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Source code for torchaudio.backend.soundfile_backend

"""The new soundfile backend which will become default in 0.8.0 onward"""
import warnings
from typing import Optional, Tuple

import torch
from torchaudio._internal import module_utils as _mod_utils

from .common import AudioMetaData


if _mod_utils.is_soundfile_available():
    import soundfile

# Mapping from soundfile subtype to number of bits per sample.
# This is mostly heuristical and the value is set to 0 when it is irrelevant
# (lossy formats) or when it can't be inferred.
# For ADPCM (and G72X) subtypes, it's hard to infer the bit depth because it's not part of the standard:
# According to https://en.wikipedia.org/wiki/Adaptive_differential_pulse-code_modulation#In_telephony,
# the default seems to be 8 bits but it can be compressed further to 4 bits.
# The dict is inspired from
# https://github.com/bastibe/python-soundfile/blob/744efb4b01abc72498a96b09115b42a4cabd85e4/soundfile.py#L66-L94
_SUBTYPE_TO_BITS_PER_SAMPLE = {
    "PCM_S8": 8,  # Signed 8 bit data
    "PCM_16": 16,  # Signed 16 bit data
    "PCM_24": 24,  # Signed 24 bit data
    "PCM_32": 32,  # Signed 32 bit data
    "PCM_U8": 8,  # Unsigned 8 bit data (WAV and RAW only)
    "FLOAT": 32,  # 32 bit float data
    "DOUBLE": 64,  # 64 bit float data
    "ULAW": 8,  # U-Law encoded. See https://en.wikipedia.org/wiki/G.711#Types
    "ALAW": 8,  # A-Law encoded. See https://en.wikipedia.org/wiki/G.711#Types
    "IMA_ADPCM": 0,  # IMA ADPCM.
    "MS_ADPCM": 0,  # Microsoft ADPCM.
    "GSM610": 0,  # GSM 6.10 encoding. (Wikipedia says 1.625 bit depth?? https://en.wikipedia.org/wiki/Full_Rate)
    "VOX_ADPCM": 0,  # OKI / Dialogix ADPCM
    "G721_32": 0,  # 32kbs G721 ADPCM encoding.
    "G723_24": 0,  # 24kbs G723 ADPCM encoding.
    "G723_40": 0,  # 40kbs G723 ADPCM encoding.
    "DWVW_12": 12,  # 12 bit Delta Width Variable Word encoding.
    "DWVW_16": 16,  # 16 bit Delta Width Variable Word encoding.
    "DWVW_24": 24,  # 24 bit Delta Width Variable Word encoding.
    "DWVW_N": 0,  # N bit Delta Width Variable Word encoding.
    "DPCM_8": 8,  # 8 bit differential PCM (XI only)
    "DPCM_16": 16,  # 16 bit differential PCM (XI only)
    "VORBIS": 0,  # Xiph Vorbis encoding. (lossy)
    "ALAC_16": 16,  # Apple Lossless Audio Codec (16 bit).
    "ALAC_20": 20,  # Apple Lossless Audio Codec (20 bit).
    "ALAC_24": 24,  # Apple Lossless Audio Codec (24 bit).
    "ALAC_32": 32,  # Apple Lossless Audio Codec (32 bit).
}


def _get_bit_depth(subtype):
    if subtype not in _SUBTYPE_TO_BITS_PER_SAMPLE:
        warnings.warn(
            f"The {subtype} subtype is unknown to TorchAudio. As a result, the bits_per_sample "
            "attribute will be set to 0. If you are seeing this warning, please "
            "report by opening an issue on github (after checking for existing/closed ones). "
            "You may otherwise ignore this warning."
        )
    return _SUBTYPE_TO_BITS_PER_SAMPLE.get(subtype, 0)


