fix output type

Signed-off-by: David Slater <[email protected]>

Author: davidslater

art/defences/preprocessor/mp3_compression.py

@@ -115,6 +115,7 @@ def wav_to_mp3(x, sample_rate):
                 x_mp3 = x_mp3 * 2 ** -15
             return x_mp3.astype(x_dtype)
 
+        x_orig_type = x.dtype
         if x.dtype != object and x.ndim == 2:
             x = x.astype(object)
 
@@ -149,6 +150,9 @@ def wav_to_mp3(x, sample_rate):
         if x.dtype != object and self.channels_first:
             x_mp3 = np.swapaxes(x_mp3, 1, 2)
 
+        if x_orig_type != object and x.dtype == object and x.ndim == 2:
+            x_mp3 = x_mp3.astype(x_orig_type)
+
         return x_mp3, y
 
     def _check_params(self) -> None: