DS already said it isn't.
He said x264 doesn't print that value.
How would x264 even know which settings you are going to use for the second pass when it prints the number at the end of the first pass. Or if it did assume certain settings, how would it estimate the CRF value without actually using those settings?
I don't know. Wouldn't you generally tell it which settings you're using for the second pass before running the first pass?
What's the purpose of the first pass if not to work those things out? Maybe if I knew the answers I wouldn't have asked the question?
Final ratefactor is the average QP used during the first pass.http://mewiki.project357.com/wiki/X264_Settings#crf
The final ratecontrol method: Constant Ratefactor
. While qp targets a certain quantizer, and bitrate targets a certain filesize, crf targets a certain 'quality'. The idea is for crf n to give the same perceptual quality as qp n, just in a smaller space. The arbitrary unit of measure for crf values is the "ratefactor"
So I guess you can see why x264 reporting a final ratefactor after the first pass fooled me into thinking it was reporting the final CRF value. Maybe it's a dumb question, but couldn't the average qp and the CRF value be the same thing?
Anyway, if I'm wrong, I'm wrong.... I don't really know what I'm talking about and I'll admit your comparison examples didn't mean much to me.
What I'm now trying to understand is if a 2 pass encode and a single pass CRF encode encodes the video differently. I understand (at least basically) a CRF encode aims for a constant perceived quality throughout the video which means quality can be sacrificed where it won't be noticed.... higher quantizers for action scenes.... that sort of thing. I understand that by setting the file size you're basically setting the quality, but the first pass needs to be run in order to determine what that quality will be.
So I've encoded a video using a CRF value of 22 and the file size finished up being 915MB. I now use 915MB for a 2 pass encode. Will the video be encoded differently or will the "quality" be distributed differently etc?