I am using ProMovie Recorder to record high quality videos using iPhone X, and I noticed a weird thing today.
Here's what I did:
- I recorded a 4K 60fps video for 6 seconds (HEVC encoding).
- I recorded a 4K 30fps video for 6 seconds (HEVC encoding).
- Both the above videos captured the same physical content.
- Both videos were captured with the same bit-rate, ~118 Mbps.
Here's what I found:
- The two videos I captured (with different fps) are of the same file size - 84MB. How? Why?
A higher frame rate video with same bit-rate as that of a video with lower frame rate should be double the file size, shouldn't it?
Why isn't there a difference in file size? More the number of frames will lead to more the file size, since we're storing extra 30 frames for every second, right? Or is the underlying HEVC encoding optimises the file size for higher frame rate videos?
Or, can slight differences in exposure cause significant file size difference?