1 files changed, 64 insertions, 0 deletions
diff --git a/src/main/java/se/lublin/humla/audio/inputmode/ActivityInputMode.java b/src/main/java/se/lublin/humla/audio/inputmode/ActivityInputMode.java
new file mode 100644
index 0000000..d7a180f
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+++ b/src/main/java/se/lublin/humla/audio/inputmode/ActivityInputMode.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2016 Andrew Comminos <andrew@comminos.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package se.lublin.humla.audio.inputmode;
+
+/**
+ * An input mode that sends audio if the amplitude exceeds a certain threshold.
+ * Created by andrew on 13/02/16.
+ */
+public class ActivityInputMode implements IInputMode {
+    // Continue speech for 250ms to prevent dropping.
+    private static final int SPEECH_DELAY = (int) (0.25 * Math.pow(10, 9));
+
+    private float mVADThreshold;
+    private long mVADLastDetected;
+
+    public ActivityInputMode(float detectionThreshold) {
+        mVADThreshold = detectionThreshold;
+    }
+
+    @Override
+    public boolean shouldTransmit(short[] pcm, int length) {
+        // Use a logarithmic energy-based scale for VAD.
+        float sum = 1.0f;
+        for (int i = 0; i < length; i++) {
+            sum += pcm[i] * pcm[i];
+        }
+        float micLevel = (float) Math.sqrt(sum / (float)length);
+        float peakSignal = (float) (20.0f * Math.log10(micLevel / 32768.0f)) / 96.0f;
+        boolean talking = (peakSignal + 1) >= mVADThreshold;
+
+        // Record the last time where VAD was detected in order to prevent speech dropping.
+        if(talking) {
+            mVADLastDetected = System.nanoTime();
+        }
+
+        talking |= (System.nanoTime() - mVADLastDetected) < SPEECH_DELAY;
+
+        return talking;
+    }
+
+    @Override
+    public void waitForInput() {
+
+    }
+
+    public void setThreshold(float threshold) {
+        mVADThreshold = threshold;
+    }
+}