H.264 rate-control encoding simulate VBR as CBR

Hi all,

we are working on the DM8168 wth the RDK 4.0, and since we can't use CBR at H.264 encoder at interlace mode, we wish to use the VBR algorithm, my questions are:

1. what are the main paramters that need to be changed in order to simulate the CBR mode?
2. what is the "price" of using the VBR algorithm , is it more latency?, is it less strict bit-rate? if so how can we set the parameters to reduce the penalty?

thank a lot,

Amir