Skip to main content
Skip table of contents

GCCV7

Overview

Compute angular 2D direction of arrival of audio sources arriving at the mic array

Discussion

This module computes angular 2D direction of arrival of audio sources arriving at the mic array

Input Pins:

    Input Pin 1:   Multichannel frequency domain data. Usually output of a WOLA Analysis Module
                          Number of channels must match the number of microphones in the micGeometry argument

Output Pins:

    Output Pin 1:   Estimated angular direction of arrival for this WOLA block in degrees. This will be an integer between 0 and 360.

    Output Pin 2:    Confidence value for this angle estimate. This will be an integer. Larger values mean more confidence.

    Output Pin 3:    Array of 360 floats denoting a histogram of possible angles of arrival for this block. Output pin 1 will be the peak of this histogram.

Module Arguments:

    numMics:   number of microphones being used

    interpFactor:   Interpolation factor for better angular resolution at the cost of more CPU resources

    fftSize:    FFTSize used by WOLA Analysis block preceding the SbDOAV2 module

    Fs:    Sampling rate of time domain data entering WOLA Analysis block

    LowerBin:    Frequency bin index of lowest WOLA bin entering SbDOAV2 input pin

Inspector Tuning Variables:

    BlocksPerHistogram: Each WOLA block we get an angle estimate for each bin. These are accumulated over BlocksPerHistogram
    WOLA blocks into a histogram. Then the peak of the histogram is output as the angle estimate. Larger values of
    BlocksPerHistogram give more accuracy but slower response time. BlocksPerHistogram value does not affect MIPS.

    smoothingCoefficient: The smoothing coefficient, (SC), is a float which takes on values between 0 and 1.
    SC operates on the relevant portion of the time domain correlation data between every mic pair. SC performs
    exponential smoothing/averaging in time over each point of the correlation functions. The equation is:
    state(n) = SC*(new data) + (1-SC)*state(n-1). This smoothing increases the accuracy of the DOA algorithm.
    SC allows us to trade off accuracy and responsiveness. The smaller the value of SC, the longer the tail
    of our exponential smoothing/averaging.
    SC smaller ---> more smoothing more accuracy but less responsiveness
    SC larger ---> less smoothing more responsiveness but less accuracy

