-odac ; For file output, replace -odac with -o undef.wav -W. ; Adapted from the example by tgrey1 in csound/manual issue #207. ; https://github.com/csound/manual/issues/207 sr = 44100 ksmps = 10 nchnls = 2 0dbfs = 1 #define FREQ1 #440# #define FREQ2 #660# instr 1 ; Csound reads this before it reads instrument 2. ; It removes FREQ2 during preprocessing, before any notes play. ; Comment out this line to make instrument 2 use 660 Hz instead. #undef FREQ2 iFreq = $FREQ1 prints "Instrument %g uses %g Hz\n", p1, iFreq a1 vco2 0.25, iFreq out a1, a1 endin instr 2 ; FREQ2 is already undefined, so Csound keeps the #else branch. #ifdef FREQ2 iFreq = $FREQ2 #else iFreq = $FREQ1 #endif prints "Instrument %g uses %g Hz\n", p1, iFreq a1 vco2 0.25, iFreq out a1, a1 endin ; Instrument 2 plays first, but both notes use 440 Hz. ; Score order does not change the order of macro processing. i2 0 2 i1 2 2 e