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From: bryce@COGSCI.BERKELEY.EDU (]} ae]]]}]]]})
Newsgroups: comp.sys.atari.st
Subject: Re: RGB to video composite for ATARI 1040/Mega ST computer.
Message-ID: <8705021243.AA24169@cogsci.berkeley.edu>
Date: Sat, 2-May-87 08:43:01 EDT
Article-I.D.: cogsci.8705021243.AA24169
Posted: Sat May  2 08:43:01 1987
Date-Received: Sun, 3-May-87 06:03:11 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: /dev/nul.nil.nul.the.bit-bucket.@cogsci.berkeley.edu
Lines: 61
Keywords: Hardware box wanted for converting RGB to composite video.
Summary: Other concerns for video work.

In article <1102@ihlpm.ATT.COM> mrg@ihlpm.ATT.COM (M R Gales) writes:
>I am in the process of making a purchasing decision on either an Atari Mega ST
>(when available) or a Commodore Amiga Computer.  One of the desired uses of my
>new computer is to use it to create video titles that I can record onto video
>tape when I edit home videos of vacations, etc.  The Amiga has composite color
>video out, which is what I need for this application. 
>[Is there anything I can buy to convert Atari RGB to composite?]

There are several much more important things to think about in chosing a
computer for video work:

WARNING: WHAT FOLLOWS ARE FACTS. NO FLAMES!!

1>  Overscan: Normal TV pictures 'flow' past the edge of the picture tube.
    Computer displays like the ST will usually consist of a 640*200 pixel
    active area in the center of the screen.  On the ST this comes with 4 
    colors per scan line.
    Other computers, among them the Amiga, allow 'overscan'.  Nominal
    resolution on the Amiga is 640*200.  Maximum is 752*484 with 16 colors
    per scan line.
    With overscan the picture can fill the full screen, like a normal
    broadcast picture does.

2>  Interlace:  NTSC video is interlaced.  This includes broadcast TV and
    video tape.  Some video gear may REQUIRE a interlaced picture
    to function properly.  Consumer gear will not care.  For your purpose
    it will mean twice the number of lines of resolution, and a
    easier time if you go beyond simple titling.  The Atari computers do
    not directly support interlaced video.  The Amiga supports interlace.

3>  Fancy stuff that (unfortunately) only the Amiga has.  This includes
    genlocking inputs so that the Amiga can sync to an external source (for
    overlays etc.).  Other fancy tricks like 'chroma key' will only be
    easy on an Amiga.

4>  [more stuff not included 'cause I'm sick of typing]


The Amiga was designed with FULL NTSC COMPATIBILITY AS A PRIMARY GOAL.  For
 example the internal clock frequency is a multiple of a primary NTSC video
 frequency, colorburst.  Careful attention was paid to the format of the
 video output. etc...

The Atari ST was designed with other criteria in mind. 

******************************************************************************
NO OTHER COMMENTS ARE EXPRESSED OR IMPLIED AS TO DIFFERENCES BETWEEN MACHINES.
******************************************************************************

In answer to the actual question asked:  Yes RGB to composite converters are
made.  I do not have any details on where and how.  These could be adapted
with a minimum of soldering to fit on a Mega St.
It is possible to create interlaced video from non, but you will never get
the 2 times increase in resolution unless you start with it.

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 "The future is not what it used to be."
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Disclaimer: I don't work for Atari, nor Apple or Commodore not IBM, sun,
 intel... in fact ?just what is it that I DO DO?   [ do-do? :-) ]
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