Clap processor: remove wasteful np.stack operations (#27454)

remove wasteful np.stack

Np.stack on large 1-D tensor, causing ~0.5s processing time on short audio (<10s). Compared to 0.02s for medium length audio

src/transformers/models/clap/feature_extraction_clap.py

@@ -242,10 +242,10 @@ class ClapFeatureExtractor(SequenceFeatureExtractor):
             if waveform.shape[0] < max_length:
                 if padding == "repeat":
                     n_repeat = int(max_length / len(waveform))
-                    waveform = np.stack(np.tile(waveform, n_repeat + 1))[:max_length]
+                    waveform = np.tile(waveform, n_repeat + 1)[:max_length]
                 if padding == "repeatpad":
                     n_repeat = int(max_length / len(waveform))
-                    waveform = np.stack(np.tile(waveform, n_repeat))
+                    waveform = np.tile(waveform, n_repeat)
                 waveform = np.pad(waveform, (0, max_length - waveform.shape[0]), mode="constant", constant_values=0)
 
             if truncation == "fusion":