audio_proc.py

import os
import librosa
import copy
import numpy as np
from scipy import signal, io

class AudioProcessor(object):
    def _init_(self,
                 bits=None,
                 sample_rate=22050,
                 num_mels=80,
                 min_level_db=-100,
                 frame_shift_ms=8.35,
                 frame_length_ms=30,
                 ref_level_db=25,
                 num_freq=1025,
                 power=1.5,
                 preemphasis=0.98,
                 signal_norm=True,
                 symmetric_norm=False,
                 max_norm=1,
                 mel_fmin=None,
                 mel_fmax=None,
                 clip_norm=True,
                 griffin_lim_iters=60,
                 do_trim_silence=True,
                 **kwargs):

        print(" > Setting up Audio Processor...")

        self.bits = bits
        self.sample_rate = sample_rate
        self.num_mels = num_mels
        self.min_level_db = min_level_db
        self.frame_shift_ms = frame_shift_ms
        self.frame_length_ms = frame_length_ms
        self.ref_level_db = ref_level_db
        self.num_freq = num_freq
        self.power = power
        self.preemphasis = preemphasis
        self.griffin_lim_iters = griffin_lim_iters
        self.signal_norm = signal_norm
        self.symmetric_norm = symmetric_norm
        self.mel_fmin = 0 if mel_fmin is None else mel_fmin
        self.mel_fmax = mel_fmax
        self.max_norm = 1.0 if max_norm is None else float(max_norm)
        self.clip_norm = clip_norm
        self.do_trim_silence = do_trim_silence
        self.n_fft, self.hop_length, self.win_length = self._stft_parameters()
        print(" | > Audio Processor attributes.")
        members = vars(self)
        for key, value in members.items():
            print("   | > {}:{}".format(key, value))

    def save_wav(self, wav, path):
        wav_norm = wav * (32767 / max(0.01, np.max(np.abs(wav))))
        io.wavfile.write(path, self.sample_rate, wav_norm.astype(np.int16))

    def _linear_to_mel(self, spectrogram):
        _mel_basis = self._build_mel_basis()
        return np.dot(_mel_basis, spectrogram)

    def _mel_to_linear(self, mel_spec):
        inv_mel_basis = np.linalg.pinv(self._build_mel_basis())
        return np.maximum(1e-10, np.dot(inv_mel_basis, mel_spec))

    def _build_mel_basis(self, ):
        n_fft = (self.num_freq - 1) * 2
        if self.mel_fmax is not None:
            assert self.mel_fmax <= self.sample_rate // 2
        return librosa.filters.mel(
            self.sample_rate,
            n_fft,
            n_mels=self.num_mels,
            fmin=self.mel_fmin,
            fmax=self.mel_fmax)

    def _normalize(self, S):
        """Put values in [0, self.max_norm] or [-self.max_norm, self.max_norm]"""
        if self.signal_norm:
            S_norm = ((S - self.min_level_db) / - self.min_level_db)
            if self.symmetric_norm:
                S_norm = ((2 * self.max_norm) * S_norm) - self.max_norm
                if self.clip_norm :
                    S_norm = np.clip(S_norm, -self.max_norm, self.max_norm)
                return S_norm
            else:
                S_norm = self.max_norm * S_norm
                if self.clip_norm:
                    S_norm = np.clip(S_norm, 0, self.max_norm)
                return S_norm
        else:
            return S

    def _denormalize(self, S):
        """denormalize values"""
        S_denorm = S
        if self.signal_norm:
            if self.symmetric_norm:
                if self.clip_norm:
                    S_denorm = np.clip(S_denorm, -self.max_norm, self.max_norm) 
                S_denorm = ((S_denorm + self.max_norm) * -self.min_level_db / (2 * self.max_norm)) + self.min_level_db
                return S_denorm
            else:
                if self.clip_norm:
                    S_denorm = np.clip(S_denorm, 0, self.max_norm)
                S_denorm = (S_denorm * -self.min_level_db /
                    self.max_norm) + self.min_level_db
                return S_denorm
        else:
            return S

    def _stft_parameters(self, ):
        """Compute necessary stft parameters with given time values"""
        n_fft = (self.num_freq - 1) * 2
        hop_length = int(self.frame_shift_ms / 1000.0 * self.sample_rate)
        win_length = int(self.frame_length_ms / 1000.0 * self.sample_rate)
        print(" | > fft size: {}, hop length: {}, win length: {}".format(
            n_fft, hop_length, win_length))
        return n_fft, hop_length, win_length

