processors/acoustic_extractor.py

# Copyright (c) 2023 Amphion.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.

import os
import torch
import numpy as np

import json
from tqdm import tqdm
from sklearn.preprocessing import StandardScaler
from utils.io import save_feature, save_txt
from utils.util import has_existed
from utils.tokenizer import extract_encodec_token
from utils.stft import TacotronSTFT
from utils.dsp import compress, audio_to_label
from utils.data_utils import remove_outlier
from preprocessors.metadata import replace_augment_name
from scipy.interpolate import interp1d

ZERO = 1e-12


def extract_utt_acoustic_features_parallel(metadata, dataset_output, cfg, n_workers=1):
    """Extract acoustic features from utterances using muliprocess

    Args:
        metadata (dict): dictionary that stores data in train.json and test.json files
        dataset_output (str): directory to store acoustic features
        cfg (dict): dictionary that stores configurations
        n_workers (int, optional): num of processes to extract features in parallel. Defaults to 1.

    Returns:
        list: acoustic features
    """
    for utt in tqdm(metadata):
        if cfg.task_type == "tts":
            extract_utt_acoustic_features_tts(dataset_output, cfg, utt)
        if cfg.task_type == "svc":
            extract_utt_acoustic_features_svc(dataset_output, cfg, utt)
        if cfg.task_type == "vocoder":
            extract_utt_acoustic_features_vocoder(dataset_output, cfg, utt)
        if cfg.task_type == "tta":
            extract_utt_acoustic_features_tta(dataset_output, cfg, utt)


def avg_phone_feature(feature, duration, interpolation=False):
    feature = feature[: sum(duration)]
    if interpolation:
        nonzero_ids = np.where(feature != 0)[0]
        interp_fn = interp1d(
            nonzero_ids,
            feature[nonzero_ids],
            fill_value=(feature[nonzero_ids[0]], feature[nonzero_ids[-1]]),
            bounds_error=False,
        )
        feature = interp_fn(np.arange(0, len(feature)))

    # Phoneme-level average
    pos = 0
    for i, d in enumerate(duration):
        if d > 0:
            feature[i] = np.mean(feature[pos : pos + d])
        else:
            feature[i] = 0
        pos += d
    feature = feature[: len(duration)]
    return feature


def extract_utt_acoustic_features_serial(metadata, dataset_output, cfg):
    """Extract acoustic features from utterances (in single process)

    Args:
        metadata (dict): dictionary that stores data in train.json and test.json files
        dataset_output (str): directory to store acoustic features
        cfg (dict): dictionary that stores configurations

    """
    for utt in tqdm(metadata):
        if cfg.task_type == "tts":
            extract_utt_acoustic_features_tts(dataset_output, cfg, utt)
        if cfg.task_type == "svc":
            extract_utt_acoustic_features_svc(dataset_output, cfg, utt)
        if cfg.task_type == "vocoder":
            extract_utt_acoustic_features_vocoder(dataset_output, cfg, utt)
        if cfg.task_type == "tta":
            extract_utt_acoustic_features_tta(dataset_output, cfg, utt)


def __extract_utt_acoustic_features(dataset_output, cfg, utt):
    """Extract acoustic features from utterances (in single process)

    Args:
        dataset_output (str): directory to store acoustic features
        cfg (dict): dictionary that stores configurations
        utt (dict): utterance info including dataset, singer, uid:{singer}_{song}_{index},
                    path to utternace, duration, utternace index

    """
    from utils import audio, f0, world, duration

    uid = utt["Uid"]
    wav_path = utt["Path"]
    if os.path.exists(os.path.join(dataset_output, cfg.preprocess.raw_data)):
        wav_path = os.path.join(
            dataset_output, cfg.preprocess.raw_data, utt["Singer"], uid + ".wav"
        )

    with torch.no_grad():
        # Load audio data into tensor with sample rate of the config file
        wav_torch, _ = audio.load_audio_torch(wav_path, cfg.preprocess.sample_rate)
        wav = wav_torch.cpu().numpy()

