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Applying digital signal processing at a higher sampling rate
============================================================================================================================================
**07-upsamp-processing.py**
This script demonstrates how to use pyo to apply processing on a sound
at a very high sampling rate.
Pyo offers two functions to upsample and downsample an audio file::
upsamp(path, outfile, up, order)
downsamp(path, outfile, down, order)
Where:
- `path` is the path to the file to process.
- `outfile` is the path where to save the resampled file.
- `up`, `down` is the resampling factor (new sampling rate will be
this value times the current sampling rate).
- `order` is the length, in samples, of the anti-aliasing lowpass filter.
.. code-block:: python
import os
from pyo import *
# Upsampling factor.
SR_FACTOR = 8
# Size, in samples, of the anti-aliasing lowpass filters.
SIZE = 512
# Sound to process.
IN_SND = "../snds/baseballmajeur_m.aif"
# Temporary audio files.
UP_SND = os.path.join(os.path.expanduser("~"), "Desktop", "temp_sound_up_%i.aif" % SR_FACTOR)
PROC_SND = os.path.join(os.path.expanduser("~"), "Desktop", "temp_sound_disto.aif")
# Output sound file.
DOWN_SND = os.path.join(os.path.expanduser("~"), "Desktop", "output_disto_down.aif")
# Retrieve info about the source file.
DUR = sndinfo(IN_SND)[1]
SR = sndinfo(IN_SND)[2]
print("Up sampling the source file %i times..." % SR_FACTOR)
upsamp(IN_SND, UP_SND, SR_FACTOR, SIZE)
print("Apply distortion at a sampling rate of %i Hz." % (SR * SR_FACTOR))
# Initialize the Server in offline mode, at the desired sampling rate.
s = Server(sr=SR * SR_FACTOR, nchnls=1, duplex=0, audio="offline").boot()
# Set the recording parameters.
s.recordOptions(dur=DUR + 0.1, filename=PROC_SND, fileformat=0, sampletype=0)
# Read the upsampled version of the source file.
sf = SfPlayer(UP_SND, loop=False, interp=4, mul=0.7)
# Apply distortion on it.
dist = Disto(sf, drive=0.75, slope=0.7, mul=0.3)
# Lowpass filtering.
filt = Biquad(dist, freq=8000, q=0.7, type=0).out()
# Start the offline processing.
s.start()
print("Down sampling the processed sound %i times..." % SR_FACTOR)
downsamp(PROC_SND, DOWN_SND, SR_FACTOR, SIZE)
# Cleanup the temporary files.
os.remove(UP_SND)
os.remove(PROC_SND)
print("Done")
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