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import warnings | |
warnings.filterwarnings('ignore') | |
import librosa | |
import numpy as np | |
from PIL import Image | |
class Mel: | |
def __init__( | |
self, | |
x_res: int = 256, | |
y_res: int = 256, | |
sample_rate: int = 22050, | |
n_fft: int = 2048, | |
hop_length: int = 512, | |
top_db: int = 80, | |
): | |
"""Class to convert audio to mel spectrograms and vice versa. | |
Args: | |
x_res (int): x resolution of spectrogram (time) | |
y_res (int): y resolution of spectrogram (frequency bins) | |
sample_rate (int): sample rate of audio | |
n_fft (int): number of Fast Fourier Transforms | |
hop_length (int): hop length (a higher number is recommended for lower than 256 y_res) | |
top_db (int): loudest in decibels | |
""" | |
self.x_res = x_res | |
self.y_res = y_res | |
self.sr = sample_rate | |
self.n_fft = n_fft | |
self.hop_length = hop_length | |
self.n_mels = self.y_res | |
self.slice_size = self.x_res * self.hop_length - 1 | |
self.fmax = self.sr / 2 | |
self.top_db = top_db | |
self.audio = None | |
def load_audio(self, audio_file: str = None, raw_audio: np.ndarray = None): | |
"""Load audio. | |
Args: | |
audio_file (str): must be a file on disk due to Librosa limitation or | |
raw_audio (np.ndarray): audio as numpy array | |
""" | |
if audio_file is not None: | |
self.audio, _ = librosa.load(audio_file, mono=True) | |
else: | |
self.audio = raw_audio | |
# Pad with silence if necessary. | |
if len(self.audio) < self.x_res * self.hop_length: | |
self.audio = np.concatenate([ | |
self.audio, | |
np.zeros((self.x_res * self.hop_length - len(self.audio), )) | |
]) | |
def get_number_of_slices(self) -> int: | |
"""Get number of slices in audio. | |
Returns: | |
int: number of spectograms audio can be sliced into | |
""" | |
return len(self.audio) // self.slice_size | |
def get_audio_slice(self, slice: int = 0) -> np.ndarray: | |
"""Get slice of audio. | |
Args: | |
slice (int): slice number of audio (out of get_number_of_slices()) | |
Returns: | |
np.ndarray: audio as numpy array | |
""" | |
return self.audio[self.slice_size * slice:self.slice_size * | |
(slice + 1)] | |
def get_sample_rate(self) -> int: | |
"""Get sample rate: | |
Returns: | |
int: sample rate of audio | |
""" | |
return self.sr | |
def audio_slice_to_image(self, slice: int) -> Image.Image: | |
"""Convert slice of audio to spectrogram. | |
Args: | |
slice (int): slice number of audio to convert (out of get_number_of_slices()) | |
Returns: | |
PIL Image: grayscale image of x_res x y_res | |
""" | |
S = librosa.feature.melspectrogram( | |
y=self.get_audio_slice(slice), | |
sr=self.sr, | |
n_fft=self.n_fft, | |
hop_length=self.hop_length, | |
n_mels=self.n_mels, | |
fmax=self.fmax, | |
) | |
log_S = librosa.power_to_db(S, ref=np.max, top_db=self.top_db) | |
bytedata = (((log_S + self.top_db) * 255 / self.top_db).clip(0, 255) + | |
0.5).astype(np.uint8) | |
image = Image.frombytes("L", log_S.shape, bytedata.tobytes()) | |
return image | |
def image_to_audio(self, image: Image.Image) -> np.ndarray: | |
"""Converts spectrogram to audio. | |
Args: | |
image (PIL Image): x_res x y_res grayscale image | |
Returns: | |
audio (np.ndarray): raw audio | |
""" | |
bytedata = np.frombuffer(image.tobytes(), dtype="uint8").reshape( | |
(image.width, image.height)) | |
log_S = bytedata.astype("float") * self.top_db / 255 - self.top_db | |
S = librosa.db_to_power(log_S) | |
audio = librosa.feature.inverse.mel_to_audio( | |
S, sr=self.sr, n_fft=self.n_fft, hop_length=self.hop_length) | |
return audio | |