Move the backend implementation to _backend

test/torchaudio_unittest/backend/dispatcher/dispatcher_test.py

@@ -4,14 +4,10 @@
 import torch
 
 from parameterized import parameterized
-from torchaudio._backend.utils import (
-    FFmpegBackend,
-    get_info_func,
-    get_load_func,
-    get_save_func,
-    SoundfileBackend,
-    SoXBackend,
-)
+from torchaudio._backend.ffmpeg import FFmpegBackend
+from torchaudio._backend.soundfile import SoundfileBackend
+from torchaudio._backend.sox import SoXBackend
+from torchaudio._backend.utils import get_info_func, get_load_func, get_save_func
 from torchaudio_unittest.common_utils import PytorchTestCase
 
 
@@ -47,7 +43,7 @@ def test_info_fileobj(self, available_backends, expected_backend):
         format = "wav"
         buffer_size = 8192
         with patch("torchaudio._backend.utils.get_available_backends", return_value=available_backends), patch(
-            f"torchaudio._backend.utils.{expected_backend.__name__}.info"
+            f"{expected_backend.__module__}.{expected_backend.__name__}.info"
         ) as mock_info:
             get_info_func()(f, format=format, buffer_size=buffer_size)
             mock_info.assert_called_once_with(f, format, buffer_size)
@@ -64,7 +60,7 @@ def test_load(self, available_backends, expected_backend):
         filename = "test.wav"
         format = "wav"
         with patch("torchaudio._backend.utils.get_available_backends", return_value=available_backends), patch(
-            f"torchaudio._backend.utils.{expected_backend.__name__}.load"
+            f"{expected_backend.__module__}.{expected_backend.__name__}.load"
         ) as mock_load:
             get_load_func()(filename, format=format)
             mock_load.assert_called_once_with(filename, 0, -1, True, True, format, 4096)
@@ -83,7 +79,7 @@ def test_load_fileobj(self, available_backends, expected_backend):
         format = "wav"
         buffer_size = 8192
         with patch("torchaudio._backend.utils.get_available_backends", return_value=available_backends), patch(
-            f"torchaudio._backend.utils.{expected_backend.__name__}.load"
+            f"{expected_backend.__module__}.{expected_backend.__name__}.load"
         ) as mock_load:
             get_load_func()(f, format=format, buffer_size=buffer_size)
             mock_load.assert_called_once_with(f, 0, -1, True, True, format, buffer_size)
@@ -102,7 +98,7 @@ def test_save(self, available_backends, expected_backend):
         format = "wav"
         sample_rate = 16000
         with patch("torchaudio._backend.utils.get_available_backends", return_value=available_backends), patch(
-            f"torchaudio._backend.utils.{expected_backend.__name__}.save"
+            f"{expected_backend.__module__}.{expected_backend.__name__}.save"
         ) as mock_save:
             get_save_func()(filename, src, sample_rate, format=format)
             mock_save.assert_called_once_with(filename, src, sample_rate, True, format, None, None, 4096)
@@ -123,7 +119,7 @@ def test_save_fileobj(self, available_backends, expected_backend):
         buffer_size = 8192
         sample_rate = 16000
         with patch("torchaudio._backend.utils.get_available_backends", return_value=available_backends), patch(
-            f"torchaudio._backend.utils.{expected_backend.__name__}.save"
+            f"{expected_backend.__module__}.{expected_backend.__name__}.save"
         ) as mock_save:
             get_save_func()(f, src, sample_rate, format=format, buffer_size=buffer_size)
             mock_save.assert_called_once_with(f, src, sample_rate, True, format, None, None, buffer_size)

test/torchaudio_unittest/backend/soundfile/info_test.py

@@ -3,8 +3,8 @@
 from unittest.mock import patch
 
 import torch
+from torchaudio._backend import soundfile as soundfile_backend
 from torchaudio._internal import module_utils as _mod_utils
-from torchaudio.backend import soundfile_backend
 from torchaudio_unittest.backend.common import get_bits_per_sample, get_encoding
 from torchaudio_unittest.common_utils import (
     get_wav_data,

test/torchaudio_unittest/backend/soundfile/load_test.py

@@ -4,8 +4,8 @@
 
 import torch
 from parameterized import parameterized
+from torchaudio._backend import soundfile as soundfile_backend
 from torchaudio._internal import module_utils as _mod_utils
-from torchaudio.backend import soundfile_backend
 from torchaudio_unittest.common_utils import (
     get_wav_data,
     load_wav,

test/torchaudio_unittest/backend/soundfile/save_test.py

@@ -1,8 +1,9 @@
 import io
 from unittest.mock import patch
 
+from torchaudio._backend import soundfile as soundfile_backend
+
 from torchaudio._internal import module_utils as _mod_utils
-from torchaudio.backend import soundfile_backend
 from torchaudio_unittest.common_utils import (
     get_wav_data,
     load_wav,

test/torchaudio_unittest/backend/sox_io/info_test.py

@@ -1,7 +1,7 @@
 import itertools
 
 from parameterized import parameterized
-from torchaudio.backend import sox_io_backend
+from torchaudio._backend import sox as sox_io_backend
 from torchaudio_unittest.backend.common import get_encoding
 from torchaudio_unittest.common_utils import (
     get_asset_path,

test/torchaudio_unittest/backend/sox_io/load_test.py

@@ -2,7 +2,7 @@
 
 import torch
 from parameterized import parameterized
-from torchaudio.backend import sox_io_backend
+from torchaudio._backend import sox as sox_io_backend
 from torchaudio_unittest.common_utils import (
     get_asset_path,
     get_wav_data,

test/torchaudio_unittest/backend/sox_io/roundtrip_test.py

@@ -1,7 +1,7 @@
 import itertools
 
 from parameterized import parameterized
-from torchaudio.backend import sox_io_backend
+from torchaudio._backend import sox as sox_io_backend
 from torchaudio_unittest.common_utils import get_wav_data, PytorchTestCase, skipIfNoExec, skipIfNoSox, TempDirMixin
 
 from .common import get_enc_params, name_func

test/torchaudio_unittest/backend/sox_io/save_test.py

@@ -2,7 +2,7 @@
 
 import torch
 from parameterized import parameterized
-from torchaudio.backend import sox_io_backend
+from torchaudio._backend import sox as sox_io_backend
 from torchaudio_unittest.common_utils import (
     get_wav_data,
     load_wav,

test/torchaudio_unittest/backend/sox_io/smoke_test.py

@@ -1,7 +1,7 @@
 import itertools
 
 from parameterized import parameterized
-from torchaudio.backend import sox_io_backend
+from torchaudio._backend import sox as sox_io_backend
 from torchaudio_unittest.common_utils import get_wav_data, skipIfNoSox, TempDirMixin, TorchaudioTestCase
 
 from .common import name_func

test/torchaudio_unittest/backend/sox_io/torchscript_test.py

@@ -4,6 +4,7 @@
 import torch
 import torchaudio
 from parameterized import parameterized
+from torchaudio._backend import sox as sox_io_backend
 from torchaudio_unittest.common_utils import (
     get_wav_data,
     load_wav,
@@ -19,12 +20,12 @@
 from .common import get_enc_params, name_func
 
 
-def py_info_func(filepath: str) -> torchaudio.backend.sox_io_backend.AudioMetaData:
-    return torchaudio.backend.sox_io_backend.info(filepath)
+def py_info_func(filepath: str) -> torchaudio.AudioMetaData:
+    return sox_io_backend.info(filepath)
 
 
 def py_load_func(filepath: str, normalize: bool, channels_first: bool):
-    return torchaudio.backend.sox_io_backend.load(filepath, normalize=normalize, channels_first=channels_first)
+    return sox_io_backend.load(filepath, normalize=normalize, channels_first=channels_first)
 
 
 def py_save_func(
@@ -36,9 +37,7 @@ def py_save_func(
     encoding: Optional[str] = None,
     bits_per_sample: Optional[int] = None,
 ):
-    torchaudio.backend.sox_io_backend.save(
-        filepath, tensor, sample_rate, channels_first, compression, None, encoding, bits_per_sample
-    )
+    sox_io_backend.save(filepath, tensor, sample_rate, channels_first, compression, None, encoding, bits_per_sample)
 
 
 @skipIfNoExec("sox")

test/torchaudio_unittest/backend/utils_test.py

@@ -27,10 +27,10 @@ class TestBackendSwitch_NoBackend(BackendSwitchMixin, common_utils.TorchaudioTes
 @common_utils.skipIfNoSox
 class TestBackendSwitch_SoXIO(BackendSwitchMixin, common_utils.TorchaudioTestCase):
     backend = "sox_io"
-    backend_module = torchaudio.backend.sox_io_backend
+    backend_module = torchaudio._backend.sox
 
