Audio Processing Kit (apkit)

This is a python library for audio processing. It includes the following functions:

• Basic I/O
• Basic Operations
• Cross-correlation and TDOA estimation
• Spatial spectral-based sound source localization
• Beamforming

Dependency

• Numpy
• Scipy

Conventions

• Arrays are numpy arrays.
• Multi-dimension array indices follow such order (if exist): channel, time, frequency.

Install

pip install -e .

Documentation

The functions of this library are listed (not exhaustively) in the following tables, separated by their categories. For the usage of the functions, please read the doc in the code or use help(apkit.FUNCTION) in python.

Basic I/O

Functions	Description
load_wav	Load wav file
load_metadata	Load metadata of a wav file without reading its data
save_wav	Store audio to a wav file

Basic Operations

Functions	Description
stft	Short time Fourier Transform
istft	Inverse short time Fourier Transform
cola_hamming	Constant-Overlap-Add hamming window
cola_rectangle	Constant-Overlap-Add rectangle window
freq_upsample	Upsampling in frequency domain by padding
power	Compute power of time domain signal
power_tf	Compute power of TF domain signal
snr	Compute signal-to-noise ratio
steering_vector	Compute steering vector from delay
compute_delay	Compute delays to microphones given DOA
neighbor_list	List of neighbor DOAs
angular_distance	Angular distance
azimuth_distance	Azimuth distance
load_pts_horizontal	Load evenly distributed DOAs in the horizontal plane
load_pts_on_sphere	Load "almost" evenly distributed DOAs on the sphere

Covariance Matrix

Functions	Description
cov_matrix	Covariance matrix
empirical_cov_mat	Covariance matrix at different frames
empirical_cov_mat_by_block	Covariance matrix at different blocks of frames

Cross-correlation and TDOA

Functions	Description
gcc_phat	GCC-PHAT
cross_correlation	Cross-correlation

Beamforming

Functions	Description
apply_beamforming	Apply beamforming given weights
bf_delay_sum	Delay sum beamformer
bf_weight_delay_sum	Delay sum beamformer weights

Note There was a "static" version of MVDR beamformer, which is not "adaptive" as it is supposed to be.

Spatial Spectrum-based DOA estimation

Functions	Description
phi_srp_phat	SRP-PHAT
phi_srp_phat_nonlin	SPR-PHAT with non-linear correction
phi_mvdr_snr	MVDR for SSL with SNR scoring
sevd_music	MUSIC (vanilla, white noise)
MUSIC	MUSIC (known noise covariance)
GSVD_MUSIC	GSVD-MUSIC (singular value decomposition)
local_maxima	Find local maxima in spatial spectrogram
merge_lm_on_azimuth	Merge local maxima with same azimuth
vec2ae	Unit vector to azimuth-elevation conversion

Example: examples/angular_spec_doa.py

Contact

Weipeng He heweipeng@gmail.com