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ILMLI2 012NON-COCHLEAR SOUND
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sumLo = 0.0; }
Each AudiomicroS class instance returns the generated
audio data to the variable sumLo. When there are
overlapping micro events inside a meso event, they will
be summed together as indicated within the expression;
sumLo = sumLo + AudiomicroS [ii]......;
When the inner loop closes, each micro space audio data
will be passed inside the update method of the
AudiomesoS class instance. The meso events generate
panning on their audio lines; hence the output of each
AudiomesoS class instance becomes a double sized array
called MesoSum[]. When there are overlapping meso
events, they will be summed to the array sum[] as
indicated within these lines;
sum[O] = sum[O] + MesoSum[O];
sum[1] = sum[1] + MesoSum[1];
Then the sumLo variable will be initialized with value 0
before the outer for loop closes. Now the generated
audio can be assigned to the *output variable, which
carries the data to the system audio driver.
Cosmosf fills 2 audio buffers, bufData and bufDataB
with this output and they can be used in order to be
reassigned as the input for the micro events. (Figure 5)
3.5. Generating audio events
Now we will have an inside look to the AudiomicroS
and the AudiomesoS Class. These objects not just
generate the audio but also the modulation sources for
the sonic attributes in audio rate inside this audio routine.
double CosmosCellM::update(double *Audio, double* poi,
float* CellFparam,int* Celllparam, float* Grnparam, float*
Filtparam, double* LFOvalues, double* bufData, double*
bufDataB)
- *Audio is a pointer to the audio assigned for the
current micro event input instance coming from
the direct feedback connection of the Cosmosf
output.
- Pointer to the phasor value giving the current
absolute time inside the Cosmosf cycle.
- Pointers to the parameter arrays imported from
the user interface via the main program.
- DSP section parameters.
- Pointer to the LFO values calculated in the main
program.
- Pointers to the recursive buffer content.
The next significant code in the CosmosCellM.update
method is the if-then conditional loop, which compares
the current phasor value with the onset time of the micro
event inside the cycle. When they match, then the micro
event DSP routine starts and generates the event audio
until the end of the relevant micro event.
if (ulong(point) >= posS && ulong(point) < posL+posS+1)
{ DSP code }
The posS variable here is the event start time and the
posL is the event duration with the variable type ulong.
There are various DSP routines and waveform
generating functions inside the DSP code. For example
to playback a loaded sample from the buffer with certain
speed and start offset, we use the ofxMaxiSample object
from the ofxMaxim addon with quadratic interpolation.
The code expression below is for the calculation of the
Sample Start point considering the values from
modulation sources like LineGen and LFO. Likewise if
Cosmosf is not in recursive buffer playing mode; the
beatx.play method, being a member of the
ofxMaxiSample class, plays the sample with the
Speedindex value from the sample buffer dataBufB.
smpstX = smpst*LineGenval[3]+LFOvalues[2];
d = beatx.playB4(Speedindex*sampleRate/sizeBN/(1 - smpstX),sizeBN*smpstX,sizeBN,dataBufB;}
The expression Speedindex*sampleRate/sizeBN/(1 -smpstX) calculates the revised playback rate value
according to the demanded start offset point considering
the sampleRate and the size of the sample as given with
the sizeBN variable. Hence according the code, the
playback rate decreases when the performed chunk size
of the sample data decreases too.
4. CONCLUSION
Despite the difficulty of expressing/explaining such
complex code structures, which is generally the case
with C++, we had a simple overlook to the significant
design features implemented in Cosmosf as a case study
of audio application development in Openframeworks.
More references of such these will encourage the
composers to develop their own tools in such platforms.
5. REFERENCES
[1] Bokesoy, S. "Feedback Implementation within
a Complex Event Generation System for
Synthesizing Sonic Structures", Proc. of
Digital Audio Effects (DAFX'06), Montreal,
Canada,pp. 199-203., 2006.
[2] Grierson M. "Maximillian: A Cross Platform
C++ Audio Synthesis Library for Artists
Learning to Program", Proc. of International
Computer Music Conference (ICMC'1O), New
York, USA, 2010.
[3] Lieberman Z., Watson T., Castro A. Online
Openframeworks Documentation Source.
http://www.openframeworks.cc/documentation,
2012.
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