Type Definition

CODE
typedef struct _ModuleGCCV7
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 numMics;                                // Number of mics in the array
    INT32 interpFactor;                           // Interpolation factor
    INT32 fftSize;                                // Size of FFT upstream from this module
    INT32 MultiSource;                            // Select single or multiple audio sources reported per block
    FLOAT32 Fs;                                   // Time domain sampling rate before WOLA/FFT
    INT32 LowerBin;                               // Frequ bin index of lowest frequ component in the WOLA block
    FLOAT32 smoothingCoefficient;                 // Smoothing coefficient for exponential smoothing of frequ domain CC data
    INT32 BlocksPerHistogram;                     // Number of blocks used to fill histogram before doing smoothing and averaging
    INT32 interpBS;                               // Block Size at interpolated rate
    FLOAT32 interpSR;                             // Sample rate at interpolated rate
    INT32 numDirs;                                // Number of look directions
    INT32 maxNumSources;                          // Maximum number of sources to identify
    INT32 useInputWeightingPin;                   // Use input weighting pin
    INT32 smoothing;                              // 0 No Smoothing 1 Smoothing
    INT32 useSmoothingPin;                        // Select use control pin for smoothing coefficient
    INT32 combineCongruentMicPairs;               // Select combining congruent mic pairs for MIPS savings
    INT32 boxcarDelay;                            // Half length of rectangular window for histogram smoothing
    INT32 gaussDelay;                             // Half length of gaussian window for histogram smoothing
    FLOAT32 gaussSigma;                           // Standard Deviation for Gaussian window
    INT32 NumHistogramStates;                     // Number of full histograms used for temporal averaging
    INT32 QCOpt;                                  // Select optimization. DONT CARE, NOT IMPLEMENTED YET
    INT32 doHistogramProcessing;                  // Add histogram processing to module outputs
    INT32 numBins;                                // Number of bins. This should be the input block size
    INT32 numPairs;                               // Number of microphone pairs
    INT32 xCorrsZeroSamp;                         // 0th sample index in the xcorr data
    INT32 statesSize;                             // Size of states array for frequency domain smoothing
    INT32 tdCurrSize;                             // Size of temp td array for time domain smoothing
    INT32 maxDelay;                               // Maximum of gaussDelay, boxcarDelay
    INT32 HistStatePtr;                           // Index of oldest entry in histogram buffer
    INT32 blockCtr;                               // Counter to keep track of number of blocks used to update histogram
    INT32 blockCtrReset;                          // Counter to keep track of number of blocks used between reset to zero of avgHistogram
    INT32 blockCtrMultiOpt;                       // Counter for multisource/multiblock optimization
    INT32 numPairsToUse;                          // Number of non-redunbdant microphone pairs
    INT32 NSRMP;                                  // Number of sets of redundant mic pairs
    INT32 maxNMPiS;                               // max number of redundant pairs in all sets of redundant pairs
    INT32 NNRMP;                                  // Number of non-redundant mic pairs
    FLOAT32 epsilon;                              // Small number
    FLOAT32 c;                                    // Speed of sound in meters per sec
    FLOAT32 windowSize;                           // How much to extend the look window when comparing measured delays with theoretical time delays. This is relative number.
    INT32 removalWindowDelta;                     // Number of samples to remove when filtering DOA Peaks
    INT32 doHistSmoothing;                        // Specifies whether to do smoothing of histogram
    INT32 doHistAveraging;                        // Specifies whether to do temporal smoothing of histogram
    FLOAT32 MinPeakThresh;                        // Minimum height of a histogram peak to be eligible to be reported as a DOA
    INT32 MinDist;                                // Distance in integer units of degrees, between peaks in histogram to count as a distinct DOA
    FLOAT32 noiseFloorDBOffset;                   // Offset, in DB, for noise floor weighting. Higher value will weight noise floor less.
    INT32 lookDirLow;                             // Min look direction, in degrees. The low end of the DOA look direction.
    INT32 lookDirHigh;                            // Max look direction, in degrees. The high end of the DOA look direction.
    INT32 tauMaxMax;                              // Maximum theoretical time delays for all mic pair
    INT32 tauMinMin;                              // Minimum theoretical time delays for all mic pair
    INT32 tdZeroSamp;                             // windowed xcorr 0 delay sample index
    INT32 tdLength;                               // Length of the xcorr vector, after windowing
    FLOAT32* micArrayCoords;                      // Microphone geometry in cartesian coordinates and in meters. The vector going from (0,0) to (1,0) is considered 0 degrees.
    FLOAT32* noiseFloorVar;                       // Microphone noise floor measurement, in db10 units.
    FLOAT32* HistEnergies;                        // Holds energy of sources at each source direction for a data block
    FLOAT32* HistAngles;                          // Holds angle for each source for a data block
    FLOAT32* HistState;                           // Holds NumHistogramStates histograms
    FLOAT32* avgHistogram;                        // Scratch array to hold average histogram
    FLOAT32* currentHistogram;                    // Scratch array to hold current histogram
    FLOAT32* smoothedHistogram;                   // Scratch array to hold smoothed histogram
    FLOAT32* histExt;                             // Scratch array to hold smoothed histogram
    FLOAT32* histCnv;                             // Scratch array to hold smoothed histogram
    INT32* histSortedAngles;                      // Scratch array for histogram peak picking
    FLOAT32* histSortedValues;                    // Scratch array for histogram peak picking
    INT32* histAnglesUsed;                        // Scratch array for histogram peak picking
    FLOAT32* valuesOutState;                      // Scratch array to hold output histogram counts
    INT32* anglesOutState;                        // Scratch array to hold output angles
    FLOAT32* GaussianWindow;                      // Gaussian window for smoothing histogram
    FLOAT32* BoxcarWindow;                        // Rectangular window for smoothing histogram
    INT32* taus;                                  // Theoretical time delays based on the mic geometry and other factors.
    FLOAT32* deltaTaus;                           // Difference between taus and taus rounded to nearest sample delay.
    FLOAT32* lookDirs;                            // Look directions, in degrees.
    INT32* tauMax;                                // Maximum theoretical time delays for each mic pair
    INT32* tauMin;                                // Minimum theoretical time delays for each mic pair
    FLOAT32* doaValues;                           // Temporary variable from the processing function
    FLOAT32* td;                                  // Temporary variable from the processing function
    INT32* Map;                                   // Map from pair processed to index of pair in micPairsNR = array of non-redundant mic pairs
    FLOAT32* states;                              // Holds current estimate of Rxx
    FLOAT32* tdCurr;                              // Temp array for new td data when doing time domain smoothing
    INT32* NMPiS;                                 // Array containing number of redundant mic pairs in each set
    INT32* CIR;                                   // Array containing channel indices of redundant mic pairs
    INT32* CINR;                                  // Array containing channel indices of non-redundant mic pairs
    void * ifft_struct_pointer;                   // Points to an instance of an IFFT module
} ModuleGCCV7Class;

Variables

Properties

Name

Type

Usage

isHidden

Default value

Range

Units

numMics

int

const

0

4

Unrestricted

interpFactor

int

const

0

4

Unrestricted

fftSize

int

const

0

256

Unrestricted

MultiSource

int

const

0

0

Unrestricted

Fs

float

const

0

16000

Unrestricted

LowerBin

int

const

0

0

Unrestricted

smoothingCoefficient

float

parameter

0

0.2

0:1

BlocksPerHistogram

int

parameter

0

32

1:200

interpBS

int

derived

0

512

Unrestricted

interpSR

float

derived

0

64000

Unrestricted

numDirs

int

const

1

360

Unrestricted

maxNumSources

int

const

1

1

Unrestricted

useInputWeightingPin

int

const

1

0

Unrestricted

smoothing

int

const

1

2

Unrestricted

useSmoothingPin

int

const

1

0

Unrestricted

combineCongruentMicPairs

int

const

1

1

Unrestricted

boxcarDelay

int

const

1

2

Unrestricted

gaussDelay

int

const

1

8

Unrestricted

gaussSigma

float

const

1

3.2

Unrestricted

NumHistogramStates

int

const

1

4

Unrestricted

QCOpt

int

const

1

1

Unrestricted

doHistogramProcessing

int

const

1

1

Unrestricted

numBins

int

const

1

129

Unrestricted

numPairs

int

const

1

6

Unrestricted

xCorrsZeroSamp

int

const

1

64

Unrestricted

statesSize

int

const

1

1

Unrestricted

tdCurrSize

int

const

1

1

Unrestricted

maxDelay

int

const

1

8

Unrestricted

HistStatePtr

int

state

1

0

Unrestricted

blockCtr

int

state

1

0

Unrestricted

blockCtrReset

int

state

1

0

Unrestricted

blockCtrMultiOpt

int

state

1

0

Unrestricted

numPairsToUse

int

const

1

6

Unrestricted

NSRMP

int

const

1

1

Unrestricted

maxNMPiS

int

const

1

1

Unrestricted

NNRMP

int

const

1

1

Unrestricted

epsilon

float

parameter

1

1e-16

Unrestricted

c

float

parameter

1

343

Unrestricted

windowSize

float

parameter

1

0

Unrestricted

removalWindowDelta

int

parameter

1

2

Unrestricted

doHistSmoothing

int

parameter

1

1

Unrestricted

doHistAveraging

int

parameter

1

1

Unrestricted

MinPeakThresh

float

parameter

1

1

0:100

MinDist

int

parameter

1

10

0:360

degrees

noiseFloorDBOffset

float

parameter

1

5

-20:20

lookDirLow

int

parameter

1

0

0:360

lookDirHigh

int

parameter

1

360

0:360

tauMaxMax

int

derived

1

0

Unrestricted

tauMinMin

int

derived

1

0

Unrestricted

tdZeroSamp

int

derived

1

1

Unrestricted

tdLength

int

derived

1

1

Unrestricted

micArrayCoords

float*

parameter

0

[4 x 2]

