jeremyabel wrote: ↑
Tue Mar 28, 2017 6:28 pm
Hmm, right now I've just been planning on plugging stuff like VCRs and old video game consoles into it. I'd love an HDMI -> NTSC SD converter that would take blackburst, but something tells me that's not the sort of thing I'd be able to find on ebay for a $30 price tag
You will absolutely need time base correction for feeds from VCRs, so you're on the right track there. One thing you might encounter with older game devices is that many of them were not strictly NTSC-compliant: at least one that comes to mind actually produced 512 lines per frame instead of 525; televisions at the time didn't especially care, but a digital device like a TBC or a DVE might.
Also, I managed to find the manuals and various other assorted documentation for the A53-D on the Abekas site: http://abekas.com/download/Legacy_Produ ... cts/A53-D/
. Seems like it's similar to the A51 in operating principles, although the user interface is entirely different, but hopefully it'll provide me enough info to sort out the A51's finer points.
The A51 (and the later A51+) were the replacement for the A53. I never figured out why they would be counting down instead of up. Many of the operating principles are very similar, though.
Just reading the section on drawings solids is insane! Multiple passes just to get a cube on the screen! What sort of video recorders did people use for that sort of thing? I can't imagine using a consumer VCR for that sort of thing! I imagine all the "3D" it's doing is fake 3D? Was there ever a system like this that could do realtime 3D broadcast effects without needing multiple passes? I know actual 3D graphics was in it's infancy in the early 90's, so was it the case that if you wanted anything more complicated / easier to work with than multipass recordings to build up a solid with the A51, you'd just go to one of the early SGI machines?
Back then, that sort of effect compositing typically used a one-inch VTR
like a Sony BVH-2000 or Ampex VPR series. If you had a lot of money (and did a lot of animation), you could get a Sony BVH-2500, which used the same general scheme that other VTRs used for still-frame playback in order to do still-frame recording -- that is, hit the button and the machine would record a single frame of video, move the tape about 5/16", then stop and wait until you want to record the next frame. We had one of the earliest production models of this machine (the sixth one off the assembly line, by its serial number!), and it was a maintenance nightmare, needing constant adjustment. Sony redesigned the record trace system almost immediately. There was also a tapeless solution: the Abekas A-64 was an early digital video disk recorder that could be controlled like a tape machine, but stored the video on an array of hard drives. This was back in the late '80s, and if I remember correctly, it could hold up to about two minutes of video. I rebuilt a used A-64 for a local production house to use for animation, and while it was a remarkable device for the time, it was less than reliable.
Cost-effective real-time 3D effects finally became possible with the A51: add several channel frames, a keyboard combiner and a video combiner, and each channel becomes a live video portion of the overall effect. You can see a hint of this toward the end of their 1991 A51 demo video