Posted By
Charles
on 2022-01-13
17:19:47
|  Re: Is there such a thing as an interlaced picture for the +4?
@Litwr, All,
I ran a few tests recently with p4fliconv of IstvanV, and I am fully convinced that he has successfully implemented REAL interlace / interlaced FLI on Plus/4. (he may not be the only one, but this one is easy to test/prove) By real interlace I also mean what you do, using TV tech terminology (576i = PAL CRT TV)
Please look at these pictures, all made with his converter, run on a real +4, and shots taken with a mobile phone. 1st two pictures are the same, they are non-intleraced "normal" Hi-Res FLI (the diff is that for the first photo I used Video port and a decent S-video - HDMI converter, 2nd is via RF cable). These should be 320*248 pixs (using Y border as well) The 3rd one is the real interesing, it is Interlaced Hi-Res FLI, and easy to see the actual double resolution, 320*496. Flashing is barely noticable anywhere on the screen, it stands still. Unfortunately this one displays picture _only_ via the RF cable, could not make it work on S-video. I also made test images in multicolor FLI mode, but they are less convincing to be real interlace.. (still can be though)
Also these 2 photos taken from Dreamtime 2k18, supposed to be Larry's converter. I suspect this is also interlaced, 400(+) lines, but less sure than with the previous example (btw this was the only pic in that slideshow where I saw the higher resolution) This one at least plays on S-video, but as you see a complete new world opens if you look at it using RF cable. The S-video looks blurry, probably due to the flashing + the camera's shutter time, the RF one stood quite still. What do you think?
I wonder if there is something "wrong" with my HW setup, or why in the world I don't get any / any reasonable interlaced output on S-video. RF unfortunately blurs the picture a lot and make it full of artefacts. Any idea is welcome. Can someone please run the PRGs on another real machine, I uploaded all PRGs + photos to Google drive. And unfortunately emulators also can't cope with this well, they will just show a flashy image. Try to compare HI (non-intl) and HI2 (interlaced) versions, these show the most obvious difference. [ link ]
And though it might be a native solution on Amiga, but on +4 this obviously requires tinkering. I have not yet checked the code of IstvanV, must be some trick with ff1d/ff1e at the end of the frame. I studied these tricks quite a lot 30+ yeras ago, but was many times uncertain what I really did or saw.  IMHO we should dig a bit deeper, as it is truly amazing!!
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