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Re: roll-up examples

From: Geoff Freed <geoff_freed@wgbh.org>
Date: Mon, 15 Dec 2008 09:52:27 -0500
To: John Birch <john.birch@screen.subtitling.com>, Public TTWG List <public-tt@w3.org>
Message-id: <C56BD95B.46E3%geoff_freed@wgbh.org>

Ah, right- I forgot to mention that the smooth-scroll display in QT player works only on the Mac.  On a Windows machine, it will appear as you describe- very difficult to read.   If you can play the demo on a Mac, you'll see that it looks much better.  I've filed a bug report with Apple over this issue.


On 12/15/08 9:43 AM, "John Birch" <john.birch@screen.subtitling.com> wrote:


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.]


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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.

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Received on Monday, 15 December 2008 14:53:17 UTC

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