I've searched fairly extensively but not been able to find detailed programming information for the Pixel Valve (DRM CRTC) and VEC (Composite TV out) encoder.
Here's some of the information I have been able to find: https://people.freedesktop.org/~narmstrong/meson_drm_doc/gpu/vc4.html
I found driver source code here for the VEC:
and for the Pixel Valve CRTC:
I know of the VideoCore® IV 3D Architecture Reference Guide at https://docs.broadcom.com/docs/12358545 but it makes no mention of the PixelValve or the VEC encoder.
This also makes no mention of the PixelValve or the VEC encoder: https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
But I don't seem to be able to find programmers reference guides that give the details that would explain how these things work and how to program them.
Any help appreciated.