Hack so that multichannel doesn't crash with librosa

spleeter/separator.py

@@ -145,8 +145,10 @@ class Separator(object):
         # TODO: fix the logic, build sometimes return, sometimes set attribute
         outputs = builder.outputs
         stft = self.stft(waveform)
-        if stft.shape[-1] != 2:
+        if stft.shape[-1] == 1:
             stft = np.concatenate([stft, stft], axis=-1)
+        elif stft.shape[-1] > 2:
+            stft = stft[:, :2]
 
         saver = tf.train.Saver()
         with tf.Session() as sess: