adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) (08/14/89)
I recently saw an article in MacWeek with a story which interested me. Well,
actually it's somewhat more than interest. I need to be able to do this!
Anyway, I read through the article, and I'll transcribe the side bar which
supposedly tells how to do it. I'm by no means an EE, but I know enough
about electronics to firmly believe that what follows makes no sense at
all.
==========
>From MacWeek, August 8th, 1989, page 20: (For those of you who don't get
MacWeek, but were at the Expo, this was the copy which was given out free.)
Reproduced without permission. Sidebar entitled, "You'll need a custom cable"
Text follows:
To get National Television System Committee-standard [editor's note: is
*that* what NTSC stands for? I always thought it was for Never Twice the Same
Color!] video from Apple's eight-bit color card for the Mac II, users need a
special cable to connect the board to video output devices like VCRs and
television monitors.
The cable requires a 15 pin male DB-15 pin connector, a male RCA plug and a
coaxial cable - standard parts available in electronics supply stores for about
$30. Many computer dealers, electronics stores and cable companies also make
custom cables. The DB-15 end of the cable plugs into the female DB-15 connector
on the Macintosh video card, and the other end plugs into a video output
device, such as a VCR.
==========
OK... I'm a little fuzzy on that last paragraph. I don't think I'll have any
trouble soldering a co-ax to an RCA plug. But how does one connect a co-ax
cable to a connector with 15 pins? Which two pins should I solder the wires
to?
Finally, there's a piece of software associated with this little hack. To
quote MacWeek again, [it is] "a free software utility developed at Apple...
[which was] first distributed at the Apple Developers's Conference in May and
soon to be available on bulletin boards like CompuServe and Usenet..." Maybe
someone with Phil & Dave's would like to make it available for ftp-ing (or
was it not on the CD?).
Anyway, I need to make some videos with my mac and I don't want to have to buy
an expensive genlock board. This seems like a quick (& VERY dirty) hack which
would save me $1000 and do a sufficiently good job to suit my needs.
Thanks...
Adam
--
"Offer me anything I ask for..." | email: adam@media-lab.media.mit.edu |
"Anything you want." +---------------------------+---------+
"I want my father back, you son of a bitch." - The Princess Bride | Sigh... |sarrel@sioux.cis.ohio-state.edu (Marc Sarrel) (08/14/89)
You're joking? Right? Someone at MacWeek is pulling our collective leg! Cottleston, Cottleston, Cottleston Pie, A fly can't bird, but a bird can fly. Ask me a riddle and I reply: "Cottleston, Cottleston, Cottleston Pie." Cottleston, Cottleston, Cottleston Pie, A fish can't whistle, and neither can I. Ask me a riddle and I reply: "Cottleston, Cottleston, Cottleston Pie." Cottleston, Cottleston, Cottleston Pie, Why does a chicken, I don't know why. Ask me a riddle and I reply: "Cottleston, Cottleston, Cottleston Pie." -=- "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) (08/14/89)
sarrel@sioux.cis.ohio-state.edu (Marc Sarrel) writes: > > You're joking? Right? Someone at MacWeek is pulling our collective > leg! > I don't think so. It wasn't the April (Fools) Issue, and it wasn't a joke, as far as I can tell, though the directions made little (if any) sense. Comeone! Someone out there must get MacWeek. What's the deal here? Adam -- "Offer me anything I ask for..." | email: adam@media-lab.media.mit.edu | "Anything you want." +---------------------------+---------+ "I want my father back, you son of a bitch." - The Princess Bride | Sigh... |
fontenot@rice.edu (Dwayne J. Fontenot) (08/15/89)
In article <475@mit-amt.MEDIA.MIT.EDU> adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) writes: > >I recently saw an article in MacWeek with a story which interested me. Well, >actually it's somewhat more than interest. I need to be able to do this! > [stuff about the following making no sense at all deleted...] > >========== >>From MacWeek, August 8th, 1989, page 20: (For those of you who don't get >MacWeek, but were at the Expo, this was the copy which was given out free.) >Reproduced without permission. Sidebar entitled, "You'll need a custom cable" >Text follows: > [stuff about assembling a special cable deleted...] > >Finally, there's a piece of software associated with this little hack. To >quote MacWeek again, [it is] "a free software utility developed at Apple... >[which was] first distributed at the Apple Developers's Conference in May and >soon to be available on bulletin boards like CompuServe and Usenet..." Maybe >someone with Phil & Dave's would like to make it available for ftp-ing (or >was it not on the CD?). > >Anyway, I need to make some videos with my mac and I don't want to have to buy >an expensive genlock board. This seems like a quick (& VERY dirty) hack which >would save me $1000 and do a sufficiently good job to suit my needs. The utility in question is distributed by Apple on the demo disk of the 32-Bit QuickDraw package. The utility is called the Macintosh II Video Card Utility (long name) and is described as a "Moitors CDEV extension". The readme file that comes with the utility emphasizes that this software is provided as a service and is _not_ supported by Apple. Hardware required: o Mac II with a 4 or 8 bit color board. o special cable (get your parents to put it together) Software required: o System 6.0.3 or later o Monitors 4.0 (included with 32-Bit QD) o General CDEV (included with 32-Bit QD) o 32-Bit QD The readme file seems pretty complete (its long so I won't post it here) and tells exactly how to construct the special cable needed. Unfortunately, since this is part of an Apple software distribution, I don't know if I can distribute it over the net. BTW, I don't remember seeing this software on Phil and Dave's... >Thanks... You're welcome... >Adam ------ Dwayne Jacques Fontenot : fontenot@uncle-bens.rice.edu Computing Information Services Microconsultant ; Rice University, Houston TX Comp Sci / Cog Ling Ugrad * This bit reserved for future expansion...
