VoidScaler is a custom firmware created by e8root for the original Open Source Scan Converter. It turns the OSSC into a low-latency downscaler to output 15KHz for CRT displays by line blending AND decimation, with almost zero lag! Installing VoidScaler onto OSSC hardware requires flashing the custom firmware .bin file to an SD card and upgrading via status display menu prompts with the remote control. This was tested and working on hardware revisions 1.6 and 1.8. Upgrading VoidScaler or flashing back to main OSSC FW is also done via sd card by entering the bootloader. This is yet to be stringently tested on all known hardware revisions and there may (or may not) be incompatible hardware. Therefore it is highly recommended to install if you have a JTAG USB Blaster on hand just in case the unit does not function after flashing. Try at your own risk. Read the VoidScaler Shmups thread for more info and instructions: https://shmups.system11.org/viewtopic.php?t=77339
VoidScaler currently downscales 1080p and 720p to 240p and 480i, and the HD15 port is the only active input. HDMI sources will require a digital to analog converter (DAC), and another will be needed to output analog RGB. I had trouble outputting component video using several known 15KHz-compliant HDMI to component converters. For most RGB-capable CRT’s, H and V sync needs to be combined externally when using an HDMI to VGA DAC, though e8root ingeniously programmed C-Sync to run on the horizontal sync line by default, mitigating the need to use a sync combiner.
Apart from the effective zero lag, one of the most impressive features is the ability to choose between line-blending and decimating. Line-blending retains pixel assets by averaging multiple rows to create 1 new row. The result is a slight reduction in sharpness which is worth the trade-off to reduce shimmer and aliasing.
While I continue to sing the praise of the OSSC Pro’s downscaling abilities, my one and only gripe is that it’s decimation to 240p is best reserved for games that are an integer-upscale of 240p like Sonic Mania, Bloodstained: Curse of the Moon, NSO classic games. VoidScaler opens the door to downscaling all other retro-inspired games by letting the user choose the method of downscaling with real scanlines and little-to-no vertical shimmer. There are some HV controls for image centering and line-offset for field adjustments, as well as aspect-ratio for 4:3 and 16:9 letterboxing.
Anyone with an OSSC not in regular use for upscaling may want to try this free downscaling firmware; although to re-iterate, it is safest to have a JTAG USB Blaster ready in case the install is not successful. See the VoidScaler thread on shmups linked above for instructions and progress updates, and the Github repo below for the latest firmware.
Github repo: https://github.com/e8root/voidscaler