Overview

ST Bass Manager

Discussion

The Bass Manager (BAM) module has the function of modifying the low-frequency part of a stereo signal. It is possible to configure the cross-over cut-off frequency and to amplify or attenuate the bass signal. The modified low-frequency content can be mixed back with the rest of the signal or output as a third signal. Implementation uses 32 bits resolution for all computations, and can be used with 32 bits input/output format at a sampling frequency of 48 kHz. with a minimum input frame size of 96 and a maximum input frame size of 480 stereo samples. This limitation corresponds to 10ms scheduling at 48 kHz sampling frequency.

Output Mode:

1 = output is a 2.0 configuration
2 = output is a 2.1 configuration (Left and Right channels are kept with low frequencies filtered out)
3 = output is a 2.1 configuration (Left and Right channel are not modified)

Type Definition

typedef struct _ModuleSTBassManager
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 nAPIResult;                             // Return status for last call into the ST API
    INT32 outputMode;                             // Output mode (1 - Stereo, 2 - 2.1 with LFE, 3 - 2.1 without LFE
    INT32 limiterReleaseTime;                     // Limiter release time in Ms (1ms:900ms)
    INT32 bassVol;                                // Bass volume in dB (-24dB:+24dB, 1dB step)
    INT32 freqXOver;                              // Crossover frequency in Hz
    INT32 enable;                                 // Block enable
    INT32 limiterEnable;                          // Limiter enable
    void * pGlobals;                              // Points to the global variables structure
} ModuleSTBassManagerClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
nAPIResult	int	state	0	0	Unrestricted
outputMode	int	const	0	1	Unrestricted
limiterReleaseTime	int	parameter	0	200	1:1:900	msec
bassVol	int	parameter	0	0	-24:1:24	dB
freqXOver	int	parameter	0	100	Unrestricted	Hz
enable	int	parameter	0	1	0:1:1
limiterEnable	int	parameter	0	1	0:1:1
pGlobals	void *	state	1		Unrestricted

Pins

Input Pins

Name: in

Description: audio input

Data type: fract32

Channel range: 2

Block size range: 96:480

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: audio output

Data type: fract32

MATLAB Usage

File Name: st_bass_manager_module.m

 M = st_bass_manager_module(NAME, OUTPUT_MODE)
 Audio Weaver wrapper for the ST Bass Manager module.  Arguments:
   NAME - name of the module.
   OUTPUT_MODE - (1, 2, or 3)
                 BAM_OUTPUT_MODE_2_0                   1 (default)
                 BAM_OUTPUT_MODE_2_1_WITH_LFE_SPLIT    2
                 BAM_OUTPUT_MODE_2_1_WITHOUT_LFE_SPLIT 3
 Copyright (c) 2017 DSP Concepts, Inc.  All Rights Reserved.
 Author:  Chris Perry