What is OpenDAFF?
OpenDAFF has been invented under the circumstances that auralization and spatial audio reproduction requires data that provide sets of impulse responses, complex or absolute spectra and band filters for a certain directions that can be queried rapidly. This includes directivity pattern of sound sources like loudspeakers, musical instruments and other objects that generate sound, but also the directivity of a sound receiver such as a human listener or a microphone with a certain characteristic.
Why OpenDAFF?
If you are looking for a multi-channel directional data format that you can query using a pair of angles, OpenDAFF can be a good choice. However, it has been initially invented to provide extremely lightweight access to the content and therefor the file format currently only supports data sets that are connected to a regular spherical grid with equiangular positions on a unit sphere (like the global coordinate system with latitudes, longitudes, north pole & south pole, also referred to as Gauss grid). This design decision allows for a nearest neighbour search on a sphere using only rounding operations enabling extensive use of the OpenDAFF API, for instance, in room acoustic simulation and real-time auralization for Virtual Reality applications where Binaural Technology plays a key role. If you only have sparse data or a functional representation such as Spherical Harmonics, an interpolation or re-sampling to a regular spherical grid is required.
Altvernatives to OpenDAFF
As already mentioned, OpenDAFF is not restricted to auralization and spatial audio, but has been implemented for these purposes and therefor might not meet your expectation. If you are looking for other (and probably more general) representations of spatial or directional content, you may want to consider alternatives like the SOFA convention.
Who is behind OpenDAFF?
OpenDAFF has been initiated by the Virtual Acoustics workgroup at the Institute of Technical Acoustics, RWTH Aachen University. As to that time there was a need to create a proper exchange format that can live up to state-of-the-art requirements in software development - in combination with an easy exchange of input data (i.e. to get rid of other people's ZIP archives with WAV files containing impulse response measurements). For this purpose and in an attempt to define a common ground for describing and exchanging directional audio input data even outside of the institute, OpenDAFF has been brought into existence.
