# HG changeset patch
# User Chris Cannam
# Date 1349707327 -3600
# Node ID cb43d088e36923727f5cdf5a35030456a0cb66b2
# Parent  7fc62809da94dac81c318025eb2dcfe77a78fb56
Implement and test detection function

diff -r 7fc62809da94 -r cb43d088e369 tempo_estimator.py
--- a/tempo_estimator.py	Mon Oct 08 15:34:50 2012 +0100
+++ b/tempo_estimator.py	Mon Oct 08 15:42:07 2012 +0100
@@ -1,9 +1,23 @@
 
 import audiofile as af
+import numpy as np
+import framer as fr
+import signal_processing as sp
+
+def detection_function(samples, hop):
+    """Given some samples and a hop size, return a function corresponding to the interest level of the samples at intervals of the hop size."""
+    n_frames = fr.get_frame_count(len(samples), hop)
+    df = np.zeros(n_frames)
+    for n in range(0, n_frames):
+        frame = fr.get_frame(samples, hop, n)
+        value = sp.rms(frame)
+        df[n] = value
+    return df
 
 def estimate_tempo_of_samples(samples, samplerate):
     """Given some audio samples and their samplerate, return their estimated tempo in bpm."""
-    df = detection_function(samples)
+    hop = 512
+    df = detection_function(samples, hop)
     acf = autocorrelation(df)
     tempo = find_tempo_from_autocorrelation(acf)
     return tempo
diff -r 7fc62809da94 -r cb43d088e369 test_tempo_estimator.py
--- a/test_tempo_estimator.py	Mon Oct 08 15:34:50 2012 +0100
+++ b/test_tempo_estimator.py	Mon Oct 08 15:42:07 2012 +0100
@@ -1,5 +1,13 @@
 
 import tempo_estimator as est
+import numpy as np
+
+def test_detection_function():
+    samples = np.array([1,0, 0,0, 0,0, 1,0, 0,0])
+    df = est.detection_function(samples, 2)
+    assert len(df) == 5
+    assert df[3] > df[2]
+    assert df[0] > df[2]
 
 def test_tempo_120bpm():
     tempo = est.estimate_tempo_of_file('testfiles/120bpm.wav')