utils.py

from __future__ import print_function, division

from Hyperparameters import Hyperparameters as hp
import numpy as np
# import tensorflow as tf
import librosa
import copy
import matplotlib
matplotlib.use('pdf')
import matplotlib.pyplot as plt
from scipy import signal
import os


def get_spectrograms(fpath):
    '''Returns normalized log(melspectrogram) and log(magnitude) from `sound_file`.
    Args:
      sound_file: A string. The full path of a sound file.
    Returns:
      mel: A 2d array of shape (T, n_mels) <- Transposed
      mag: A 2d array of shape (T, 1+n_fft/2) <- Transposed
    '''

    # Loading sound file
    y, sr = librosa.load(fpath, sr=hp.sr)

    # Trimming
    y, _ = librosa.effects.trim(y)

    # Preemphasis
    y = np.append(y[0], y[1:] - hp.preemphasis * y[:-1])

    # stft
    linear = librosa.stft(y=y,
                          n_fft=hp.n_fft,
                          hop_length=hp.hop_length,
                          win_length=hp.win_length)

    # magnitude spectrogram
    mag = np.abs(linear)  # (1+n_fft//2, T)

    # mel spectrogram
    mel_basis = librosa.filters.mel(hp.sr, hp.n_fft, hp.n_mels)  # (n_mels, 1+n_fft//2)
    mel = np.dot(mel_basis, mag)  # (n_mels, t)

    # to decibel
    mel = 20 * np.log10(np.maximum(1e-5, mel))
    mag = 20 * np.log10(np.maximum(1e-5, mag))

    # normalize
    mel = np.clip((mel - hp.ref_db + hp.max_db) / hp.max_db, 1e-8, 1)
    mag = np.clip((mag - hp.ref_db + hp.max_db) / hp.max_db, 1e-8, 1)

    # Transpose
    mel = mel.T.astype(np.float32)  # (T, n_mels)
    mag = mag.T.astype(np.float32)  # (T, 1+n_fft//2)

    return mel, mag


def spectrogram2wav(mag):
    '''# Generate wave file from spectrogram'''
    # transpose
    mag = mag.T

    # de-noramlize
    mag = (np.clip(mag, 0, 1) * hp.max_db) - hp.max_db + hp.ref_db

    # to amplitude
    mag = np.power(10.0, mag * 0.05)

    # wav reconstruction
    wav = griffin_lim(mag)

    # de-preemphasis
    wav = signal.lfilter([1], [1, -hp.preemphasis], wav)

    # trim
    wav, _ = librosa.effects.trim(wav)

    return wav.astype(np.float32)


def griffin_lim(spectrogram):
    '''Applies Griffin-Lim's raw.
    '''
    X_best = copy.deepcopy(spectrogram)
    for i in range(hp.n_iter):
        X_t = invert_spectrogram(X_best)
        est = librosa.stft(X_t, hp.n_fft, hp.hop_length, win_length=hp.win_length)
        phase = est / np.maximum(1e-8, np.abs(est))
        X_best = spectrogram * phase
    X_t = invert_spectrogram(X_best)
    y = np.real(X_t)

    return y


def invert_spectrogram(spectrogram):
    '''
    spectrogram: [f, t]
    '''
    return librosa.istft(spectrogram, hp.hop_length, win_length=hp.win_length, window="hann")


def plot_alignment(alignment, gs):
    """Plots the alignment
    alignments: A list of (numpy) matrix of shape (encoder_steps, decoder_steps)
    gs : (int) global step
    """
    fig, ax = plt.subplots()
    im = ax.imshow(alignment)

    # cbar_ax = fig.add_axes([0.85, 0.15, 0.05, 0.7])
    fig.colorbar(im)
    plt.title('{} Steps'.format(gs))
    plt.savefig('{}/alignment_{}k.png'.format(hp.logdir, gs // 1000), format='png')


def learning_rate_decay(init_lr, global_step, warmup_steps=4000.):
    '''Noam scheme from tensor2tensor'''
    step = tf.cast(global_step + 1, dtype=tf.float32)
    return init_lr * warmup_steps ** 0.5 * tf.minimum(step * warmup_steps ** -1.5, step ** -0.5)


def load_spectrograms(fpath):
    fname = os.path.basename(fpath)
    mel, mag = get_spectrograms(fpath)
    t = mel.shape[0]
    num_paddings = hp.r - (t % hp.r) if t % hp.r != 0 else 0  # for reduction
    mel = np.pad(mel, [[0, num_paddings], [0, 0]], mode="constant")
    mag = np.pad(mag, [[0, num_paddings], [0, 0]], mode="constant")
    return fname, mel.reshape((-1, hp.n_mels * hp.r)), mag