can x264 do cbr?

[rubypin]

in the programe, i found four models, i consider it as:
if(i_force_qp) ......................all frames use the sanme QP
else if (rc->b_abr)......................1 pass abr
else if(rc->b_2pass)....................2 pass abr
else /*CQP*/ ...........................1 pass cqp

am i right?
so where is the 1pass cbr?

another question:
what's the use of vbv in x264?
i find set vbv_maxrate and vbv_buffersize only changes the value of cbr_decay,and then cplxr_sum,wanted_bits_window, but i dont know why?
maybe i misunderstand vbv and buffer? the use of buffer is make the vriable birtate can be transported in constant bandwidth channel, is vbv same?

if do not set vbv, do we use buffer in x264?

[Sharktooth]

CBR can be achieved restricting ABR mode to produce constant bitrate. It has already been discussed, :search:.

[rubypin]

sorry,i searched,but didint make clear it.
how to restrict? the meaning of constant bitrate is for each frame with same size or same bitrate each second?
can you help me about the use of vbv?

[Trahald]

http://forum.doom9.org/showthread.php?p=699479#post699479 mentions how to acheive cbr. akupenguins post below the post i pasted answers your question about if cbr is at the frame level. the thread also touches on vbv

[DarkZell666]

Why do all these people with an asiatic woman for avatar dig into the source code wanting to know about x264's ratecontrol ? :D
Chen & rubypin have got to be cousins or something ... :p

[rubypin]

Why do all these people with an asiatic woman for avatar dig into the source code wanting to know about x264's ratecontrol ? :D
Chen & rubypin have got to be cousins or something ... :p
:D not all asiatic cousins~ i am chinese, maybe chen also, but i dont know her;)