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]`.
.. warning::
``normalize`` argument does not perform volume normalization.
It only converts the sample type to `torch.float32` from the native sample
type.
When the input format is WAV with integer type, such as 32-bit signed integer, 16-bit
signed integer, 24-bit signed integer, and 8-bit unsigned integer, 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. Since torch does not
support ``int24`` dtype, 24-bit signed PCM are converted to ``int32`` tensors.
``normalize`` argument 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.
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 converts the native sample type to ``float32``.
Default: ``True``.
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)
