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RE: roll-up examples

From: John Birch <john.birch@screen.subtitling.com>
Date: Mon, 15 Dec 2008 14:43:57 -0000
Message-ID: <4476B296B92A4741A49B0BD017590700AA79FE@sss-uk-ex-02.screen.subtitling.local>
To: "Geoff Freed" <geoff_freed@wgbh.org>, "Public TTWG List" <public-tt@w3.org>
Geoff, 
 
Thanks very much for posting these...
 
On my player the QT movie shows a very annoying aspect. When it redraws
the captions to roll them up, the entire caption region disappears. 
This gives a very difficult to read presentation. I don't find the QT
implementation acceptable but YMMV. :-)
 
[It would seem to me that the correct presentation could have been
achieved with two regions.... drawing into each alternately and swapping
the z-index.]
 
John

________________________________

From: public-tt-request@w3.org [mailto:public-tt-request@w3.org] On
Behalf Of Geoff Freed
Sent: 15 December 2008 13:29
To: Public TTWG List
Subject: roll-up examples



from the 12/12/08 minutes:

> SH:  GA is going to take a look at providing clearer semantics, JB is
going to look at SS's implementations, 
> SH will look at semantics, GF and AK will send links of demos.  Will
review where we are at the end of January.

here are a few examples of roll-up captions:

-- http://ncamftp.wgbh.org/onscreen/demos/upper_third.mov
two-row roll-up captions in the upper-third of the screen.  the captions
are open line-21 (EIA-608) captions.

-- http://ncamftp.wgbh.org/onscreen/demos/lower_third.mov
three-row roll-up captions in the lower-third of the screen.  these
captions are also open line-21 (EIA-608) captions.

-- http://ncamftp.wgbh.org/onscreen/demos/emergencyCrawl.mov
an example of how quicktime has implemented roll-up SCC captions.  these
are closed captions, so you'll have to turn them on to see them:  right
click on the video and choose Show Closed Captioning, or open View/Show
Closed Captioning.


note:  the 608 examples display captions that scroll smoothly in the
vertical direction, where the top row rolls out of the way as the bottom
row rolls in.  the QT example shows an implementation slightly different
from the 608 examples, where the top row disappears all at once as the
bottom row rolls into view.  in my view, either are acceptable although
the smoother the scroll, the less jarring the text is to read.  

g.


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Received on Monday, 15 December 2008 14:44:42 GMT

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