[whatwg] Video proposals
Nicholas Shanks
contact at nickshanks.com
Fri Mar 16 04:05:05 PDT 2007
Discussion on aspect ratio:
>>> You may want to consider aspect ratio too: ratio="preserve" being
>>> default, ratio="1.333" could indicate 4:3 or get tricky and accept
>>> "16:9" for precision reasons.
>>
>> Wouldn't we simply always want to use the authored size?
> Do videos encode what size they are best displayed in? I hate
> entering height and width for images.
The reason I requested this is because:
1) If you specify both a width and a height, video content that
doesn't match that gets distorted.
2) If you want an element to have a fixed width, but variable height
dependant on the aspect of the video, or fixed height and variable
width, yet still have a non-zero initial value for the variable
parameter (so that the <video> element occupies some screen area),
you cannot achieve this without distorting the final image by setting
both width and height.
3) Thinking about it more, the ratio should be explicitly advisory
and only valid until the downloaded video can provide it's own width
and height.
I envisage:
<video src="foo" width="386px" aspect="59:54"></video>
<p>Some content below the video</p>
Then, when the video is finally downloaded and it's inherent
dimensions (and thus aspect ratio) are known, re-layout can occur if
the aspect values don't match, but more importantly can be avoided if
they do.
The width given is an integer number of CSS pixels, by providing an
aspect ratio, the UA can calculate the resultant height in device
pixels without the user having to provide a height and associated
rounding errors (or plain mistakes). The example above has an
irrational height.
4) Only two of {width, height, aspect} can be specified on any video
element.
- Nicholas.
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