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Re: Real-time captions in streaming media

From: Andrew Kirkpatrick <andrew_kirkpatrick@wgbh.org>
Date: Thu, 25 Apr 2002 11:47:06 -0400
To: <w3c-wai-ig@w3.org>
Message-ID: <B8ED9D3A.10629%andrew_kirkpatrick@wgbh.org>
MAGpie is an offline (not real-time) captioning tool.  If you want to offer
real-time captions, you will need a captioning stenographer.  The output
from the steno is most commonly sent to line 21 of television's vertical
blanking interval. 

As Joe correctly indicated, getting the caption data to the media player is
the problem.  Some solutions to this by companies like Wordcasters and
Speche Communications (now owned by Stenograph) use their software to send
information from the stenographer to a streaming server, which passes the
information to the user's browser when a java applet that is resident in a
web page requests to be included in the stream.

WGBH now has a tool that takes steno output and converts the data for
streaming on the Web to RealPlayer and WindowsMedia.  This tool can also be
used to recapture Line 21 data from previously captioned video.  This tool
is currently available for use (ask for details off-list).

Alternatively, you could offer "burned-in" captions, which are encoded along
with the video and are permanently part of the video.  This process tends to
result in lower-quality captions since the captions are compressed along
with the video for streaming on the web, and also eliminates any possibility
of searching the captions in the future.  If the captions remain as text,
searching is possible.


On 4/25/02 9:59 AM,  Charles McCathieNevile (charles@w3.org) wrote:

> I am not sure that Magpie does allow you to caption things that are streaming
> live, which I think is what Joe is saying.
> i.e. how do you caption a webcast live?
Andrew Kirkpatrick, Technical Project Coordinator
CPB/WGBH National Center for Accessible Media
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E-mail: andrew_kirkpatrick@wgbh.org
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Received on Thursday, 25 April 2002 11:47:39 UTC

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