sofalizer
SOFAlizer uses head-related transfer functions (HRTFs) to create virtual loudspeakers around the user for binaural listening via headphones (audio formats up to 9 channels supported). The HRTFs are stored in SOFA files (see http://www.sofacoustics.org/ for a database). SOFAlizer is developed at the Acoustics Research Institute (ARI) of the Austrian Academy of Sciences.
To enable compilation of this filter you need to configure FFmpeg with
--enable-libmysofa
.
The filter accepts the following options:
- sofa
Set the SOFA file used for rendering.
- gain
Set gain applied to audio. Value is in dB. Default is 0.
- rotation
Set rotation of virtual loudspeakers in deg. Default is 0.
- elevation
Set elevation of virtual speakers in deg. Default is 0.
- radius
Set distance in meters between loudspeakers and the listener with near-field HRTFs. Default is 1.
- type
Set processing type. Can be time or freq. time is processing audio in time domain which is slow. freq is processing audio in frequency domain which is fast. Default is freq.
- speakers
Set custom positions of virtual loudspeakers. Syntax for this option is: <CH> <AZIM> <ELEV>[|<CH> <AZIM> <ELEV>|...]. Each virtual loudspeaker is described with short channel name following with azimuth and elevation in degrees. Each virtual loudspeaker description is separated by ’|’. For example to override front left and front right channel positions use: ’speakers=FL 45 15|FR 345 15’. Descriptions with unrecognised channel names are ignored.
- lfegain
Set custom gain for LFE channels. Value is in dB. Default is 0.
- framesize
Set custom frame size in number of samples. Default is 1024. Allowed range is from 1024 to 96000. Only used if option ‘type’ is set to freq.
- normalize
Should all IRs be normalized upon importing SOFA file. By default is enabled.
- interpolate
Should nearest IRs be interpolated with neighbor IRs if exact position does not match. By default is disabled.
- minphase
Minphase all IRs upon loading of SOFA file. By default is disabled.
- anglestep
Set neighbor search angle step. Only used if option interpolate is enabled.
- radstep
Set neighbor search radius step. Only used if option interpolate is enabled.
Examples
- Using ClubFritz6 sofa file:
sofalizer=sofa=/path/to/ClubFritz6.sofa:type=freq:radius=1
- Using ClubFritz12 sofa file and bigger radius with small rotation:
sofalizer=sofa=/path/to/ClubFritz12.sofa:type=freq:radius=2:rotation=5
- Similar as above but with custom speaker positions for front left, front right, back left and back right
and also with custom gain:
"sofalizer=sofa=/path/to/ClubFritz6.sofa:type=freq:radius=2:speakers=FL 45|FR 315|BL 135|BR 225:gain=28"