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[whatwg] video tag: pixel aspect ratio

From: Eric Carlson <eric.carlson@apple.com>
Date: Wed, 15 Oct 2008 14:48:31 -0700
Message-ID: <0D03B1A2-B2FD-4ECD-A35E-C2F593DA3BF6@apple.com>

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.

eric
Received on Wednesday, 15 October 2008 14:48:31 UTC

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