STGraphicEq
Overview
ST graphic EQ
Discussion
The Graphical equalizer (GrEq) module is in charge of fine tuning the sound spectrum according to user personal preferences. This is done by modifying gain factors at fixed frequencies represented by sliders. The number of bands is determined at the initialization phase and can be 5, 8 or 10. The gain factors are adjustable from -12 dB to +12 dB in standard mode. 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. GrEq module supports stereo interleaved 32 bits I/O data, 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.
GrEq library is configured with 6 gain presets. When the user selects one preset, the gains in the user_gain_per_band_dB[] table are discarded .
0 : no preset, use the gains in the user_gain_per_band_dB[]
1 : Pop
2 : Jazz
3 : Rock
4 : Vocal
5 : Classical
6 : HipHop
Type Definition
typedef struct _ModuleSTGraphicEq
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
INT32 text; // Text explaining that sliders are for user mode only
INT32 nAPIResult; // Return status for last call into the ST API
INT32 nBands; // Number bands
INT32 preset; // preset index (0 - none, 1 - Pop, 2 - Jazz, 3 - Rock, 4 - Vocal, 5 - Classical, 6 - HipHop
INT32 enable; // Block enable
INT32* userGain; // Up to 10 bands of gain (-12 dB - +12 dB in 1 dB steps)
INT32* actualGain; // Up to 10 bands of gain (-12 dB - +12 dB in 1 dB steps)
void * pGlobals; // Points to the global variables structure
} ModuleSTGraphicEqClass;
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
text | int | const | 0 | 0 | Unrestricted | |
nAPIResult | int | state | 0 | 0 | Unrestricted | |
nBands | int | const | 0 | 5 | 5, 8, 10 | |
preset | int | parameter | 0 | 0 | 0:1:6 | |
enable | int | parameter | 0 | 1 | 0:1:1 | |
userGain | int* | parameter | 0 | [1 x 5] | -12:1:12 | dB |
actualGain | int* | state | 0 | [1 x 5] | Unrestricted | |
pGlobals | void * | const | 0 | Unrestricted |
Pins
Input Pins
Name: in
Description: audio input
Data type: fract32
Channel range: 2
Block size range: 96:480
Sample rate range: 48000
Complex support: Real
Output Pins
Name: out
Description: audio output
Data type: fract32
MATLAB Usage
File Name: st_graphic_eq_module.m
M = st_graphic_eq_module(NAME, NO_BANDS)
Audio Weaver wrapper for the ST Gain Manager module. Arguments:
NAME - name of the module.
NO_BANDS - 5, 8, or 10 bands
No Bands Center Frequencies
5 bands - 125, 400, 1278, 4088, 13074
8 bands - 100, 203, 412, 837, 1698, 3447, 6998, 14206
10 bands - 62, 115, 214, 399, 742, 1380, 2567, 4775, 8882, 16520
Copyright (c) 2017 DSP Concepts, Inc. All Rights Reserved.
Author: Chris Perry