_SUBTYPE_TO_ENCODING = {
    "PCM_S8": "PCM_S",
    "PCM_16": "PCM_S",
    "PCM_24": "PCM_S",
    "PCM_32": "PCM_S",
    "PCM_U8": "PCM_U",
    "FLOAT": "PCM_F",
    "DOUBLE": "PCM_F",
    "ULAW": "ULAW",
    "ALAW": "ALAW",
    "VORBIS": "VORBIS",
}


def _get_encoding(format: str, subtype: str):
    if format == "FLAC":
        return "FLAC"
    return _SUBTYPE_TO_ENCODING.get(subtype, "UNKNOWN")


[docs]@_mod_utils.requires_soundfile() def info(filepath: str, format: Optional[str] = None) -> AudioMetaData: """Get signal information of an audio file. Note: ``filepath`` argument is intentionally annotated as ``str`` only, even though it accepts ``pathlib.Path`` object as well. This is for the consistency with ``"sox_io"`` backend, which has a restriction on type annotation due to TorchScript compiler compatiblity. Args: filepath (path-like object or file-like object): Source of audio data. format (str or None, optional): Not used. PySoundFile does not accept format hint. Returns: AudioMetaData: meta data of the given audio. """ sinfo = soundfile.info(filepath) return AudioMetaData( sinfo.samplerate, sinfo.frames, sinfo.channels, bits_per_sample=_get_bit_depth(sinfo.subtype), encoding=_get_encoding(sinfo.format, sinfo.subtype), )
_SUBTYPE2DTYPE = { "PCM_S8": "int8", "PCM_U8": "uint8", "PCM_16": "int16", "PCM_32": "int32", "FLOAT": "float32", "DOUBLE": "float64", }
[docs]@_mod_utils.requires_soundfile() def load( filepath: str, frame_offset: int = 0, num_frames: int = -1, normalize: bool = True, channels_first: bool = True, format: Optional[str] = None, ) -> Tuple[torch.Tensor, int]: """Load audio data from file. Note: The formats this function can handle depend on the soundfile installation. This function is tested on the following formats; * WAV * 32-bit floating-point * 32-bit signed integer * 16-bit signed integer * 8-bit unsigned integer * FLAC * OGG/VORBIS * SPHERE By default (``normalize=True``, ``channels_first=True``), this function returns Tensor with ``float32`` dtype and the shape of `[channel, time]`. The samples are normalized to fit in the range of ``[-1.0, 1.0]``. When the input format is WAV with integer type, such as 32-bit signed integer, 16-bit signed integer and 8-bit unsigned integer (24-bit signed integer is not supported), by providing ``normalize=False``, this function can return integer Tensor, where the samples are expressed within the whole range of the corresponding dtype, that is, ``int32`` tensor for 32-bit signed PCM, ``int16`` for 16-bit signed PCM and ``uint8`` for 8-bit unsigned PCM. ``normalize`` parameter has no effect on 32-bit floating-point WAV and other formats, such as ``flac`` and ``mp3``. For these formats, this function always returns ``float32`` Tensor with values normalized to ``[-1.0, 1.0]``. Note: ``filepath`` argument is intentionally annotated as ``str`` only, even though it accepts ``pathlib.Path`` object as well. This is for the consistency with ``"sox_io"`` backend, which has a restriction on type annotation due to TorchScript compiler compatiblity. Args: filepath (path-like object or file-like object): Source of audio data. frame_offset (int, optional): Number of frames to skip before start reading data. num_frames (int, optional): Maximum number of frames to read. ``-1`` reads all the remaining samples, starting from ``frame_offset``. This function may return the less number of frames if there is not enough frames in the given file. normalize (bool, optional): When ``True``, this function always return ``float32``, and sample values are normalized to ``[-1.0, 1.0]``. If input file is integer WAV, giving ``False`` will change the resulting Tensor type to integer type. This argument has no effect for formats other than integer WAV type. channels_first (bool, optional): When True, the returned Tensor has dimension `[channel, time]`. Otherwise, the returned Tensor's dimension is `[time, channel]`. format (str or None, optional): Not used. PySoundFile does not accept format hint. Returns: (torch.Tensor, int): Resulting Tensor and sample rate. If the input file has integer wav format and normalization is off, then it has integer type, else ``float32`` type. If ``channels_first=True``, it has `[channel, time]` else `[time, channel]`. """ with soundfile.SoundFile(filepath, "r") as file_: if file_.format != "WAV" or normalize: dtype = "float32" elif file_.subtype not in _SUBTYPE2DTYPE: raise ValueError(f"Unsupported subtype: {file_.subtype}") else: dtype = _SUBTYPE2DTYPE[file_.subtype] frames = file_._prepare_read(frame_offset, None, num_frames) waveform = file_.read(frames, dtype, always_2d=True) sample_rate = file_.samplerate waveform = torch.from_numpy(waveform) if channels_first: waveform = waveform.t() return waveform, sample_rate
def _get_subtype_for_wav(dtype: torch.dtype, encoding: str, bits_per_sample: int): if not encoding: if not bits_per_sample: subtype = { torch.uint8: "PCM_U8", torch.int16: "PCM_16", torch.int32: "PCM_32", torch.float32: "FLOAT", torch.float64: "DOUBLE", }.get(dtype) if not subtype: raise ValueError(f"Unsupported dtype for wav: {dtype}") return subtype if bits_per_sample == 8: return "PCM_U8" return f"PCM_{bits_per_sample}" if encoding == "PCM_S": if not bits_per_sample: return "PCM_32" if bits_per_sample == 8: raise ValueError("wav does not support 8-bit signed PCM encoding.") return f"PCM_{bits_per_sample}" if encoding == "PCM_U": if bits_per_sample in (None, 8): return "PCM_U8" raise ValueError("wav only supports 8-bit unsigned PCM encoding.") if encoding == "PCM_F": if bits_per_sample in (None, 32): return "FLOAT" if bits_per_sample == 64: return "DOUBLE" raise ValueError("wav only supports 32/64-bit float PCM encoding.") if encoding == "ULAW": if bits_per_sample in (None, 8): return "ULAW" raise ValueError("wav only supports 8-bit mu-law encoding.") if encoding == "ALAW": if bits_per_sample in (None, 8): return "ALAW" raise ValueError("wav only supports 8-bit a-law encoding.") raise ValueError(f"wav does not support {encoding}.") def _get_subtype_for_sphere(encoding: str, bits_per_sample: int): if encoding in (None, "PCM_S"): return f"PCM_{bits_per_sample}" if bits_per_sample else "PCM_32" if encoding in ("PCM_U", "PCM_F"): raise ValueError(f"sph does not support {encoding} encoding.") if encoding == "ULAW": if bits_per_sample in (None, 8): return "ULAW" raise ValueError("sph only supports 8-bit for mu-law encoding.") if encoding == "ALAW": return "ALAW" raise ValueError(f"sph does not support {encoding}.") def _get_subtype(dtype: torch.dtype, format: str, encoding: str, bits_per_sample: int): if format == "wav": return _get_subtype_for_wav(dtype, encoding, bits_per_sample) if format == "flac": if encoding: raise ValueError("flac does not support encoding.") if not bits_per_sample: return "PCM_16" if bits_per_sample > 24: raise ValueError("flac does not support bits_per_sample > 24.") return "PCM_S8" if bits_per_sample == 8 else f"PCM_{bits_per_sample}" if format in ("ogg", "vorbis"): if encoding or bits_per_sample: raise ValueError("ogg/vorbis does not support encoding/bits_per_sample.") return "VORBIS" if format == "sph": return _get_subtype_for_sphere(encoding, bits_per_sample) if format in ("nis", "nist"): return "PCM_16" raise ValueError(f"Unsupported format: {format}")
[docs]@_mod_utils.requires_soundfile() def save( filepath: str, src: torch.Tensor, sample_rate: int, channels_first: bool = True, compression: Optional[float] = None, format: Optional[str] = None, encoding: Optional[str] = None, bits_per_sample: Optional[int] = None, ): """Save audio data to file. Note: The formats this function can handle depend on the soundfile installation. This function is tested on the following formats; * WAV * 32-bit floating-point * 32-bit signed integer * 16-bit signed integer * 8-bit unsigned integer * FLAC * OGG/VORBIS * SPHERE Note: ``filepath`` argument is intentionally annotated as ``str`` only, even though it accepts ``pathlib.Path`` object as well. This is for the consistency with ``"sox_io"`` backend, which has a restriction on type annotation due to TorchScript compiler compatiblity. Args: filepath (str or pathlib.Path): Path to audio file. src (torch.Tensor): Audio data to save. must be 2D tensor. sample_rate (int): sampling rate channels_first (bool, optional): If ``True``, the given tensor is interpreted as `[channel, time]`, otherwise `[time, channel]`. compression (float of None, optional): Not used. It is here only for interface compatibility reson with "sox_io" backend. format (str or None, optional): Override the audio format. When ``filepath`` argument is path-like object, audio format is inferred from file extension. If the file extension is missing or different, you can specify the correct format with this argument. When ``filepath`` argument is file-like object, this argument is required. Valid values are ``"wav"``, ``"ogg"``, ``"vorbis"``, ``"flac"`` and ``"sph"``. encoding (str or None, optional): Changes the encoding for supported formats. This argument is effective only for supported formats, sush as ``"wav"``, ``""flac"`` and ``"sph"``. Valid values are; - ``"PCM_S"`` (signed integer Linear PCM) - ``"PCM_U"`` (unsigned integer Linear PCM) - ``"PCM_F"`` (floating point PCM) - ``"ULAW"`` (mu-law) - ``"ALAW"`` (a-law) bits_per_sample (int or None, optional): Changes the bit depth for the supported formats. When ``format`` is one of ``"wav"``, ``"flac"`` or ``"sph"``, you can change the bit depth. Valid values are ``8``, ``16``, ``24``, ``32`` and ``64``. Supported formats/encodings/bit depth/compression are: ``"wav"`` - 32-bit floating-point PCM - 32-bit signed integer PCM - 24-bit signed integer PCM - 16-bit signed integer PCM - 8-bit unsigned integer PCM - 8-bit mu-law - 8-bit a-law Note: Default encoding/bit depth is determined by the dtype of the input Tensor. ``"flac"`` - 8-bit - 16-bit (default) - 24-bit ``"ogg"``, ``"vorbis"`` - Doesn't accept changing configuration. ``"sph"`` - 8-bit signed integer PCM - 16-bit signed integer PCM - 24-bit signed integer PCM - 32-bit signed integer PCM (default) - 8-bit mu-law - 8-bit a-law - 16-bit a-law - 24-bit a-law - 32-bit a-law """ if src.ndim != 2: raise ValueError(f"Expected 2D Tensor, got {src.ndim}D.") if compression is not None: warnings.warn( '`save` function of "soundfile" backend does not support "compression" parameter. ' "The argument is silently ignored." ) if hasattr(filepath, "write"): if format is None: raise RuntimeError("`format` is required when saving to file object.") ext = format.lower() else: ext = str(filepath).split(".")[-1].lower() if bits_per_sample not in (None, 8, 16, 24, 32, 64): raise ValueError("Invalid bits_per_sample.") if bits_per_sample == 24: warnings.warn( "Saving audio with 24 bits per sample might warp samples near -1. " "Using 16 bits per sample might be able to avoid this." ) subtype = _get_subtype(src.dtype, ext, encoding, bits_per_sample) # sph is a extension used in TED-LIUM but soundfile does not recognize it as NIST format, # so we extend the extensions manually here if ext in ["nis", "nist", "sph"] and format is None: format = "NIST" if channels_first: src = src.t() soundfile.write(file=filepath, data=src, samplerate=sample_rate, subtype=subtype, format=format)

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