Description

Writes amplitude and/or frequency data to function tables.

Syntax

kflag pvsftw fsrc, ifna [, ifnf]

Initialization

ifna -- A table, at least inbins in size, that stores amplitude data. Ignored if ifna = 0

ifnf -- A table, at least inbins in size, that stores frequency data. Ignored if ifnf = 0

Performance

kflag -- A flag that has the value of 1 when new data is available, 0 otherwise.

fsrc -- a PVOC-EX formatted source.

Enables the contents of fsrc to be exchanged with function tables, for custom processing. Except when the frame overlap equals ksmps (which will generally not be the case), the frame data is not updated each control period. The data in ifna, ifnf should only be processed when kflag is set to 1. To process only frequency data, set ifna to zero.

As the functions tables are required only to store data from fsrc, there is no advantage in defining then in the score. They should generally be created in the instrument using ftgen.

By exporting amplitude data, say, from one fsig and importing it into another, basic cross-synthesis (as in pvscross) can be performed, with the option to modify the data beforehand using the table manipulation opodes.

Note that the format data in the source fsig is not written to the tables. This therefore offers a means of transferring amplitude and frequency data between non-identical fsigs. Used this way, these opcodes become potentially pathological, and can be relied upon to produce unexpected results. In such cases, resynthesis using pvsadsyn would almost certainly be required.

To perform a straight copy from one fsig to another one of identical format, the conventional assignment syntax can be used:

It is not necessary to use function tables in this case.

Examples

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

<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 pvsftw.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

; analyze sound file, creating a PVOC-EX file
ires1 system_i 1,{{ pvanal fox.wav fox.pvx }}          ; default settings

instr 1

inbins	=	512
ifn	ftgen	0,0,inbins,10,1		; make ftable
fsrc	pvsdiskin "fox.pvx", 1, 1	; read PVOCEX file
kflag	pvsftw	fsrc,ifn		; export amps to table,
kamp	init	0
if      kflag==0   kgoto contin		; only proc when frame is ready							
	tablew	kamp,1,ifn		; kill lowest bins, for obvious effect
	tablew	kamp,2,ifn
	tablew	kamp,3,ifn
	tablew	kamp,4,ifn
; read modified data back to fsrc
	pvsftr	fsrc,ifn
contin:
; and resynth
aout	pvsynth	fsrc
	outs	aout, aout

endin

</CsInstruments>
<CsScore>
i 1 0 5.5
e
</CsScore>
</CsoundSynthesizer>

See also

Tools for Real-time Spectral Processing (pvs opcodes)

Credits

New in version 4.13