 
 @common_utils.skipIfNoModule("soundfile")
 class TestBackendSwitch_soundfile(BackendSwitchMixin, common_utils.TorchaudioTestCase):
     backend = "soundfile"
-    backend_module = torchaudio.backend.soundfile_backend
+    backend_module = torchaudio._backend.soundfile

torchaudio/__init__.py

@@ -11,7 +11,7 @@
     transforms,
     utils,
 )
-from .backend.common import AudioMetaData
+from ._backend.backend import AudioMetaData
 
 
 try:
@@ -20,6 +20,9 @@
     pass
 
 
+################################################################################
+# Backend stuff - to be cleaned up after 2.1 release
+################################################################################
 def _is_backend_dispatcher_enabled():
     import os
 
@@ -29,11 +32,23 @@ def _is_backend_dispatcher_enabled():
 if _is_backend_dispatcher_enabled():
     from ._backend import _init_backend, get_audio_backend, list_audio_backends, set_audio_backend
 else:
-    from .backend import _init_backend, get_audio_backend, list_audio_backends, set_audio_backend
+    from ._backend.legacy.utils import _init_backend, get_audio_backend, list_audio_backends, set_audio_backend
 
 
 _init_backend()
 
+del _init_backend
+
+
+# For backward compatibility.
+# Looking at the previous __init__.py, we did not explicitly export `backend` here
+# but, it was leaking and accessible as an attribute of torchaudio module.
+#
+# Perhaps we should remove it after couple of releases like 2.3?
+from . import backend  # noqa
+
+################################################################################
+
 
 __all__ = [
     "AudioMetaData",

torchaudio/_backend/backend.py

@@ -4,7 +4,7 @@
 
 from torch import Tensor
 
-from torchaudio.backend.common import AudioMetaData
+from .common import AudioMetaData
 
 
 class Backend(ABC):

torchaudio/_backend/common.py

@@ -0,0 +1,53 @@
+# TODO: Switch to dataclass when we completely get rid of torchscript support in I/O
+class AudioMetaData:
+    """AudioMetaData()
+
+    Return type of ``torchaudio.info`` function.
+
+    :ivar int sample_rate: Sample rate
+    :ivar int num_frames: The number of frames
+    :ivar int num_channels: The number of channels
+    :ivar int bits_per_sample: The number of bits per sample. This is 0 for lossy formats,
+        or when it cannot be accurately inferred.
+    :ivar str encoding: Audio encoding
+        The values encoding can take are one of the following:
+
+            * ``PCM_S``: Signed integer linear PCM
+            * ``PCM_U``: Unsigned integer linear PCM
+            * ``PCM_F``: Floating point linear PCM
+            * ``FLAC``: Flac, Free Lossless Audio Codec
+            * ``ULAW``: Mu-law
+            * ``ALAW``: A-law
+            * ``MP3`` : MP3, MPEG-1 Audio Layer III
+            * ``VORBIS``: OGG Vorbis
+            * ``AMR_WB``: Adaptive Multi-Rate Wideband
+            * ``AMR_NB``: Adaptive Multi-Rate Narrowband
+            * ``OPUS``: Opus
+            * ``HTK``: Single channel 16-bit PCM
+            * ``UNKNOWN`` : None of above
+    """
+
+    def __init__(
+        self,
+        sample_rate: int,
+        num_frames: int,
+        num_channels: int,
+        bits_per_sample: int,
+        encoding: str,
+    ):
+        self.sample_rate = sample_rate
+        self.num_frames = num_frames
+        self.num_channels = num_channels
+        self.bits_per_sample = bits_per_sample
+        self.encoding = encoding
+
+    def __str__(self):
+        return (
+            f"AudioMetaData("
+            f"sample_rate={self.sample_rate}, "
+            f"num_frames={self.num_frames}, "
+            f"num_channels={self.num_channels}, "
+            f"bits_per_sample={self.bits_per_sample}, "
+            f"encoding={self.encoding}"
+            f")"
+        )

torchaudio/_backend/ffmpeg.py

@@ -5,11 +5,12 @@
 
 import torch
 import torchaudio
-from torchaudio.backend.common import AudioMetaData
 from torchaudio.io import StreamWriter
 
 from .backend import Backend
 
+from .common import AudioMetaData
+
 if torchaudio._extension._FFMPEG_EXT is not None:
     StreamReaderFileObj = torchaudio._extension._FFMPEG_EXT.StreamReaderFileObj
 else:

torchaudio/backend/utils.py → torchaudio/_backend/legacy/utils.py

@@ -3,9 +3,10 @@
 from typing import List, Optional
 
 import torchaudio
+from torchaudio._backend import soundfile as soundfile_backend, sox as sox_io_backend
 from torchaudio._internal import module_utils as _mod_utils
 
-from . import no_backend, soundfile_backend, sox_io_backend
+from . import no_backend
 
 __all__ = [
     "list_audio_backends",