Fix Audio feature mp3 resampling (#3096)

* Test resampling dataset with mp3 Audio feature

* Fix resampling mp3 Audio feature

* Fix resampling mp3 Audio feature

* Fix test

src/datasets/features/audio.py

@@ -64,14 +64,14 @@ def _decode_example_with_torchaudio(self, value):
             raise ImportError("To support decoding 'mp3' audio files, please install 'sox'.") from err
 
         array, sampling_rate = torchaudio.load(value)
-        array = array.numpy()
-        if self.mono:
-            array = array.mean(axis=0)
         if self.sampling_rate and self.sampling_rate != sampling_rate:
             if not hasattr(self, "_resampler"):
                 self._resampler = T.Resample(sampling_rate, self.sampling_rate)
-            array = self._resampler(array, sampling_rate, self.sampling_rate)
+            array = self._resampler(array)
             sampling_rate = self.sampling_rate
+        array = array.numpy()
+        if self.mono:
+            array = array.mean(axis=0)
         return array, sampling_rate
 
     def decode_batch(self, values):

tests/features/test_audio.py

@@ -122,6 +122,34 @@ def test_resampling_at_loading_dataset_with_audio_feature(shared_datadir):
     assert column[0]["sampling_rate"] == 16000
 
 
+@require_sox
+@require_sndfile
+def test_resampling_at_loading_dataset_with_audio_feature_mp3(shared_datadir):
+    audio_path = str(shared_datadir / "test_audio_44100.mp3")
+    data = {"audio": [audio_path]}
+    features = Features({"audio": Audio(sampling_rate=16000)})
+    dset = Dataset.from_dict(data, features=features)
+    item = dset[0]
+    assert item.keys() == {"audio"}
+    assert item["audio"].keys() == {"path", "array", "sampling_rate"}
+    assert item["audio"]["path"] == audio_path
+    assert item["audio"]["array"].shape == (39707,)
+    assert item["audio"]["sampling_rate"] == 16000
+    batch = dset[:1]
+    assert batch.keys() == {"audio"}
+    assert len(batch["audio"]) == 1
+    assert batch["audio"][0].keys() == {"path", "array", "sampling_rate"}
+    assert batch["audio"][0]["path"] == audio_path
+    assert batch["audio"][0]["array"].shape == (39707,)
+    assert batch["audio"][0]["sampling_rate"] == 16000
+    column = dset["audio"]
+    assert len(column) == 1
+    assert column[0].keys() == {"path", "array", "sampling_rate"}
+    assert column[0]["path"] == audio_path
+    assert column[0]["array"].shape == (39707,)
+    assert column[0]["sampling_rate"] == 16000
+
+
 @require_sndfile
 def test_resampling_after_loading_dataset_with_audio_feature(shared_datadir):
     audio_path = str(shared_datadir / "test_audio_44100.wav")
@@ -152,6 +180,37 @@ def test_resampling_after_loading_dataset_with_audio_feature(shared_datadir):
     assert column[0]["sampling_rate"] == 16000
 
 
+@require_sox
+@require_sndfile
+def test_resampling_after_loading_dataset_with_audio_feature_mp3(shared_datadir):
+    audio_path = str(shared_datadir / "test_audio_44100.mp3")
+    data = {"audio": [audio_path]}
+    features = Features({"audio": Audio()})
+    dset = Dataset.from_dict(data, features=features)
+    item = dset[0]
+    assert item["audio"]["sampling_rate"] == 44100
+    dset = dset.cast_column("audio", Audio(sampling_rate=16000))
+    item = dset[0]
+    assert item.keys() == {"audio"}
+    assert item["audio"].keys() == {"path", "array", "sampling_rate"}
+    assert item["audio"]["path"] == audio_path
+    assert item["audio"]["array"].shape == (39707,)
+    assert item["audio"]["sampling_rate"] == 16000
+    batch = dset[:1]
+    assert batch.keys() == {"audio"}
+    assert len(batch["audio"]) == 1
+    assert batch["audio"][0].keys() == {"path", "array", "sampling_rate"}
+    assert batch["audio"][0]["path"] == audio_path
+    assert batch["audio"][0]["array"].shape == (39707,)
+    assert batch["audio"][0]["sampling_rate"] == 16000
+    column = dset["audio"]
+    assert len(column) == 1
+    assert column[0].keys() == {"path", "array", "sampling_rate"}
+    assert column[0]["path"] == audio_path
+    assert column[0]["array"].shape == (39707,)
+    assert column[0]["sampling_rate"] == 16000
+
+
 @require_sndfile
 def test_dataset_with_audio_feature_map_is_not_decoded(shared_datadir):
     audio_path = str(shared_datadir / "test_audio_44100.wav")