I know it’s impossible to increase vertical resolution without a framebuffer, but it should be 100% possible to add blank pixels to the left and right of the image with the linebuffer.
For instance, with line triple, it could put 180 black pixels before and after each line of information, bringing the resolution up to 1280×720 and massively increasing compatibility.
I’m using a 1080p monitor that supports any resolution up to a little over its native, but (with the exception of 720×480) the image is stretched to fit the monitor and can only be set to 4:3 if the resolution is 4:3, so I had to decrease the horizontal resolution of 480i/480p sampling/output to 1280 pixels as opposed to 1440. If there were a padding option, I could simply pad the image to keep its aspect ratio intact at 1440×960.
Not possible on current hardware, I’ll copy/paste Marqs answer from shmups 🙂
To decouple output (total) line width from sampling rate you’d need a separate clock signal which is both highly configurable and accurate. Add a couple dozen extra line buffers and you could then decouple vertical as well – which is what I’ll be doing with cps2_digiav project in near future. Line3x generic 4:3 mode on ossc is a bit of an exception as it uses fixed (4/3)*3*Fs = 4*Fs for output, but in general you’d need a dedicated clock generator.