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RE: TT and subtitling

From: <Johnb@screen.subtitling.com>
Date: Mon, 3 Feb 2003 14:25:09 -0000
Message-ID: <11E58A66B922D511AFB600A0244A722E6C601B@NTMAIL>
To: glenn@xfsi.com
Cc: public-tt@w3.org

GAA wrote:

> 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.
So do you see the form of the presentation unit as always being a bitmap? I
would favour not defining the presentation unit at all - since its form will
be largely dependent upon the qualities of the display surface. I see that
there is a useful distinction to be made between the two however, not least
to illustrate any overheads and implications in converting from access units
to presentation units.

regards John Birch

The views and opinions expressed are the author's own and do not necessarily
reflect the views and opinions of the Screen Subtitling Systems Limited.
Received on Monday, 3 February 2003 09:49:19 UTC

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