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In article <01bc7046$1257d920$0e25e3c7@iag>,
Scott E. Johnston <doodah1@gate.net> wrote:
>I was wondering if anyone can tell me how the closed captions are on DVD's.
> Is the signal degraded?  Do I still need a special decoder to see them?  I
>would dearly love to take a DVD-Laptop on planes, hospital visits, long
>drives and watch a movie!

The closed-caption information on DVD is not stored in the video signal the
way TV broadcast and videotapes do.  The information is fully digital, with
the maker of the DVD disc able to choose typeface style as well as multiple
languages.  You control it thru your remote control (or on your laptop, 
using DVD playing software that supports closed captioning.)  The closed
captioning text is overlayed by your DVD player or software directly without
the need for a separate decoder.

I find DVD closed captioning handy on a noisy day (neighbors mowing their
lawn, etc) and my TV does *not* support closed captioning by itself: the
magic's all in the DVD player.
 
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> The closed-caption information on DVD is not stored in the video signal
the
> way TV broadcast and videotapes do.  The information is fully digital,
with
> the maker of the DVD disc able to choose typeface style as well as
multiple
> languages.  You control it thru your remote control (or on your laptop, 
> using DVD playing software that supports closed captioning.)  The closed
> captioning text is overlayed by your DVD player or software directly
without
> the need for a separate decoder.

Thanks, I appreciate the response.  (BTW, my information has the CC's being
carried on an audio signal, Channel 21, when over the air.  For what I have
been led to understand, it was originally a video signal but now audio.  I
think that's the way it is now.  Least ways I've been told so!  ;))))


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*Scott*
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>>In the News: "A new study says marijuana does not make a good
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doodah1@gate.net [NEW ADDRESS]
http://www.iag.net/~doodah
Scott E. Johnston

It can't be tested that way because line 21 and digital captioning are not 
the same. Digital is a different method requiring digital decoding; TV is
analog coding requiring analog decoding.

On 4 Jun 1997, Wes wrote:
>Correct me if I'm wrong but I'm sure the closed captioning is present in
>the audio portion of the signal.  Try this.  Play a closed caption LD on
>your player connecting the audio only to the receiver/preamp.  Feed only
>the video signal to the television.  Now try the closed captioning on the
>tv.  No closed captioning right?
>
>Jim Nitchals <jimn8@netcom.com> wrote in article
><jimn8EB7vzJ.724@netcom.com>...
>
>> The closed-caption information on DVD is not stored in the video signal
>the way TV broadcast and videotapes do.  
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According to Jim Nitchals <jimn8@netcom.com>:
> The closed-caption information on DVD is not stored in the video
> signal the way TV broadcast and videotapes do.  The information is
> fully digital, with the maker of the DVD disc able to choose
> typeface style as well as multiple languages.

You're getting closed captions confused with subtitles -- the two
ARE different.

Since closed captions are for the hearing impaired, they encode more
information than subtitles.  For instance, an important sound might
be noted, and a visual indication of who is speaking is often used.
To see the closed captions, you still need a converter or a modern
TV that can display the data that the DVD encodes in the standard
way (in the vertical blanking interval).

Subtitles are for people who can hear, but can't understand the
spoken language.  Since you are expected to be able to hear the
sound effects and the voices of who is speaking, they only translate
spoken words and hardly ever deviate from the center of the screen
with any kind of speaker-oriented cues.  To see the subtitles you
don't need any special equipment -- the DVD player displays them
merged into the video output.

While most DVDs allow you to select from multiple subtitle languages,
most of the ones I've seen have one CC language.  There are
exceptions, though -- I believe that _Singing_in_the_Rain_ is an
example of a DVD with multiple language choices in the subtitles and
the closed-captioning.

..wayne..

Closed captioning in analog media is encoded on line 21 of the vertical
blanking. Most DVD players support line 21 closed captioning as well as
subpicture captioning. With subpicture captioning the captions are
displayed the same way subtitles are on DVD, a series of images which
overlay the video with transparent and opaque areas (the opaque being
the text). For subpicture captioning you do not need an external
decoder. If you have a line 21 captioning decoder you could display two
sets of captioning information at the same time.

