alpass — Reverberates an input signal with a flat frequency response.
ilpt -- loop time in seconds, which determines the “echo density” of the reverberation. This in turn characterizes the “color” of the filter whose frequency response curve will contain ilpt * sr/2 peaks spaced evenly between 0 and sr/2 (the Nyquist frequency). Loop time can be as large as available memory will permit. The space required for an n second loop is 4n*sr bytes. The delay space is allocated and returned as in delay.
iskip (optional, default=0) -- initial disposition of delay-loop data space (cf. reson). The default value is 0.
insmps (optional, default=0) -- delay amount, as a number of samples.
xrvt -- the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude).
This filter reiterates the input with an echo density determined by loop time ilpt. The attenuation rate is independent and is determined by xrvt, the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude). Output will begin to appear immediately.
Here is an example of the alpass opcode. It uses the file alpass.csd.
Example 48. Example of the alpass 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 ;;;RT audio out ;-iadc ;;;uncomment -iadc if RT audio input is needed too ; For Non-realtime ouput leave only the line below: ; -o alpass.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> sr = 44100 ksmps = 100 nchnls = 2 0dbfs = 1 gamix init 0 instr 1 acps expon p4, p3, p5 asig vco 0.6, acps, 1 outs asig, asig gamix = gamix + asig endin instr 99 arvt1 line 3.5*1.5, p3, 6 arvt2 line 3.5, p3, 4 ilpt = 0.1 aleft alpass gamix, arvt1, ilpt aright alpass gamix, arvt2, ilpt*2 outs aleft, aright gamix = 0 ; clear mixer endin </CsInstruments> <CsScore> f1 0 4096 10 1 i 1 0 3 20 2000 i 99 0 8 e </CsScore> </CsoundSynthesizer>