maxaccum — Accumulates the maximum value of audio signals.
maxaccum compares two audio-rate variables and stores the maximum value between them into the first.
aAccumulator -- audio variable to store the maximum value
aInput -- signal that aAccumulator is compared to
The maxaccum opcode is designed to accumulate the maximum value from among many audio signals that may be in different note instances, different channels, or otherwise cannot all be compared at once using the max opcode. Its semantics are similar to vincr since aAccumulator is used as both an input and an output variable, except that maxaccum keeps the maximum value instead of adding the signals together. maxaccum performs the following operation on each pair of samples:
if (aInput > aAccumulator) aAccumulator = aInput
aAccumulator will usually be a global audio variable. At the end of any given computation cycle (k-period), after its value is read and used in some way, the accumulator variable should usually be reset to zero (perhaps by using the clear opcode). Care must be taken however if aInput is negative at any point, in which case the accumulator should be initialized and reset to some large enough negative value that will always be less than the input signals to which it is compared.
Here is an example of the maxaccum opcode. It uses the file maxaccum.csd.
Example 579. Example of the maxabs 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 ;;;realtime audio out ;-iadc ;;;uncomment -iadc if realtime audio input is needed too ; For Non-realtime ouput leave only the line below: ; -o maxaccum.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> sr = 44100 ksmps = 32 nchnls = 2 0dbfs = 1 instr 1 ;saw asig vco2 .2, p4 outs asig, asig gasaw = asig endin instr 2 ;sine aout poscil .3, p4, 1 outs aout, aout gasin = aout endin instr 10 accum init 0 maxaccum accum, gasaw + gasin ;saw and sine accumulated outs accum, accum clear accum endin </CsInstruments> <CsScore> f 1 0 4096 10 1 i 1 0 7 330 i 2 3 3 440 i 1 10 7 330 ;same notes but without maxaccum, for comparison i 2 13 3 440 i 10 0 6 ;accumulation note stops after 6 seconds e </CsScore> </CsoundSynthesizer>