Fix crash in CPU mode.

Signed-off-by: Daniel Galvez <[email protected]>

nemo/collections/asr/parts/preprocessing/features.py

@@ -63,8 +63,12 @@ def normalize_batch(x, seq_len, normalize_type):
         batch_size = x.shape[0]
         max_time = x.shape[2]
 
-        # When doing stream capture to a graph, item() is not allowed becuase it calls cudaStreamSynchronize()
-        if not torch.cuda.is_current_stream_capturing() and torch.any(seq_len == 1).item():
+        # When doing stream capture to a graph, item() is not allowed
+        # becuase it calls cudaStreamSynchronize(). Therefore, we are
+        # sacrificing some error checking when running with cuda graphs.
+        if (torch.cuda.is_available()
+            and not torch.cuda.is_current_stream_capturing()
+            and torch.any(seq_len == 1).item()):
             raise ValueError(
                 "normalize_batch with `per_feature` normalize_type received a tensor of length 1. This will result "
                 "in torch.std() returning nan. Make sure your audio length has enough samples for a single "