[whatwg] video tag: pixel aspect ratio

Peter Kasting pkasting at google.com
Sun Nov 30 22:11:40 PST 2008

On Sun, Nov 30, 2008 at 9:11 PM, Ian Hickson <ian at hixie.ch> wrote:

> > I might be missing something here, but:
> > 1) I don't remember any major media system I've dealt with so far having
> > an explicit pixel aspect ratio override API,
> > 2) on the web, neither QT plug-in nor Flash have it,
> That might explain the large number of videos on the Web that are rendered
> at the wrong ratio without anyone doing anything about it. :-)

Or, perhaps, "authors don't care" or "the people who embed videos for
playback without access to the original source files are unlikely to know
much about getting aspect ratios correct, especially when it involves using
confusing attributes that people are not supposed to use" might explain it.
 I'm not sure what data could be used to determine which hypothesis is

> 5) there's no _actual_ data that proves it's necessary (shouldn't the
> > software or video web site fix the videos upfront?)
> Anecdotally, I see this quite a lot (several times a week).

Anecdotally, I never see this, and I watch a lot of video.  YouTube's recent
widescreen move has made me see a lot of boxed video, but that's not the

The plural of anecdote is not data.  To repeat the question, what sorts of
_data_ motivate this?

> Based on this, it seems to me this attribute should not be in the spec
> > by default, and we should switch the burden of the proof to people who
> > want it (rather than it being on people who don't want it as it seems to
> > be the case today), and finally wait to see 1) if there's a real need
> > for a solution here and 2) if the best solution is indeed a pixel aspect
> > ratio override.
> I'm certainly open to other solutions. What do you suggest?

>From reading the above paragraph, "do nothing, for now".  I don't see a
problem in need of an HTML 5 spec solution.

On Mon, 17 Nov 2008, Peter Kasting wrote:
> > The potential for problems seems
> > greater than the upside from authors correctly using this to do
> > emergency-overrides of particular videos whose sources they don't
> > control.
> I don't understand why this attribute would cause problems. Can you
> elaborate?

* Authors specify the wrong ratio, causing videos to look worse
* Authors, blindly copy-and-pasting, believe this attribute is required and
specify it everywhere, increasing the likelihood of both of these bullet

If you think the likelihood of the first bullet is low, consider the
confusion evident on this thread, and then extend that to authors who have
even less of a clue.  The attribute is confusing because your intended use
-- as a hack that people shouldn't use -- is confusing.

Videos encoded at the wrong aspect ratio are a real problem, but they are
one of an extremely large number of real problems, most of which we
(rightly) are not trying to solve.  I think you have given a few reasons why
we _aren't_ trying to solve others.  I don't understand why we're trying to
solve this one.

I don't think it is the end of the world if this attribute goes in, but I
see very little benefit to it, and I am always for removing items with
marginal utility.

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