        # extract features
        if cfg.preprocess.extract_duration:
            durations, phones, start, end = duration.get_duration(
                utt, wav, cfg.preprocess
            )
            save_feature(dataset_output, cfg.preprocess.duration_dir, uid, durations)
            save_txt(dataset_output, cfg.preprocess.lab_dir, uid, phones)
            wav = wav[start:end].astype(np.float32)
            wav_torch = torch.from_numpy(wav).to(wav_torch.device)

        if cfg.preprocess.extract_linear_spec:
            from utils.mel import extract_linear_features

            linear = extract_linear_features(wav_torch.unsqueeze(0), cfg.preprocess)
            save_feature(
                dataset_output, cfg.preprocess.linear_dir, uid, linear.cpu().numpy()
            )

        if cfg.preprocess.extract_mel:
            from utils.mel import extract_mel_features

            if cfg.preprocess.mel_extract_mode == "taco":
                _stft = TacotronSTFT(
                    sampling_rate=cfg.preprocess.sample_rate,
                    win_length=cfg.preprocess.win_size,
                    hop_length=cfg.preprocess.hop_size,
                    filter_length=cfg.preprocess.n_fft,
                    n_mel_channels=cfg.preprocess.n_mel,
                    mel_fmin=cfg.preprocess.fmin,
                    mel_fmax=cfg.preprocess.fmax,
                )
                mel = extract_mel_features(
                    wav_torch.unsqueeze(0), cfg.preprocess, taco=True, _stft=_stft
                )
                if cfg.preprocess.extract_duration:
                    mel = mel[:, : sum(durations)]
            else:
                mel = extract_mel_features(wav_torch.unsqueeze(0), cfg.preprocess)
            save_feature(dataset_output, cfg.preprocess.mel_dir, uid, mel.cpu().numpy())

        if cfg.preprocess.extract_energy:
            if (
                cfg.preprocess.energy_extract_mode == "from_mel"
                and cfg.preprocess.extract_mel
            ):
                energy = (mel.exp() ** 2).sum(0).sqrt().cpu().numpy()
            elif cfg.preprocess.energy_extract_mode == "from_waveform":
                energy = audio.energy(wav, cfg.preprocess)
            elif cfg.preprocess.energy_extract_mode == "from_tacotron_stft":
                _stft = TacotronSTFT(
                    sampling_rate=cfg.preprocess.sample_rate,
                    win_length=cfg.preprocess.win_size,
                    hop_length=cfg.preprocess.hop_size,
                    filter_length=cfg.preprocess.n_fft,
                    n_mel_channels=cfg.preprocess.n_mel,
                    mel_fmin=cfg.preprocess.fmin,
                    mel_fmax=cfg.preprocess.fmax,
                )
                _, energy = audio.get_energy_from_tacotron(wav, _stft)
            else:
                assert cfg.preprocess.energy_extract_mode in [
                    "from_mel",
                    "from_waveform",
                    "from_tacotron_stft",
                ], f"{cfg.preprocess.energy_extract_mode} not in supported energy_extract_mode [from_mel, from_waveform, from_tacotron_stft]"
            if cfg.preprocess.extract_duration:
                energy = energy[: sum(durations)]
                phone_energy = avg_phone_feature(energy, durations)
                save_feature(
                    dataset_output, cfg.preprocess.phone_energy_dir, uid, phone_energy
                )

            save_feature(dataset_output, cfg.preprocess.energy_dir, uid, energy)

        if cfg.preprocess.extract_pitch:
            pitch = f0.get_f0(wav, cfg.preprocess)
            if cfg.preprocess.extract_duration:
                pitch = pitch[: sum(durations)]
                phone_pitch = avg_phone_feature(pitch, durations, interpolation=True)
                save_feature(
                    dataset_output, cfg.preprocess.phone_pitch_dir, uid, phone_pitch
                )
            save_feature(dataset_output, cfg.preprocess.pitch_dir, uid, pitch)

            if cfg.preprocess.extract_uv:
                assert isinstance(pitch, np.ndarray)
                uv = pitch != 0
                save_feature(dataset_output, cfg.preprocess.uv_dir, uid, uv)

        if cfg.preprocess.extract_audio:
            save_feature(dataset_output, cfg.preprocess.audio_dir, uid, wav)

        if cfg.preprocess.extract_label:
            if cfg.preprocess.is_mu_law:
                # compress audio
                wav = compress(wav, cfg.preprocess.bits)
            label = audio_to_label(wav, cfg.preprocess.bits)
            save_feature(dataset_output, cfg.preprocess.label_dir, uid, label)

        if cfg.preprocess.extract_acoustic_token:
            if cfg.preprocess.acoustic_token_extractor == "Encodec":
                codes = extract_encodec_token(wav_path)
                save_feature(
                    dataset_output, cfg.preprocess.acoustic_token_dir, uid, codes
                )


def extract_utt_acoustic_features_tts(dataset_output, cfg, utt):
    __extract_utt_acoustic_features(dataset_output, cfg, utt)


def extract_utt_acoustic_features_svc(dataset_output, cfg, utt):
    """Extract acoustic features from utterances (in single process)

    Args:
        dataset_output (str): directory to store acoustic features
        cfg (dict): dictionary that stores configurations
        utt (dict): utterance info including dataset, singer, uid:{singer}_{song}_{index},
                    path to utternace, duration, utternace index

    """
    from utils import audio, f0, world, duration

    uid = utt["Uid"]
    wav_path = utt["Path"]

    with torch.no_grad():
        # Load audio data into tensor with sample rate of the config file
        wav_torch, _ = audio.load_audio_torch(wav_path, cfg.preprocess.sample_rate)
        wav = wav_torch.cpu().numpy()

        # extract features
        if cfg.preprocess.extract_mel:
            from utils.mel import extract_mel_features

            mel = extract_mel_features(wav_torch.unsqueeze(0), cfg.preprocess)
            save_feature(dataset_output, cfg.preprocess.mel_dir, uid, mel.cpu().numpy())

        if cfg.preprocess.extract_energy:
            energy = (mel.exp() ** 2).sum(0).sqrt().cpu().numpy()
            save_feature(dataset_output, cfg.preprocess.energy_dir, uid, energy)

        if cfg.preprocess.extract_pitch:
            pitch = f0.get_f0(wav, cfg.preprocess)
            save_feature(dataset_output, cfg.preprocess.pitch_dir, uid, pitch)

            if cfg.preprocess.extract_uv:
                assert isinstance(pitch, np.ndarray)
                uv = pitch != 0
                save_feature(dataset_output, cfg.preprocess.uv_dir, uid, uv)


def extract_utt_acoustic_features_tta(dataset_output, cfg, utt):
    __extract_utt_acoustic_features(dataset_output, cfg, utt)


def extract_utt_acoustic_features_vocoder(dataset_output, cfg, utt):
    """Extract acoustic features from utterances (in single process)

    Args:
        dataset_output (str): directory to store acoustic features
        cfg (dict): dictionary that stores configurations
        utt (dict): utterance info including dataset, singer, uid:{singer}_{song}_{index},
                    path to utternace, duration, utternace index

    """
    from utils import audio, f0, world, duration

    uid = utt["Uid"]
    wav_path = utt["Path"]

    with torch.no_grad():
        # Load audio data into tensor with sample rate of the config file
        wav_torch, _ = audio.load_audio_torch(wav_path, cfg.preprocess.sample_rate)
        wav = wav_torch.cpu().numpy()

        # extract features
        if cfg.preprocess.extract_mel:
            from utils.mel import extract_mel_features

            mel = extract_mel_features(wav_torch.unsqueeze(0), cfg.preprocess)
            save_feature(dataset_output, cfg.preprocess.mel_dir, uid, mel.cpu().numpy())

        if cfg.preprocess.extract_energy:
            if (
                cfg.preprocess.energy_extract_mode == "from_mel"
                and cfg.preprocess.extract_mel
            ):
                energy = (mel.exp() ** 2).sum(0).sqrt().cpu().numpy()
            elif cfg.preprocess.energy_extract_mode == "from_waveform":
                energy = audio.energy(wav, cfg.preprocess)
            else:
                assert cfg.preprocess.energy_extract_mode in [
                    "from_mel",
                    "from_waveform",
                ], f"{cfg.preprocess.energy_extract_mode} not in supported energy_extract_mode [from_mel, from_waveform, from_tacotron_stft]"

            save_feature(dataset_output, cfg.preprocess.energy_dir, uid, energy)

        if cfg.preprocess.extract_pitch:
            pitch = f0.get_f0(wav, cfg.preprocess)
            save_feature(dataset_output, cfg.preprocess.pitch_dir, uid, pitch)

            if cfg.preprocess.extract_uv:
                assert isinstance(pitch, np.ndarray)
                uv = pitch != 0
                save_feature(dataset_output, cfg.preprocess.uv_dir, uid, uv)

        if cfg.preprocess.extract_audio:
            save_feature(dataset_output, cfg.preprocess.audio_dir, uid, wav)

