Re: CfC: Create Media Task Force

On Apr 11, 2012, at 9:20 PM, Robert O'Callahan wrote:

On Wed, Apr 11, 2012 at 4:07 PM, Mark Watson <watsonm@netflix.com<mailto:watsonm@netflix.com>> wrote:
On Apr 10, 2012, at 6:47 PM, "Robert O'Callahan" <robert@ocallahan.org<mailto:robert@ocallahan.org>> wrote:
> Obviously the W3C should not bless, or be seen as blessing, a specification that cannot be interoperably implemented. Therefore, the Media TF needs to be constituted to ensure that it either produces a spec that can be interoperably implemented (e.g., Encrypted Media plus details of the CDMs that will be used and how any UA can access them), or nothing at all. If this condition can't be imposed from the outset, then I oppose creating the TF.

Just for my understanding, do you mean that a detailed API should be defined for CDMs (in any particular language?), or that some or all CDMs themselves must be fully specified ? (Or something else?)

I think there are multiple possible ways to meet this goal for each CDM.

One way would be to have the complete workings of the CDM documented/specified in enough detail that it can be freely reimplemented; this would be ideal, but I don't expect it to happen, since that I assume any CDM so documented would fail the Hollywood placebo test.

If this could work, we would certainly have proposed it.

If you mean 'documented in W3C', the problem is that any proposal for a useful fully-specified CDM is quite likely to be covered by patents held by non-W3C members. In order to meet W3C's RF requirements, someone would need to do a full patent search and legal review and approach those patent holders to ask for RF rights. I'm not sure if W3C has resources for this kind of work ? Or that it would be a good investment given the low probability of success on last part.

IANAL, so the above is just what I'm told. I'd be more than happy to be proved wrong (for example if someone in W3C has a full proposal to which they know they hold all the rights).

If you mean documented anywhere, I don't think it's a necessary feature of such technologies that how they work is secret, any more than encryption algorithms need to be secret. It does help that encryption algorithms are by their nature hard to understand, where as DRM algorithms probably aren't. You could look at OMA DRM (http://www.openmobilealliance.org/technical/release_program/drm_v2_0.aspx) as a proof point, for example.


Alternatively, for a platform that offers built-in DRM API, you could define a CDM that maps onto that API, and explain the mapping in enough detail that any UA running on that platform could implement it.

Alternatively, for a proprietary DRM product, you could define a CDM that maps onto that product and explain that mapping in enough detail that any UA running where that product is present could implement it.

These are both important goals that I support. I don't see them as alternatives: we need both.

I'm not sure what the W3C's role is in achieving those or how we formulate them into the Task Force objectives ?

We do already require interoperable implementations for a specification to progress (where I assume by "interoperable" we mean two UA implementations which, given the same input HTML/CSS/Javascript/Media/user input will produce the same output - pixels on the screen, sounds from the speaker etc.)

Would it be sufficient in this case to be more specific and require that there is at least one interoperable UA implementation from an implementor who is not also a DRM vendor ? This would provide an incentive for the DRM vendors to ensure that one or both of the above do happen in parallel with the specification work.

[This is a detail, but the second objective could also be achieved if it is clear what API a UA needs to provide so that a CDM which wraps the proprietary DRM product can be created *and* the DRM vendors then do create such CDMs.]

…Mark


Thanks,
Rob
--
“You have heard that it was said, ‘Love your neighbor and hate your enemy.’ But I tell you, love your enemies and pray for those who persecute you, that you may be children of your Father in heaven. ... If you love those who love you, what reward will you get? Are not even the tax collectors doing that? And if you greet only your own people, what are you doing more than others?" [Matthew 5:43-47]