bmartin@uhccux.uhcc.hawaii.edu (Brian Martin) (08/15/89)
In article <SARREL.89Aug14100509@sioux.cis.ohio-state.edu> sarrel@sioux.cis.ohio-state.edu (Marc Sarrel) writes: > >You're joking? Right? Someone at MacWeek is pulling our collective >leg! The software actually exists; it's on the Apple Color disk which includes the 32-bit color quickdraw, Monitors 4.0, a new General cdev, and the Macintosh II video card utility cdev. A friend of mine made up the appropriate cable, and we were able to drive a television monitor directly off of the Apple video card. The picture quality is quite good, with support for an 8-bit gray scale but no color. The biggest drawback when we tried it was that the menu bars and both right and left sides of the screen were cut off--makes it difficult to demonstrate a user-friendly system with pull-down menus, or to open a disk partition on the right side of the screen. Also, there was a very annoying flicker on screen. All in all, quite a let down. We're looking into replacing the apple color card with the new Raster Ops ColorBoard 264, which MacWeek says will provide NTSC output in addition to driving the Apple RGB monitor. -- Brian
dxjsb@dcatla.UUCP (Jack S. Brindle) (08/15/89)
adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) writes: >Comeone! Someone out there must get MacWeek. What's the deal here? If y'all would take a good look at the 32 bit Quickdraw demo disk (which came with 32 bit Quickdraw), you might find an interesting surprise. It is called the Macintosh II Video Card Utility, and allows you to set up the video card for NTSC/RS-170 compatible output. There is a read me file on the disk that explains the whole setup. It looks quite interesting, actually. Thanks again, Apple! Jack B.
georgeh@microsoft.UUCP (George Hu) (08/16/89)
Yes, the MacII -> NTSC is quite real, although it is far from perfect. I have built the cable, and successfully gotten it to work. I tried it both with a multiscanning monitor that accepts NTSC and a regular VCR. On both, I had the following problems: 1) It is too large for the screen, so the menu bar and other edges are cut off. (This was mentioned in another MacWeek article) 2) Everything is quite blurry -- regular text is out of the question. 3) You see double images. 4) The image is in B&W only. (It's supposed to be that way) The cable is simple to build, and costs very little. My cable was pretty crude, and wasn't shielded, so maybe someone out there can get better results. MacWeek had an article in the same issue on how to make NTSC images look good by using large colorful objects, and staying away from the border. These are my own experiences, and your mileage may vary.
adam@mit-amt.MEDIA.MIT.EDU (Adam Glass) (08/16/89)
georgeh@microsoft.UUCP (George Hu) writes: > ... > 4) The image is in B&W only. (It's supposed to be that way) > ... > MacWeek had an article in the same issue on how to make NTSC > images look good by using large colorful objects, and staying > away from the border. ^^^^^^^^? Wait a sec... didn't you say that it was b&w above? Actually, I haven't made it yet, but won't it be b/&w with grays? And if you want color entered into the picture, won't you need an encoder to translate the color (RGB) into NTSC? And if that is the case, wouldn't you just be better off buying an encoder and letting it do ALL the translation? MacWeek says to use lots of color (Translation: Use lots of gray.) But isn't the hack supposed to be able to kick out more-stable video if you use 2 color (b&w, no grays) mode? Sigh... Adam -- "Offer me anything I ask for..." "Anything you want." "I want my father back, you son of a bitch." - The Princess Bride
captkidd@athena.mit.edu (Ivan Cavero Belaunde) (08/16/89)
In article <4568@uhccux.uhcc.hawaii.edu> bmartin@uhccux.UUCP (Brian Martin) writes: > The biggest >drawback when we tried it was that the menu bars and both right and >left sides of the screen were cut off--makes it difficult to >demonstrate a user-friendly system with pull-down menus, or to open >a disk partition on the right side of the screen. Also, there >was a very annoying flicker on screen. All in all, quite a let down. While I haven't seen this hack work, we have the same problems when we try to output NTSC video with our NuVista 2M board (overlaying video an graphics on the monitor is no problem - it is the NTSC [TV] output which flickers and loses the edges). It is my understanding that this is a problem with NTSC video's limited bandwidth. >We're looking into replacing the apple color card with the new Raster >Ops ColorBoard 264, which MacWeek says will provide NTSC output in >addition to driving the Apple RGB monitor. Don't be surprised if the RasterOps board's output also loses the edges and flickers. -Ivan Internet: captkidd@athena.mit.edu
ralph@lzfme.att.com (Ralph Brandi) (08/17/89)
