Limit max bitrate on CRF encodes?

[mastrboy]

Is there a way to set a hard limit on max bitrate when using CRF for encoding?

I have a source which averages at 1000 bitrate when doing a CRF 17, but just 2-3 scenes it suddenly jumps up to almost 10000 and that makes my computer struggle a little when decoding the frames...

[pengvado]

Yes, you can combine CRF with VBV. I don't know what you should pick for vbv-bufsize, though, since cpu-time is only a side effect, not what VBV was designed for.

[mastrboy]

i read up a little in vbv-buffer and it seems it was designed for helping decoding when streaming and not limit bitrate usage in CRF, i'll do some test to see if it helps on the CPU spikes i'm getting when decoding.

Thanks for answering

[turab]

...it was designed for helping decoding when streaming...

In your case that translates to

...limit bitrate usage in CRF...

When streaming, you don't want the bitrate to go above a certain threshold because of bandwidth constraints. VBV sets an upper limit hence why it's useful. It's also what you're looking for, since in your case a high bitrate is slowing down playback speed noticeably.