I wanted to be able to see different color for different frequency bands. I ended up making my own tool (not for public use), maybe this can inspire? See attachment.

Technical stuff:
I use amplitude, top half is left bottom right.
Used compute shaders to process the data and draw it on a texture. The texture only needs update when i zoom or cursor moves to far to left or right. If i updated the texture each frame it runs at about 5fps.