    def _amp_to_db(self, x):
        min_level = np.exp(self.min_level_db / 20 * np.log(10))
        return 20 * np.log10(np.maximum(min_level, x))

    def _db_to_amp(self, x):
        return np.power(10.0, x * 0.05)

    def apply_preemphasis(self, x):
        if self.preemphasis == 0:
            raise RuntimeError(" !! Preemphasis is applied with factor 0.0. ")
        return signal.lfilter([1, -self.preemphasis], [1], x)

    def apply_inv_preemphasis(self, x):
        if self.preemphasis == 0:
            raise RuntimeError(" !! Preemphasis is applied with factor 0.0. ")
        return signal.lfilter([1], [1, -self.preemphasis], x)

    def spectrogram(self, y):
        if self.preemphasis != 0:
            D = self._stft(self.apply_preemphasis(y))
        else:
            D = self._stft(y)
        S = self._amp_to_db(np.abs(D)) - self.ref_level_db
        return self._normalize(S)

    def melspectrogram(self, y):
        if self.preemphasis != 0:
            D = self._stft(self.apply_preemphasis(y))
        else:
            D = self._stft(y)
        S = self._amp_to_db(self._linear_to_mel(np.abs(D))) - self.ref_level_db
        return self._normalize(S)

    def inv_spectrogram(self, spectrogram):
        """Converts spectrogram to waveform using librosa"""
        S = self._denormalize(spectrogram)
        S = self._db_to_amp(S + self.ref_level_db)  # Convert back to linear
        # Reconstruct phase
        if self.preemphasis != 0:
            return self.apply_inv_preemphasis(self._griffin_lim(S**self.power))
        else:
            return self._griffin_lim(S**self.power)

    def inv_mel_spectrogram(self, mel_spectrogram):
        '''Converts mel spectrogram to waveform using librosa'''
        D = self._denormalize(mel_spectrogram)
        S = self._db_to_amp(D + self.ref_level_db)
        S = self._mel_to_linear(S)  # Convert back to linear
        if self.preemphasis != 0:
            return self.apply_inv_preemphasis(self._griffin_lim(S**self.power))
        else:
            return self._griffin_lim(S**self.power)

    def _griffin_lim(self, S):
        angles = np.exp(2j * np.pi * np.random.rand(*S.shape))
        S_complex = np.abs(S).astype(np.complex)
        y = self._istft(S_complex * angles)
        for i in range(self.griffin_lim_iters):
            angles = np.exp(1j * np.angle(self._stft(y)))
            y = self._istft(S_complex * angles)
        return y

    def _stft(self, y):
        return librosa.stft(
            y=y,
            n_fft=self.n_fft,
            hop_length=self.hop_length,
            win_length=self.win_length,
        )

    def _istft(self, y):
        return librosa.istft(
            y, hop_length=self.hop_length, win_length=self.win_length)

    def find_endpoint(self, wav, threshold_db=-40, min_silence_sec=0.8):
        window_length = int(self.sample_rate * min_silence_sec)
        hop_length = int(window_length / 4)
        threshold = self._db_to_amp(threshold_db)
        for x in range(hop_length, len(wav) - window_length, hop_length):
            if np.max(wav[x:x + window_length]) < threshold:
                return x + hop_length
        return len(wav)

    def trim_silence(self, wav):
        """ Trim silent parts with a threshold and 0.1 sec margin """
        margin = int(self.sample_rate * 0.1)
        wav = wav[margin:-margin]
        return librosa.effects.trim(
            wav, top_db=40, frame_length=1024, hop_length=256)[0]

    def load_wav(self, filename, encode=False):
        x, sr = librosa.load(filename, sr=self.sample_rate)
        if self.do_trim_silence:
            x = self.trim_silence(x)
        # sr, x = io.wavfile.read(filename)
        assert self.sample_rate == sr
        return x

    def encode_16bits(self, x):
        return np.clip(x * 2*15, -215, 2*15 - 1).astype(np.int16)

    def quantize(self, x):
        return (x + 1.) * (2**self.bits - 1) / 2

    def dequantize(self, x):
        return 2 * x / (2**self.bits - 1) - 1