The BASS_BFX_BQF type exposes the following members.
Bandwidth in octaves (0.1...4...n), Q is not in use (fBandwidth has priority over fQ). Default = 1 (0=not in use).
The bandwidth in octaves (between -3 dB frequencies for for BANDPASS and NOTCH or between midpoint (dBgain/2) gain frequencies for PEAKINGEQ).
Cut-off frequency (Center in PEAKINGEQ and Shelving filters) in Hz (1...info.freq/2). Default = 200Hz.
Gain in dB (-15...0...+15). Default 0dB (used only for PEAKINGEQ and Shelving filters).
EE kinda definition of Q (0.1...1...n), if bandwidth is not in use. Default = 0.0 (0=not in use).
A shelf slope parameter (linear, used only with Shelving filters) (0...1...n). Default = 0.0.
When fS=1, the shelf slope is as steep as you can get it and remain monotonically increasing or decreasing gain with frequency.
A BASSFXChan flag to define on which channels to apply the effect.
Default: -1 (BASS_BFX_CHANALL) - all channels.
Defines which BiQuad filter should be used.