        if cfg.preprocess.extract_label:
            if cfg.preprocess.is_mu_law:
                # compress audio
                wav = compress(wav, cfg.preprocess.bits)
            label = audio_to_label(wav, cfg.preprocess.bits)
            save_feature(dataset_output, cfg.preprocess.label_dir, uid, label)


def cal_normalized_mel(mel, dataset_name, cfg):
    mel_min, mel_max = load_mel_extrema(cfg, dataset_name)
    mel_norm = normalize_mel_channel(mel, mel_min, mel_max)
    return mel_norm


def cal_mel_min_max(dataset, output_path, cfg, metadata=None):
    dataset_output = os.path.join(output_path, dataset)

    if metadata is None:
        metadata = []
        for dataset_type in ["train", "test"] if "eval" not in dataset else ["test"]:
            dataset_file = os.path.join(dataset_output, "{}.json".format(dataset_type))
            with open(dataset_file, "r") as f:
                metadata.extend(json.load(f))

    tmp_mel_min = []
    tmp_mel_max = []
    for item in metadata:
        mel_path = os.path.join(
            dataset_output, cfg.preprocess.mel_dir, item["Uid"] + ".npy"
        )
        if not os.path.exists(mel_path):
            continue
        mel = np.load(mel_path)
        if mel.shape[0] != cfg.preprocess.n_mel:
            mel = mel.T
        # mel: (n_mels, T)
        assert mel.shape[0] == cfg.preprocess.n_mel

        tmp_mel_min.append(np.min(mel, axis=-1))
        tmp_mel_max.append(np.max(mel, axis=-1))

    mel_min = np.min(tmp_mel_min, axis=0)
    mel_max = np.max(tmp_mel_max, axis=0)

    ## save mel min max data
    mel_min_max_dir = os.path.join(dataset_output, cfg.preprocess.mel_min_max_stats_dir)
    os.makedirs(mel_min_max_dir, exist_ok=True)

    mel_min_path = os.path.join(mel_min_max_dir, "mel_min.npy")
    mel_max_path = os.path.join(mel_min_max_dir, "mel_max.npy")
    np.save(mel_min_path, mel_min)
    np.save(mel_max_path, mel_max)


def denorm_for_pred_mels(cfg, dataset_name, split, pred):
    """
    Args:
        pred: a list whose every element is (frame_len, n_mels)
    Return:
        similar like pred
    """
    mel_min, mel_max = load_mel_extrema(cfg.preprocess, dataset_name)
    recovered_mels = [
        denormalize_mel_channel(mel.T, mel_min, mel_max).T for mel in pred
    ]

    return recovered_mels


def load_mel_extrema(cfg, dataset_name):
    data_dir = os.path.join(cfg.processed_dir, dataset_name, cfg.mel_min_max_stats_dir)

    min_file = os.path.join(data_dir, "mel_min.npy")
    max_file = os.path.join(data_dir, "mel_max.npy")

    mel_min = np.load(min_file)
    mel_max = np.load(max_file)

    return mel_min, mel_max


def denormalize_mel_channel(mel, mel_min, mel_max):
    mel_min = np.expand_dims(mel_min, -1)
    mel_max = np.expand_dims(mel_max, -1)
    return (mel + 1) / 2 * (mel_max - mel_min + ZERO) + mel_min


def normalize_mel_channel(mel, mel_min, mel_max):
    mel_min = np.expand_dims(mel_min, -1)
    mel_max = np.expand_dims(mel_max, -1)
    return (mel - mel_min) / (mel_max - mel_min + ZERO) * 2 - 1


def normalize(dataset, feat_dir, cfg):
    dataset_output = os.path.join(cfg.preprocess.processed_dir, dataset)
    print(f"normalize {feat_dir}")

    max_value = np.finfo(np.float64).min
    min_value = np.finfo(np.float64).max

    scaler = StandardScaler()
    feat_files = os.listdir(os.path.join(dataset_output, feat_dir))

    for feat_file in tqdm(feat_files):
        feat_file = os.path.join(dataset_output, feat_dir, feat_file)
        if not feat_file.endswith(".npy"):
            continue
        feat = np.load(feat_file)
        max_value = max(max_value, max(feat))
        min_value = min(min_value, min(feat))
        scaler.partial_fit(feat.reshape((-1, 1)))
    mean = scaler.mean_[0]
    std = scaler.scale_[0]
    stat = np.array([min_value, max_value, mean, std])
    stat_npy = os.path.join(dataset_output, f"{feat_dir}_stat.npy")
    np.save(stat_npy, stat)
    return mean, std, min_value, max_value


