This is an example of Video Artifact Premium MJPEG restoration filters. The original source is a very low quality 320x240 5 fps MJPEG file from a year 2000 cheap camera. There are heavy MJPEG compression artifacts those very visible on Full HD displays.
I removed blocking, compression noise, ringing artifacts and added a resolution grain. The result now looks better.
The source, low quality MJPEG video after resize to 720p, crop.
MJPEG blocking artifacts are removed, 2x crop.
Ringing and details, 1x crop.
Man, 2x crop.
MJPEG ringing artifacts are removed, 2x crop.
Leaves, 2x crop.
Chicken, 1.5x crop.
The final result, 1.2x crop.
Difference / Before / After