Assuming all the other components are the same. The graphic card is a 3080. Which CPU will create the 4K video faster? Thanks
That will be dependent on software as well as hardware.
Do you have a specific model for each of the CPUs? The efficiency of the CPU matters, so a 1st gen with more cores might lose against a 5th gen.
Memory bandwidth will be important for video. That 48 core may have more memory bandwidth, but if it is an old CPU, then the memory on the 16 core might be faster even if there are fewer memory channels.
We need more specifics.