DExx-vd isl for Downscaling

Type: Decimate. Sharp, jaggy and shimmer for non-integer 2D games. Option to window into 16:9 to preserve original aspect ratio

Setup required: Flash SD card, minimal configuration on unit

Cost and availability: Low cost to benefit provided a DE-10 Nano is already on hand. It is also compatible with 2 lesser known FPGA development boards, see the GitHub and Wiki for more info. The DExx is currently sold at Video Game Perfection.

The DExx and OSSC Pro were built on the same firmware, and requires a separate FPGA board to run, so anyone with a DE-10 Nano for the MiSTer project can have a premium downscaler very similar to the OSSC Pro on a software level at about 1/3rd the cost. Although in execution, the DExx addon can be a messy setup:

The ‘all in’ DExx attached to a DE-10 Nano, complete with status LED display, extended audio ribbon cable, and AV input board via a custom scart coupler.

Since publishing the Downscaling Chronicles episode on the DExx, Marqs has updated the software to version 0.73 which reduces the lag generally under 2 frames to be on par with the OSSC Pro. I experienced constant loss in sync when the input resolution and format were 480p via RGBHV, and downscaling 1080p is limited by the dot clock which can have odd pixel behaviour as demonstrated in Episode 8: The Downscaler Wars. Marqs suggested a fix, though I saw no improvement. Therefore in my experience, the DExx is best used for downscaling 720p sources.

The output of the DE-10 Nano is ultra sharp, but line decimation is prone to shimmer and jaggies, especially when the game is not an integer upscale of 240p. It has the same vertical stretch as the RetroTink 5x, AND an aspect-preserving output which letterboxes 16:9 inside of a 4:3 window. In this mode, sprites will not be stretched, but assets drawn to deleted lines will be missing:

Above is a downscale of Super Mario Maker on the Nintendo WiiU with a 16:9 aspect preserved output. As this is a 720p game, 2/3rds of the lines responsible for total vertical resolution are discarded, shaving off Mario’s moustache in the process.

If you’re a Mister owner that is willing to make some major QOL sacrifices such as the enclosure for the MiSTer, SNAC support and dual analog/digital video output, what the DExx addon lacks in the league of the OSSC Pro and RetroTink 5x, it makes up for being less than half the price.

Verdict: Recommended