plectrum

commit df2fe15d3fad657871fea75d1e4aead4c9c8b1cc
parent a98751f74deeb268d62fe35a8a81706d38632057
Author: gstraube <gstraube@mailbox.org>
Date:   Thu, 25 May 2017 14:30:02 +0200

Find closest note to detected pitch and calculate the deviation in cent

Diffstat:
M
app/build.gradle
 | 
1
+
M
app/src/main/java/com/github/cythara/MainActivity.java
 | 
11
+++++++++--
A
app/src/main/java/com/github/cythara/Note.java
 | 
27
+++++++++++++++++++++++++++
A
app/src/main/java/com/github/cythara/PitchComparator.java
 | 
34
++++++++++++++++++++++++++++++++++
A
app/src/main/java/com/github/cythara/PitchDifference.java
 | 
12
++++++++++++
A
app/src/test/java/com/github/cythara/PitchComparatorTest.java
 | 
31
+++++++++++++++++++++++++++++++

6 files changed, 114 insertions(+), 2 deletions(-)
diff --git a/app/build.gradle b/app/build.gradle
@@ -27,4 +27,5 @@ dependencies {
     compile 'com.android.support:appcompat-v7:25.3.1'
     compile 'com.android.support.constraint:constraint-layout:1.0.2'
     testCompile 'junit:junit:4.12'
+    testCompile group: 'org.hamcrest', name: 'hamcrest-all', version: '1.3'
 }
diff --git a/app/src/main/java/com/github/cythara/MainActivity.java b/app/src/main/java/com/github/cythara/MainActivity.java
@@ -8,6 +8,7 @@ import android.util.Log;
 import android.widget.TextView;
 
 import java.lang.ref.WeakReference;
+import java.util.Locale;
 
 import be.tarsos.dsp.AudioDispatcher;
 import be.tarsos.dsp.AudioEvent;
@@ -56,13 +57,19 @@ public class MainActivity extends AppCompatActivity {
                         float pitch = pitchDetectionResult.getPitch();
 
                         if (pitch != -1) {
+                            PitchDifference pitchDifference = PitchComparator.retrieveNote(pitch);
+
+                            String msg = String.format(Locale.US, "Closest: %s Diff: %f Freq: %f",
+                                    pitchDifference.closest.getGuitarString(),
+                                    pitchDifference.deviation, pitch);
+
                             Message message = new Message();
                             Bundle bundle = new Bundle();
-                            bundle.putString("pitch", String.valueOf(pitch));
+                            bundle.putString("pitch", msg);
                             message.setData(bundle);
                             activity.updateHandler.sendMessage(message);
 
-                            Log.d("com.github.cythara", "Pitch: " + pitch);
+                            Log.d("com.github.cythara", msg);
                         }
                     }
                 };
diff --git a/app/src/main/java/com/github/cythara/Note.java b/app/src/main/java/com/github/cythara/Note.java
@@ -0,0 +1,27 @@
+package com.github.cythara;
+
+enum Note {
+
+    E2("E", 82.41f),
+    A2("A", 110f),
+    D3("D", 146.83f),
+    G3("G", 196f),
+    B3("B", 246.94f),
+    E4("E", 329.63f);
+
+    private final String guitarString;
+    private final float frequency;
+
+    Note(String guitarString, float frequency) {
+        this.guitarString = guitarString;
+        this.frequency = frequency;
+    }
+
+    public String getGuitarString() {
+        return guitarString;
+    }
+
+    public float getFrequency() {
+        return frequency;
+    }
+}
diff --git a/app/src/main/java/com/github/cythara/PitchComparator.java b/app/src/main/java/com/github/cythara/PitchComparator.java
@@ -0,0 +1,34 @@
+package com.github.cythara;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+class PitchComparator {
+
+    static PitchDifference retrieveNote(float pitch) {
+        Note[] notes = Note.values();
+        Arrays.sort(notes, new Comparator<Note>() {
+            @Override
+            public int compare(Note o1, Note o2) {
+                return Float.compare(o1.getFrequency(), o2.getFrequency());
+            }
+        });
+
+        double minCentDifference = Float.POSITIVE_INFINITY;
+        Note closest = Note.E4;
+        for (Note note : notes) {
+            double centDifference = 1200d * log2(note.getFrequency() / pitch);
+
+            if (Math.abs(centDifference) < Math.abs(minCentDifference)) {
+                minCentDifference = centDifference;
+                closest = note;
+            }
+        }
+
+        return new PitchDifference(closest, minCentDifference);
+    }
+
+    private static double log2(float number) {
+        return Math.log(number) / Math.log(2);
+    }
+}
diff --git a/app/src/main/java/com/github/cythara/PitchDifference.java b/app/src/main/java/com/github/cythara/PitchDifference.java
@@ -0,0 +1,12 @@
+package com.github.cythara;
+
+class PitchDifference {
+
+    final Note closest;
+    final double deviation;
+
+    PitchDifference(Note closest, double deviation) {
+        this.closest = closest;
+        this.deviation = deviation;
+    }
+}
diff --git a/app/src/test/java/com/github/cythara/PitchComparatorTest.java b/app/src/test/java/com/github/cythara/PitchComparatorTest.java
@@ -0,0 +1,31 @@
+package com.github.cythara;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static com.github.cythara.Note.*;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.Matchers.closeTo;
+
+public class PitchComparatorTest {
+
+    @Test
+    public void retrieveNote() throws Exception {
+        Map<Float, PitchDifference> expectations = new HashMap<>();
+        expectations.put(20f, new PitchDifference(E2, 2451.3832933619105));
+        expectations.put(500f, new PitchDifference(E4, -721.296654095616));
+        expectations.put(197.67f, new PitchDifference(G3, -14.688333908767358));
+        expectations.put(128.415f, new PitchDifference(D3, 231.99964198777823));
+
+        for (Float pitch : expectations.keySet()) {
+            PitchDifference actual = PitchComparator.retrieveNote(pitch);
+            PitchDifference expected = expectations.get(pitch);
+
+            Assert.assertThat(actual.closest, is(expected.closest));
+            Assert.assertThat(actual.deviation, closeTo(expected.deviation, 0.001));
+        }
+    }
+}