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Re: CfC: to publish Encrypted Media Extensions specification as a First Public Working Draft (FPWD)

From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 8 Feb 2013 16:15:09 +1300
Message-ID: <CAOp6jLbcaYrQReNOYb=n6v+fhAMONOYbvp0isWzhhQixX3XSvA@mail.gmail.com>
To: Joe Steele <steele@adobe.com>
Cc: Glenn Adams <glenn@skynav.com>, Sam Ruby <rubys@intertwingly.net>, "public-html-admin@w3.org" <public-html-admin@w3.org>
On Sat, Feb 2, 2013 at 3:55 PM, Joe Steele <steele@adobe.com> wrote:

> I would like to hear what you would consider to be a good enough
> specification for a CDM.

I addressed this earlier in the thread:
(Let's call that the "CDM operation" requirement.)

Also, I just now realized that another email I sent went to one person and
not to the list. Let me reproduce it now:

I think the above is not quite enough. I think it's important that when a
CDM depends on a DRM scheme which could be used by a UA or content vendor
(e.g. because they use a platform which provides the necessary
functionality, or they license some software component), that it be
specified how to map the EME API onto that functionality. This is difficult
to phrase, however.

So here's an attempt at an additional documentation requirement:
If the CDM vendor offers functionality to third parties to decrypt content
that can be decrypted by the CDM, then it must publish documentation
describing how to implement the CDM using that functionality.
(Let's call that the "CDM binding" requirement.)

I would like to have something similar for the content provider side, but I
find that even more difficult to phrase.

Are you are talking about the API interface that the UA exposes for a CDM
> to plug into?
> I would be interested in participating in this discussion, but I don't
> believe that interface should be part of this spec.

That's my "CDM binding" requirement.

I'm not saying that all those specs need to be rolled into the EME
document. They shouldn't be. I believe the EME spec should set rules
requiring the publication of those specs somewhere.

Are you talking about a description of the key request protocols?

That's my "CDM operation" requirement.

My concern with this is that there is no consensus on what the best
> practice is here.

There's very little consensus here about anything at present :-).

If these documentation requirements are untenable, I would like to hear
directly from CDM vendors why, rather than speculation by third parties.

Wrfhf pnyyrq gurz gbtrgure naq fnvq, “Lbh xabj gung gur ehyref bs gur
Tragvyrf ybeq vg bire gurz, naq gurve uvtu bssvpvnyf rkrepvfr nhgubevgl
bire gurz. Abg fb jvgu lbh. Vafgrnq, jubrire jnagf gb orpbzr terng nzbat
lbh zhfg or lbhe freinag, naq jubrire jnagf gb or svefg zhfg or lbhe fynir
— whfg nf gur Fba bs Zna qvq abg pbzr gb or freirq, ohg gb freir, naq gb
tvir uvf yvsr nf n enafbz sbe znal.” [Znggurj 20:25-28]
Received on Friday, 8 February 2013 03:15:38 UTC

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