[tf-signal] Fix exception when input shape is unknown in mfccs_from_log_mel_spectrograms.

PiperOrigin-RevId: 184400783

2 files changed, 10 insertions, 1 deletions

diff --git a/tensorflow/contrib/signal/python/kernel_tests/mfcc_ops_test.py b/tensorflow/contrib/signal/python/kernel_tests/mfcc_ops_test.py
index c04f1cf5ba..e7743bdcba 100644
--- a/tensorflow/contrib/signal/python/kernel_tests/mfcc_ops_test.py
+++ b/tensorflow/contrib/signal/python/kernel_tests/mfcc_ops_test.py
@@ -20,6 +20,7 @@ from __future__ import print_function
 
 from tensorflow.contrib.signal.python.ops import mfcc_ops
 from tensorflow.python.framework import dtypes
+from tensorflow.python.framework import tensor_shape
 from tensorflow.python.ops import array_ops
 from tensorflow.python.ops import random_ops
 from tensorflow.python.ops import spectral_ops_test_util
@@ -49,6 +50,14 @@ class MFCCTest(test.TestCase):
         signal = random_ops.random_normal((2, 3, 5))
         mfcc_ops.mfccs_from_log_mel_spectrograms(signal).eval()
 
+  def test_unknown_shape(self):
+    """A test that the op runs when shape and rank are unknown."""
+    with spectral_ops_test_util.fft_kernel_label_map():
+      with self.test_session(use_gpu=True):
+        signal = array_ops.placeholder_with_default(
+            random_ops.random_normal((2, 3, 5)), tensor_shape.TensorShape(None))
+        self.assertIsNone(signal.shape.ndims)
+        mfcc_ops.mfccs_from_log_mel_spectrograms(signal).eval()
 
 if __name__ == "__main__":
   test.main()
diff --git a/tensorflow/contrib/signal/python/ops/mfcc_ops.py b/tensorflow/contrib/signal/python/ops/mfcc_ops.py
index 6cef95f742..4e842f7f10 100644
--- a/tensorflow/contrib/signal/python/ops/mfcc_ops.py
+++ b/tensorflow/contrib/signal/python/ops/mfcc_ops.py
@@ -105,4 +105,4 @@ def mfccs_from_log_mel_spectrograms(log_mel_spectrograms, name=None):
       num_mel_bins = array_ops.shape(log_mel_spectrograms)[-1]
 
     dct2 = spectral_ops.dct(log_mel_spectrograms)
-    return dct2 * math_ops.rsqrt(num_mel_bins * 2.0)
+    return dct2 * math_ops.rsqrt(math_ops.to_float(num_mel_bins) * 2.0)