Files
file	saf_default_hrirs.c
	Default HRIR data.

file	saf_hrir.c
	Public source for the HRIR/HRTF processing module (SAF_HRIR_MODULE)

file	saf_hrir.h
	Main header for the HRIR/HRTF processing module (SAF_HRIR_MODULE)

Functions
void	estimateITDs (float hrirs, int N_dirs, int hrir_len, int fs, float itds_s)
	Estimates the interaural time-differences (ITDs) for each HRIR based on the cross-correlation between the left and right channels, which are first low-pass filtered at 750Hz.

void	HRIRs2HRTFs_afSTFT (float hrirs, int N_dirs, int hrir_len, int hopsize, int LDmode, int hybridmode, float_complex hrtf_fb)
	Passes zero padded HRIRs through the afSTFT filterbank.

void	HRIRs2HRTFs_qmf (float hrirs, int N_dirs, int hrir_len, int hopsize, int hybridmode, float_complex hrtf_fb)
	Passes zero padded HRIRs through the qmf filterbank.

void	HRIRs2HRTFs (float hrirs, int N_dirs, int hrir_len, int fftSize, float_complex hrtfs)
	Converts HRIRs to HRTFs for a given FFT size.

void	diffuseFieldEqualiseHRTFs (int N_dirs, float itds_s, float centreFreq, int N_bands, float weights, int applyEQ, int applyPhase, float_complex hrtfs)
	Applies pre-processing to a set of HRTFs, which can either be diffuse-field EQ of an (optionally weighted) average of all HRTFs (CTF), phase simplification based on ITDs, or both.

void	interpHRTFs (float_complex hrtfs, float itds, float freqVector, float interp_table, int N_hrtf_dirs, int N_bands, int N_interp_dirs, float_complex *hrtf_interp)
	Interpolates a set of HRTFs based on a specified interpolation table.

void	binauralDiffuseCoherence (float_complex hrtfs, float itds, float freqVector, int N_hrtf_dirs, int N_bands, float HRTFcoh)
	Computes the binaural diffuse coherence per frequency for a given HRTF set, as described in [1].

void	resampleHRIRs (float hrirs_in, int hrirs_N_dirs, int hrirs_in_len, int hrirs_in_fs, int hrirs_out_fs, int padToNextPow2, float hrirs_out, int hrirs_out_len)
	Resamples a set of HRIRs from its original samplerate to a new samplerate.

Variables
const float	__default_hrirs [836][2][256]
	The default HRIR data for SAF.

const float	__default_hrir_dirs_deg [836][2]
	The measurement directions used for the default HRIR dataset.

const int	__default_N_hrir_dirs
	The number of directions/measurements in the default HRIR dataset.

const int	__default_hrir_len
	The length of the filters, in samples, for the default HRIR dataset.

const int	__default_hrir_fs
	The samplerate used to measure the default HRIR filters

Detailed Description

HRIR/HRTF processing module

Function Documentation

◆ binauralDiffuseCoherence()

void binauralDiffuseCoherence	(	float_complex *	hrtfs,
		float *	itds,
		float *	freqVector,
		int	N_hrtf_dirs,
		int	N_bands,
		float *	HRTFcoh )

Computes the binaural diffuse coherence per frequency for a given HRTF set, as described in [1].

Parameters

[in]	hrtfs	HRTFs as filterbank coeffs FLAT: N_bands x NUM_EARS x N_hrtf_dirs
[in]	itds	The inter-aural time difference (ITD) for each HRIR; N_hrtf_dirs x 1
[in]	freqVector	Frequency vector; N_bands x 1
[in]	N_hrtf_dirs	Number of HRTF directions
[in]	N_bands	Number of frequency bands
[out]	HRTFcoh	Binaural coherence per frequency; N_bands x 1

See also: [1] A. Politis, "Diffuse-field coherence of sensors with arbitrary directional responses," arXiv preprint arXiv:1608.07713,2016.

Definition at line 322 of file saf_hrir.c.

◆ diffuseFieldEqualiseHRTFs()

void diffuseFieldEqualiseHRTFs	(	int	N_dirs,
		float *	itds_s,
		float *	centreFreq,
		int	N_bands,
		float *	weights,
		int	applyEQ,
		int	applyPhase,
		float_complex *	hrtfs )

Applies pre-processing to a set of HRTFs, which can either be diffuse-field EQ of an (optionally weighted) average of all HRTFs (CTF), phase simplification based on ITDs, or both.

Note: 'weights' (if used) should sum to 4pi. 'itds_s' and 'centreFreq' are only required if applyPhase==1, so can be set to NULL otherwise.

Warning: This function is NOT suitable for binaural room impulse responses (BRIRs)!

Parameters

[in]	N_dirs	Number of HRTFs
[in]	itds_s	HRIR ITDs (set to NULL if not needed); N_dirs x 1
[in]	centreFreq	Frequency vector (set to NULL if not needed); N_bands x 1
[in]	N_bands	Number of frequency bands/bins
[in]	weights	Grid weights (set to NULL if not available); N_dirs x 1
[in]	applyEQ	Diffuse-field EQ / CTF; 0:disabled, 1:enabled
[in]	applyPhase	Phase simplification; 0:disabled, 1:enabled
[in,out]	hrtfs	The HRTFs; FLAT: N_bands x NUM_EARS x N_dirs

Definition at line 173 of file saf_hrir.c.

◆ estimateITDs()

void estimateITDs	(	float *	hrirs,
		int	N_dirs,
		int	hrir_len,
		int	fs,
		float *	itds_s )

Estimates the interaural time-differences (ITDs) for each HRIR based on the cross-correlation between the left and right channels, which are first low-pass filtered at 750Hz.

Parameters

[in]	hrirs	HRIRs; FLAT: N_dirs x NUM_EARS x hrir_len
[in]	N_dirs	Number of HRIRs
[in]	hrir_len	Length of the HRIRs in samples
[in]	fs	Sampling rate of the HRIRs
[out]	itds_s	ITDs in seconds; N_dirs x 1

Definition at line 40 of file saf_hrir.c.

◆ HRIRs2HRTFs()

void HRIRs2HRTFs	(	float *	hrirs,
		int	N_dirs,
		int	hrir_len,
		int	fftSize,
		float_complex *	hrtfs )

Converts HRIRs to HRTFs for a given FFT size.

Note: If the HRIRs are shorter than the FFT size (hrir_len<fftSize), then the HRIRs are zero-padded. If they are longer, then they are truncated.

Parameters

[in]	hrirs	HRIRs; FLAT: N_dirs x NUM_EARS x hrir_len
[in]	N_dirs	Number of HRIRs
[in]	hrir_len	Length of the HRIRs in samples
[in]	fftSize	FFT size
[out]	hrtfs	HRTFs; FLAT: (fftSize/2+1) x NUM_EARS x N_dirs

Definition at line 139 of file saf_hrir.c.

◆ HRIRs2HRTFs_afSTFT()

void HRIRs2HRTFs_afSTFT	(	float *	hrirs,
		int	N_dirs,
		int	hrir_len,
		int	hopsize,
		int	LDmode,
		int	hybridmode,
		float_complex *	hrtf_fb )

Passes zero padded HRIRs through the afSTFT filterbank.

The filterbank coefficients are then normalised with the energy of an impulse, which is centered at approximately the beginning of the median HRIR peak.

Warning: This function is NOT suitable for binaural room impulse responses (BRIRs)!

Parameters

[in]	hrirs	HRIRs; FLAT: N_dirs x NUM_EARS x hrir_len
[in]	N_dirs	Number of HRIRs
[in]	hrir_len	Length of the HRIRs in samples
[in]	hopsize	Hop size in samples
[in]	LDmode	Low-Delay mode, 0:disabled, 1:enabled
[in]	hybridmode	Hybrid-filtering, 0:disabled, 1:enabled
[out]	hrtf_fb	HRTFs as filterbank coeffs; FLAT: (hybrid ? hopsize+5 : hopsize+1) x NUM_EARS x N_dirs

Definition at line 110 of file saf_hrir.c.

◆ HRIRs2HRTFs_qmf()

void HRIRs2HRTFs_qmf	(	float *	hrirs,
		int	N_dirs,
		int	hrir_len,
		int	hopsize,
		int	hybridmode,
		float_complex *	hrtf_fb )

Passes zero padded HRIRs through the qmf filterbank.

The filterbank coefficients are then normalised with the energy of an impulse, which is centered at approximately the beginning of the median HRIR peak.

Warning: This function is NOT suitable for binaural room impulse responses (BRIRs)!

Parameters

[in]	hrirs	HRIRs; FLAT: N_dirs x NUM_EARS x hrir_len
[in]	N_dirs	Number of HRIRs
[in]	hrir_len	Length of the HRIRs in samples
[in]	hopsize	Hop size in samples
[in]	hybridmode	0:disabled, 1:enabled
[out]	hrtf_fb	HRTFs as filterbank coeffs; FLAT: (hybrid ? hopsize+7 : hopsize+1) x NUM_EARS x N_dirs

Definition at line 125 of file saf_hrir.c.

