Here is another fun experiment. Shotcut has a hidden GPU (OpenGL via Movit) processing mode that does linear color processing, and in this mode Shotcut’s player can display the OpenGL texture from the processing as long as there are no CPU-based filters used. Thus the File > Export Frame is not a down-sampled output.
Here is a red capital O from Text: Rich composited over cyan color clip using 2 video tracks (make sure the filter is not selected when using Export Frame):
Now, I change the background color of Text: Rich to the cyan color, and this forces Qt Painter to do the compositing:
