Overview

Phase Difference Post Filter

Type Definition

typedef struct _ModulePhaseDifferencePostFilter
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    FLOAT32 filterDelayThreshold;                 // Threshold to determine if a time-freq bin is within the specified direction
    FLOAT32 targetWidth;                          // The width of the target direction, in degrees. Calculated from targetDir, micSpacing, and filterDelayThreshold
    FLOAT32 maskAttenDB;                          // dB units - attenuation in the time-freq bin if the sound from that bin is not in the specified direction
    FLOAT32 maskAtten;                            // Linear units - attenuation in the time-freq bin if the sound from that bin is not in the specified direction
    FLOAT32 timeDomainSR;                         // Sample rate - in time domain
    FLOAT32 targetDir;                            // Target direction, in degrees. NOT Implemented
    FLOAT32 micSpacing;                           // Mic Spacing, in meters.
    INT32 fftSize;                                // FFT Size
    INT32 numBins;                                // Number of bins
    INT32 numFilters;                             // Number of Gammatone Filters
    FLOAT32 epsilon;                              // A small number
    FLOAT32* gtFilterMag;                         // Matrix holding the magnitude of gammatone filter coefficients (real)
    FLOAT32* phaseDiff;                           // Phase difference, in radians. Part of scratch.
    FLOAT32* oneOverExpectedPhaseDiff;            // One over the expected phase difference.
    FLOAT32* W;                                   // Gammatone domain weights
    FLOAT32* mu;                                  // Mask
    FLOAT32* mu_g;                                // Mask after Gammatone filterbank
} ModulePhaseDifferencePostFilterClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
filterDelayThreshold	float	parameter	0	0.2	0:10
targetWidth	float	derived	0	6.5544	Unrestricted
maskAttenDB	float	parameter	0	-40	-60:0
maskAtten	float	derived	0	0.01	Unrestricted
timeDomainSR	float	const	0	16000	Unrestricted
targetDir	float	parameter	0	0	Unrestricted
micSpacing	float	parameter	0	0.075	Unrestricted
fftSize	int	const	0	512	Unrestricted
numBins	int	const	0	257	Unrestricted
numFilters	int	const	0	40	Unrestricted
epsilon	float	const	0	1e-19	Unrestricted
gtFilterMag	float*	derived	0	[256 x 40]	Unrestricted
phaseDiff	float*	derived	1	[257 x 1]	Unrestricted
oneOverExpectedPhaseDiff	float*	derived	1	[257 x 1]	Unrestricted
W	float*	derived	1	[40 x 1]	Unrestricted
mu	float*	derived	1	[257 x 1]	Unrestricted
mu_g	float*	derived	1	[257 x 1]	Unrestricted

Pins

Input Pins

Name: in

Description: input

Data type: float

Channel range: 2

Block size range: 257

Sample rate range: Unrestricted

Complex support: Complex

Output Pins

Name: out

Description: output

Data type: float

Scratch Pins

Channel count: 1

Block size: 257

Sample rate: 48000

Channel count: 1

Block size: 257

Sample rate: 48000

MATLAB Usage

File Name: phase_difference_post_filter_module.m

 M=phase_difference_post_filter_module(NAME, numFilters, fftSize)
 Creates a phase difference post filter module
 Currently, only 2 channels are supported.
 
  description TBD
 
 Arguments:
     NAME - name of the module.