Is it possible to encode one video at the same time on CPU and GPU?

Question

Video cards

Is there software that can do this?

Answer 1

It's possible.
Divide the video into two parts (the duration of each should be related approximately as the encoding performance on cpu and gpu is related), and start encoding them with two processes at once, with different cpu and gpu usage settings, respectively. At the end of their work, merge the result without recoding into one file (some containers allow you to do this by simple copying, for example ts).
As you know, in this way you can parallelize video processing not only within one machine and its video cards (if the software cannot, or for example gpu from different manufacturers), but also within several. Note - each part should be longer and a multiple of the distance between keyframes (usually about 4-10 seconds), this is not mandatory but desirable for the effectiveness of the result.