How to Load SOFA Files into FFmpeg
This guide provides a straightforward tutorial on how to load and use
Spatially Oriented Format for Acoustics (SOFA) files within FFmpeg. You
will learn the exact command-line syntax required to apply Head-Related
Transfer Function (HRTF) spatial audio to your multi-channel audio
tracks using the sofalizer and headphone
filters.
Prerequisites
To load SOFA files, your FFmpeg build must be compiled with the
libmysofa library. You can verify if your installation
supports it by running the following command in your terminal:
ffmpeg -filters | grep sofaIf you see sofalizer or references to
mysofa in the output, your FFmpeg build is ready.
Method 1: Using the Sofalizer Filter
The sofalizer filter is the most direct way to apply
spatial audio using a SOFA file. It takes a multi-channel audio input
and renders it as binaural 3D audio for headphones.
Use the following basic command structure:
ffmpeg -i input_surround.wav -af "sofalizer=sofa='/path/to/your/file.sofa'" output_binaural.wavKey Parameters for Sofalizer:
sofa: Specifies the absolute or relative path to your.sofafile.gain: Adjusts the gain in dB (default is 0). Useful if the spatialization process lowers the overall volume.type: Sets the processing type. You can choose betweentime(time domain, default) orfreq(frequency domain, which can be faster for long impulse responses).
Example with custom parameters:
ffmpeg -i input_51.wav -af "sofalizer=sofa='spatial_profile.sofa':gain=9:type=freq" output_spatial.wavMethod 2: Using the Headphone Filter
FFmpeg also features a headphone filter, which can map
specific input channels to virtual speaker positions defined by a SOFA
file.
The command below maps a 5.1 surround sound input to virtual positions using a SOFA file:
ffmpeg -i input_51.wav -af "headphone=map=FL|FR|FC|LFE|BL|BR:sofa='/path/to/your/file.sofa'" output_binaural.wavKey Parameters for Headphone:
map: Specifies the order of the input channels to be mapped (e.g., Front LeftFL, Front RightFR, etc.).sofa: Points to the path of your SOFA configuration file.type: Choose betweentimeorfreqprocessing domains.