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Re: Encrypted Media proposal (was RE: ISSUE-179: av_param - Chairs Solicit Alternate Proposals or Counter-Proposals)

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Fri, 2 Mar 2012 10:59:06 -0800
Message-ID: <CAAWBYDDcL3CNFPZVgPkJS=Y7tjRPvY_Dx_HR+5U2OWTc+o3u_A@mail.gmail.com>
To: Glenn Adams <glenn@skynav.com>
Cc: Silvia Pfeiffer <silviapfeiffer1@gmail.com>, Henri Sivonen <hsivonen@iki.fi>, Mark Watson <watsonm@netflix.com>, "<public-html@w3.org>" <public-html@w3.org>
On Fri, Mar 2, 2012 at 10:42 AM, Glenn Adams <glenn@skynav.com> wrote:
> On Fri, Mar 2, 2012 at 11:19 AM, Tab Atkins Jr. <jackalmage@gmail.com>
> wrote:
>> On Fri, Mar 2, 2012 at 10:14 AM, Glenn Adams <glenn@skynav.com> wrote:
>> > On Fri, Mar 2, 2012 at 4:07 AM, Silvia Pfeiffer
>> > <silviapfeiffer1@gmail.com>
>> > wrote:
>> >> On Fri, Mar 2, 2012 at 8:41 PM, Henri Sivonen <hsivonen@iki.fi> wrote:
>> >> > On Thu, Mar 1, 2012 at 11:57 PM, Mark Watson <watsonm@netflix.com>
>> >> > wrote:
>> >> >> The underlying content protection systems are things like PlayReady
>> >> >> (from
>> >> >> Microsoft), Widevine (from Google) and Marlin. Adobe have something,
>> >> >> but I
>> >> >> don't know what they call it.
>> >> >
>> >> > As a co-proposer, does Microsoft plan to integrate PlayReady into IE?
>> >> > As a co-proposer, does Google plan to integrate Widevine into Chrome?
>> >> > Do the co-proposers plan to make their CDMs available to other
>> >> > browsers? Do the co-proposers plan to provide APIs that'd allow
>> >> > adding
>> >> > other CDMs to their browsers?
>> >>
>> >> I'm confused. I thought the whole idea of the proposal was to just
>> >> provide an API for adding CDMs into browsers such that when you have
>> >> the library installed on your computer, any browser is able to make
>> >> use of it, no matter if it's Google's Widevine library or Microsoft's
>> >> PlayReady - e.g. Firefox would be able to make use of these and any
>> >> other CDM library. There would be no need to implement something
>> >> additional into browsers. If this is false, somebody better clarify
>> >> how else it is supposed to work.
>> >
>> >
>> > Yes, that is indeed the idea. But Henri keeps wanting to drill down into
>> > the
>> > CDMs themselves, which is really out of scope for the proposal.
>>
>> Given that the CDM is a necessary component of the mechanisms
>> described in the spec, the details of the CDM are extremely relevant.
>> There's no way to implement the spec without involving a CDM.
>
>
> Of course, at the black box level for the purpose of defining the API
> behavior of the CDM, it is necessary to define semantics. However, a single
> instance of a no-op CDM (that translates plaintext to plaintext) would be
> sufficient to verify that behavior and test the API. Any other details of
> the CDM implementation, including licensing, trade secrets, patent
> encumbrance, etc., should be out of scope. At least that's my opinion and I
> would guess the opinion of the proposers.
>
> I understand, however, that a browser implementer may have interests in what
> goes into a particular CDM if they have to put it in their product, but I
> would suggest that is out of scope of discussing the utility or functional
> usage of a CDM as accessed through the proposed interface.

No.  Again, a working CDM is *required* for this API to be of any use.
 If implementing a working CDM is troublesome or impossible for
various reasons, that makes the API itself useless.

~TJ
Received on Friday, 2 March 2012 18:59:54 GMT

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