How to learn more about ffmpeg output when encoding?

Question

fmpeg

Every time ffmpeg encodes a video, it gives detailed information
like this

[libx264 @ 0x3b7c6c0] frame I:9     Avg QP:29.01  size:  5202
[libx264 @ 0x3b7c6c0] frame P:1291  Avg QP:31.07  size:  1183
[libx264 @ 0x3b7c6c0] frame B:1204  Avg QP:34.17  size:   233
[libx264 @ 0x3b7c6c0] consecutive B-frames:  8.7% 77.6% 12.3%  1.4%
[libx264 @ 0x3b7c6c0] mb I  I16..4:  8.1% 73.2% 18.7%
[libx264 @ 0x3b7c6c0] mb P  I16..4:  0.3%  1.8%  0.3%  P16..4: 49.2% 14.0%  7.1%  0.0%  0.0%    skip:27.2%
[libx264 @ 0x3b7c6c0] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8: 43.1%  2.2%  0.3%  direct: 0.5%  skip:53.9%  L0:37.2% L1:60.1% BI: 2.7%
[libx264 @ 0x3b7c6c0] 8x8 transform intra:73.7% inter:72.4%
[libx264 @ 0x3b7c6c0] coded y,uvDC,uvAC intra: 73.5% 72.9% 36.0% inter: 12.5% 10.7% 0.9%
[libx264 @ 0x3b7c6c0] i16 v,h,dc,p: 37% 23% 15% 25%
[libx264 @ 0x3b7c6c0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 16% 13% 17%  7%  9% 10%  9%  8% 11%
[libx264 @ 0x3b7c6c0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 19% 15% 19%  6% 10%  9%  9%  5%  7%
[libx264 @ 0x3b7c6c0] i8c dc,h,v,p: 60% 15% 19%  6%
[libx264 @ 0x3b7c6c0] Weighted P-Frames: Y:26.4% UV:5.7%
[libx264 @ 0x3b7c6c0] ref P L0: 63.8% 21.3% 10.2%  3.9%  0.8%
[libx264 @ 0x3b7c6c0] ref B L0: 90.9%  8.6%  0.6%
[libx264 @ 0x3b7c6c0] ref B L1: 97.6%  2.4%
[libx264 @ 0x3b7c6c0] kb/s:177.51

I understand part of it, but where can I read more about all these coefficients?
For example, it is clear that here frame I: 9 , the number of I frames, etc...
What is it?
[libx264 @ 0x3b7c6c0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 16% 13% 17% 7% 9% 10% 9% 8% 11%