hrtfer

  aleft, aright   hrtfer    asig, kaz, kelev, "HRTFcompact"

Description

Output is binaural (headphone) 3D audio.

Initialization

kAz - azimuth value in degrees. Positive values represent position on the right, negative values are positions on the left.

kElev - elevation value in degrees. Positive values represent position above horizontal, negative values are positions above horizontal.

At present, the only file which can be used with hrtfer is HRTFcompact. It must be passed to the opcode as the last argument within quotes as shown above.

HRTFcompact my be obtained via anonymous ftp from:

  ftp://ftp.maths.bath.ac.uk/pub/dream/utilities/Analysis/HRTFcompact

Performance

These unit generators place a mono input signal in a virtual 3D space around the listener by convolving the input with the appropriate HRTF data specified by the opcode's azimuth and elevation values. hrtfer allows these values to be k-values, allowing for dynamic spatialization. hrtfer can only place the input at the requested position because the HRTF is loaded in at i-time (remember that currently, CSound has a limit of 20 files it can hold in memory, otherwise it causes a segmentation fault). The output will need to be scaled either by using balance or by multiplying the output by some scaling constant.

Note - the sampling rate of the orchestra must be 44.1kHz. This is because 44.1kHz is the sampling rate at which the HRTFs were measured. In order to be used at a different rate, the HRTFs would need to be re-sampled at the desired rate.

Example

  kaz          linseg  0, p3, -360  ; move the sound in circle
  kel          linseg  -40, p3, 45  ; around the listener, changing
                                    ; elevation as its turning
  asrc         soundin "soundin.1"
  aleft,aright hrtfer  asrc, kaz, kel, "HRTFcompact"
  aleftscale   =       aleft * 200
  arightscale  =       aright * 200
               outs    aleftscale, arightscale

Authors

Eli Breder & David MacIntyre
Montreal
1996