X264 - log explanation needed

[opti2k4]

Hi everyone!

I am doing a graduation work at my university about video coding and i need to make some graph from those parameters in x264 work log, but the problem is i don't know almost 80% of stuff what is there in the log.

This is example:

x264 [info]: using cpu capabilities: MMX MMXEXT SSE SSE2 SSSE3
x264 [warning]: max bitrate less than average bitrate, ignored.
x264 [warning]: Error: 2pass curve failed to converge
x264 [warning]: target: 113774.00 kbit/s, expected: 36017.19 kbit/s, avg QP: 10.0006
x264 [warning]: try reducing target bitrate or reducing qp_min (currently 10)
x264 [info]: slice I:15 Avg QP:10.00 size:253889 PSNR Mean Y:48.80 U:52.25 V:53.06 Avg:49.68 Global:49.59
x264 [info]: slice P:646 Avg QP:10.00 size:202922 PSNR Mean Y:49.16 U:51.78 V:52.43 Avg:49.92 Global:49.83
x264 [info]: slice B:575 Avg QP:11.71 size:156112 PSNR Mean Y:47.45 U:50.30 V:51.19 Avg:48.28 Global:48.23
x264 [info]: mb I I16..4: 2.2% 81.1% 16.7%
x264 [info]: mb P I16..4: 0.9% 45.6% 9.9% P16..4: 15.2% 16.7% 10.3% 0.0% 0.0% skip: 1.5%
x264 [info]: mb B I16..4: 1.6% 2.3% 12.8% B16..8: 15.3% 10.5% 54.2% direct: 2.3% skip: 1.1%
x264 [info]: 8x8 transform intra:67.4% inter:40.2%
x264 [info]: direct mvs spatial:69.4% temporal:30.6%
x264 [info]: ref P 75.5% 17.1% 7.4%
x264 [info]: ref B 81.2% 14.5% 4.4%
x264 [info]: SSIM Mean Y:0.9927661
x264 [info]: PSNR Mean Y:48.359 U:51.101 V:51.860 Avg:49.153 Global:49.008 kb/s:34863.86


Is there a help file where is every word explained (like what is QP, what is the difference between global PSNR and average,what is size in I,P,B slices ? Thx for help

[check]

x264 [warning]: max bitrate less than average bitrate, ignored.You set --vbv-maxrate below --bitrate
x264 [warning]: Error: 2pass curve failed to converge
x264 [warning]: target: 113774.00 kbit/s, expected: 36017.19 kbit/s, avg QP: 10.0006
x264 [warning]: try reducing target bitrate or reducing qp_min (currently 10)Exactly what it says. Your target bitrate was not reached because the output was already saturated.
x264 [info]: slice I:15 Avg QP:10.00 size:253889 PSNR Mean Y:48.80 U:52.25 V:53.06 Avg:49.68 Global:49.59
x264 [info]: slice P:646 Avg QP:10.00 size:202922 PSNR Mean Y:49.16 U:51.78 V:52.43 Avg:49.92 Global:49.83
x264 [info]: slice B:575 Avg QP:11.71 size:156112 PSNR Mean Y:47.45 U:50.30 V:51.19 Avg:48.28 Global:48.23For each of I, P, B frames: number of frames, average quantizer, average size (in bits?). Mean PSNR for each colour plane, as well as average and global. PSNR is a measure of how the output image compares to the input image. Higher values are better.
x264 [info]: mb I I16..4: 2.2% 81.1% 16.7% Percentage of I frame macroblocks that are 16x16, 8x8, 4x4.
x264 [info]: mb P I16..4: 0.9% 45.6% 9.9% P16..4: 15.2% 16.7% 10.3% 0.0% 0.0% skip: 1.5%
x264 [info]: mb B I16..4: 1.6% 2.3% 12.8% B16..8: 15.3% 10.5% 54.2% direct: 2.3% skip: 1.1%As above, for P and B frames. First three numbers refer to use of I MBs, the second set to P MBs, and skip refers to skipped MBs. Direct refers to ???
x264 [info]: 8x8 transform intra:67.4%
x264 [info]: direct mvs spatial:69.4% temporal:30.6%More breakdown of types, this time for the 8x8 MB transform, and for direct B MBs.
x264 [info]: ref P 75.5% 17.1% 7.4%
x264 [info]: ref B 81.2% 14.5% 4.4%Number of frames using 1/2/3 references for P/B frames.
x264 [info]: SSIM Mean Y:0.9927661
x264 [info]: PSNR Mean Y:48.359 U:51.101 V:51.860 Avg:49.153 Global:49.008 kb/s:34863.86More quality metrics.

[foxyshadis]

Direct refers to ???

Similar to a skip but more flexible. Both take no bits.

Definitions of things like quantizer, PSNR, and other aspects of video coding can be found in many online glossaries, and you might want to check out the H.264 spec if you're mainly working with it. You might find tools like elecard streameye, h264_info, and avidemux (with custom scripts) handy for gathering more frame information, as well as x264's --verbose option, if you don't want to build a custom ffmpeg or JM.

[Sergey A. Sablin]

Similar to a skip but more flexible. Both take no bits.
direct means no motion information is transmitted. coefficients are present. so it costs bits. like skips do, both in cavlc and cabac - it all depends on contexts and current state on entropy coder. cavlc encodes the number of skips, cabac encodes skip or not skip.