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RE: how does EME/DRM effect captioning

From: John Simmons <johnsim@microsoft.com>
Date: Wed, 3 Apr 2013 17:16:21 +0000
To: Janina Sajka <janina@rednote.net>, Mark Watson <watsonm@netflix.com>
CC: Glenn Adams <glenn@skynav.com>, Henri Sivonen <hsivonen@iki.fi>, "Steve Faulkner" <faulkner.steve@gmail.com>, HTMLWG WG <public-html-media@w3.org>, HTML Accessibility Task Force <public-html-a11y@w3.org>
Message-ID: <dfc6f6c029a346b3a6d5c219e256ca10@BY2PR03MB042.namprd03.prod.outlook.com>
As a data point, the Common File Format used by UltraViolet (which is fragmented MP4 for a reason) prohibits the encryption of closed captioning.

In general, the model that works best for the web is one where "late binding" of tracks from a variety of sources are combined together into a composition. One of those tracks could be captioning, and with late binding, there is no upper limit on the number of captioning tracks that can be defined to be included in that composition.


John C. Simmons | Media Platform Architect | Microsoft Corporation | direct 425-707-2911 | mobile 425-269-5759


-----Original Message-----
From: Janina Sajka [mailto:janina@rednote.net] 
Sent: Wednesday, April 03, 2013 8:50 AM
To: Mark Watson
Cc: Glenn Adams; Henri Sivonen; Steve Faulkner; HTMLWG WG; HTML Accessibility Task Force
Subject: Re: how does EME/DRM effect captioning

Mark Watson writes:
snip ...

> ... we deliver captions/subtitles separately in a (unencrypted) TTML 
> file.
> 

Seems to me this is the optimal approach.

1.)	Minimizes any potential barriers for users
2.)	Benefits service providers by supporting open ansillary
services, like indexing.

Am I wrong? Is there any actual use case for encrypting captions? What did I miss here?

Janina


-- 

Janina Sajka,	Phone:	+1.443.300.2200
			sip:janina@asterisk.rednote.net
		Email:	janina@rednote.net

Linux Foundation Fellow
Executive Chair, Accessibility Workgroup:	http://a11y.org

The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
Chair,	Protocols & Formats	http://www.w3.org/wai/pf
	Indie UI			http://www.w3.org/WAI/IndieUI/
Received on Wednesday, 3 April 2013 17:17:37 UTC

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