XSRP: eXtensible Steered Response Power

This repository contains the code for the paper:

Steered Response Power for Sound Source Localization: A Tutorial Review

GUI Application

The repository includes a real-time GUI application for interactive sound source localization. The GUI provides:

• Real-time polar visualization: Live polar plots showing SRP maps and detected source directions
• Interactive controls: Adjustable parameters including smoothing speed, averaging samples, angular resolution, and SRP map sharpening
• Bandpass filtering: Configurable high-pass and low-pass filters for preprocessing
• SRP mode selection: Choose between time-domain and frequency-domain SRP-PHAT processing
• Frequency weighting: Optional frequency-domain weighting methods (coherence, sparsity, PAR) for improved source detection
• Noise floor calibration: Record and subtract ambient noise for improved source detection
• Microphone configuration: Load microphone array configurations from YAML files
• Exponential smoothing tracker: Temporal smoothing of DOA estimates to reduce jitter

To run the GUI:

# If installed via pip with GUI extras:
xsrp-gui

# Or during development:
uv run python -m xsrp.gui

The following functionality is currently implemented:

Core SRP Algorithms

• Conventional SRP-PHAT in the time domain: Taking the DFT, applying the phase transform, followed by the IDFT as described by Dibiase et al. [1]
• Conventional SRP-PHAT in the frequency domain: Same as above without the IDFT step, enabling per-frequency processing
• SRP with temporal cross-correlation: Time-domain SRP using cross-correlation without phase transform
• Multi-source SRP: Extension for localizing multiple simultaneous sound sources

Signal Processing Features

• Parabolic interpolation: Fractional sample interpolation of the cross-correlation function for improved time resolution
• Volumetric SRP: Projects the average of N-closest correlation values instead of only the one associated with the microphone pair's Time Difference of Arrival (TDOA), improving robustness
• SRP map sharpening: Exponentiation of SRP maps to enhance peaks and suppress sidelobes
• Bandpass filtering: Preprocessing with configurable high-pass and low-pass filters

Frequency-Domain Weighting Methods

Frequency-domain weighting methods for narrowband SRP maps (available in frequency-domain mode):

• Coherence-based weighting: Weights frequencies by spatial coherence across microphone pairs (high coherence indicates real sources, low coherence indicates noise/sidelobes)
• Sparsity-based weighting: Weights frequencies by the sparsity (Gini coefficient) of their SRP maps (sparse/peaked maps indicate real sources, diffuse maps indicate sidelobes)
• Peak-to-Average Ratio (PAR): Weights frequencies by the ratio of peak to average SRP values (high PAR indicates dominant peaks)

Real-Time Processing

• Streaming SRP: Frame-based processing for real-time audio streams
• Exponential smoothing tracker: Temporal smoothing of SRP maps and DOA estimates to reduce jitter
• Noise floor calibration: Automatic calibration and subtraction of noise floor SRP maps for improved source detection

Grid and Visualization

• Grid creation functions: Support for Positional Source Localization (2D/3D Cartesian grids) and Direction of Arrival (DOA) Estimation (1D azimuth, 2D azimuth-elevation)
• Visualization tools: Polar plots, cross-correlation visualizations, and SRP map comparisons

Installation

From PyPI

Install the core package:

pip install xsrp

Install with GUI support (includes PyQt5, matplotlib, pyaudio, etc.):

pip install xsrp[gui]

After installing with GUI support, you can run the GUI application:

xsrp-gui

Development Installation

We recommend using uv for dependency management. Change directory to the xsrp folder and run the following commands:

1. Install uv (if not already installed): curl -LsSf https://astral.sh/uv/install.sh | sh
2. Install dependencies: uv sync
3. Activate the virtual environment: source .venv/bin/activate (or use uv run to run commands in the environment)

You can then optionally run the tests to verify that everything is working correctly:

4. uv run pytest tests (or make test)

You may want to check the images that were generated in the tests/temp folder.

To run the GUI during development:

uv run python -m xsrp.gui