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Re: TTML and aspect ratio

From: David Ronca <dronca@netflix.com>
Date: Tue, 29 Jan 2013 17:56:17 +0000
To: "public-tt@w3.org" <public-tt@w3.org>
Message-ID: <F7DC5134CE82754A878475EEBA450B3B30BDE6@EXMB105.corp.netflix.com>
CEA-608 mandates a 32x15 grid in a 4:3 display area.  CEA-708 allows either 32x15 (4:3) or 42:15 (16:9).  For 4:3, the position 10%,10% is a different location on the screen than it is for 16:9 content.. Further, displaying CEA-608 caption in a 16x9 display area will result in very poor presentation (as will presenting 16x9 CEA-708 caption in a 4:3 display area).  In reviewing the W3C-TTML, we can find no well-defined means to inform the client of the proper aspect ratio of the caption display area.  My question is how should a client determine the correct aspect ratio for the caption viewing area?
David Ronca
Manager, Encoding Tools
Netflix, Inc.
Received on Wednesday, 30 January 2013 10:51:30 UTC

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