RE: EME impact on accessibility

Hi Alistair, I agree this puts us in a tricky situation as we cannot conceive all of the possible research that might happen in this field.  In addition to the items in your list (some of which I have raised questions on) I also think tools can be created that might also buffer video and detect flashing content and hide the video reduce luminance etc. to reduce issues cases with flashing content.  There are some many aspects of automation and other accessibility features beyond captions and audio description that we need a way to modify the stream but do it in a verified and agreed upon way.   Just as approved user agents can decrypt and render with keys there should be a way for researchers to test these new accessibility concepts and create features that could be certified or approved to assist but still protect copyright holders.


From: Alastair Campbell []
Sent: Wednesday, April 05, 2017 9:22 AM
Subject: EME impact on accessibility

Hi everyone,

I’m trying to get some information to make a choice without getting into a bun-fight on a contentious topic. I’d like to get to the facts of the situation without talking about the good/bad of EME in general, so please bare that in mind.

The W3C has “Encrypted Media Extensions” [1] at Proposed Recommendation stage, the spec that defines the API from the browser to a DRM module. Several W3C members are objecting to it on the grounds of the impact is has on security and accessibility.

What I’d like to focus on is the theoretical and practical implications for accessibility. For example, from my reading:

-          Captions.
If captions are available they must be un-encrypted, so there shouldn’t be an issue there.

-          Audio description.
I assume audio-description would simply be a separate audio stream or separate video, I don’t see an issue there.

Other items raised by people to do with accessibility are as follows, with my own comments under the item:

-          Enlargement of content.
I’m not sure how this is affected. The video is encrypted, but I believe that its size can be adjusted within a page. Captions and the timings that drive them are not encrypted so should not be affected by EME.

-          Auto captioning of the audio stream.
So encrypting the video & audio would (theoretically at least) prevent a 3rd party from running auto-captioning software on the audio.

However, the companies with the capability to do that (Youtube, Microsoft, Amazon etc) are very closely correlated with the companies applying the DRM. Would this be an issue in practice? Presumably the responsibility for providing captions is on the provider who has the non-encrypted copy, therefore they are not prevented from auto-captioning?

-          Facial recognition.
I’m not entirely sure what the purpose of this would be, identifying people/actors/characters as they come and go? I can tell Amazon already has that information as meta-data for their videos as the interface can show you who is in the scene. I suspect they add that with a more manual process though, as it doesn’t match whether the face is on screen or not, just whether they are in the scene.
Theoretically this would prevent 3rd party access to facial recognition, but is it something that would be the responsibility of the provider anyway? Not sure.

-          Color filtering.
On iOS (at least) colour filtering can be done at the hardware level, and if you have colour issues then presumably you’d want it on all the time, not than just videos?

Given that EME has been implemented in browsers for several years, the question is whether the W3C blesses the spec, and I’d like some solid information on the accessibility aspects before commenting.

Kind regards,



Received on Wednesday, 5 April 2017 13:34:27 UTC