Encoders for grayscale video

NVENC doesn’t seem to support greyscale video, requiring me to encode greyscale data in color formats. Is there any third party software to encode in greyscale, or are there any plans to write a greyscale encoder?

in NVENC api, there is a “monoChromeEncoding” option for grayscale encoding. but I have never used it. so i don’t know whether it properly works or not.