jdchrist@watcgl.waterloo.edu (Dan Christensen) (11/01/88)
I am trying to videotape what is appearing on the Iris monitor. In other words, I want NTSC output. I read the section of the 'Peripherals' manual, on the video boards, and have tried changing everything I could find. Has anyone been able to do this? I also read about a device called the RGB/Videolink from RGB Technology in Iris Universe, Summer '88. Does this thing work well? What does it cost? Thanks Dan Christensen jdchrist@watcgl.uwaterloo.ca
king@client2.DRETOR.UUCP (Stephen King) (11/02/88)
In article <6554@watcgl.waterloo.edu> jdchrist@watcgl.waterloo.edu (Dan Christensen) writes: >I am trying to videotape what is appearing on the Iris monitor. >In other words, I want NTSC output. I read the section of the >'Peripherals' manual, on the video boards, and have tried changing >everything I could find. Has anyone been able to do this? To the best of my knowledge, no stock IRIS will output NTSC. You can get the RS-170 display option (could be called NTSC) which provides RGB video with the same timing specs as NTSC, but not videotapable composite video; that requires a colour modulator. There is a cheap colour modulator available - ACK! - I can't find the description, but it is about $300 US. I built a colour modulator using the MC1377 chip, cost about $35 and works well enough, considering the price. The easiest way to do what you want is simply to point a video camera at the IRIS screen and shoot. The other devices are scan convertors costing $thousands which convert the IRIS output to RS-170, or, perhaps, NTSC. I have yet to see these things work, so cannot comment on their performance. This is a common question, so please post the results of your inquiry, and the performance of any device that you hook up to you system. Thanks. -- =-=-=-= Stephen J King =-=-=-=-=-=-= DCIEM Human Factors Division =-=-=-= {utzoo|mnetor}!dciem!zorac!dretor!king or king%dretor@zorac.dciem.dnd.ca
blbates@AERO4.LARC.NASA.GOV (Brent Bates TAD/ACB ms294 x2601) (11/02/88)
I have seen a demo tape from RGB Technology. It was very short, but ok. I just found out that we have an RGB/Videolink, but have not had a chance to see how well it works. It cost between $13-15,000 depending on the options you get. I have seen only one other company with similar equipment and it was more expesive and didn't seem as complete either. There are cheaper ways, but you only get about 1/4 of the screen and you have to have the RS-170A option on your IRIS. I hope that helps some.
phil@BRL.MIL (Phil Dykstra) (11/02/88)
What we are presently using here for NTSC from an Iris is a Lyon-Lamb ENC-VI NTSC Encoder (cost ~4500). In my opinion, there are higher quality encoders on the market (RGB Technologies, Faroudja CTE-N), but this is one of the cheapest (and includes a Sync generator and Black/ ColorBars generator). In software, you need to set the Iris for 30Hz interlaced (which means that the main monitor becomes useless until you go back to 60Hz). You get the lower left hand corner of the screen (~640x480 pixels). If you want the full IRIS screen to come out in NTSC you will need a "frame scan converter". These are more expensive (~25k). See e.g. Photron. SGI also sells an RGB -> NTSC encoder board for the 4Ds. We bought one but sadly have not been able to use it. Why is because the SGI board outputs a fully positive video signal (i.e. blanking is around +0.3V) rather than a bipolar signal with blanking at 0VDC. While I haven't found anything in the RS170A spec that requires an absolute voltage level (it all looks to be AC coupled), much to my surprise our Sony BVU850 seems to REQUIRE blanking to be at 0VDC (or at the very least average picture level to be at 0VDC). Black levels get all messed up when recorded from the SGI board but come out okay from the ENC-VI. I don't know who's to "blame", if anyone, but its something to keep in mind. [nothing works the way it is supposed to] - Phil <phil@brl.mil> uunet!brl!phil
king@client2.dciem.dnd.ca (Stephen King) (11/04/88)
In article <8811012036.AA04802@aero4.larc.nasa.gov> blbates@AERO4.LARC.NASA.GOV (Brent Bates TAD/ACB ms294 x2601) writes: > [...] There are cheaper ways, but >you only get about 1/4 of the screen and you have to have the RS-170A option >on your IRIS. I hope that helps some. This does not seem to make complete (hardware) sense: if you have the RS-170 option, then you should be getting the full screen. We do. Must be some sort of weird software that gives you this problem :-) Unless you are saying that information within the confines of the screen is lost; this is more likely as something has to be sacrificed when moving to the lower resolution. We have run most of the demos in RS-170 mode with no problem. Perhaps SGI would care to enlighten us on this matter ? -- {utzoo|mnetor}!dciem!zorac!dretor!king or king%dretor@zorac.dciem.dnd.ca Stephen J King =-= DCIEM Human Factors Division =-= (416) 635-2149
king@client2.dciem.dnd.ca (Stephen King) (11/05/88)
In article <8811020355.aa14353@SPARK.BRL.MIL> phil@BRL.MIL (Phil Dykstra) writes: > [...] You get the lower left hand corner of the screen >(~640x480 pixels). I must confess, I am somewhat confused by this. Admittedly, we have not run our IRIS at NTSC rates for some time, but I am sure that such S/W as the ARCH demo produced a full screen. Could it depend on the model ? (ours is an old 2400) > [...] Why is because the SGI >board outputs a fully positive video signal (i.e. blanking is around >+0.3V) rather than a bipolar signal with blanking at 0VDC. Have you tried AC coupling the thing with some large capacitors? :-) -- {utzoo|mnetor}!dciem!zorac!dretor!king or king%dretor@zorac.dciem.dnd.ca Stephen J King =-= DCIEM Human Factors Division =-= (416) 635-2149