def load_normalized(feat_dir, dataset_name, cfg):
    dataset_output = os.path.join(cfg.preprocess.processed_dir, dataset_name)
    stat_npy = os.path.join(dataset_output, f"{feat_dir}_stat.npy")
    min_value, max_value, mean, std = np.load(stat_npy)
    return mean, std, min_value, max_value


def cal_pitch_statistics_svc(dataset, output_path, cfg, metadata=None):
    # path of dataset
    dataset_dir = os.path.join(output_path, dataset)
    save_dir = os.path.join(dataset_dir, cfg.preprocess.pitch_dir)
    os.makedirs(save_dir, exist_ok=True)
    if has_existed(os.path.join(save_dir, "statistics.json")):
        return

    if metadata is None:
        # load singers and ids
        singers = json.load(open(os.path.join(dataset_dir, "singers.json"), "r"))

        # combine train and test metadata
        metadata = []
        for dataset_type in ["train", "test"] if "eval" not in dataset else ["test"]:
            dataset_file = os.path.join(dataset_dir, "{}.json".format(dataset_type))
            with open(dataset_file, "r") as f:
                metadata.extend(json.load(f))
    else:
        singers = list(set([item["Singer"] for item in metadata]))
        singers = {
            "{}_{}".format(dataset, name): idx for idx, name in enumerate(singers)
        }

    # use different scalers for each singer
    pitch_scalers = [[] for _ in range(len(singers))]
    total_pitch_scalers = [[] for _ in range(len(singers))]

    for utt_info in tqdm(metadata, desc="Loading F0..."):
        # utt = f'{utt_info["Dataset"]}_{utt_info["Uid"]}'
        singer = utt_info["Singer"]
        pitch_path = os.path.join(
            dataset_dir, cfg.preprocess.pitch_dir, utt_info["Uid"] + ".npy"
        )
        # total_pitch contains all pitch including unvoiced frames
        if not os.path.exists(pitch_path):
            continue
        total_pitch = np.load(pitch_path)
        assert len(total_pitch) > 0
        # pitch contains only voiced frames
        pitch = total_pitch[total_pitch != 0]
        spkid = singers[f"{replace_augment_name(dataset)}_{singer}"]

        # update pitch scalers
        pitch_scalers[spkid].extend(pitch.tolist())
        # update total pitch scalers
        total_pitch_scalers[spkid].extend(total_pitch.tolist())

    # save pitch statistics for each singer in dict
    sta_dict = {}
    for singer in tqdm(singers, desc="Singers statistics"):
        spkid = singers[singer]
        # voiced pitch statistics
        mean, std, min, max, median = (
            np.mean(pitch_scalers[spkid]),
            np.std(pitch_scalers[spkid]),
            np.min(pitch_scalers[spkid]),
            np.max(pitch_scalers[spkid]),
            np.median(pitch_scalers[spkid]),
        )

        # total pitch statistics
        mean_t, std_t, min_t, max_t, median_t = (
            np.mean(total_pitch_scalers[spkid]),
            np.std(total_pitch_scalers[spkid]),
            np.min(total_pitch_scalers[spkid]),
            np.max(total_pitch_scalers[spkid]),
            np.median(total_pitch_scalers[spkid]),
        )
        sta_dict[singer] = {
            "voiced_positions": {
                "mean": mean,
                "std": std,
                "median": median,
                "min": min,
                "max": max,
            },
            "total_positions": {
                "mean": mean_t,
                "std": std_t,
                "median": median_t,
                "min": min_t,
                "max": max_t,
            },
        }

    # save statistics
    with open(os.path.join(save_dir, "statistics.json"), "w") as f:
        json.dump(sta_dict, f, indent=4, ensure_ascii=False)


def cal_pitch_statistics(dataset, output_path, cfg):
    # path of dataset
    dataset_dir = os.path.join(output_path, dataset)
    if cfg.preprocess.use_phone_pitch:
        pitch_dir = cfg.preprocess.phone_pitch_dir
    else:
        pitch_dir = cfg.preprocess.pitch_dir
    save_dir = os.path.join(dataset_dir, pitch_dir)

    os.makedirs(save_dir, exist_ok=True)
    if has_existed(os.path.join(save_dir, "statistics.json")):
        return
    # load singers and ids
    singers = json.load(open(os.path.join(dataset_dir, "singers.json"), "r"))

