エンコードログ

これでエンコードしたログもさらしておくと
1pass

avis [info]: 720x480 @ 26.62 fps (60278 frames)
x264 [info]: using cpu capabilities MMX MMXEXT SSE SSE2 3DNow! 
x264 [info]: slice I:493   Avg QP:21.26  size: 42792
x264 [info]: slice P:23528 Avg QP:23.62  size: 18932
x264 [info]: slice B:36257 Avg QP:24.40  size:  4084
x264 [info]: mb I  I16..4: 45.0%  0.0% 55.0%
x264 [info]: mb P  I16..4: 25.7%  0.0%  0.0%  P16..4: 49.7%  0.0%  0.0%  0.0%  0.0%    skip:24.7%
x264 [info]: mb B  I16..4:  0.7%  0.0%  0.0%  B16..8: 11.1%  0.0%  0.0%  direct: 7.2%  skip:81.0%
x264 [info]: final ratefactor: 24.94
x264 [info]: direct mvs  spatial:99.8%  temporal:0.2%
x264 [info]: kb/s:2171.6

encoded 60278 frames, 10.64 fps, 2171.67 kb/s

2pass

avis [info]: 720x480 @ 26.62 fps (60278 frames)
x264 [info]: using cpu capabilities MMX MMXEXT SSE SSE2 3DNow! 
x264 [info]: slice I:493   Avg QP:17.46  size: 50845
x264 [info]: slice P:23528 Avg QP:20.12  size: 17890
x264 [info]: slice B:36257 Avg QP:20.33  size:  3689
x264 [info]: mb I  I16..4: 20.1% 46.4% 33.5%
x264 [info]: mb P  I16..4:  2.3%  5.0%  3.8%  P16..4: 60.1% 12.7%  9.3%  0.4%  0.2%    skip: 6.3%
x264 [info]: mb B  I16..4:  0.0%  0.1%  0.1%  B16..8: 14.4%  1.0%  1.9%  direct: 1.5%  skip:81.0%
x264 [info]: 8x8 transform  intra:45.2%  inter:54.3%
x264 [info]: direct mvs  spatial:93.6%  temporal:6.4%
x264 [info]: ref P  52.9% 16.2% 15.3%  8.2%  7.4%
x264 [info]: ref B  47.3% 20.8% 15.4%  8.9%  7.6%
x264 [info]: kb/s:2048.3

encoded 60278 frames, 1.31 fps, 2048.48 kb/s
desired video bitrate of this job: 2048 kbit/s - obtained video bitrate (approximate): 2051 kbit/s

3pass

avis [info]: 720x480 @ 26.62 fps (60278 frames)
x264 [info]: using SAR=8/9
x264 [info]: using cpu capabilities MMX MMXEXT SSE SSE2 3DNow! 
x264 [info]: slice I:493   Avg QP:17.97  size: 47986
x264 [info]: slice P:23528 Avg QP:20.12  size: 18037
x264 [info]: slice B:36257 Avg QP:20.58  size:  3629
x264 [info]: mb I  I16..4: 19.9% 45.0% 35.1%
x264 [info]: mb P  I16..4:  2.2%  5.1%  3.8%  P16..4: 60.5% 12.5%  9.0%  0.4%  0.2%    skip: 6.3%
x264 [info]: mb B  I16..4:  0.0%  0.1%  0.1%  B16..8: 16.4%  1.0%  1.9%  direct: 1.5%  skip:79.1%
x264 [info]: 8x8 transform  intra:45.4%  inter:55.2%
x264 [info]: direct mvs  spatial:87.6%  temporal:12.4%
x264 [info]: ref P  53.0% 16.1% 15.3%  8.2%  7.4%
x264 [info]: ref B  48.1% 20.8% 15.8%  8.1%  7.3%
x264 [info]: kb/s:2047.9

encoded 60278 frames, 1.58 fps, 2048.03 kb/s
desired video bitrate of this job: 2048 kbit/s - obtained video bitrate (approximate): 2051 kbit/s