Add TorchScript-able "save" func to sox_io backend (#732)

This is a part of PRs to add new "sox_io" backend. #726 and depends on #718, #728 and #731.

This PR adds `save` function to "sox_io" backend, which can save Tensor to a file with the following audio formats;
 - `wav`
 - `mp3`
 - `flac`
 - `ogg/vorbis`

test/common_utils.py

@@ -92,28 +92,34 @@ def set_audio_backend(backend):
 class TempDirMixin:
     """Mixin to provide easy access to temp dir"""
     temp_dir_ = None
+    base_temp_dir = None
     temp_dir = None
 
-    def setUp(self):
-        super().setUp()
-        self._init_temp_dir()
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        # If TORCHAUDIO_TEST_TEMP_DIR is set, use it instead of temporary directory.
+        # this is handy for debugging.
+        key = 'TORCHAUDIO_TEST_TEMP_DIR'
+        if key in os.environ:
+            cls.base_temp_dir = os.environ[key]
+        else:
+            cls.temp_dir_ = tempfile.TemporaryDirectory()
+            cls.base_temp_dir = cls.temp_dir_.name
 
-    def tearDown(self):
+    @classmethod
+    def tearDownClass(cls):
         super().tearDownClass()
-        self._clean_up_temp_dir()
+        if isinstance(cls.temp_dir_, tempfile.TemporaryDirectory):
+            cls.temp_dir_.cleanup()
 
-    def _init_temp_dir(self):
-        self.temp_dir_ = tempfile.TemporaryDirectory()
-        self.temp_dir = self.temp_dir_.name
-
-    def _clean_up_temp_dir(self):
-        if self.temp_dir_ is not None:
-            self.temp_dir_.cleanup()
-            self.temp_dir_ = None
-            self.temp_dir = None
+    def setUp(self):
+        self.temp_dir = os.path.join(self.base_temp_dir, self.id())
 
     def get_temp_path(self, *paths):
-        return os.path.join(self.temp_dir, *paths)
+        path = os.path.join(self.temp_dir, *paths)
+        os.makedirs(os.path.dirname(path), exist_ok=True)
+        return path
 
 
 class TestBaseMixin:

test/sox_io_backend/sox_utils.py

@@ -31,7 +31,16 @@ def gen_audio_file(
             'Use get_wav_data and save_wav to generate wav file for accurate result.')
     command = [
         'sox',
-        '-V',  # verbose
+        '-V3',  # verbose
+        '-R',
+        # -R is supposed to be repeatable, though the implementation looks suspicious
+        # and not setting the seed to a fixed value.
+        # https://fossies.org/dox/sox-14.4.2/sox_8c_source.html
+        # search "sox_globals.repeatable"
+    ]
+    if bit_depth is not None:
+        command += ['--bits', str(bit_depth)]
+    command += [
         '--rate', str(sample_rate),
         '--null',  # no input
         '--channels', str(num_channels),
@@ -60,7 +69,7 @@ def convert_audio_file(
         src_path, dst_path,
         *, bit_depth=None, compression=None):
     """Convert audio file with `sox` command."""
-    command = ['sox', '-V', str(src_path)]
+    command = ['sox', '-V3', '-R', str(src_path)]
     if bit_depth is not None:
         command += ['--bits', str(bit_depth)]
     if compression is not None:

test/sox_io_backend/test_info.py

@@ -28,7 +28,7 @@ class TestInfo(TempDirMixin, PytorchTestCase):
     def test_wav(self, dtype, sample_rate, num_channels):
         """`sox_io_backend.info` can check wav file correctly"""
         duration = 1
-        path = self.get_temp_path(f'{dtype}_{sample_rate}_{num_channels}.wav')
+        path = self.get_temp_path('data.wav')
         data = get_wav_data(dtype, num_channels, normalize=False, num_frames=duration * sample_rate)
         save_wav(path, data, sample_rate)
         info = sox_io_backend.info(path)
@@ -44,7 +44,7 @@ def test_wav(self, dtype, sample_rate, num_channels):
     def test_wav_multiple_channels(self, dtype, sample_rate, num_channels):
         """`sox_io_backend.info` can check wav file with channels more than 2 correctly"""
         duration = 1
-        path = self.get_temp_path(f'{dtype}_{sample_rate}_{num_channels}.wav')
+        path = self.get_temp_path('data.wav')
         data = get_wav_data(dtype, num_channels, normalize=False, num_frames=duration * sample_rate)
         save_wav(path, data, sample_rate)
         info = sox_io_backend.info(path)
@@ -60,7 +60,7 @@ def test_wav_multiple_channels(self, dtype, sample_rate, num_channels):
     def test_mp3(self, sample_rate, num_channels, bit_rate):
         """`sox_io_backend.info` can check mp3 file correctly"""
         duration = 1
-        path = self.get_temp_path(f'{sample_rate}_{num_channels}_{bit_rate}k.mp3')
+        path = self.get_temp_path('data.mp3')
         sox_utils.gen_audio_file(
             path, sample_rate, num_channels,
             compression=bit_rate, duration=duration,
@@ -79,7 +79,7 @@ def test_mp3(self, sample_rate, num_channels, bit_rate):
     def test_flac(self, sample_rate, num_channels, compression_level):
         """`sox_io_backend.info` can check flac file correctly"""
         duration = 1
-        path = self.get_temp_path(f'{sample_rate}_{num_channels}_{compression_level}.flac')
+        path = self.get_temp_path('data.flac')
         sox_utils.gen_audio_file(
             path, sample_rate, num_channels,
             compression=compression_level, duration=duration,
@@ -97,7 +97,7 @@ def test_flac(self, sample_rate, num_channels, compression_level):
     def test_vorbis(self, sample_rate, num_channels, quality_level):
         """`sox_io_backend.info` can check vorbis file correctly"""
         duration = 1
-        path = self.get_temp_path(f'{sample_rate}_{num_channels}_{quality_level}.vorbis')
+        path = self.get_temp_path('data.vorbis')
         sox_utils.gen_audio_file(
             path, sample_rate, num_channels,
             compression=quality_level, duration=duration,

