[whatwg] video tag: pixel aspect ratio

Sander van Zoest sander at vanzoest.com
Wed Oct 15 15:05:45 PDT 2008

On Wed, Oct 15, 2008 at 2:48 PM, Eric Carlson <eric.carlson at apple.com>wrote:

> On Oct 15, 2008, at 1:04 PM, Ralph Giles wrote:
>  On Wed, Oct 15, 2008 at 12:31 PM, Sander van Zoest <sander at vanzoest.com>
>> wrote:
>>  Following that logic, why add the attribute at all?
>> Well, I like the pixelaspect attribute because incorrect aspect ratios
>> drive me up the wall. Because the video and its embedding page are
>> often served from different locations, it's nice to have a way to fix
>> it the doesn't require editing the video file.
>>   I agree that incorrectly encoded videos are annoying, but I don't think
> we should have this attribute at all because I don't think it passes the
> "will it be commonly used" smell test.
>  I am also afraid that it will difficult to use correctly, since you
> frequently have to use clean aperture in conjunction with pixel aspect ratio
> to get the correct display size. For example (you probably know this, but
> for the benefit of others following the discussion) DV NTSC video is
> 720x480, has Rec.601 aspect ratio (10:11), and should be displayed at
> 640x480. Multiplying 720x480 by 10:11 doesn't give 640x480 however, you have
> to crop to clean aperture (704x480) first. We *definitely* don't want to
> expose CLASP.
>  I don't think it should be included in the first version of the spec.

Certainly not. I forgot about the required crop. I am now even more
convinced it doesn't belong in the spec.
Let the container handle this detail.

-- Sander
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