haque@umn-cs.UUCP (Samudra E. Haque) (04/22/87)
We have a SUN 3/110c with a color console. We have a whole bunch of video equipment, that can take RGB as well as composite NTSC video. Some of these can do (NTSC-->RGB) or (RGB-->NTSC). I have tried hooking up the RGB+sync connectors to a Sony RGB monitor .. but all I get is garbage. (this looks like 4 console pictures, rotated 90 degrees and squeezed horizontally.) Can anybody guide me as to how I could interface the console display to standard RGB equipment. We have several graphics applications that look great in color on the screen -- and would like to tape them among otherthings. Thanks a lot Samudra E. Haque Computer Science Systems Group University of Minnesota, Mpls. haque@umn-cs.arpa or haque@umn-cs.uucp or (612) 625-0876
dave@onfcanim.UUCP (04/30/87)
In article <1505@umn-cs.UUCP> haque@umn-cs.UUCP (Samudra E. Haque) writes: >We have a SUN 3/110c with a color console. > >We have a whole bunch of video equipment, that can take RGB as well as >composite NTSC video. Some of these can do (NTSC-->RGB) or >(RGB-->NTSC). > >I have tried hooking up the RGB+sync connectors to a Sony RGB monitor >.. but all I get is garbage. (this looks like 4 console pictures, >rotated 90 degrees and squeezed horizontally.) You have a problem of mismatched scan rates. The boxes that convert RGB to composite NTSC and back will convert the colour encoding for you, but they likely do nothing about incompatible scan rates. In order to encode an RGB image into NTSC, it must meet (at least approximately) the NTSC standards for the format of the picture. NTSC images have 525 scan lines total, with about 485 of them containing the image. The horizontal sweep frequency is 15734 Hz and vertical sweep is 59.94 Hz. 2:1 interlace is used, so all of the odd-numbered scan lines are displayed in 1/60 second, and all of the even-numbered ones in the following 1/60 second. Most workstation displays do *not* adhere to these standards. They typically do not use interlace, in order to avoid flicker; this doubles the horizontal sweep rate necessary to get the same number of lines. Then they typically display more than 480 lines, with the horizontal sweep rates going up again in proportion to the number of lines added. Though I don't know the exact figures for the Sun, a typical workstation screen will be run at 50-65 KHz horizontal sweep in order to display 770-1024 lines of pixels without flicker. So the horizontal sweep of your Sony monitor is about 4 times too slow for the signal you are feeding it, which is why you see what looks like 4 copies of the screen squashed together side-by-side. There are only three solutions I know of: 1) get a workstation/framebuffer that can put out RGB video timed according to the NTSC spec 2) aim a good TV camera at the Sun's screen (don't laugh!) 3) buy a specialized piece of hardware to digitize the Sun's video output, do filtering to compress it to about 640x480 pixels, and then send it out at NTSC rates. Lyon Lamb announced something that would do this at last year's SIGGRAPH. Warning: it will likely cost more than the Sun, since it is a frame buffer with video input as well as output. No matter what, you can't reproduce the lovely crisp images from the Sun screen in NTSC. You can't get more than 485 lines vertically, and horizontal resolution is even more limited, particularly in colour. Another problem is colour: a frame buffer can produce fully-saturated colours at high intensity, some of which are "illegal" when NTSC encoded. You'll have to avoid using fully-saturated yellow and cyan.
hank@spook.UUCP (Hank Cohen) (05/05/87)
In article <15298@onfcanim.UUCP> dave@onfcanim.UUCP (Dave Martindale) writes: > >2) aim a good TV camera at the Sun's screen (don't laugh!) > For the best results and to avoid any annoying flicker from scan rate mismatch make a movie of the screen, point a film camara at the screen, and then convert the film to video. This is very expensive but even the best of video camaras will have scan rate mismatch problems that cause aweful flicker in the resulting video. If you are doing commercial quality production then this is the best way to go.
pickard@venera.isi.edu.UUCP (05/06/87)
In article <107@spook.UUCP> hank@masscomp.UUCP (Hank Cohen) writes: >In article <15298@onfcanim.UUCP> dave@onfcanim.UUCP (Dave Martindale) writes: >> >>2) aim a good TV camera at the Sun's screen (don't laugh!) >> >For the best results and to avoid any annoying flicker from scan rate >mismatch make a movie of the screen, point a film camara at the >screen, and then convert the film to video. This is very expensive >but even the best of video camaras will have scan rate mismatch problems >that cause aweful flicker in the resulting video. If you are doing >commercial quality production then this is the best way to go. If you're planning to do a lot of filming and don't want to spend a lot of money, I suggest investing in (retrofitting?) a long persistence phosphor monitor for your Sun. It is possible to get a good picture by aiming a NTSC camera at it. Personally, I have used this technique at 30Hz interlaced (shooting off a RGB monitor), and had very good results. In fact, as long as you keep glare off the screen, the results are very comparable to encoding the signal from RGB to NTSC. Kelly.