Add test for MP3-in-WAV.

Author: psobot

tests/audio/correct/mp3_in_wav_44100Hz.wav

@@ -1290,6 +1290,26 @@ def test_real_mp3_parsing_with_no_channels():
         assert f.read(f.frames).shape == (0, 0)
 
 
+def test_mp3_in_wav_format():
+    """
+    Test reading WAV files that contain MP3-compressed audio data
+    (WAVE_FORMAT_MPEGLAYER3, format tag 0x55).
+
+    This is a valid but unusual format where a WAV container holds MP3 data.
+    Some audio software produces files in this format.
+    """
+    filename = os.path.join(os.path.dirname(__file__), "audio", "correct", "mp3_in_wav_44100Hz.wav")
+    with pedalboard.io.AudioFile(filename) as f:
+        assert f.samplerate == 44100
+        assert f.num_channels == 2
+        assert f.frames >= 44100  # At least 1 second of audio
+
+        # Read the audio and verify it's not silent
+        audio = f.read(f.frames)
+        assert audio.shape[0] == 2
+        assert np.amax(np.abs(audio)) > 0.1  # Should have actual audio content
+
+
 @pytest.mark.parametrize("samplerate", [44100, 32000])
 @pytest.mark.parametrize("chunk_size", [1, 2, 16])
 @pytest.mark.parametrize("target_samplerate", [44100, 32000, 22050, 1234.56])