information about the x264 log

[chros]

I have searched the forum (and tried Google), but I can't find any info about the information that the x264 log contains.
eg:

avis [info]: 1280x544 @ 23.98 fps (239470 frames)
x264 [info]: using cpu capabilities: MMX MMXEXT SSE SSE2 3DNow!
x264 [warning]: VBV maxrate specified, but no bufsize.
mp4 [info]: initial delay 834166 (scale 10000000)
x264 [info]: slice I:2323  Avg QP:19.01  size: 78885a 0:00:00
x264 [info]: slice P:101512 Avg QP:21.38  size: 28261
x264 [info]: slice B:135635 Avg QP:22.36  size:  9179
x264 [info]: mb I  I16..4: 19.1% 75.0%  5.9%
x264 [info]: mb P  I16..4:  6.8% 17.0%  1.1%  P16..4: 36.9% 6.0%  7.8%  0.0%  0.0%    skip:14.4%
x264 [info]: mb B  I16..4:  0.3%  1.0%  0.2%  B16..8: 26.6%  2.0%  4.4%  direct: 4.5%  skip:61.0%
x264 [info]: 8x8 transform  intra:68.8%  inter:73.5%
x264 [info]: direct mvs  spatial:96.3%  temporal:3.7%
x264 [info]: ref P  68.0% 17.8%  6.6%  4.6%  2.9%
x264 [info]: ref B  83.3% 10.7%  2.9%  1.9%  1.2%
x264 [info]: kb/s:3441.8

encoded 239470 frames, 3.55 fps, 3441.84 kb/s

Can somebody explain all the lines or give me a link?

Thanks

[Dark Shikari]

avis [info]: 1280x544 @ 23.98 fps (239470 frames)

Information about the input file (resolution, framerate, number of frames).

x264 [info]: using cpu capabilities: MMX MMXEXT SSE SSE2 3DNow!

Your processor is an Athlon 64 and it supports the aforementioned processor extensions used by x264.

x264 [warning]: VBV maxrate specified, but no bufsize.

You're specifying a maximum bitrate but no buffer size. If you're encoding for a specific hardware device, you should specify the appropriate buffer size along with the max rate.

mp4 [info]: initial delay 834166 (scale 10000000)

Some sort of delay value relating to the mp4 muxing.

x264 [info]: slice I:2323 Avg QP:19.01 size: 78885a 0:00:00
x264 [info]: slice P:101512 Avg QP:21.38 size: 28261
x264 [info]: slice B:135635 Avg QP:22.36 size: 9179

The number of each frame type. Also the average quantizer value for each of the frame types. Lower QP generally means better quality at the cost of more bitrate.

x264 [info]: mb I I16..4: 19.1% 75.0% 5.9%
x264 [info]: mb P I16..4: 6.8% 17.0% 1.1% P16..4: 36.9% 6.0% 7.8% 0.0% 0.0% skip:14.4%
x264 [info]: mb B I16..4: 0.3% 1.0% 0.2% B16..8: 26.6% 2.0% 4.4% direct: 4.5% skip:61.0%

This shows you the various types of partitions used for each of the different block types. For example, 5.9% of the I-frame partitions are 4x4 blocks. This is controlled by the --partitions commandline.

x264 [info]: 8x8 transform intra:68.8% inter:73.5%

Since you used the -8x8dct commandline, this section documents how often the 8x8 transform was actually used.

x264 [info]: direct mvs spatial:96.3% temporal:3.7%

Since you used --direct auto, the default, this states how often either --direct spatial or --direct temporal were used as chosen by the encoder.

x264 [info]: ref P 68.0% 17.8% 6.6% 4.6% 2.9%
x264 [info]: ref B 83.3% 10.7% 2.9% 1.9% 1.2%

You used 5 reference frames in your encoding, and this shows how often they were used for P-frames and B-frames. This is good for seeing how useful each extra reference frame is.

x264 [info]: kb/s:3441.8

The bitrate of the raw H.264 stream.

encoded 239470 frames, 3.55 fps, 3441.84 kb/s

The framerate that the video was encoded at (i.e. how fast x264 encoded the video) and the final bitrate including the MP4 muxing overhead.

[chros]

Thanks Dark for the detail explanation !
I'll chow myself through it, then if I have some question, I'll shoot it ...

ps: am I right, that I can't find it? If I am, this should be a sticky ...

[yaous]

x264 [info]: coded y,uvDC,uvAC intra: 32.1% 39.2% 15.9% inter: 17.9% 13.6% 1.5%

what does that mean?

[Dark Shikari]

Coded block %s for intra and inter 8x8 blocks, respectively (and for luma, chroma DC, chroma AC, respectively).

[yaous]

I'm sorry for my ignorance..

What does 'Coded block' mean?

[Dark Shikari]

A block with at least one nonzero DCT coefficient.

[yaous]

Thanks for the explanation

[tebasuna51]

I'm using 4 ref-frames.
How can interpret this log:

x264 [info]: ref P L0: 49.8%  9.8% 23.5% 12.2%  4.2%  0.5%
x264 [info]: ref B L0: 84.6% 12.4%  3.0%
x264 [info]: ref B L1: 92.2%  7.8%

I suppose L0 is previous ref-frames and L1 future ref-frames.
But with ref P seems use until 6 ref-frames.

[nurbs]

With --weightp 2 you get 2 extra refs (by duplication IIRC). They don't take up DPB space.

[tebasuna51]

Thanks nurbs.

[Boulder]

Are those extra refs "worth" the same as adding 2 refs in the settings? For example, I've set 5 refs and get 48.2% 8.6% 26.4% 7.6% 8.9% 0.3% 0.0% in the log for P-frames (with --weightp 2 enabled). Should I actually set a higher ref value since the fifth one is used in almost 9% of cases?