vbv maxrate not working ?

[juGGaKNot]

Format profile : High@L4.0
Format settings, CABAC : Yes
Format settings, ReFrames : 14 frames
Duration : 11mn 9s
Bit rate mode : Variable
Bit rate : 4 000 Kbps
Maximum bit rate : 27.8 Mbps
Width : 1 024 pixels
Height : 576 pixels
Frame rate : 30.000 fps
Writing library : x264 core 68 r1195M 5d75a9b
Encoding settings : cabac=1 / ref=14 / deblock=1:1:1 / analyse=0x3:0x133 / me=tesa / subme=10 / psy_rd=1.0:0.0 / mixed_ref=1 / me_range=24 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / chroma_qp_offset=-2 / threads=3 / nr=0 / decimate=0 / mbaff=0 / bframes=4 / b_pyramid=0 / b_adapt=2 / b_bias=0 / direct=3 / wpredb=1 / keyint=300 / keyint_min=30 / scenecut=40 / rc=2pass / bitrate=4000 / ratetol=1.0 / qcomp=1.00 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=20000 / vbv_bufsize=20000 / ip_ratio=1.10 / pb_ratio=1.10 / aq=2:1.00

I just encoded a file that has 28 MB max bitrate, vbv_maxrate is 20000, is this right ?

[nurbs]

Basically your maximum bitrate can be somewhere around (<) vbv_maxrate + vbv_bufsize for a short time without violating vbv. It's more complicated than that actually, but I never bothered with the details. I can remember other threads, probably in the avc subforum, about it where it was explained in full.

[juGGaKNot]

I see, i ask because this is the first file where playback suffers ( small freeze from time to time )

[nurbs]

I know people generally take the same bufsize as maxrate, but does your device actually have the required buffer size? Also decoding cost scales with bitrate, especially CABAC, so it could be that your playback device is just to slow to handle the spike. You can also try to look at the file with "Bitrate Viewer" or a similar application and check if the stuttering is in the same place as the bitrate spike just to be sure.

[juGGaKNot]

on pc ( x2 4000+ divx7 and 9800gt )

the vbv is for ps3