test/sox_io_backend/test_load.py

@@ -24,7 +24,7 @@ def assert_wav(self, dtype, sample_rate, num_channels, normalize, duration):
 
         Wav data loaded with sox_io backend should match those with scipy
         """
-        path = self.get_temp_path(f'{dtype}_{sample_rate}_{num_channels}_{normalize}.wav')
+        path = self.get_temp_path('reference.wav')
         data = get_wav_data(dtype, num_channels, normalize=normalize, num_frames=duration * sample_rate)
         save_wav(path, data, sample_rate)
         expected = load_wav(path, normalize=normalize)[0]
@@ -58,8 +58,8 @@ def assert_mp3(self, sample_rate, num_channels, bit_rate, duration):
         By combining i & ii, step 2. and 4. allows to load reference mp3 data
         without using torchaudio
         """
-        path = self.get_temp_path(f'{sample_rate}_{num_channels}_{bit_rate}_{duration}.mp3')
-        ref_path = f'{path}.wav'
+        path = self.get_temp_path('1.original.mp3')
+        ref_path = self.get_temp_path('2.reference.wav')
 
         # 1. Generate mp3 with sox
         sox_utils.gen_audio_file(
@@ -80,8 +80,8 @@ def assert_flac(self, sample_rate, num_channels, compression_level, duration):
 
         This test takes the same strategy as mp3 to compare the result
         """
-        path = self.get_temp_path(f'{sample_rate}_{num_channels}_{compression_level}_{duration}.flac')
-        ref_path = f'{path}.wav'
+        path = self.get_temp_path('1.original.flac')
+        ref_path = self.get_temp_path('2.reference.wav')
 
         # 1. Generate flac with sox
         sox_utils.gen_audio_file(
@@ -102,8 +102,8 @@ def assert_vorbis(self, sample_rate, num_channels, quality_level, duration):
 
         This test takes the same strategy as mp3 to compare the result
         """
-        path = self.get_temp_path(f'{sample_rate}_{num_channels}_{quality_level}_{duration}.vorbis')
-        ref_path = f'{path}.wav'
+        path = self.get_temp_path('1.original.vorbis')
+        ref_path = self.get_temp_path('2.reference.wav')
 
         # 1. Generate vorbis with sox
         sox_utils.gen_audio_file(

test/sox_io_backend/test_roundtrip.py

@@ -0,0 +1,52 @@
+import itertools
+
+from torchaudio.backend import sox_io_backend
+from parameterized import parameterized
+
+from ..common_utils import (
+    TempDirMixin,
+    PytorchTestCase,
+    skipIfNoExec,
+    skipIfNoExtension,
+)
+from .common import (
+    get_test_name,
+    get_wav_data,
+)
+
+
+@skipIfNoExec('sox')
+@skipIfNoExtension
+class TestRoundTripIO(TempDirMixin, PytorchTestCase):
+    """save/load round trip should not degrade data for lossless formats"""
+    @parameterized.expand(list(itertools.product(
+        ['float32', 'int32', 'int16', 'uint8'],
+        [8000, 16000],
+        [1, 2],
+    )), name_func=get_test_name)
+    def test_wav(self, dtype, sample_rate, num_channels):
+        """save/load round trip should not degrade data for wav formats"""
+        original = get_wav_data(dtype, num_channels, normalize=False)
+        data = original
+        for i in range(10):
+            path = self.get_temp_path(f'{i}.wav')
+            sox_io_backend.save(path, data, sample_rate)
+            data, sr = sox_io_backend.load(path, normalize=False)
+            assert sr == sample_rate
+            self.assertEqual(original, data)
+
+    @parameterized.expand(list(itertools.product(
+        [8000, 16000],
+        [1, 2],
+        list(range(9)),
+    )), name_func=get_test_name)
+    def test_flac(self, sample_rate, num_channels, compression_level):
+        """save/load round trip should not degrade data for flac formats"""
+        original = get_wav_data('float32', num_channels)
+        data = original
+        for i in range(10):
+            path = self.get_temp_path(f'{i}.flac')
+            sox_io_backend.save(path, data, sample_rate, compression=compression_level)
+            data, sr = sox_io_backend.load(path)
+            assert sr == sample_rate
+            self.assertEqual(original, data)