    # combine train and test metadata
    metadata = []
    for dataset_type in ["train", "test"] if "eval" not in dataset else ["test"]:
        dataset_file = os.path.join(dataset_dir, "{}.json".format(dataset_type))
        with open(dataset_file, "r") as f:
            metadata.extend(json.load(f))

    # use different scalers for each singer
    pitch_scalers = [[] for _ in range(len(singers))]
    total_pitch_scalers = [[] for _ in range(len(singers))]

    for utt_info in metadata:
        utt = f'{utt_info["Dataset"]}_{utt_info["Uid"]}'
        singer = utt_info["Singer"]
        pitch_path = os.path.join(dataset_dir, pitch_dir, utt_info["Uid"] + ".npy")
        # total_pitch contains all pitch including unvoiced frames
        if not os.path.exists(pitch_path):
            continue
        total_pitch = np.load(pitch_path)
        assert len(total_pitch) > 0
        # pitch contains only voiced frames
        # pitch = total_pitch[total_pitch != 0]
        if cfg.preprocess.pitch_remove_outlier:
            pitch = remove_outlier(total_pitch)
        spkid = singers[f"{replace_augment_name(dataset)}_{singer}"]

        # update pitch scalers
        pitch_scalers[spkid].extend(pitch.tolist())
        # update total pitch scalers
        total_pitch_scalers[spkid].extend(total_pitch.tolist())

    # save pitch statistics for each singer in dict
    sta_dict = {}
    for singer in singers:
        spkid = singers[singer]
        # voiced pitch statistics
        mean, std, min, max, median = (
            np.mean(pitch_scalers[spkid]),
            np.std(pitch_scalers[spkid]),
            np.min(pitch_scalers[spkid]),
            np.max(pitch_scalers[spkid]),
            np.median(pitch_scalers[spkid]),
        )

        # total pitch statistics
        mean_t, std_t, min_t, max_t, median_t = (
            np.mean(total_pitch_scalers[spkid]),
            np.std(total_pitch_scalers[spkid]),
            np.min(total_pitch_scalers[spkid]),
            np.max(total_pitch_scalers[spkid]),
            np.median(total_pitch_scalers[spkid]),
        )
        sta_dict[singer] = {
            "voiced_positions": {
                "mean": mean,
                "std": std,
                "median": median,
                "min": min,
                "max": max,
            },
            "total_positions": {
                "mean": mean_t,
                "std": std_t,
                "median": median_t,
                "min": min_t,
                "max": max_t,
            },
        }

    # save statistics
    with open(os.path.join(save_dir, "statistics.json"), "w") as f:
        json.dump(sta_dict, f, indent=4, ensure_ascii=False)


def cal_energy_statistics(dataset, output_path, cfg):
    # path of dataset
    dataset_dir = os.path.join(output_path, dataset)
    if cfg.preprocess.use_phone_energy:
        energy_dir = cfg.preprocess.phone_energy_dir
    else:
        energy_dir = cfg.preprocess.energy_dir
    save_dir = os.path.join(dataset_dir, energy_dir)
    os.makedirs(save_dir, exist_ok=True)
    print(os.path.join(save_dir, "statistics.json"))
    if has_existed(os.path.join(save_dir, "statistics.json")):
        return
    # load singers and ids
    singers = json.load(open(os.path.join(dataset_dir, "singers.json"), "r"))

    # combine train and test metadata
    metadata = []
    for dataset_type in ["train", "test"] if "eval" not in dataset else ["test"]:
        dataset_file = os.path.join(dataset_dir, "{}.json".format(dataset_type))
        with open(dataset_file, "r") as f:
            metadata.extend(json.load(f))

    # use different scalers for each singer
    energy_scalers = [[] for _ in range(len(singers))]
    total_energy_scalers = [[] for _ in range(len(singers))]

    for utt_info in metadata:
        utt = f'{utt_info["Dataset"]}_{utt_info["Uid"]}'
        singer = utt_info["Singer"]
        energy_path = os.path.join(dataset_dir, energy_dir, utt_info["Uid"] + ".npy")
        # total_energy contains all energy including unvoiced frames
        if not os.path.exists(energy_path):
            continue
        total_energy = np.load(energy_path)
        assert len(total_energy) > 0
        # energy contains only voiced frames
        # energy = total_energy[total_energy != 0]
        if cfg.preprocess.energy_remove_outlier:
            energy = remove_outlier(total_energy)
        spkid = singers[f"{replace_augment_name(dataset)}_{singer}"]

