vbap4

vbap4 — Distributes an audio signal among 4 channels.

Description

Distributes an audio signal among 4 channels.

Syntax

ar1, ar2, ar3, ar4 vbap4 asig, kazim [, kelev] [, kspread]

Performance

asig -- audio signal to be panned

kazim -- azimuth angle of the virtual source

kelev (optional) -- elevation angle of the virtual source

kspread (optional) -- spreading of the virtual source (range 0 - 100). If value is zero, conventional amplitude panning is used. When kspread is increased, the number of loudspeakers used in panning increases. If value is 100, the sound is applied to all loudspeakers.

vbap4 takes an input signal, asig and distributes it among 4 outputs, according to the controls kazim and kelev, and the configured loudspeaker placement. If idim = 2, kelev is set to zero. The distribution is performed using Vector Base Amplitude Panning (VBAP - See reference). VBAP distributes the signal using loudspeaker data configured with vbaplsinit. The signal is applied to, at most, two loudspeakers in 2-D loudspeaker configurations, and three loudspeakers in 3-D loudspeaker configurations. If the virtual source is panned outside the region spanned by loudspeakers, the nearest loudspeakers are used in panning.

[Warning] Warning

Please note that all vbap panning opcodes require the vbap system to be initialized using vbaplsinit.

Examples

See the entry for vbap8 for an example of usage of the vbap opcodes.

Reference

Ville Pulkki: Virtual Sound Source Positioning Using Vector Base Amplitude Panning Journal of the Audio Engineering Society, 1997 June, Vol. 45/6, p. 456.

Examples

Here is an example of the vbap4 opcode. It uses the file vbap4.csd.

Example 945. Example of the vbap4 opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac  ;;;realtime audio out
;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o vbap4.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 4	;quad
0dbfs  = 1

vbaplsinit 2, 4, 0, 90, 180, 270

instr 1

asig diskin2 "beats.wav", 1, 0, 1			;loop beats.wav
kaz  line 0, p3, p4					;come from right rear speaker &	
a1,a2,a3,a4 vbap4  asig, 180, 100, kaz			;change spread of soundsource
     printks "spread of source = %d\n", 1, kaz		;print spread value
     outq a1,a2,a3,a4

endin 
</CsInstruments>
<CsScore>

i 1 0 12 100

e
</CsScore>
</CsoundSynthesizer>


Its output should include lines like these:

spread of source = 0
spread of source = 8
spread of source = 17
spread of source = 25
spread of source = 33
spread of source = 42
spread of source = 50
spread of source = 58
spread of source = 67
spread of source = 75
spread of source = 83
spread of source = 92
spread of source = 100
      

See Also

vbap16, vbap16move, vbap4move, vbap8, vbap8move, vbaplsinit, vbapz, vbapzmove

Credits

Author: Ville Pulkki
Sibelius Academy Computer Music Studio
Laboratory of Acoustics and Audio Signal Processing
Helsinki University of Technology
Helsinki, Finland
May 2000

New in Csound Version 4.06. Input parameters accept k-rate since Csund 5.09.