MiSTer FPGA Forum

I'm outputting video via VGA to CRT television. Isn't it possible to apply one of the "scale filters" on the image without actually scaling?

I understand filters adding borders to LCD pixels etc. wouldn't work, but composite horizontal (or even vertical) blur shouldn't be a problem to apply?

To answer my own question, no. (should have just looked at the Verilog before asking :p)

I made a picture of video signal path in the cores. Here one can see easily that the filtering upscaler is completely bypassed when using video signal that comes directly from the emulator. Maybe it could be possible to set scaler's output resolution to same as input resolution but dunno how well that would work and how to configure such a thing.

You can make custom video_modes as low as 240p to use the scaler, whatever will sync to your TV. Set vga_scaler=1 and you can have the analog out use the scaler too. There's a thread in the A0486 forum about how to get that core working on SD TVs (since the core does not have any direct analog/unscaled output), that should give you an idea where to start.

Most CRTs you can make the width whatever you like, the scaler will support up to around 1920. Use aspect ratio = full/wide and the 1920 will be filled up by your content, the CRT will take care to squish it down to 4:3. That kind of "super resolution" can be fire-and-forget for getting something fairly sharp, otherwise you have to start dialing in integer scales of common resolutions on each core.