dconv — A direct convolution opcode.
isize -- the size of the convolution buffer to use. if the buffer size is smaller than the size of ifn, then only the first isize values will be used from the table.
ifn -- table number of a stored function containing the impulse response for convolution.
Rather than the analysis/resynthesis method of the convolve opcode, dconv uses direct convolution to create the result. For small tables it can do this quite efficiently, however larger table require much more time to run. dconv does (isize * ksmps) multiplies on every k-cycle. Therefore, reverb and delay effects are best done with other opcodes (unless the times are short).
dconv was designed to be used with time varying tables to facilitate new realtime filtering capabilities.
Here is an example of the dconv opcode. It uses the file dconv.csd.
Example 103. Example of the dconv 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 ; Audio out Audio in No messages -odac -iadc -d ;;;RT audio I/O ; For Non-realtime ouput leave only the line below: ; -o dconv.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> sr = 44100 kr = 4410 ksmps = 10 nchnls = 1 #define RANDI(A) #kout randi 1, kfq, $A*.001+iseed, 1 tablew kout, $A, itable# instr 1 itable init 1 iseed init .6 isize init ftlen(itable) kfq line 1, p3, 10 $RANDI(0) $RANDI(1) $RANDI(2) $RANDI(3) $RANDI(4) $RANDI(5) $RANDI(6) $RANDI(7) $RANDI(8) $RANDI(9) $RANDI(10) $RANDI(11) $RANDI(12) $RANDI(13) $RANDI(14) $RANDI(15) asig rand 10000, .5, 1 asig butlp asig, 5000 asig dconv asig, isize, itable out asig *.5 endin </CsInstruments> <CsScore> f1 0 16 10 1 i1 0 10 e </CsScore> </CsoundSynthesizer>