        # update energy scalers
        energy_scalers[spkid].extend(energy.tolist())
        # update total energyscalers
        total_energy_scalers[spkid].extend(total_energy.tolist())

    # save energy statistics for each singer in dict
    sta_dict = {}
    for singer in singers:
        spkid = singers[singer]
        # voiced energy statistics
        mean, std, min, max, median = (
            np.mean(energy_scalers[spkid]),
            np.std(energy_scalers[spkid]),
            np.min(energy_scalers[spkid]),
            np.max(energy_scalers[spkid]),
            np.median(energy_scalers[spkid]),
        )

        # total energy statistics
        mean_t, std_t, min_t, max_t, median_t = (
            np.mean(total_energy_scalers[spkid]),
            np.std(total_energy_scalers[spkid]),
            np.min(total_energy_scalers[spkid]),
            np.max(total_energy_scalers[spkid]),
            np.median(total_energy_scalers[spkid]),
        )
        sta_dict[singer] = {
            "voiced_positions": {
                "mean": mean,
                "std": std,
                "median": median,
                "min": min,
                "max": max,
            },
            "total_positions": {
                "mean": mean_t,
                "std": std_t,
                "median": median_t,
                "min": min_t,
                "max": max_t,
            },
        }

    # save statistics
    with open(os.path.join(save_dir, "statistics.json"), "w") as f:
        json.dump(sta_dict, f, indent=4, ensure_ascii=False)


def copy_acoustic_features(metadata, dataset_dir, src_dataset_dir, cfg):
    """Copy acoustic features from src_dataset_dir to dataset_dir

    Args:
        metadata (dict): dictionary that stores data in train.json and test.json files
        dataset_dir (str): directory to store acoustic features
        src_dataset_dir (str): directory to store acoustic features
        cfg (dict): dictionary that stores configurations

    """