In article <01bc707c$e9851580$4228f3cd@shithead>, "Wes"
<rstover@comsource.net> wrote:

>Correct me if I'm wrong but I'm sure the closed captioning is present in
>the audio portion of the signal.  Try this.  Play a closed caption LD on
>your player connecting the audio only to the receiver/preamp.  Feed only
>the video signal to the television.  Now try the closed captioning on the
>tv.  No closed captioning right?

Consider yourself corrected.  :-)

You might be thinking of some other captioning system. The US standard for
Closed Caption is carried on line 21 of the NTSC video signal. When video
is encoded for MPEG-2, line 21 (and many others) are thrown away, since
they can be regenerated by the player. The original spec for DVD included
a couple of ways to carry CC, but these were removed from the final spec.
Oddly enough, most current DVDs and DVD players actually seem to work with
traditional closed captions -- presumably because they were based on the
draft spec. I don't know if this support will continue.

Independent of line 21 CC (which requires a decoder in your TV), DVD has
subpicture tracks, which can carry any graphical information. It's much
more flexible, since in addition to regular text there can be oversized
text, foreign language text, ideograms, pictures, bouncing balls on
lyrics, etc. The subpicture tracks can be identified as containing
captions for the hard of hearing or for children, which are different than
regular subtitiles.

_________________________________________________________
Jim "The Frog" Taylor, Director of Information Technology
<mailto:jimtaylor@videodiscovery.com>
Videodiscovery -Multimedia Education for Science and Math
Seattle, WA, 206-285-5400 <http://www.videodiscovery.com>

alt.video.dvd FAQ <http://www.videodiscovery.com/vdyweb/dvd>

Correct me if I'm wrong but I'm sure the closed captioning is present in
the audio portion of the signal.  Try this.  Play a closed caption LD on
your player connecting the audio only to the receiver/preamp.  Feed only
the video signal to the television.  Now try the closed captioning on the
tv.  No closed captioning right?



Jim Nitchals <jimn8@netcom.com> wrote in article
<jimn8EB7vzJ.724@netcom.com>...

> The closed-caption information on DVD is not stored in the video signal
the
> way TV broadcast and videotapes do.  
>  

Wes <rstover@comsource.net> wrote:
>Correct me if I'm wrong but I'm sure the closed captioning is present in
>the audio portion of the signal.  Try this.  Play a closed caption LD on
>your player connecting the audio only to the receiver/preamp.  Feed only
>the video signal to the television.  Now try the closed captioning on the
>tv.  No closed captioning right?

DVD: Digital Video/Versatile Disc.  We're discussing the 5" DVD discs
(the NEW digital video format with the same form factor as CD's.)

I thought closed captioning in traditional video media was encoded on
line 20 or 21 of the vertical blank signal.  Wherever it is now, on DVD
the decoding and display of the captioning is done *BY THE PLAYER.*
As I specifically mentioned, my TV has NO closed-captioning support
built in, yet I get it on DVD movies if I choose it by remote control.
Closed captioning on most DVD movie discs includes multiple languages 
(also selectable by the user.)

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Wes (rstover@comsource.net) wrote:
: Correct me if I'm wrong but I'm sure the closed captioning is present in
: the audio portion of the signal.  Try this.  Play a closed caption LD on
: your player connecting the audio only to the receiver/preamp.  Feed only
: the video signal to the television.  Now try the closed captioning on the
: tv.  No closed captioning right?
: 

Wrong. U.S. closed-captioning is stored in Line 21, Fields 1 and 2 of the 
vertical blanking interval, i.e., in the picture.

: 
: 
: Jim Nitchals <jimn8@netcom.com> wrote in article
: <jimn8EB7vzJ.724@netcom.com>...
: 
: > The closed-caption information on DVD is not stored in the video signal
: the
: > way TV broadcast and videotapes do.  
: >  
: 

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                                   joeclark@interlog.com
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