How to write testbench for digital circuits that output video/audio signal
We compare to a c model for what you describe.  The c model was made first and represents the block that takes digital video samples and converts them to analog output.  That output being samples to our d/a.  

We take the c model as golden and compare it's output to the output of the up block in the testbench.

This is followed up with real world testing using a custom fpga development system.

That sounds like what you'd want if you are doing a video or analog block.  Now there are things like verilog-ams. That integrate verilog and analog simulation but I've never gotten involved in that.