[请教]如何看x264的info

刚用500k 2pass压了一部动画，从数值上看合格吗

Log for job job1

avis [info]: 640x480 @ 23.98 fps (32366 frames)
x264 [info]: using cpu capabilities: MMX MMXEXT SSE SSE2 SSSE3
x264 [warning]: VBV maxrate specified, but no bufsize.
x264 [info]: slice I:301 Avg QP:24.78 size: 17645
x264 [info]: slice P:12055 Avg QP:28.40 size: 5086
x264 [info]: slice B:20010 Avg QP:28.23 size: 859
x264 [info]: mb I I16..4: 42.1% 0.0% 57.9%
x264 [info]: mb P I16..4: 17.5% 0.0% 0.0% P16..4: 44.5% 0.0% 0.0% 0.0% 0.0%skip:37.9%
x264 [info]: mb B I16..4: 0.4% 0.0% 0.0% B16..8: 11.7% 0.0% 0.0% direct: 6.2% skip:81.7%
x264 [info]: final ratefactor: 28.73
x264 [info]: direct mvs spatial:99.5% temporal:0.5%
x264 [info]: kb/s:496.7

encoded 32366 frames, 93.83 fps, 496.72 kb/s

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Starting postprocessing of job...
Job completed successfully and deletion of intermediate files is activated
Postprocessing finished!
End of log for job1
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Looking for job processor for job...
Processor found!


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Starting job job2 at 7:40:11
Starting preprocessing of job...
Preprocessing finished!
encoder commandline:
--pass 2 --bitrate 500 --stats "H:\EyeShield21\x264.stats" --ref 8 --mixed-refs --no-fast-pskip --bframes 3 --b-pyramid --b-rdo --bime --weightb --direct auto --filter 1,1 --subme 6 --trellis 1 --analyse p8x8,b8x8,i4x4,i8x8 --8x8dct --vbv-maxrate 25000 --me umh --threads auto --thread-input --progress --no-psnr --no-ssim --output "H:\EyeShield21\x264.mp4" "H:\EyeShield21\x264.avs"
successfully started encoding
Processing ended at 8:17:33
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Log for job job2

avis [info]: 640x480 @ 23.98 fps (32366 frames)
x264 [info]: using cpu capabilities: MMX MMXEXT SSE SSE2 SSSE3
x264 [warning]: VBV maxrate specified, but no bufsize.
mp4 [info]: initial delay 208542 (scale 2500000)
x264 [info]: slice I:301 Avg QP:23.92 size: 17619
x264 [info]: slice P:12055 Avg QP:26.80 size: 5069
x264 [info]: slice B:20010 Avg QP:27.53 size: 899
x264 [info]: mb I I16..4: 35.9% 47.9% 16.2%
x264 [info]: mb P I16..4: 11.6% 8.5% 1.6% P16..4: 43.2% 7.8% 2.9% 0.0% 0.0%skip:24.4%
x264 [info]: mb B I16..4: 0.1% 0.2% 0.0% B16..8: 24.5% 0.4% 0.9% direct: 0.6% skip:73.3%
x264 [info]: 8x8 transform intra:40.4% inter:75.9%
x264 [info]: direct mvs spatial:85.6% temporal:14.4%
x264 [info]: ref P 68.4% 15.6% 7.3% 2.4% 2.0% 1.9% 1.4% 0.9%
x264 [info]: ref B 84.3% 9.3% 2.8% 1.2% 0.7% 0.8% 0.5% 0.4%
x264 [info]: kb/s:500.2

encoded 32366 frames, 14.48 fps, 500.23 kb/s

desired video bitrate of this job: 500 kbit/s - obtained video bitrate (approximate): 502 kbit/s

偶尔会有RP好的时候


Log for job job2

avis [info]: 864x480 @ 23.98 fps (34034 frames)
x264 [info]: using cpu capabilities: MMX MMXEXT SSE SSE2 3DNow!
x264 [warning]: VBV maxrate specified, but no bufsize.
mp4 [info]: initial delay 2002 (scale 24000)
x264 [info]: slice I:334 Avg QP:11.56 size: 46185
x264 [info]: slice P:8272 Avg QP:12.72 size: 13145
x264 [info]: slice B:25428 Avg QP:13.68 size: 2094
x264 [info]: mb I I16..4: 24.3% 33.3% 42.4%
x264 [info]: mb P I16..4: 4.9% 5.2% 3.0% P16..4: 37.9% 8.5% 5.3% 0.5% 0.4%skip:34.2%
x264 [info]: mb B I16..4: 0.1% 0.1% 0.1% B16..8: 13.7% 0.6% 1.4% direct: 2.5% skip:81.6%
x264 [info]: 8x8 transform intra:37.4% inter:23.9%
x264 [info]: ref P 68.0% 12.8% 7.8% 4.5% 3.7% 3.3%
x264 [info]: ref B 72.1% 13.7% 6.0% 3.3% 2.6% 2.4%
x264 [info]: kb/s:999.9

I P B的QP都达到22？
我这个不是DVDrip，是片源稍差的xvid，x264不会比不过rmvb吧（在100MB左右）
之前的一个贴子你不是说QP小于30就可以了吗？
到底是码率不够还是压制方法不对？

怎么分析出来的，看上去还可以的