SofaCollider

A SOFA interface for the SuperCollider language.

What is SOFA

SOFA is a data format for binaural audio and head-related transfer functions.

Binaural audio

If you're not familiar with these concepts, UC Davis's CIPIC lab website has a good introduction to the topic.

SOFA Format

The SOFA format is a type of data file that stores impulse response information, as well as spatial data of sound sources as well as the listener. The purpose of the SOFA format is to standardize how this data is stored so that binaural data can more easily be used.

SofaCollider

Many interfaces for SOFA already exist for languages such as matlab and C++, but none yet exist for the SuperCollider language. SofaCollider is a Quark for SuperCollider that establishes an interface for working with SOFA data.

Usage

In order to use the SOFA interface, you'll first needs some HRTFs. The SofaCollider Quark aims to make this very easy by providing a simple interface to pre-existing databases of HRTFs.

~subjectID = 3;
CIPIC.downloadSubject(~subjectID); // Download the CIPIC subject_003 hrtf data

// create a new Simple Free-Field HRIR object from the downloaded data
~hrtfPath = CIPIC.subjectLocalPath(~subjectID);
~hrtf = SimpleFreeFieldHRIR.newFromFile(~hrtfPath);

Once you've created an hrtf object, you can query various metadata about the object. For example:

postf("hrtf.sofaConvention: %\n", ~hrtf.sofaConvention);
postf("hrtf.listenerPosition.at(0): %\n", ~hrtf.listenerPosition.at(0));

Installing

If you're familiar with installing quarks, this should be relatively straightforward. If you have all the prerequisities isntalled, just run the following function on your SuperCollider IDE:

Quarks.install('https://github.com/josiest/SofaCollider')

If you've never installed a quark before, you'll likely need to install git. You may also find it helpful to review the SuperCollider instruction pages on installing quarks.

Requirements

In order to install and use the SofaCollider Quark, you of course need to have SuperCollider installed, but you'll also need matlab or octave installed, as well as the SOFA matlab/octave package, and any dependencies it may need. A full list of dependencies below

• SuperCollider: Please refer to the SuperCollider website for installation instructions.

• Octave: Please refer to the octave website for installation instructions.

  Specifying a custom command path (NOT RECOMMENDED):

  If you don't have octave installed in the normal place it would be installed, you'll likely need to specify a custom commmand to run when using octave. For example, if your octave command is in ~/Downloads/octave you can write

  ~octaveCmd = "~/Downloads/octave".standardizePath;
  SofaColliderConfig.octaveCmd_(~octaveCmd);
  

  NOTE: This must be done after the SofaCollider quark has been installed.

• Octave NetCDF package: Once you have octave installed, you can use octave's package manager to install the NetCDF package.

  Within octave run the following command:

  pkg install -forge netcdf
  

  You will likely also need to install netcdf for your system in order for this package to work properly. On debian-based linux systems you can acheive this with the command sudo apt install libnetcdf-dev.

• SOFA Matlab/Octave API: This package is not officially registered with Octave's package manager so you'll need to manually download the package source code into a specific place so that the SofaCollider Quark can see where it is. There are two ways to do this:

  Option 1: Tell SofaCollider where to find the API

  While it may be cleaner to install the API in a way that matches how official packages are installed, this has some amount of a learning curve - and there might be other reasons you might want it installed in a specific place. In order to accomodate for either of these things, SofaCollider provides an interface to specify where the SOFA Matlab/Octave API repository exists.

  For example, if the API is in ~/Downloads/API_MO you could write

  ~path = "~/Downloads/API_MO".standardizePath;
  SofaColliderConfig.sofaOctaveRepo_(~path);
  

  NOTE: you must have SofaCollider installed first for this method to work. This is possible because the the SOFA M/O API requirement is only a requirement for using the SOFA interface - this method doesn't use that functionality of the quark.

  Option 2: Install API to default directory

  Navigate to your user application support directory - you can find this from SuperCollider from the output of

  Platform.userAppSupportDir

  This will give the SuperCollider support directory, so you'll want to navigate to the parent directory. On unix systems it might look something like ~/.local/share

  If it doesn't already exist, make the directory system octave/packages and navigate inside it and run the following command

  git clone https://github.com/sofacoustics/API_MO.git sofa