# -*- coding: utf-8 -*-
"""
Audio Data Augmentation
=======================

**Author**: `Moto Hira <moto@meta.com>`__

``torchaudio`` provides a variety of ways to augment audio data.

In this tutorial, we look into a way to apply effects, filters,
RIR (room impulse response) and codecs.

At the end, we synthesize noisy speech over phone from clean speech.
"""

import torch
import torchaudio
import torchaudio.functional as F

print(torch.__version__)
print(torchaudio.__version__)

import matplotlib.pyplot as plt

######################################################################
# Preparation
# -----------
#
# First, we import the modules and download the audio assets we use in this tutorial.
#

from IPython.display import Audio

from torchaudio.utils import download_asset

SAMPLE_WAV = download_asset("tutorial-assets/steam-train-whistle-daniel_simon.wav")
SAMPLE_RIR = download_asset("tutorial-assets/Lab41-SRI-VOiCES-rm1-impulse-mc01-stu-clo-8000hz.wav")
SAMPLE_SPEECH = download_asset("tutorial-assets/Lab41-SRI-VOiCES-src-sp0307-ch127535-sg0042-8000hz.wav")
SAMPLE_NOISE = download_asset("tutorial-assets/Lab41-SRI-VOiCES-rm1-babb-mc01-stu-clo-8000hz.wav")


######################################################################
# Applying effects and filtering
# ------------------------------
#
# :py:class:`torchaudio.io.AudioEffector` allows for directly applying
# filters and codecs to Tensor objects, in a similar way as ``ffmpeg``
# command
#
# `AudioEffector Usages <./effector_tutorial.html>` explains how to use
# this class, so for the detail, please refer to the tutorial.
#

# Load the data
waveform1, sample_rate = torchaudio.load(SAMPLE_WAV, channels_first=False)

# Define effects
effect = ",".join(
    [
        "lowpass=frequency=300:poles=1",  # apply single-pole lowpass filter
        "atempo=0.8",  # reduce the speed
        "aecho=in_gain=0.8:out_gain=0.9:delays=200:decays=0.3|delays=400:decays=0.3"
        # Applying echo gives some dramatic feeling
    ],
)


# Apply effects
def apply_effect(waveform, sample_rate, effect):
    effector = torchaudio.io.AudioEffector(effect=effect)
    return effector.apply(waveform, sample_rate)


waveform2 = apply_effect(waveform1, sample_rate, effect)

print(waveform1.shape, sample_rate)
print(waveform2.shape, sample_rate)

######################################################################
# Note that the number of frames and number of channels are different from
# those of the original after the effects are applied. Let’s listen to the
# audio.
#


def plot_waveform(waveform, sample_rate, title="Waveform", xlim=None):
    waveform = waveform.numpy()

    num_channels, num_frames = waveform.shape
    time_axis = torch.arange(0, num_frames) / sample_rate

    figure, axes = plt.subplots(num_channels, 1)
    if num_channels == 1:
        axes = [axes]
    for c in range(num_channels):
        axes[c].plot(time_axis, waveform[c], linewidth=1)
        axes[c].grid(True)
        if num_channels > 1:
            axes[c].set_ylabel(f"Channel {c+1}")
        if xlim:
            axes[c].set_xlim(xlim)
    figure.suptitle(title)


######################################################################
#


def plot_specgram(waveform, sample_rate, title="Spectrogram", xlim=None):
    waveform = waveform.numpy()

    num_channels, _ = waveform.shape

    figure, axes = plt.subplots(num_channels, 1)
    if num_channels == 1:
        axes = [axes]
    for c in range(num_channels):
        axes[c].specgram(waveform[c], Fs=sample_rate)
        if num_channels > 1:
            axes[c].set_ylabel(f"Channel {c+1}")
        if xlim:
            axes[c].set_xlim(xlim)
    figure.suptitle(title)


######################################################################
# Original
# ~~~~~~~~
#

plot_waveform(waveform1.T, sample_rate, title="Original", xlim=(-0.1, 3.2))
plot_specgram(waveform1.T, sample_rate, title="Original", xlim=(0, 3.04))
Audio(waveform1.T, rate=sample_rate)

