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RE: RE: RE: RE: Re: Re: TTML and aspect ratio

From: David Ronca <dronca@netflix.com>
Date: Mon, 4 Feb 2013 21:16:29 +0000
To: "public-tt@w3.org" <public-tt@w3.org>
Message-ID: <F7DC5134CE82754A878475EEBA450B3B314A60@EXMB105.corp.netflix.com>
The dimensions of 1080p are 1920x1080.  Based on your math, the top-left will be 192,108.  But if you present CEA-608 captions on a 1080p video, this is not correct.  CEA-608 defines the width of the caption area as 133.3% of the picture height (caption area height defined as 100% of picture height).  The coordinate 192,108 is outside of the CEA-608 defined caption area.  The CEA-608 caption area is physically mapped to the absolute region L= 240 T=0 W=1440 H= 1080, and the position 10%,10% corresponds to the absolute pixel position 384,108.

From: Sean Hayes <Sean.Hayes@microsoft.com>
Date: Mon, 4 Feb 2013 19:00:49 +0000
RE: RE: RE: Re: Re: TTML and aspect ratio

So assuming the video is  1080 x 609; then the top left of the drawn region will be 108, 60.9
The absolute pixel position of the first character will depend somewhat on the font selected, but it will be offset from that origin.

However that answer is not really picking up on my point that the region should be cantered; and to do that in an aspect ratio agnostic manner requires a central anchor point on regions, which we don't currently have - but which has been proposed.
Received on Monday, 4 February 2013 21:17:00 UTC

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