter, should we move those tests into the main directory (I see they are now working) ? Or, if others would like to add ClearKey tests, should they add them to the Google folder ?

...Mark

On Tue, Jul 19, 2016 at 7:18 PM, Mark Watson <watsonm@netflix.com<mailto:watsonm@netflix.com>> wrote:
All,

Sukhmal has created a Pull Request for a temporary session test case using DRM Today. We have tested this on Chrome with Widevine and it should work on Edge with PlayReady as well:

https://github.com/w3c/web-platform-tests/pull/3313


Please review this and comment on whether it is a good template / model for us to work from. We can quickly migrate more of the Google clearkey tests to drmtoday as well as implementing tests for other session types based on this model.

...Mark