######################################################################
# Effects applied
# ~~~~~~~~~~~~~~~
#

plot_waveform(waveform2.T, sample_rate, title="Effects Applied", xlim=(-0.1, 3.2))
plot_specgram(waveform2.T, sample_rate, title="Effects Applied", xlim=(0, 3.04))
Audio(waveform2.T, rate=sample_rate)


######################################################################
# Simulating room reverberation
# -----------------------------
#
# `Convolution
# reverb <https://en.wikipedia.org/wiki/Convolution_reverb>`__ is a
# technique that's used to make clean audio sound as though it has been
# produced in a different environment.
#
# Using Room Impulse Response (RIR), for instance, we can make clean speech
# sound as though it has been uttered in a conference room.
#
# For this process, we need RIR data. The following data are from the VOiCES
# dataset, but you can record your own — just turn on your microphone
# and clap your hands.
#

rir_raw, sample_rate = torchaudio.load(SAMPLE_RIR)
plot_waveform(rir_raw, sample_rate, title="Room Impulse Response (raw)")
plot_specgram(rir_raw, sample_rate, title="Room Impulse Response (raw)")
Audio(rir_raw, rate=sample_rate)

######################################################################
# First, we need to clean up the RIR. We extract the main impulse and normalize
# it by its power.
#

rir = rir_raw[:, int(sample_rate * 1.01) : int(sample_rate * 1.3)]
rir = rir / torch.linalg.vector_norm(rir, ord=2)

plot_waveform(rir, sample_rate, title="Room Impulse Response")

######################################################################
# Then, using :py:func:`torchaudio.functional.fftconvolve`,
# we convolve the speech signal with the RIR.
#

speech, _ = torchaudio.load(SAMPLE_SPEECH)
augmented = F.fftconvolve(speech, rir)

######################################################################
# Original
# ~~~~~~~~
#

plot_waveform(speech, sample_rate, title="Original")
plot_specgram(speech, sample_rate, title="Original")
Audio(speech, rate=sample_rate)

######################################################################
# RIR applied
# ~~~~~~~~~~~
#

plot_waveform(augmented, sample_rate, title="RIR Applied")
plot_specgram(augmented, sample_rate, title="RIR Applied")
Audio(augmented, rate=sample_rate)


######################################################################
# Adding background noise
# -----------------------
#
# To introduce background noise to audio data, we can add a noise Tensor to
# the Tensor representing the audio data according to some desired
# signal-to-noise ratio (SNR)
# [`wikipedia <https://en.wikipedia.org/wiki/Signal-to-noise_ratio>`__],
# which determines the intensity of the audio data relative to that of the noise
# in the output.
#
# $$ \\mathrm{SNR} = \\frac{P_{signal}}{P_{noise}} $$
#
# $$ \\mathrm{SNR_{dB}} = 10 \\log _{{10}} \\mathrm {SNR} $$
#
# To add noise to audio data per SNRs, we
# use :py:func:`torchaudio.functional.add_noise`.

speech, _ = torchaudio.load(SAMPLE_SPEECH)
noise, _ = torchaudio.load(SAMPLE_NOISE)
noise = noise[:, : speech.shape[1]]

snr_dbs = torch.tensor([20, 10, 3])
noisy_speeches = F.add_noise(speech, noise, snr_dbs)


######################################################################
# Background noise
# ~~~~~~~~~~~~~~~~
#

plot_waveform(noise, sample_rate, title="Background noise")
plot_specgram(noise, sample_rate, title="Background noise")
Audio(noise, rate=sample_rate)

######################################################################
# SNR 20 dB
# ~~~~~~~~~
#

snr_db, noisy_speech = snr_dbs[0], noisy_speeches[0:1]
plot_waveform(noisy_speech, sample_rate, title=f"SNR: {snr_db} [dB]")
plot_specgram(noisy_speech, sample_rate, title=f"SNR: {snr_db} [dB]")
Audio(noisy_speech, rate=sample_rate)

######################################################################
# SNR 10 dB
# ~~~~~~~~~
#

snr_db, noisy_speech = snr_dbs[1], noisy_speeches[1:2]
plot_waveform(noisy_speech, sample_rate, title=f"SNR: {snr_db} [dB]")
plot_specgram(noisy_speech, sample_rate, title=f"SNR: {snr_db} [dB]")
Audio(noisy_speech, rate=sample_rate)