◆ interpHRTFs()

void interpHRTFs	(	float_complex *	hrtfs,
		float *	itds,
		float *	freqVector,
		float *	interp_table,
		int	N_hrtf_dirs,
		int	N_bands,
		int	N_interp_dirs,
		float_complex *	hrtf_interp )

Interpolates a set of HRTFs based on a specified interpolation table.

Note: For 'interp_table' you can use e.g. VBAPgainTable2InterpTable() to take a conventional energy-normalised VBAP gain table, and convert it to an amplitude-normalised interpolation table. Note: amplitude-normalised VBAP gains are the same as triangular interpolation weights.; If itds!=NULL && freqVector!=NULL, then the interpolation is performed by applying interpolation gains to the HRTF magnitudes and HRIR inter- aural time differences (ITDs) separately. The inter-aural phase differences (IPDs) are then reintroduced for each frequency band. If itds==NULL || freqVector==NULL then the interpolatation is applied directly on the complex spectra.

Warning: This function is NOT suitable for binaural room impulse responses (BRIRs)!

Parameters

[in]	hrtfs	HRTFs as filterbank coeffs; FLAT: N_bands x NUM_EARS x N_hrtf_dirs
[in]	itds	The inter-aural time difference (ITD) for each HRIR (set to NULL if you do not want phase simplication to be applied); N_hrtf_dirs x 1
[in]	freqVector	Frequency vector (set to NULL if you do not want phase simplication to be applied); N_bands x 1
[in]	interp_table	Amplitude-Normalised VBAP gain table; FLAT: N_interp_dirs x N_hrtf_dirs
[in]	N_hrtf_dirs	Number of HRTF directions
[in]	N_bands	Number of frequency bands
[in]	N_interp_dirs	Number of interpolated hrtf positions
[out]	hrtf_interp	interpolated HRTFs; FLAT: N_bands x NUM_EARS x N_interp_dirs

Definition at line 241 of file saf_hrir.c.

◆ resampleHRIRs()

void resampleHRIRs	(	float *	hrirs_in,
		int	hrirs_N_dirs,
		int	hrirs_in_len,
		int	hrirs_in_fs,
		int	hrirs_out_fs,
		int	padToNextPow2,
		float **	hrirs_out,
		int *	hrirs_out_len )

Resamples a set of HRIRs from its original samplerate to a new samplerate.

Note: The included speex_resampler.h is used by default. If SAF_USE_INTEL_IPP is defined, then the IPP resampler is employed instead.

Parameters

[in]	hrirs_in	Input HRIRs; FLAT: hrirs_N_dirs x NUM_EARS x hrirs_in_len
[in]	hrirs_N_dirs	Number of HRIRs
[in]	hrirs_in_len	Length of input HRIRs, in samples
[in]	hrirs_in_fs	Original sampling rate, in Hz
[in]	hrirs_out_fs	New sampling rate, in Hz
[in]	padToNextPow2	1: length of output HRIRs padded to next 2^x, 0: no
[out]	hrirs_out	Resampled HRIRs; FLAT: hrirs_N_dirs x NUM_EARS x hrirs_out_len
[out]	hrirs_out_len	(&) New HRIR length

Definition at line 365 of file saf_hrir.c.

Variable Documentation

◆ __default_hrir_dirs_deg

const float __default_hrir_dirs_deg[836][2]

extern

The measurement directions used for the default HRIR dataset.

Definition at line 871 of file saf_default_hrirs.c.

◆ __default_hrir_fs

const int __default_hrir_fs

extern

The samplerate used to measure the default HRIR filters

Definition at line 1714 of file saf_default_hrirs.c.

◆ __default_hrir_len

const int __default_hrir_len

extern

The length of the filters, in samples, for the default HRIR dataset.

Definition at line 1712 of file saf_default_hrirs.c.

◆ __default_hrirs

const float __default_hrirs[836][2][256]

extern

The default HRIR data for SAF.

Definition at line 32 of file saf_default_hrirs.c.

◆ __default_N_hrir_dirs

const int __default_N_hrir_dirs

extern

The number of directions/measurements in the default HRIR dataset.

Definition at line 1710 of file saf_default_hrirs.c.

Files

Functions

Variables

Detailed Description

Function Documentation

◆ binauralDiffuseCoherence()

◆ diffuseFieldEqualiseHRTFs()

◆ estimateITDs()

◆ HRIRs2HRTFs()

◆ HRIRs2HRTFs_afSTFT()

◆ HRIRs2HRTFs_qmf()

◆ interpHRTFs()

◆ resampleHRIRs()

Variable Documentation

◆ __default_hrir_dirs_deg

◆ __default_hrir_fs

◆ __default_hrir_len

◆ __default_hrirs

◆ __default_N_hrir_dirs