Performing orchestras, scores, and input files (.csd files)

There are different ways to perform input files. Let's start a Csound instance:



In [1]:

    
import ctcsound
cs = ctcsound.Csound()

Doing it the classical way, we compile an orchestra and a score file, passing also some flags. Note that the first argument, indicating the program name, is mandatory. This is due to the C origin of Csound. You can give as first argument to cs.compile_ any string such as "dummy" or "myProgram", etc. The usage, calling C programs, is to pass the program name.

If the compilation is successful, the Csound instance is ready to run a performance. Then orchestra and score are performed and the Csound instance is reset, to be ready for another performance:



In [2]:

    
ret = cs.compile_("csound", "-o", "dac", "examples/02-a.orc", "examples/02-a.sco")
if ret == ctcsound.CSOUND_SUCCESS:
    cs.perform()
    cs.reset()

We can do the same with a single input file (.csd file):



In [3]:

    
ret = cs.compile_("csound", "examples/02-a.csd")
if ret == ctcsound.CSOUND_SUCCESS:
    cs.perform()
    cs.reset()

Csound offers also the possibility to compile directly a csd file. As this can be done during a performance to replace or add new instruments and events (more on this later), cs.start() has to be called here, because Csound is not actually running a performance (due to the preceding cs.reset():



In [4]:

    
ret = cs.compileCsd("examples/02-a.csd")
if ret == ctcsound.CSOUND_SUCCESS:
    cs.start()
    cs.perform()
    cs.reset()

Finally, instead of compiling a csd from an input file, we can do it from a string:



In [5]:

    
csd = '''
<CsoundSynthesizer>

<CsOptions>
  -d -o dac -m0
</CsOptions>

<CsInstruments>
sr     = 48000
ksmps  = 100
nchnls = 2
0dbfs  = 1

          instr 1
idur      =         p3
iamp      =         p4
icps      =         cpspch(p5)
irise     =         p6
idec      =         p7
ipan      =         p8

kenv      linen     iamp, irise, idur, idec
kenv      =         kenv*kenv
asig      poscil    kenv, icps
a1, a2    pan2      asig, ipan
          outs      a1, a2
          endin
</CsInstruments>

<CsScore>
i 1 0 1 0.5 8.06 0.05 0.3 0.5
e 1.5
</CsScore>
</CsoundSynthesizer>
'''
ret = cs.compileCsdText(csd)
if ret == ctcsound.CSOUND_SUCCESS:
    cs.start()
    cs.perform()
    cs.reset()

Instead of performing an entire score with a single cs.perform() command, it is possible to run a loop, performing a buffer (ksmps samples long with cs.performKsmps(), or -b frames long with cs.performBuffer()) during each pass. Note that cs.performKsmps() and cs.performBuffer() return False while the score is not finished. Here, a dot is displayed for each pass in the loop:



In [6]:

    
ret = cs.compile_("csound", "examples/02-a.csd")
if ret == ctcsound.CSOUND_SUCCESS:
    while not cs.performKsmps():
        print('.', end='')
    print()
    cs.reset()









    



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In [7]:

    
ret = cs.compile_("csound", "examples/02-a.csd")
if ret == ctcsound.CSOUND_SUCCESS:
    while not cs.performBuffer():
        print('.', end='')
    print()
    cs.reset()









    



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