######################################################################
# SNR 3 dB
# ~~~~~~~~
#

snr_db, noisy_speech = snr_dbs[2], noisy_speeches[2:3]
plot_waveform(noisy_speech, sample_rate, title=f"SNR: {snr_db} [dB]")
plot_specgram(noisy_speech, sample_rate, title=f"SNR: {snr_db} [dB]")
Audio(noisy_speech, rate=sample_rate)


######################################################################
# Applying codec to Tensor object
# -------------------------------
#
# :py:class:`torchaudio.io.AudioEffector` can also apply codecs to
# a Tensor object.
#

waveform, sample_rate = torchaudio.load(SAMPLE_SPEECH, channels_first=False)


def apply_codec(waveform, sample_rate, format, encoder=None):
    encoder = torchaudio.io.AudioEffector(format=format, encoder=encoder)
    return encoder.apply(waveform, sample_rate)


######################################################################
# Original
# ~~~~~~~~
#

plot_waveform(waveform.T, sample_rate, title="Original")
plot_specgram(waveform.T, sample_rate, title="Original")
Audio(waveform.T, rate=sample_rate)

######################################################################
# 8 bit mu-law
# ~~~~~~~~~~~~
#

mulaw = apply_codec(waveform, sample_rate, "wav", encoder="pcm_mulaw")
plot_waveform(mulaw.T, sample_rate, title="8 bit mu-law")
plot_specgram(mulaw.T, sample_rate, title="8 bit mu-law")
Audio(mulaw.T, rate=sample_rate)

######################################################################
# G.722
# ~~~~~
#

g722 = apply_codec(waveform, sample_rate, "g722")
plot_waveform(g722.T, sample_rate, title="G.722")
plot_specgram(g722.T, sample_rate, title="G.722")
Audio(g722.T, rate=sample_rate)

######################################################################
# Vorbis
# ~~~~~~
#

vorbis = apply_codec(waveform, sample_rate, "ogg", encoder="vorbis")
plot_waveform(vorbis.T, sample_rate, title="Vorbis")
plot_specgram(vorbis.T, sample_rate, title="Vorbis")
Audio(vorbis.T, rate=sample_rate)

######################################################################
# Simulating a phone recoding
# ---------------------------
#
# Combining the previous techniques, we can simulate audio that sounds
# like a person talking over a phone in a echoey room with people talking
# in the background.
#

sample_rate = 16000
original_speech, sample_rate = torchaudio.load(SAMPLE_SPEECH)

plot_specgram(original_speech, sample_rate, title="Original")

# Apply RIR
rir_applied = F.fftconvolve(speech, rir)

plot_specgram(rir_applied, sample_rate, title="RIR Applied")

# Add background noise
# Because the noise is recorded in the actual environment, we consider that
# the noise contains the acoustic feature of the environment. Therefore, we add
# the noise after RIR application.
noise, _ = torchaudio.load(SAMPLE_NOISE)
noise = noise[:, : rir_applied.shape[1]]

snr_db = torch.tensor([8])
bg_added = F.add_noise(rir_applied, noise, snr_db)

plot_specgram(bg_added, sample_rate, title="BG noise added")

# Apply filtering and change sample rate
effect = ",".join(
    [
        "lowpass=frequency=4000:poles=1",
        "compand=attacks=0.02:decays=0.05:points=-60/-60|-30/-10|-20/-8|-5/-8|-2/-8:gain=-8:volume=-7:delay=0.05",
    ]
)

filtered = apply_effect(bg_added.T, sample_rate, effect)
sample_rate2 = 8000

plot_specgram(filtered.T, sample_rate2, title="Filtered")

# Apply telephony codec
codec_applied = apply_codec(filtered, sample_rate2, "g722")
plot_specgram(codec_applied.T, sample_rate2, title="G.722 Codec Applied")


######################################################################
# Original speech
# ~~~~~~~~~~~~~~~
#

Audio(original_speech, rate=sample_rate)

######################################################################
# RIR applied
# ~~~~~~~~~~~
#

Audio(rir_applied, rate=sample_rate)

######################################################################
# Background noise added
# ~~~~~~~~~~~~~~~~~~~~~~
#

Audio(bg_added, rate=sample_rate)

######################################################################
# Filtered
# ~~~~~~~~
#

Audio(filtered.T, rate=sample_rate2)

######################################################################
# Codec applied
# ~~~~~~~~~~~~~
#

Audio(codec_applied.T, rate=sample_rate2)