In article <13545@bloom-beacon.MIT.EDU> captkidd@athena.mit.edu (Ivan Cavero Belaunde) writes: >In article <4568@uhccux.uhcc.hawaii.edu> bmartin@uhccux.UUCP (Brian Martin) writes: >> The biggest >>drawback when we tried it was that the menu bars and both right and >>left sides of the screen were cut off--makes it difficult to >>demonstrate a user-friendly system with pull-down menus, or to open >>a disk partition on the right side of the screen. Also, there >>was a very annoying flicker on screen. All in all, quite a let down. >While I haven't seen this hack work, we have the same problems when we try >to output NTSC video with our NuVista 2M board (overlaying video an >graphics on the monitor is no problem - it is the NTSC [TV] output which >flickers and loses the edges). It is my understanding that this is a problem >with NTSC video's limited bandwidth. The flicker is a result of the fact that NTSC signals are interlaced; The complete frame is updated 30 times every second (29.97, if you want to get really picky). Each frame is made up of two fields. And there's nothing you can do about it, except adapt your drawings to the limitations of NTSC (f'rinstance, avoid horizontal single pixel lines, or even lines with an odd number of pixels as a width). The edge problem is not strictly speaking an artifact of NTSC, but rather of the way consumer TVs are made. They use a technique called overscan, so that the entire picture tube has a picture on it. This is supposedly more aesthetically pleasing for the general public. Computer monitors, on the other hand, are underscanned, so you don't miss any information. When I worked at a television station as a camera operator, it was a rule of thumb to ignore the outside 15 or 20% of the screen in composing our shots. Some of us even used a grease pencil to mark on our camera monitors what was likely to be lost by the time the picture got to people's homes. In other words, you just have to live with it. Or wait for HDTV.... -- Ralph Brandi [most gateways in the known universe]!att!lzfme!ralph Work flows toward the competent until they are submerged.
pepke@loligo.cc.fsu.edu (Eric Pepke) (08/17/89)
In article <7386@microsoft.UUCP> georgeh@microsoft.UUCP (George Hu) writes: > >Yes, the MacII -> NTSC is quite real, although it is far from perfect. >I have built the cable, and successfully gotten it to work. >I tried it both with a multiscanning monitor that accepts NTSC >and a regular VCR. On both, I had the following problems: > >1) It is too large for the screen, so the menu bar and other edges are cut off. >(This was mentioned in another MacWeek article) >2) Everything is quite blurry -- regular text is out of the question. >3) You see double images. >4) The image is in B&W only. (It's supposed to be that way) It's soapbox time for what little I know about video: 1) is due to the overscanning of TV's. NTSC has 525 lines per frame. Some are stolen for vertical retrace, and the remainder scan an area that is a bit larger than the visible area of the tube. This was decided upon a long time ago, because the high frequencies involved in retracing caused bad artifacts near the edge of the screen. 2) is due to a couple of factors. Your cables may have bad impedence and cause some ringing, but even if the cables were perfect, there would still be some problems. NTSC can only guarantee about 300 pixels per line for gray scale, fewer for color depending on the color. Remember that NTSC is a massive kludge which had to make signals compatible with already assigned bandwidth and TV's that were built in the forties. The bandwidth never used to be a problem because the analog devices that were used to produce the signal (tubes) were inherently slow and had inherent low-pass filtering. Now we have transistors and current feedback loops and stuff, and the frequencies are much higher. Studios now use things called comb filters to smooth out the signals a bit before broadcast. Many of the better industrial RGB to NTSC converters also have comb filters. Another problem, flicker, is due to the fact that NTSC is interlaced, so alternate lines are refreshed 1/30 sec. apart. If one line is black and the next line is white, the eye sees flicker. Again, in normal video this is seldom a problem, as home-quality vidicon-based cameras can only resolve about 200 lines, and although studios usually use higher-quality image orthicon cameras, they do filtering. You can effectively do the filtering in software, but it takes a lot of work. This is a good application for fuzzy fonts. As an aside, the reason that TV's scan at the same rate as the line frequency is not because they derive their scan rate from the line, as some people believe. Back a long time ago, it was impossible completely to keep the line frequency from getting through the power supply and causing problems. If the frame frequency is close to the line frequency, one might see bands slowly crawling up or down the screen, while if it is different, one might see bands quickly flickering across the screen. The former is less distracting. By the way, has anybody tried Apple's hack running the color signals through an RGB-NTSC filter? Eric Pepke INTERNET: pepke@gw.scri.fsu.edu Supercomputer Computations Research Institute MFENET: pepke@fsu Florida State University SPAN: scri::pepke Tallahassee, FL 32306-4052 BITNET: pepke@fsu Disclaimer: My employers seldom even LISTEN to my opinions. Meta-disclaimer: Any society that needs disclaimers has too many lawyers.