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AES-CTR inside vs. outside the media container (was: Re: Encrypted Media proposal: Summary of the discussion so far)

From: Henri Sivonen <hsivonen@iki.fi>
Date: Wed, 7 Mar 2012 14:54:49 +0200
Message-ID: <CAJQvAuff24QNSF61zBCRzbsOwgeOmmSdja=HG93fK46p-irX+Q@mail.gmail.com>
To: Mark Watson <watsonm@netflix.com>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, Christian Kaiser <kaiserc@google.com>, "<public-html@w3.org>" <public-html@w3.org>
On Mon, Mar 5, 2012 at 2:57 AM, Mark Watson <watsonm@netflix.com> wrote:
> This is how we at Netflix are able to work with multiple CDMs but one set of media files using the ISO Common Encryption standard for mp4 files.

Other than ISO Common Encryption being already deployed, what's the
benefit of encrypting codec data the mp4 container using AES-CTR as
opposed to encrypting the entire mp4 file using AES-CTR?

(Presumably in non-streaming cases, it might be useful to be able to
read embedded metadata even if the media is unrenderable, but in the
streaming Web case, that doesn't seem like an important benefit.)

-- 
Henri Sivonen
hsivonen@iki.fi
http://hsivonen.iki.fi/
Received on Wednesday, 7 March 2012 12:55:25 UTC

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