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Manipulating audio signal in input
============================================================================================================================================
**02-audio-in.py**
The expression illustrated in this example use a phasor signal
in input as the running phase of a self-modulated sine wave.
Here is the complete expression:
.. code-block:: scheme
(sin (+ (* twopi $x[0]) (* $y[-1] 0.8)))
From inner to outer expression, we have:
.. code-block:: scheme
(* $y[-1] 0.8)
Where `$y[-1]` is the last output sample multiplied by a feedback
factor (0.8). Then we have the running phase, `$x[0]` is the current
input sample, rescaled to the range 0 -> 2pi for the `sin` function:
.. code-block:: scheme
(* twopi $x[0])
We add the output delay to the running phase:
.. code-block:: scheme
(+ (* twopi $x[0]) (* $y[-1] 0.8))
This gives the modulated running phase driving the `sin` function:
.. code-block:: scheme
(sin (+ (* twopi $x[0]) (* $y[-1] 0.8)))
Complete example
----------------
.. code-block:: python
from pyo import *
s = Server().boot()
expression = """
// Self-modulated sine wave with running phase given in input.
// Try different feedback factors between 0 and 1.
(sin (+ (* twopi $x[0]) (* $y[-1] 0.8)))
"""
# External signal used as the running phase.
input = Phasor(86)
input.ctrl()
# Create the Expr object and show its expression editor. To
# re-evaluate the expression hit Ctrl+Enter when the editor
# has the focus.
expr = Expr(input, expression, mul=0.5)
expr.editor()
# Shows the generated signal.
sc = Scope(expr)
# Converts the mono signal to stereo and sends it to the soundcard.
pan = Pan(expr).out()
s.gui(locals())
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