MiSTer FPGA Forum

Does anybody know if there are plans for proper support of interlaced output? Currently 480i analog output seems to be a 240p signal with alternating video frames and hence the picture is not as beautiful as it should be. To see that iconic boot and ps logos in full resolution would be such a relief!

Maybe someone can point out the cores that have 480i output (I am just curious and wanted to learn how it is done in fpga source code)?

For now, analog output is an afterthought and understandably not the main focus as there are bigger fish to fry. It's still very early days.

Please be patient, I'm sure it will come later down the line once the core matures.

There's a few SNES games with full interlacing (alternating every other line, instead of top half vs bottom half.) I used the UI from the briefing from Air Strike Patrol. You can see this article for more info.

I want to express the greatest gratitude to Robert Peip and paulb-nl for the beautiful interlaced output in the latest release - output is crystal clear now, small font in Chrono Cross menus is perfect now! Thank you so very much!

So I am going to oversimplify and gloss over alot here

The way NTSC and PAL works, the various signals with in video not just be at the right frequency but also have the right timing.
Especially with NTSC, the whole video signal is built around what signals activate at what time.
Sync instructions, color burst, ect has precise timings when each signal is to be delivered during each scan line, and each frame.

There alot to cover and unpack, so I can't cover everything. Also the math to figure out the exact timing on a NTSC image is a nightmare.
Here for example is the NTSC color burst frequency of exactly 315/88 Mhz or approx. 3.57954 MHz.
And the math behind it is also why NTSC framerate is 59.94hz instead of 60hz (it's literally how the math works out).

This video can explain that better than I can
https://youtu.be/3GJUM6pCpew

Example V Sync not hitting it's right timing during the VSync Blank will cause a rolling picture. The Line for V Blank takes place on a scan line off the display's picture in extreme overscan territory. Its the black bar you see in Rolling picture when the V Sync is lost.

I feel that wasn't analog support was a afterthought, it was that figuring out analog was a mess and thus made a lower priority.

The Image is still not interlaced for me one the PS1 Core. It still looks like its deinterlacing, with only some lines flickering.

I played with the nightly build on my CRT with Ridge Racer Turbo which runs at 480i and the interlacing seemed alright.