dave@onfcanim.UUCP (Dave Martindale) (11/07/88)
In article <8811020355.aa14353@SPARK.BRL.MIL> phil@BRL.MIL (Phil Dykstra) writes: > >SGI also sells an RGB -> NTSC encoder board for the 4Ds. We bought >one but sadly have not been able to use it. Why is because the SGI >board outputs a fully positive video signal (i.e. blanking is around >+0.3V) rather than a bipolar signal with blanking at 0VDC. While >I haven't found anything in the RS170A spec that requires an absolute >voltage level (it all looks to be AC coupled), much to my surprise our >Sony BVU850 seems to REQUIRE blanking to be at 0VDC (or at the very >least average picture level to be at 0VDC). Black levels get all >messed up when recorded from the SGI board but come out okay from the >ENC-VI. RS-170 video can be capacitively coupled (and often is at the input of a piece of equipment). If the equipment depends on blanking being at a specific DC level, it will have a "DC restorer" circuit that clamps a reference part of the signal to ground - usually the blanking level found in the "back porch" after the sync pulse, though the tip of the sync pulse could conceivably be used too. If your Sony lacks input coupling capacitors, its DC restorer may be fighting the SGI board output - capacitively coupling the signal should fix this. If the Sony simply lacks its own DC restorer and really does depend on the absolute voltage levels in its input (unlikely), then just pass the signal through a video distribution amplifier which does DC restoration (these are readily available). If the Sony has its own DC restoration and a capacitively coupled input, then there has to be something "out-of-spec" in the video signal that you are feeding it that causes it to be confused - incorrect sync or video amplitude, incorrect sync pulse width, or the like.
dunlap@bombadl.SGI.COM (D. Christopher Dunlap) (11/08/88)
In article <1173@client2.dciem.dnd.ca>, king@client2.dciem.dnd.ca (Stephen King) writes: > In article <8811020355.aa14353@SPARK.BRL.MIL> phil@BRL.MIL (Phil Dykstra) writes: > > [...] You get the lower left hand corner of the screen > >(~640x480 pixels). > > I must confess, I am somewhat confused by this. Admittedly, we have not run > our IRIS at NTSC rates for some time, but I am sure that such S/W as the > ARCH demo produced a full screen. Could it depend on the model ? (ours is > an old 2400) > > -- > {utzoo|mnetor}!dciem!zorac!dretor!king or king%dretor@zorac.dciem.dnd.ca > Stephen J King =-= DCIEM Human Factors Division =-= (416) 635-2149 It's the software. Has to do with the projection of the 3D objects onto the screen space. If you only switch to NTSC, then you get the "lower-third-of-the-screen" phenomenon. If you do a complete job with the software, then you get a correct image, just lower resolution. I'll have one of the Graphoids post a followup with more detail. chris D. Christopher Dunlap Hardware Product Support Silicon Graphics
chandlee@alpine.SGI.COM (Chandlee Harrell) (11/18/88)
Iris 3000s are shipped with two video options. The two defaults provide video timings for 1280 by 1024 60hz monitors and 640 by 480 RS170/NTSC monitors. A customer can request that the RS170 option be replaced with either PAL/SECAM timings or for a 1280 by 1024 interlaced 30hz monitor. All Iris 4D systems ship with all four of the above timing options. When in RS170 mode, the Iris outputs the three components of RGB in the correct RS170 timings, un-encoded. The bottom leftmost rectangle of 640 by 480 pixels is displayed on the full RS170 monitor screen. An option board may be purchased from Silicon Graphics for Iris 4D systems which takes the three RGB outputs and color encodes them into a composite video signal. This signal is appropriate for connecting directly to any television, or to a VCR. The composite video output does not match up to broadcast quality; there is some minor difference that I am not familiar with. This should only be a concern for the media organizations, not for those of us creating video presentations. (Otherwise one buys a much more expensive broadcast quality color encoder.) This option board is called (internally, at least) the CG2/3. It also provides the genlocking capability. This is the capability to sync up and overlay the video from two separate systems (while in either high res 60hz or NTSC modes). So option one for video taping on an Iris 4D is to buy a CG2/3. The bottom left quarter of the screen may be recorded directly into any recording device that accepts NTSC composite video. Option two allows you to video tape the full picture on your 1280 by 1024 high resolution display. Pixel averaging is done to reduce 4 pixels down to one giving the appropriate number of pixels (640 - 480) for NTSC. Pixel averaging provides better images over simply drawing the image into the bottom leftmost portion of your screen because a certain amount of anti-aliasing takes place in the pixel averaging. It also allows full screen video taping. Option two is available from vendors like RGB Technologies (don't know their pricing). The output from these systems is, again, standard composite video. Note: Silicon Graphics has some ongoing development that should help those desiring the pixel averaged approach.
