I wanted to display animations on a LED matrix connected to a Raspberry Pi and wrote this little external: https://github.com/fhchl/ltbl
It is a wrapper of https://github.com/hzeller/rpi-rgb-led-matrix. Just send a list with an RGB value for each pixel to the external to draw the picture on the LED matrix!
Hope this is useful for anyone. I used it for an animation on a Raspberry Pi 4 that mixed a dozen
pix_mix. Just dumped the mixed image directly into the external via
pix_dump. The animation ran smooth with 30fps on a 64x64 matrix and was even quite OK when I had another Pd process running in parallel that did some sound processing. However, I used an external sound card and followed all the recommendations in the rpi-rgb-led-matrix readme for smooth frames.