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RE: TT and subtitling

From: Glenn A. Adams <glenn@xfsi.com>
Date: Mon, 3 Feb 2003 08:19:14 -0500
Message-ID: <7249D02C4D2DFD4D80F2E040E8CAF37C01FAC7@longxuyen.xfsi.com>
To: <Johnb@screen.subtitling.com>
Cc: <public-tt@w3.org>
Re: difference in access and presentation units, it would depend
upon how the latter is defined. For example, if defined as the
bitmap to be BLTed into a graphics plane, then if the access
unit were that bitmap, there would not be a difference; however,
if the access unit were a compressed image, e.g., JPEG, PNG,
etc., then there would be a non-zero decoding time. Further,
but if the access unit were text which required layout and
glyph rasterization, then there would be a fair difference,
and non-zero decoding time as well.

	-----Original Message-----
	From: Johnb@screen.subtitling.com [mailto:Johnb@screen.subtitling.com] 
	Sent: Monday, February 03, 2003 5:06 AM
	To: Glenn A. Adams
	Cc: public-tt@w3.org
	Subject: RE: TT and subtitling


		As for access unit vs presentation unit, I would tend to use the
		former when talking about the coded representation and its delivery
		and buffering modes, and use the latter term for talking about its
		decoded to-be or currently presented modes. 

	I must admit I find this a sublte distinction - do you anticipate there being a major difference between the format of an access unit and a presentation unit for TT? (encryption and compression issues aside).  
Received on Monday, 3 February 2003 08:19:17 UTC

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