[Bug 27077] New: Cababilities need to clearly specify that they are constant over time

https://www.w3.org/Bugs/Public/show_bug.cgi?id=27077

            Bug ID: 27077
           Summary: Cababilities need to clearly specify that they are
                    constant over time
           Product: WebRTC Working Group
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Media Capture and Streams
          Assignee: public-media-capture@w3.org
          Reporter: harald@alvestrand.no
                CC: public-media-capture@w3.org

>From Jan-Ivar, in bug 25777:

While examples are nice, I would argue they're no replacement for
specification.

Are capabilities accurate?

While it is possible to deduce from the applyConstraints algorithm [1] that
capabilities are allowed to be a super-set of what the UA supports, I find no
mention of this where Capabilities is defined [2].

I've read the definition a couple of times, and even though it uses the word
"subset" four times in one paragraph, it still seems to equate what the
capabilities read with what "the UA supports", which doesn't allow for
capabilities to be either-or (e.g. super framerate OR super resolution).

I think it would help implementations if the spec stated that returned
capabilities must a set or super-set of what the UA supports.

Are capabilities constant?

I find conflicting text on this in the spec:

"The UA may choose new settings for the Capabilities of the object at any time.
When it does so it must attempt to satisfy the current Constraints, in the
manner described in the algorithm above." [2]

vs.

"Source capabilities are effectively constant. Applications should be able to
depend on a specific source having the same capabilities for any session." [3]

[1]
http://w3c.github.io/mediacapture-main/getusermedia.html#dfn-applyconstraints
[2] http://w3c.github.io/mediacapture-main/getusermedia.html#capabilities
[3] http://w3c.github.io/mediacapture-main/getusermedia.html#terminology
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Received on Thursday, 16 October 2014 13:07:49 UTC