Does half framerate mean half bitrate for the same quality using hevc-h2.65

[pluviophile]

I searched the forum but I didn't find a clear answer. Sorry if I missed something. I'm lowering the framerates of some 60 fps clips to 24 fps using hevc(h.265). 60 fps clips are at 10 mbps vbr. How low of a bitrate can I go for the 24 fps without losing quality? Thank you.

[VoodooFX]

Does half framerate mean half bitrate for the same quality

No.

60 fps clips are at 10 mbps vbr. How low of a bitrate can I go for the 24 fps without losing quality?

Theoretically, to ~0.01 mbps and lower, it depends from the video content & codec, and your personal understanding of "without losing quality". Most likely that bitrate would be ~same.

[pluviophile]

Does half framerate mean half bitrate for the same quality

No.

60 fps clips are at 10 mbps vbr. How low of a bitrate can I go for the 24 fps without losing quality?

Theoretically, to ~0.01 mbps and lower, it depends from the video content & codec, and your personal understanding of "without losing quality". Most likely that bitrate would be ~same.

you went out of your way to misunderstand the question. i did mention the source file is 10 mbps at 60 fps so obviously what i am asking is what bitrate would be equally the same quality to that clip at 24 fps.

[VoodooFX]

you went out of your way to misunderstand the question.

so obviously what i am asking is

I understand it perfectly.

i did mention the source file is 10 mbps at 60 fps

How much this describes "video content" or "codec", or "quality"!?

what bitrate would be equally the same quality to that clip at 24 fps.

Answer by my understanding of "equally the same quality": Bitrate would be only higher, probably ~10 times.
For answer to your probable understanding of "equally the same quality": Look at the last sentence in my previous post.

[Cornucopia]

If there is ANY correspondence between framerate and bitrate (very rarely), it is that it is most likely NOT linear, or if it is, it isn't a 1:1 45degree diagonal line. Higher and higher framerates have successively less and less differences between frames, so the delta becomes less, so the amount of ADDITIONAL bitrate to accommodate those minor changes becomes less and less. Diminishing compounded investment yields bigger returns.
The converse should also be true: lowering the framerate by HALF (e.g. from 60 to 30) means each change is a bigger change (1/60th sec later vs 1/30th sec later), so more relative residual bitrate must be retained in order to retain equivalent quality.
So, for example, source 60fps @ 60mbps, dropping to 30fps might take 32 or 35 or 40 mbps vs your presumed expectation of 30mbps. All other things being equal (especially perceived quality), which they probably aren't since one is a later generation than the other.

This pretty well holds true regardless of codec (assuming you are using the same codec, and encoder in the comparison).


Scott