W3C home > Mailing lists > Public > public-html-media@w3.org > March 2013

Re: how does EME/DRM effect captioning

From: Glenn Adams <glenn@skynav.com>
Date: Thu, 28 Mar 2013 11:01:04 -0600
Message-ID: <CACQ=j+d2LH+cA+j8q+Tz++sh8j8firV4xijPU04ntaKsn=rhCg@mail.gmail.com>
To: Henri Sivonen <hsivonen@iki.fi>
Cc: Steve Faulkner <faulkner.steve@gmail.com>, HTMLWG WG <public-html-media@w3.org>, HTML Accessibility Task Force <public-html-a11y@w3.org>
On Thu, Mar 28, 2013 at 10:26 AM, Henri Sivonen <hsivonen@iki.fi> wrote:

> (Moving from public-html to public-html-media.)
> On Thu, Mar 28, 2013 at 4:59 PM, Glenn Adams <glenn@skynav.com> wrote:
> > I expect that CDM providers will be aware of these requirements and work
> > with UA vendors to ensure that external requirements on accessibility are
> > met.
> Surely in the Web case the regulatory requirements apply to content
> providers. Surely there is no regulatory requirement that the captions
> be DRMed. Also, it doesn't make sense that the content provider could
> throw anything at the browser and the browser would be responsible by
> regulation for rendering captions delivered in an unfavorable way.

There are different sets of requirements (in the U.S.) pertaining to
content providers and content presentation devices (e.g., a device
containing a UA that is presenting content). Of course there is no
requirement that captions be DRMed and I did not suggest otherwise. Nor did
I suggest that a browser must be responsible for presenting unaccessible
caption content. What I did say is that CDM vendors may be obligated to
expose captions to the UA in plain text form under some circumstances, and
it would be the responsibility of the manufacturer of a regulated device to
make use of that content as regulation requires.

> If CDMs and browsers don't support DRMed captions (my reading of the
> Chromium source code suggests that Chrome with Widevine doesn't and to
> me that looks like a very reasonable decision), the way content
> providers can meet the regulatory requirements is that they provide a
> non-DRMed WebVTT captions to be rendered by the browser without the
> involvement of the CDM.

Sure, providing unencrypted captions in TTML or WebVTT is an option, as is
providing either or both of these in addition to captions embedded in an
encrypted video stream.

Are you saying something new here that I didn't already say or suggest?
Received on Thursday, 28 March 2013 17:01:53 UTC

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