[Bug 25092] Need a way to inform script that resolution restrictions are applied

https://www.w3.org/Bugs/Public/show_bug.cgi?id=25092

--- Comment #24 from Mark Watson <watsonm@netflix.com> ---
Discussion on www-style concluded [1] that media queries was not the right way
to handle the resolution restrictions arising from downscaling.

There already exist tools which can be used to determine physical display
resolution and thus influence bitrate choice on that basis.

For the dynamic, content-related, case of HDPC-driven downscaling, we should
define something EME-specific.

My original suggestion was to define an event specifically for this case of
resolution restrictions. There are two subcases depending on whether
downscaling is supported:
(a) resolution restricted and downscaling supported (playback continues)
(b) resolution restricted and downscaling not supported (playback stops)

We also have the alternative of requiring that different policies be associated
with different key ids (fake ones if necessary) and indicating the status with
respect to each policy through the usable key ids mechanism. Thus, there would
be a key id associated with the policy that 'requires HDCP x.y for resolution
z'. That key id would be marked as unusable to indicate that resolution z
cannot be supported. Whether there is downscaling or the playback is stopped
might be indicated by a key status or just by the fact of whether playback is
continuing or not.

This alternative could work, but it seems rather complex and the fake key ids
seem awkward. I also do not like the application responsibility for the linkage
between fake key id and policy: it does not seem that this could be done in a
keysystem-independent way (some keysystems may support applications specifying
the 'fake key id <-> policy' correspondance at the server side, but others
might have it hard-coded into the CDM). To address this - since resolution
restriction is IIUC the only example of a restriction leading to a desire to
switch streams - I wonder if we should expose the resolution restriction
explicitly with the key status ?



[1] http://lists.w3.org/Archives/Public/www-style/2014Nov/0373.html

-- 
You are receiving this mail because:
You are the QA Contact for the bug.

Received on Tuesday, 16 December 2014 17:34:23 UTC