[Bug 15140] The video element's poster attribute requires clarification in relation to precedence

https://www.w3.org/Bugs/Public/show_bug.cgi?id=15140

--- Comment #7 from Ian Devlin <ian@iandevlin.com> 2011-12-15 14:33:31 UTC ---
(In reply to comment #3)
> I don't understand what's vague in the spec here. Can you walk me through the
> reading of the spec that leads you to conclude that IE9 is conforming here?

The specification says the following:
"The poster attribute gives the address of an image file that the user agent
can show while no video data is available"

The problem bit here is "can show while no video data is available".

Taking an example where a valid poster attribute has been defined and the
video's metadata has been loaded:

IE9 has video data available, therefore it shows it, overriding the poster
attribute. The fact that the video data doesn't contain the first frame, or
does and it's blank, is irrelevant to IE9 as it has "video data available" and
there's no requirement for it to keep showing the poster image based on the
definition in the spec.

To me, whilst I don't agree with the behaviour, IE9 can be said to be
conforming to the spec.

Now if the spec. said something like:

"The poster attribute gives the address of an image file that the user agent
must show if present (or regardless of having video data available)".

Then IE9 wouldn't conform to the spec.

That said, since you don't think that IE9 is conforming, is this because
further down "not having video data available" is defined as either "having
nothing" or only "having metadata" - then perhaps IE9 is incorrectly defining
"having metadata" as "having video data available".
If this is the case, then you are correct. IE9 doesn't conform to the spec.

I suspect we need input from Microsoft here on what IE's definition of "have
video data" actually is.

Note:
>From brief tests with IE9, setting the preload attribute to "auto" or
"metadata" causes the poster attribute to be hidden. A value of "none" for
preload correctly causes the poster to be displayed.

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Received on Thursday, 15 December 2011 14:33:41 UTC