I have done some reworking of the bandwidth calculation. Now there are 2 adaptive modes. The default is now a fixed adaptive bandwidth, which is chosen at the start of encoding based on either the quality or bitrate setting. The other is the same variable bandwidth as before, but with a different formula. I did this mainly to make the bandwidth filter work better. There is a distinct quality difference in the high frequencies when using the fixed adaptive bandwidth coupled with the bandwidth pre-encoding filter.
commandline option changes:
'-bwfilter 1' = enable bandwidth filter
'-w -1' = fixed adaptive bandwidth (default)
'-w -2' = variable adaptive bandwidth (cannot use bandwidth filter w/ this mode)