MiSTer FPGA Forum

With the new scaling system the way scandoublerFX interacts with the scaler was changed. It seems before that the scaler took the orginal undoubled analog (usually 240p) and then did its own version of scandoublefx. You could see this with 25% scanlines where every other line on analog would be darkened, while it was more like 1 out of 4 or 5 lines (depending on your scale) slightly darkened on the HDMI side.

According to the update, this has now been changed so that the scandoubled analog source is used as the basis for the scaling. So now 25% scanlines gives you thick bars on the scaled output, since its roughly half the output being darkened now.

I assume this change was made to free up more resources for the fancier filters and masks that have been added, which is great. What I'm wondering is, maybe the scandoubler should be completely disconnected from the scaler, or at least provide the option, especially if that was how it was partially implemented before.

I've had nothing but headaches trying to set up dual output to a VGA monitor and 1080p LCD TV. Scandoubling interferes with scanline filters, integer scaling, and 5x cut options. If the scaler just completely ignored the scandoubler these problems would go away. The scanline filters also offer far more control than just importing the scandoubler ones.

Don't know how easy or hard such a switch would be, but I thought I might bring it up now before the new scaling system is finalized.

It would be nice to be able to use the same config for my VGA monitor and my 1080p LCD with 5x scaling. I don't get the point of scandoubling on the HDMI (except with direct video) when it already has more robust scaling and filters.

While I'd still like to see this addressed, we do have some new options to work with thanks to scaler updates.

If you are using scandoublerfx scanlines for your VGA monitor, over on the HDMI side in signal processing try "sharp interpolation" for the Horizontal and Vertical slots, but use "SOFT interpolation" in the third "scan" slot. This will make the scandoublerfx scanlines blend better and, more interestingly, they more or less seem to work even at non-integer scales in 1080p, no visible banding. Meanwhile the rest of the image remains fairly sharp if you want that. You might get better results trying other blur type filters, but it goes to show the usefulness of the "scan" slot now.