fix downbeat output bug

CHANGES.rst

@@ -4,6 +4,10 @@ Release Notes
 Version 0.14.dev
 ----------------
 
+Bug fixes:
+
+* Fix downbeat output bug (#128)
+
 API relevant changes:
 
 * Refactored the `ml.rnn` to `ml.nn` and converted the models to pickles (#110)

madmom/features/beats.py

@@ -1022,7 +1022,7 @@ def process(self, activations):
                            beat_numbers[beat_positions])).T
         # return the downbeats or beats and their beat number
         if self.downbeats:
-            return beats[beats[:, 1] == 1][0, :]
+            return beats[beats[:, 1] == 1][:, 0]
         else:
             return beats
 

tests/test_bin.py

@@ -258,6 +258,7 @@ def setUp(self):
                                        ACTIVATIONS_PATH)
         self.result = np.loadtxt("%s/sample.gmm_pattern_tracker.txt" %
                                  DETECTIONS_PATH)
+        self.downbeat_result = self.result[self.result[:, 1] == 1][:, 0]
 
     def test_help(self):
         _, ret_code = run_program([self.bin, '-h'])
@@ -295,6 +296,11 @@ def test_run(self):
         result = np.fromstring(data, sep='\n').reshape((-1, 2))
         self.assertTrue(np.allclose(result, self.result))
 
+    def test_run_downbeats(self):
+        data, _ = run_program([self.bin, '--downbeats', 'single', sample_file])
+        result = np.fromstring(data, sep='\n')
+        self.assertTrue(np.allclose(result, self.downbeat_result))
+
 
 class TestLogFiltSpecFluxProgram(unittest.TestCase):
 

tests/test_features_beats.py

@@ -132,3 +132,8 @@ def test_process(self):
         self.assertTrue(np.allclose(beats, [[0.08, 3], [0.42, 4], [0.76, 1],
                                             [1.1, 2], [1.44, 3], [1.78, 4],
                                             [2.12, 1], [2.46, 2], [2.8, 3]]))
+
+    def test_process_downbeats(self):
+        self.processor.downbeats = True
+        beats = self.processor(sample_mb_features)
+        self.assertTrue(np.allclose(beats, [0.76, 2.12]))