dunlap@bombadl.SGI.COM (D. Christopher Dunlap) (11/19/88)
In article <22213@sgi.SGI.COM>, chandlee@alpine.SGI.COM (Chandlee Harrell) writes: > > > Iris 3000s are shipped with two video options. The two defaults > provide video timings for 1280 by 1024 60hz monitors and 640 by 480 > RS170/NTSC monitors. A customer can request that the RS170 > option be replaced with either PAL/SECAM timings or for a 1280 by > 1024 interlaced 30hz monitor. > 2xxx and 3xxx systems have 60Hz, non-interlaced video at 1024 by 768. The default secondary monitor type is 30Hz, interlaced RGB at 1024 by 768. RS-170 or PAL can be ordered as an option. (No-charge if ordered with the original system, changing the video types on an existing system costs a little bit... ask your sales-rep about prices) > All Iris 4D systems ship with all four of the above timing options. > 4D systems have 60Hz, non-interlaced video at 1280 by 1024. They don't support the 1024 by 768 of the older systems. > When in RS170 mode, the Iris outputs the three components of RGB > in the correct RS170 timings, un-encoded. The bottom leftmost rectangle > of 640 by 480 pixels is displayed on the full RS170 monitor screen. Well, I'm not positive about the 4D, but the 2xxx and 3xxx systems need to have a Genlock board (CG1) and be sync'd to an external sync before the output is "correct RS170 timings", assuming that "correct" is taken to mean "Broadcast Quality". Anyone interested in more specific timing specifications for the 60Hz non-interlaced and 30Hz interlaced video (1280 by 1024 or 1024 by 768) drop me an email and I'll mail it back to you. Enough interest and I MIGHT post. There's snow at my mom's house. Maybe I WILL go home for thanksgiving, chris
dave@onfcanim.UUCP (Dave Martindale) (11/23/88)
In article <22219@sgi.SGI.COM> dunlap@bombadl.SGI.COM (D. Christopher Dunlap) writes: > >> When in RS170 mode, the Iris outputs the three components of RGB >> in the correct RS170 timings, un-encoded. The bottom leftmost rectangle >> of 640 by 480 pixels is displayed on the full RS170 monitor screen. > > >Well, I'm not positive about the 4D, but the 2xxx and 3xxx systems >need to have a Genlock board (CG1) and be sync'd to an external sync >before the output is "correct RS170 timings", assuming that "correct" >is taken to mean "Broadcast Quality". It's not broadcast quality in that the clock oscillator isn't within the 3ppm accuracy required for broadcast. On the other hand, all the funny equalizing pulses and so on are there and in the correct place. The "right" way to generate broadcast-spec NTSC is to use a standard sync generator as a timing source for everything, and genlock the IRIS to it. That way, the subcarrier and sync are locked together as they should be. However, I once tried setting up an IRIS that lacked a genlock board for videotaping. I connected the IRIS sync output to the genlock input of the sync generator (you may need some attenuation here, since separate sync is usually 4V p-p and the genlock input is probably expecting composite video with 300 mV sync). This locked the sync generator's sync to the IRIS; it worked fine because the number of lines and the interlace is done correctly in the IRIS. The sync generator's colour subcarrier was NOT locked to sync anymore, since there was no colour burst for it to lock to, so subcarrier just drifted with respect to sync. This doesn't meet broadcast spec, but is good enough for recording on a 3/4 or 1/2 inch VCR. In fact, the drift rate of subcarrier with respect to sync was only a few Hz, indicating that the oscillator in the IRIS was only a few Hz off the correct frequency. The video produced wasn't broadcast quality, but it was an awful lot better than what you get coming out of a 3/4 inch or worse VCR. To make this kludge work, you need a sync generator that will lock its sync to a B&W signal on its genlock input without getting upset about the lack of colour burst, and without killing its subcarrier output. If you have one that will lock subcarrier as well as sync, you're even better off. (All of the above was done with a 3000; I haven't tried it with a 4D).
sac90286@uxa.cso.uiuc.edu (11/30/88)
We have a Genlock board installed on our Iris 4D-70GT. Unfortunately, SGI failed to give us ANY documentation whatsoever to use this board. We would like to videotape the Iris screen for presentations and such like. Is some special software required to use this board? If so, can somebody suggest a way to get a copy of it faster than going through SGI (i.e. is there a network-accessible file server somewhere where we can ftp it)? Thanks for any assistance you can render.