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Re: [Public WebGL] EME and its interaction with WebGL



At this early stage I don't suppose that browser developers would have
fully thought out ideas of what exactly will be possible with EME video,
but there are basically two approaches that could be taken to achieve a
vague semblance of self-consistency:
 - either one decides that EME's goal is only to prevent ripping at the
stream level. Under that theory, EME video wouldn't be subject to more
WebGL-related restrictions than regular video.
 - or one decides that EME really tries to prevent people from reading
back decoded frames. In which case one could think that that is similar
to not-same-origin video; except that if one wants to prevent not just
regular Web content, but also privileged code like Firefox add-ons from
getting the frames, that won't be enough, and in that case one would
have to add a lot of drastic restrictions on what can be done with EME
video that would include disabling usage in WebGL and much more (since
at that point EME video would need a separate rendering pipeline
bypassing the browser compositor completely).

Until these decisions are made (and I don't know that they are as of
yet) we can't know the answers to your specific questions.

Benoit


On 13-02-28 09:56 AM, Florian Bösch wrote:
> I was wondering about the implications of having an EME element
> (video) on the page and its interaction with WebGL.
>
> The HTMLVideoElement can be used by calls to texture2D, and as I've
> shown dependent lookups and vertex shader lookups can be used to
> extract content (other than toDataURL and readPixels).
>
> Is it a given that the presence of an EME video on a page also
> containing a gl context will disable:
> - dependent lookups in fragment shaders?
> - vertex shader texture lookups?
> - toDataURL of canvases?
> - readPixels?


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