hrtfmove2 — Generates dynamic 3d binaural audio for headphones using a Woodworth based spherical head model with improved low frequency phase accuracy.

This opcode takes a source signal and spatialises it in the 3 dimensional space around a listener using head related transfer function (HRTF) based filters.

*ifilel* -- left HRTF spectral data file

*ifiler* -- right HRTF spectral data file

Note | |
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Spectral datafiles (based on the MIT HRTF database) are available in 3 different sampling rates: 44.1, 48 and 96 khz and are labelled accordingly. Input and processing |

*ioverlap* -- optional, number of overlaps for STFT processing (default 4). See STFT section of manual.

*iradius* -- optional, head radius used for phase spectra calculation in centimeters (default 9.0)

*isr* - optional, default 44.1kHz, legal values: 44100, 48000 and 96000.

*asrc* -- Input/source signal.

*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 below horizontal (min -40).

Artifact-free user-defined trajectories are made possible using an interpolation algorithm based on spectral
magnitude interpolation and a derived phase spectrum based on the Woodworth spherical head model.
Accuracy is increased for the data set provided by extracting and applying a frequency dependent scaling factor
to the phase spectra, leading to a more precise low frequency interaural time difference.
Users can control head radius for the phase derivation, allowing a crude level of individualisation.
The dynamic source version of the opcode uses a Short Time Fourier Transform algorithm to avoid artefacts
caused by derived phase spectra changes. STFT processing means this opcode is more computationally intensive
than *hrtfmove* using phase truncation, but phase is constantly updated by *hrtfmove2*.

Here is an example of the hrtfmove2 opcode. It uses the file *hrtfmove2.csd*.

**Example 320. Example of the htrfmove2 opcode.**

<CsoundSynthesizer> <CsOptions> ; Select flags here ; realtime audio out -o dac ; For Non-realtime ouput leave only the line below: ; -o hrtf.wav </CsOptions> <CsInstruments> sr = 44100 kr = 4410 ksmps = 10 nchnls = 2 gasrc init 0 instr 1 ;a plucked string kamp = p4 kcps = cpspch(p5) icps = cpspch(p5) a1 pluck kamp, kcps, icps, 0, 1 gasrc = a1 endin instr 10 ;uses output from instr1 as source kaz linseg 0, p3, 720 ;2 full rotations aleft,aright hrtfmove2 gasrc, kaz,0, "hrtf-44100-left.dat","hrtf-44100-right.dat" outs aleft, aright endin </CsInstruments> <CsScore> ; Play Instrument 1: a simple arpeggio i1 0 .2 15000 8.00 i1 + .2 15000 8.04 i1 + .2 15000 8.07 i1 + .2 15000 8.11 i1 + .2 15000 9.02 i1 + 1.5 15000 8.11 i1 + 1.5 15000 8.07 i1 + 1.5 15000 8.04 i1 + 1.5 15000 8.00 i1 + 1.5 15000 7.09 i1 + 1.5 15000 8.00 ; Play Instrument 10 for 10 seconds. i10 0 10 </CsScore> </CsoundSynthesizer>

More information on this opcode: *http://www.csounds.com/journal/issue9/newHRTFOpcodes.html* , written by Brian Carty