plot_amp_phase_spec.py

#!/usr/bin/env python3

# MIT License

# Copyright (C) 2024 by Akira TAMAMORI

# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation files
# (the Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:

# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

import librosa
import matplotlib.pyplot as plt
import numpy as np
import soundfile as sf
from scipy import signal

WIN_LEN = 512
HOP_LEN = 128
N_FFT = WIN_LEN


def plot_stft_spec(stft_spec, fs, out_figfile):
    """Plot amplitude & phase spectrum."""
    fig, ax = plt.subplots(2, 1, figsize=(12, 8), sharex=True)
    img1 = librosa.display.specshow(
        librosa.amplitude_to_db(np.abs(stft_spec), ref=np.max),
        sr=fs,
        hop_length=HOP_LEN,
        n_fft=N_FFT,
        win_length=WIN_LEN,
        y_axis="mel",
        x_axis="time",
        cmap="jet",
        ax=ax[0],
        fmax=8192,
    )
    ax[0].set_xlabel("")
    ax[0].set_ylabel("Frequency [Hz]")
    cbar = fig.colorbar(
        img1,
        ax=ax[0],
        format="%+2.f",
        pad=0.02,
        fraction=0.02,
    )
    cbar.set_label("Amplitude [dB]", rotation=270, labelpad=15)

    pos2 = librosa.display.specshow(
        np.angle(stft_spec),
        sr=fs,
        hop_length=HOP_LEN,
        n_fft=N_FFT,
        win_length=WIN_LEN,
        y_axis="mel",
        x_axis="time",
        cmap="hsv",
        ax=ax[1],
        fmax=8192,
    )
    ax[1].set_xlabel("Time (s)")
    ax[1].set_ylabel("Frequency [Hz]")
    cbar = fig.colorbar(
        pos2, ax=ax[1], ticks=[-np.pi + 0.0001, 0, np.pi], pad=0.02, fraction=0.02
    )
    cbar.ax.set_yticklabels(["-$\pi$", "0", "$\pi$"])
    cbar.set_label("Phase [rad]", rotation=270, labelpad=15)
    plt.tight_layout()
    plt.savefig(out_figfile)
    plt.show()


def main(wav_file):
    """Plot figures."""
    audio, fs = sf.read(wav_file)
    if audio.dtype in [np.int16, np.int32]:
        audio = (audio / np.iinfo(audio.dtype).max).astype(np.float64)
    audio = audio.astype(np.float64)

    stft_old_scipy = signal.stft(
        audio, fs=fs, nperseg=WIN_LEN, noverlap=(WIN_LEN - HOP_LEN), nfft=WIN_LEN
    )
    plot_stft_spec(stft_old_scipy[-1], fs, "scipy_spec.png")

    SFT = signal.ShortTimeFFT(
        win=signal.windows.hann(WIN_LEN),
        hop=HOP_LEN,
        fs=fs,
        mfft=WIN_LEN,
        phase_shift=0,
    )
    stft_scipy = SFT.stft(audio)
    plot_stft_spec(stft_scipy, fs, "scipy_spec_phaseshift_0.png")

    SFT = signal.ShortTimeFFT(
        win=signal.windows.hann(WIN_LEN),
        hop=HOP_LEN,
        fs=fs,
        mfft=WIN_LEN,
        phase_shift=None,
    )
    stft_scipy = SFT.stft(audio)
    plot_stft_spec(stft_scipy, fs, "scipy_spec_phaseshift_none.png")


if __name__ == "__main__":
    main(wav_file="./ONOMATOPEE300_001.wav")