    if cfg.preprocess.extract_mel:
        if not has_existed(os.path.join(dataset_dir, cfg.preprocess.mel_dir)):
            os.makedirs(
                os.path.join(dataset_dir, cfg.preprocess.mel_dir), exist_ok=True
            )
            print(
                "Copying mel features from {} to {}...".format(
                    src_dataset_dir, dataset_dir
                )
            )
            for utt_info in tqdm(metadata):
                src_mel_path = os.path.join(
                    src_dataset_dir, cfg.preprocess.mel_dir, utt_info["Uid"] + ".npy"
                )
                dst_mel_path = os.path.join(
                    dataset_dir, cfg.preprocess.mel_dir, utt_info["Uid"] + ".npy"
                )
                # create soft-links
                if not os.path.exists(dst_mel_path):
                    os.symlink(src_mel_path, dst_mel_path)
    if cfg.preprocess.extract_energy:
        if not has_existed(os.path.join(dataset_dir, cfg.preprocess.energy_dir)):
            os.makedirs(
                os.path.join(dataset_dir, cfg.preprocess.energy_dir), exist_ok=True
            )
            print(
                "Copying energy features from {} to {}...".format(
                    src_dataset_dir, dataset_dir
                )
            )
            for utt_info in tqdm(metadata):
                src_energy_path = os.path.join(
                    src_dataset_dir, cfg.preprocess.energy_dir, utt_info["Uid"] + ".npy"
                )
                dst_energy_path = os.path.join(
                    dataset_dir, cfg.preprocess.energy_dir, utt_info["Uid"] + ".npy"
                )
                # create soft-links
                if not os.path.exists(dst_energy_path):
                    os.symlink(src_energy_path, dst_energy_path)
    if cfg.preprocess.extract_pitch:
        if not has_existed(os.path.join(dataset_dir, cfg.preprocess.pitch_dir)):
            os.makedirs(
                os.path.join(dataset_dir, cfg.preprocess.pitch_dir), exist_ok=True
            )
            print(
                "Copying pitch features from {} to {}...".format(
                    src_dataset_dir, dataset_dir
                )
            )
            for utt_info in tqdm(metadata):
                src_pitch_path = os.path.join(
                    src_dataset_dir, cfg.preprocess.pitch_dir, utt_info["Uid"] + ".npy"
                )
                dst_pitch_path = os.path.join(
                    dataset_dir, cfg.preprocess.pitch_dir, utt_info["Uid"] + ".npy"
                )
                # create soft-links
                if not os.path.exists(dst_pitch_path):
                    os.symlink(src_pitch_path, dst_pitch_path)
        if cfg.preprocess.extract_uv:
            if not has_existed(os.path.join(dataset_dir, cfg.preprocess.uv_dir)):
                os.makedirs(
                    os.path.join(dataset_dir, cfg.preprocess.uv_dir), exist_ok=True
                )
                print(
                    "Copying uv features from {} to {}...".format(
                        src_dataset_dir, dataset_dir
                    )
                )
                for utt_info in tqdm(metadata):
                    src_uv_path = os.path.join(
                        src_dataset_dir, cfg.preprocess.uv_dir, utt_info["Uid"] + ".npy"
                    )
                    dst_uv_path = os.path.join(
                        dataset_dir, cfg.preprocess.uv_dir, utt_info["Uid"] + ".npy"
                    )
                    # create soft-links
                    if not os.path.exists(dst_uv_path):
                        os.symlink(src_uv_path, dst_uv_path)
    if cfg.preprocess.extract_audio:
        if not has_existed(os.path.join(dataset_dir, cfg.preprocess.audio_dir)):
            os.makedirs(
                os.path.join(dataset_dir, cfg.preprocess.audio_dir), exist_ok=True
            )
            print(
                "Copying audio features from {} to {}...".format(
                    src_dataset_dir, dataset_dir
                )
            )
            for utt_info in tqdm(metadata):
                src_audio_path = os.path.join(
                    src_dataset_dir, cfg.preprocess.audio_dir, utt_info["Uid"] + ".npy"
                )
                dst_audio_path = os.path.join(
                    dataset_dir, cfg.preprocess.audio_dir, utt_info["Uid"] + ".npy"
                )
                # create soft-links
                if not os.path.exists(dst_audio_path):
                    os.symlink(src_audio_path, dst_audio_path)
    if cfg.preprocess.extract_label:
        if not has_existed(os.path.join(dataset_dir, cfg.preprocess.label_dir)):
            os.makedirs(
                os.path.join(dataset_dir, cfg.preprocess.label_dir), exist_ok=True
            )
            print(
                "Copying label features from {} to {}...".format(
                    src_dataset_dir, dataset_dir
                )
            )
            for utt_info in tqdm(metadata):
                src_label_path = os.path.join(
                    src_dataset_dir, cfg.preprocess.label_dir, utt_info["Uid"] + ".npy"
                )
                dst_label_path = os.path.join(
                    dataset_dir, cfg.preprocess.label_dir, utt_info["Uid"] + ".npy"
                )
                # create soft-links
                if not os.path.exists(dst_label_path):
                    os.symlink(src_label_path, dst_label_path)


def align_duration_mel(dataset, output_path, cfg):
    print("align the duration and mel")

    dataset_dir = os.path.join(output_path, dataset)
    metadata = []
    for dataset_type in ["train", "test"] if "eval" not in dataset else ["test"]:
        dataset_file = os.path.join(dataset_dir, "{}.json".format(dataset_type))
        with open(dataset_file, "r") as f:
            metadata.extend(json.load(f))

    utt2dur = {}
    for index in tqdm(range(len(metadata))):
        utt_info = metadata[index]
        dataset = utt_info["Dataset"]
        uid = utt_info["Uid"]
        utt = "{}_{}".format(dataset, uid)

        mel_path = os.path.join(dataset_dir, cfg.preprocess.mel_dir, uid + ".npy")
        mel = np.load(mel_path).transpose(1, 0)
        duration_path = os.path.join(
            dataset_dir, cfg.preprocess.duration_dir, uid + ".npy"
        )
        duration = np.load(duration_path)
        if sum(duration) != mel.shape[0]:
            duration_sum = sum(duration)
            mel_len = mel.shape[0]
            mismatch = abs(duration_sum - mel_len)
            assert mismatch <= 5, "duration and mel length mismatch!"
            cloned = np.array(duration, copy=True)
            if duration_sum > mel_len:
                for j in range(1, len(duration) - 1):
                    if mismatch == 0:
                        break
                    dur_val = cloned[-j]
                    if dur_val >= mismatch:
                        cloned[-j] -= mismatch
                        mismatch -= dur_val
                        break
                    else:
                        cloned[-j] = 0
                        mismatch -= dur_val

            elif duration_sum < mel_len:
                cloned[-1] += mismatch
            duration = cloned
        utt2dur[utt] = duration
        np.save(duration_path, duration)

    return utt2dur