A statistical multiplexer (statmux) system for encoding multiple channels of digital television data is provided with improved algorithms for determining bitrate for encoding and decoding to account for signal complexity. The variable bit rate (VBR) encoders and encoding are provided in a statmux system by employing a CBR (constant bit rate) adapter. A CBR adapter can provide correcting state updates on a per-frame basis to a CBR encoder element, thereby enabling VBR capability.