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bformdec

Decodes an ambisonic B format signal into loudspeaker specific signals.

Note that this opcode is deprecated as it is inaccurate, and is replaced by the much better opcode bformdec1 which replicates all the important features.

Syntax

ao1, ao2 bformdec isetup, aw, ax, ay, az [, ar, as, at, au, av \
                  [, abk, al, am, an, ao, ap, aq]]
ao1, ao2, ao3, ao4 bformdec isetup, aw, ax, ay, az [, ar, as, at, \
                            au, av [, abk, al, am, an, ao, ap, aq]]
ao1, ao2, ao3, ao4, ao5 bformdec isetup, aw, ax, ay, az [, ar, as, \
                                 at, au, av [, abk, al, am, an, ao, ap, aq]]
ao1, ao2, ao3, ao4, ao5, ao6, ao7, ao8 bformdec isetup, aw, ax, ay, az \
                                                [, ar, as, at, au, av  \
                                                [, abk, al, am, an, ao, ap, aq]]

Initialization

isetup -- loudspeaker setup. There are five supported setups:

1 denotes stereo setup. There must be two output cells with loudspeaker positions assumed to be (330/0, 30/0).

2 denotes quad setup. There must be four output cells. Loudspeaker positions assumed to be (45°/0), (135°/0), (225/0), (315/0).

3 is a 5.1 surround setup. There must be five output cells. LFE channel is not supported. Loudspeaker positions assumed to be (330/0), (30/0), (0/0), (250/0), (110/0).

4 denotes eight loudspeaker circle setup. There must be eight output cells. Loudspeaker positions assumed to be (22.5/0), (67.5/0), (112.5/0), (157.5/0), (202.5/0), (247.5/0), (292.5/0), (337.5/0).

5 means an eight loudspeaker cubic setup. There must be eight output cells. Loudspeaker positions assumed to be (45/0), (45/30), (135/0), (135/30), (225/0), (225/30), (315/0), (315/30).

Performance

aw, ax, ay, ... -- input signal in the B format.

ao1 .. ao8 -- loudspeaker specific output signals.

Example

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

Example of the bformdec opcode.
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<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in    No messages
;-odac           -iadc     -d     ;;;RT audio I/O
; For Non-realtime ouput leave only the line below:
 -o bformenc.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>
sr = 44100
kr = 4410
ksmps = 10
nchnls = 8

;bformenc is deprecated, please use bformenc1

instr 1
  ; generate pink noise
  anoise pinkish 1000

  ; two full turns
  kalpha line 0, p3, 720
  kbeta = 0

  ; fade ambisonic order from 2nd to 0th during second turn
  kord0 = 1
  kord1 linseg 1, p3 / 2, 1, p3 / 2, 0
  kord2 linseg 1, p3 / 2, 1, p3 / 2, 0

  ; generate B format
  aw, ax, ay, az, ar, as, at, au, av bformenc anoise, kalpha, kbeta, kord0, kord1, kord2

  ; decode B format for 8 channel circle loudspeaker setup
  a1, a2, a3, a4, a5, a6, a7, a8 bformdec 4, aw, ax, ay, az, ar, as, at, au, av

  ; write audio out
  outo a1, a2, a3, a4, a5, a6, a7, a8

</CsInstruments>
<CsScore>

; Play Instrument #1 for 20 seconds.
i 1 0 20
e


</CsScore>
</CsoundSynthesizer>

Credits

Author: Samuel Groner
2005

New in version 5.07. Deprecated in 5.09