Multipass CBR?

[U149113]

Just noticed that v.2.67 has a selection for Multipass CBR. If CBR is set as far as bit allocation, what is the possible reason for a Multipass CBR setting? Seems like a waste to do more than one pass for a CBR.

[Sulik]

Probably mostly a waste of time, but CBR is never truly CBR: it can be VBR-like within the constraints of the VBV buffer.
However, the vbv buffer size is usually limited by the format (DVD and MPEG-2 MP@ML has a limit of 224KB), and there is not much the second pass will be able to do.