Pyroomacoustics is a software package aimed at the rapid development and testing of audio array processing algorithms. The content of the package can be divided into three main components:
- Intuitive Python object-oriented interface to quickly construct different simulation scenarios involving multiple sound sources and microphones in 2D and 3D rooms;
- Fast C++ implementation of the image source model and ray tracing for general polyhedral rooms to efficiently generate room impulse responses and simulate the propagation between sources and receivers;
- Reference implementations of popular algorithms for STFT, beamforming, direction finding, adaptive filtering, source separation, and single channel denoising.
Together, these components form a package with the potential to speed up the time to market of new algorithms by significantly reducing the implementation overhead in the performance evaluation step. Please refer to this notebook for a demonstration of the different components of this package.
Consider the following scenario.
Suppose, for example, you wanted to produce a radio crime drama, and it so happens that, according to the scriptwriter, the story line absolutely must culminate in a satanic mass that quickly degenerates into a violent shootout, all taking place right around the altar of the highly reverberant acoustic environment of Oxford's Christ Church cathedral. To ensure that it sounds authentic, you asked the Dean of Christ Church for permission to record the final scene inside the cathedral, but somehow he fails to be convinced of the artistic merit of your production, and declines to give you permission. But recorded in a conventional studio, the scene sounds flat. So what do you do?
—Schnupp, Nelken, and King, Auditory Neuroscience, 2010
Faced with this difficult situation, pyroomacoustics can save the day by simulating the environment of the Christ Church cathedral!
At the core of the package is a room impulse response (RIR) generator based on the image source model that can handle
- Convex and non-convex rooms
- 2D/3D rooms
The core image source model and ray tracing modules are written in C++ for better performance.
The philosophy of the package is to abstract all necessary elements of an experiment using an object-oriented programming approach. Each of these elements is represented using a class and an experiment can be designed by combining these elements just as one would do in a real experiment.
Let's imagine we want to simulate a delay-and-sum beamformer that uses a linear array with four microphones in a shoe box shaped room that contains only one source of sound. First, we create a room object, to which we add a microphone array object, and a sound source object. Then, the room object has methods to compute the RIR between source and receiver. The beamformer object then extends the microphone array class and has different methods to compute the weights, for example delay-and-sum weights. See the example below to get an idea of what the code looks like.
The Room class also allows one to process sound samples emitted by sources, effectively simulating the propagation of sound between sources and microphones. At the input of the microphones composing the beamformer, an STFT (short time Fourier transform) engine allows to quickly process the signals through the beamformer and evaluate the output.