[comp.sys.mac] MicroTV and NTSC

sarrel@cherokee.cis.ohio-state.edu (Marc Sarrel) (08/16/89)

I've been following these two subject threads (the Micro TV in a
window on a Mac II and the cable and software that will get NTSC
output from an Apple video card) and it occurred to me that technology
has now advanced to the point where you could hook the NTSC video
output from the video card to the NTSC input to the MicroTV and have a
live picture of what you were doing on the mac screen in a window...

_Somebody_ had to say it... :-)

M.C. Escher would be proud!
-=-
"Master, why is the letter 'i' the symbol for current?"  "Because there is
no letter 'i' in the word 'current'."  "Master, why do we use the letter
'j' for sqrt(-1)?"  "Because we use the letter 'i' for current."  Whereupon
the Master struck the Disciple, and the Disciple became enlightened.

adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) (08/16/89)

sarrel@cherokee.cis.ohio-state.edu (Marc Sarrel) writes:
> I've been following these two subject threads (the Micro TV in a
> window on a Mac II and the cable and software that will get NTSC
> output from an Apple video card) and it occurred to me that technology
> has now advanced to the point where you could hook the NTSC video
> output from the video card to the NTSC input to the MicroTV and have a
> live picture of what you were doing on the mac screen in a window...

Uh, I don't think so...

The video out hooks to a monitor or vcr. You don't see what you're doing
unless you have a monitor hooked to the vcr (if that is where the mac is
sending the signal) or the mac (if you have a direct hookup). So you could
thoroughly confuse your MicroTV and your mac, but you won't be able to see
it. More problems: the MicroTV supposedly slows the mac down 30%. Well, the
software that slows the scan rate of the card down to NTSC scan speed slows
the computer down 40 ro 60%. You're going to have one _SLOW_ machine, if
it works at all.

Good luck...

Adam

--
"Offer me anything I ask for..."          (mail address in message header)
"Anything you want."
"I want my father back, you son of a bitch." - The Princess Bride

afoster@ogccse.ogc.edu (Allan Foster) (08/24/89)

In article <494@mit-amt.MEDIA.MIT.EDU> adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) writes:
>sarrel@cherokee.cis.ohio-state.edu (Marc Sarrel) writes:
>> I've been following these two subject threads (the Micro TV in a
>> window on a Mac II and the cable and software that will get NTSC
>>...
>> live picture of what you were doing on the mac screen in a window...
>
>Uh, I don't think so...
>
>The video out hooks to a monitor or vcr. You don't see what you're doing
>unless you have a monitor hooked to the vcr (if that is where the mac is
>...
>software that slows the scan rate of the card down to NTSC scan speed slows
>the computer down 40 ro 60%. You're going to have one _SLOW_ machine, if
>it works at all.
>
>
No Not at all.
Sure you caould have the set up described.  With a splitter out on the
video cable so that it hooked up to both the MicroTV and a monitor
you could indeed se what you were doing in a window.  Make for some interesting
recursive stuff tooo...

As far as slowing the machine down...  MicroTV does slow the mac down a bit
but I think that 30% may be a bit excessive.  As far as the NTSC code
slowing the mac down 50% NO WAY!  I wrote an init to do that 18 months
ago and there was no apparent slowdown at all.  Why should there be?

All the init does is change some of the hardware registers in the card
changing what it displays, the mac should not change speed at all!

Regards

PS. I would really like to see myself in a window!

Allan
-- 
Allan Foster      UUCP  : tektronix!ogcvax!afoster
UseNet: afoster@cse.ogc.edu      GEnie  : A.FOSTER
AppleLink : D1663                  MacNet : FOSTER    

adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) (08/24/89)

afoster@ogccse.ogc.edu (Allan Foster) writes:
> adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) writes:
>>software that slows the scan rate of the card down to NTSC scan speed slows
>>the computer down 40 ro 60%. You're going to have one _SLOW_ machine, if
>>it works at all.
>
> No Not at all.

You're wrong. It was stated earlier that MicroTV will slow the computer down
up to 30%. And Apple specified that your computer will be slowed down by the
RS-170 hack (I'm not certain of the percentages, but 40-60% sounds familiar).

> Sure you caould have the set up described.  With a splitter out on the
> video cable so that it hooked up to both the MicroTV and a monitor
> you could indeed se what you were doing in a window.  Make for some
> interesting recursive stuff tooo...

No, you're wrong again. Hook a camera (only do this with chip cameras --
you'll burn tube cameras!) directly to a monitor such that you can see
realtime movement when you move the camera. Point the camera DIRECTLY at
the TV. What do you see? Depending upon how your equipment is setup/white
balanced/etc., you will see one solid color in the monitor (usually white)
-- feedback. Point the camera at the edges, and you can see neat "recursion".
The MicroTV/NTSC hacks will give you pure feedback white -- the output of
the video card will be directly channeled into the MicroTV, resulting in
uninteresting solid video feedback.

> ago and there was no apparent slowdown at all.  Why should there be?
>
> All the init does is change some of the hardware registers in the card
> changing what it displays, the mac should not change speed at all!

It's the flicker filter that makes the video stable. Apparently, it looks
jittery and unstable without the filter.

> PS. I would really like to see myself in a window!

Why?

Adam
--
"What?! He didn't fall? Inconceivable!"  (email: adam@media-lab.media.mit.edu)
"You keep using that word... I do not think it means what you think it means."
(All stolen quotes taken from The Princess Bride) Hmm... 18 spaces left. Moof!