June 22, 2013

Generating Audio Spectrograms in Python

A spectrogram is a visual representation of the spectrum of frequencies in a sound sample.

more info: wikipedia spectrogram

Spectrogram code in Python, using Matplotlib:
(source on GitHub)

"""Generate a Spectrogram image for a given WAV audio sample.

A spectrogram, or sonogram, is a visual representation of the spectrum
of frequencies in a sound.  Horizontal axis represents time, Vertical axis
represents frequency, and color represents amplitude.
"""


import os
import wave

import pylab


def graph_spectrogram(wav_file):
    sound_info, frame_rate = get_wav_info(wav_file)
    pylab.figure(num=None, figsize=(19, 12))
    pylab.subplot(111)
    pylab.title('spectrogram of %r' % wav_file)
    pylab.specgram(sound_info, Fs=frame_rate)
    pylab.savefig('spectrogram.png')


def get_wav_info(wav_file):
    wav = wave.open(wav_file, 'r')
    frames = wav.readframes(-1)
    sound_info = pylab.fromstring(frames, 'Int16')
    frame_rate = wav.getframerate()
    wav.close()
    return sound_info, frame_rate


if __name__ == '__main__':
    wav_file = 'sample.wav'
    graph_spectrogram(wav_file)

Spectrogram code in Python, using timeside:
(source on GitHub)

"""Generate a Spectrogram image for a given audio sample.

Compatible with several audio formats: wav, flac, mp3, etc.
Requires: https://code.google.com/p/timeside/

A spectrogram, or sonogram, is a visual representation of the spectrum
of frequencies in a sound.  Horizontal axis represents time, Vertical axis
represents frequency, and color represents amplitude.
"""


import timeside


audio_file = 'sample.wav'

decoder = timeside.decoder.FileDecoder(audio_file)
grapher = timeside.grapher.Spectrogram(width=1920, height=1080)
(decoder | grapher).run()
grapher.render('spectrogram.png')

happy audio hacking.

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