Unrestricted

noiseFloorVar

float*

parameter

1

[129 x 1]

-500:500

HistEnergies

float*

state

0

[1 x 1]

Unrestricted

HistAngles

float*

state

0

[1 x 1]

Unrestricted

HistState

float*

state

0

[1440 x 1]

Unrestricted

avgHistogram

float*

state

0

[360 x 1]

Unrestricted

currentHistogram

float*

state

0

[360 x 1]

Unrestricted

smoothedHistogram

float*

state

0

[360 x 1]

Unrestricted

histExt

float*

state

0

[376 x 1]

Unrestricted

histCnv

float*

state

0

[392 x 1]

Unrestricted

histSortedAngles

int*

state

0

[360 x 1]

Unrestricted

histSortedValues

float*

state

0

[360 x 1]

Unrestricted

histAnglesUsed

int*

state

0

[360 x 1]

Unrestricted

valuesOutState

float*

state

0

[10 x 1]

Unrestricted

anglesOutState

int*

state

0

[10 x 1]

Unrestricted

GaussianWindow

float*

parameter

1

[17 x 1]

Unrestricted

BoxcarWindow

float*

parameter

1

[5 x 1]

Unrestricted

taus

int*

derived

1

[6 x 360]

Unrestricted

deltaTaus

float*

derived

1

[6 x 360]

Unrestricted

lookDirs

float*

derived

1

[1 x 360]

Unrestricted

tauMax

int*

derived

1

[6 x 1]

Unrestricted

tauMin

int*

derived

1

[6 x 1]

Unrestricted

doaValues

float*

state

0

[360 x 1]

Unrestricted

td

float*

state

0

[1 x 6]

Unrestricted

Map

int*

derived

0

[6 x 1]

Unrestricted

states

float*

state

0

[1 x 1]

Unrestricted

tdCurr

float*

state

0

[1 x 1]

Unrestricted

NMPiS

int*

derived

0

[100 x 1]

Unrestricted

CIR

int*

derived

0

[100 x 1]

Unrestricted

CINR

int*

derived

0

[100 x 1]

Unrestricted

ifft_struct_pointer

void *

state

1

Unrestricted

Pins

Input Pins

Name: micIn

Description: Microphone array input - in frequency domain

Data type: float

Channel range: 4

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Complex

Output Pins

Name: estDirs

Description: Estimated directions, in degrees

Data type: float

Name: estEnergy

Description: Estimated relative energy for each estimated direction

Data type: float

Name: HistValues

Description: Histogram output values

Data type: float

Scratch Pins

Channel count: 1

Block size: 513

Sample rate: 48000

Channel count: 1

Block size: 1024

Sample rate: 48000

Channel count: 1

Block size: 1024

Sample rate: 48000

MATLAB Usage

File Name: gcc_v7_module.m

CODE
M = gcc_v7_module(NAME, numMics, interpFactor, fftSize, FS, LOWERBIN)
 GCCV7 module identifies the 2D angular direction of an audio source received at the mic array.  
 The module takes multichannel frequency domain data as input, (usually the output of a WOLA 
 Analysis module).  The module produces 2 outputs per block: 
 1.)Angle = estimated angular direction of arrival in degrees. This will be an integer between 0 and 360.
 2.)Confidence value for this angle estimate.  Larger values mean more confidence in the angle estimate.  
 Arguments:
    NAME - name of the module.
    numMics - number of microphones in the microphone array
    interpFactor - how much to interpolate for better estimation at the
    cost of more MIPS
    fftSize - Size of the FFT operation done upstream from this module.
    FS              - Sampling rate of time domain data entering WOLA Analysis block
    LOWERBIN        - Frequency bin index of lowest WOLA bin entering GCCV7 input pin

JavaScript errors detected

Please note, these errors can depend on your browser setup.

If this problem persists, please contact our support.