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 (http://en.wikipedia.org/wiki/Video_compression_picture_types). 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:3441.8The bitrate of the raw H.264 stream.

encoded 239470 frames, 3.55 fps, 3441.84 kb/sThe 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?