Posted By
TLC
on 2023-06-04
06:40:55
|  Re: Emulation video option you never knew you wanted until now!
Got the thing up and running today. I don't know what this is going to be good for, though. Anyway...
The test setup consisted of a stock (unmodified) Plus/4, a 1551 drive, Moon Buggy, a couple of gadgets, plus a '90s portable (13"?) household TV. I tried to record the video with my smartphone held in one hand, while controlling (well... sort of) the game with my other hand.
I managed to test both RF and S-Video, even though the TV I used had no support for the latter one. I happen to have a one-off analog composite video decoder box, that demodulates composite and separate luma-chroma PAL/NTSC video signals to analog RGB. (Hacked that together some 15 years ago, when I thought I had no other means to watch the Drean Commodore 16's screen in colours).
So...
This is stock RF. (Plus/4 --> RF --> TV set)
This is S-Video. (Plus/4 --> separate luma/chroma i.e. S-Video --> analog video decoder box --> analog RGB (SCART) --> TV set)
I could also test how true interlaced video would look like. I happen to have a late 2000's TV HDD/DVD recorder unit at hand. The way these devices work, is a full A/D - D/A cycle. That is, even for video pass-through, they digitize the source video (RF, composite, RGB, ...whatever) into a memory framebuffer, then produce an output analog RGB signal by scanning the framebuffer with standard (interlaced) timing.
This is RF, via the HDD/DVD recorder's RF tuner + complete resampling, standard interlaced video sync. (Plus/4 --> RF --> DVD recorder --> analog RGB (SCART) --> TV set)
Finally, I replaced the TV with my Commodore 1084S. (Pardon the noticeable colour differences, the portable TV's saturation setting is a bit off, probably needs a bit of overhaul after all the years.)
This is S-Video on a late '80s (Philips made) 1084S. (Plus/4 --> S-Video --> 1084S)
I can't see that much difference TBH. RF is pretty noisy, but isn't still at all that bad. Didn't notice any stuttering in either setups. There's a bit of S-Video colour subcarrier "crosstalk" on the S-Video recording, noticeable on the picture's dark blue field. Standard interlaced looked almost perfectly identical to original 312p video with/on this noisy RF signal source and portable TV setup. (Video doesn't show that well, but, it didn't look much different IRL either. Maybe that has something to do with the relatively small resolution of this CRT. Once I tested the recorder with the 1084S, and there, the visible artifacts of interlacing (i.e. vertically "running" scanlines and flickering vertical edges of picture content) looked much more pronounced. That might have had something to do with the 1084S' finer crt mask and better resolution.)
Video quality is obviously less than suitable, I couldn't manage to record in 50Hz or 100Hz.
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