Add AudioCompression (ulaw)

README.md

@@ -21,6 +21,9 @@ and streams audio. Room for improvement includes:
 At the time this project was forked from _Protect Baby Monitor_ there was no obvious open source solution for a
 baby monitor for Android in F-Droid.
 
+# License information
+_Child Monitor_ is licensed under the GPLv3. The Ulaw encoding / decoding code is licensed under the Apache License, Version 2.0 and taken from the Android Open Source Project.
+
 # Thanks
 Audio file originals from [freesound](https://freesound.org).
 This whole project originally created by [brarcher](https://github.com/brarcher/protect-baby-monitor).

app/src/main/java/de/rochefort/childmonitor/AudioCodecDefines.java

@@ -18,13 +18,15 @@ package de.rochefort.childmonitor;
 
 import android.media.AudioFormat;
 
+import de.rochefort.childmonitor.audio.G711UCodec;
+
 public class AudioCodecDefines {
     public static final int FREQUENCY = 11025;
     public static final int ENCODING = AudioFormat.ENCODING_PCM_16BIT;
+    public static final G711UCodec CODEC = new G711UCodec();
     public static final int CHANNEL_CONFIGURATION_IN = AudioFormat.CHANNEL_IN_MONO;
     public static final int CHANNEL_CONFIGURATION_OUT = AudioFormat.CHANNEL_OUT_MONO;
 
-
     private AudioCodecDefines() {
         throw new IllegalStateException("Do not instantiate!");
     }

app/src/main/java/de/rochefort/childmonitor/AudioListener.java

@@ -17,5 +17,5 @@
 package de.rochefort.childmonitor;
 
 public interface AudioListener {
-    void onAudio(byte[] audioBytes);
+    void onAudio(short[] audioBytes);
 }

app/src/main/java/de/rochefort/childmonitor/ListenActivity.java

@@ -16,6 +16,8 @@
  */
 package de.rochefort.childmonitor;
 
+import static de.rochefort.childmonitor.AudioCodecDefines.CODEC;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.Socket;
@@ -31,6 +33,8 @@ import android.widget.TextView;
 import android.support.v4.app.NotificationCompat;
 import android.support.v4.app.NotificationManagerCompat;
 
+import de.rochefort.childmonitor.audio.G711UCodec;
+
 public class ListenActivity extends Activity
 {
     final String TAG = "ChildMonitor";
@@ -69,21 +73,26 @@ public class ListenActivity extends Activity
 
         try
         {
-            final byte [] buffer = new byte[byteBufferSize];
+            final byte [] readBuffer = new byte[byteBufferSize];
+            final short [] decodedBuffer = new short[byteBufferSize*2];
 
             while(socket.isConnected() && read != -1 && Thread.currentThread().isInterrupted() == false)
             {
-                read = is.read(buffer);
+                read = is.read(readBuffer);
+                int decoded = CODEC.decode(decodedBuffer, readBuffer, read, 0);
 
-                if(read > 0)
+                if(decoded > 0)
                 {
-                    audioTrack.write(buffer, 0, read);
+                    audioTrack.write(decodedBuffer, 0, decoded);
-                    byte[] readBytes = new byte[read];
+                    short[] decodedBytes = new short[decoded];
-                    System.arraycopy(buffer, 0, readBytes, 0, read);
+                    System.arraycopy(decodedBuffer, 0, decodedBytes, 0, decoded);
-                    listener.onAudio(readBytes);
+                    listener.onAudio(decodedBytes);
                 }
             }
         }
+        catch (Exception e) {
+            Log.e(TAG, "Connection failed", e);
+        }
         finally
         {
             audioTrack.stop();
@@ -125,7 +134,7 @@ public class ListenActivity extends Activity
 
         final AudioListener listener = new AudioListener() {
             @Override
-            public void onAudio(final byte[] audioData) {
+            public void onAudio(final short[] audioData) {
                 runOnUiThread(new Runnable() {
                     @Override
                     public void run() {

app/src/main/java/de/rochefort/childmonitor/MonitorActivity.java

@@ -16,6 +16,8 @@
  */
 package de.rochefort.childmonitor;
 
+import static de.rochefort.childmonitor.AudioCodecDefines.CODEC;
+
 import java.io.IOException;
 import java.io.OutputStream;
 import java.net.InetAddress;
@@ -53,13 +55,9 @@ public class MonitorActivity extends Activity {
     private int currentPort;
 
     private void serviceConnection(Socket socket) {
-            runOnUiThread(new Runnable() {
+            runOnUiThread(() -> {
-                @Override
-                public void run()
-                {
                 final TextView statusText = (TextView) findViewById(R.id.textStatus);
                 statusText.setText(R.string.streaming);
-                }
             });
 
             final int frequency = AudioCodecDefines.FREQUENCY;
@@ -75,21 +73,24 @@ public class MonitorActivity extends Activity {
                     bufferSize
             );
 
-            final int byteBufferSize = bufferSize*2;
+            final int pcmBufferSize = bufferSize*2;
-            final byte[] buffer = new byte[byteBufferSize];
+            final short[] pcmBuffer = new short[pcmBufferSize];
+            final byte[] ulawBuffer = new byte[pcmBufferSize];
 
             try {
                 audioRecord.startRecording();
                 final OutputStream out = socket.getOutputStream();
 
-                socket.setSendBufferSize(byteBufferSize);
+                socket.setSendBufferSize(pcmBufferSize);
                 Log.d(TAG, "Socket send buffer size: " + socket.getSendBufferSize());
 
                 while (socket.isConnected() && !Thread.currentThread().isInterrupted()) {
-                    final int read = audioRecord.read(buffer, 0, bufferSize);
+                    final int read = audioRecord.read(pcmBuffer, 0, bufferSize);
-                    out.write(buffer, 0, read);
+                    int encoded = CODEC.encode(pcmBuffer, read, ulawBuffer, 0);
+                    out.write(ulawBuffer, 0, encoded);
+
                 }
-            } catch (IOException e) {
+            } catch (Exception e) {
                 Log.e(TAG, "Connection failed", e);
             } finally {
                 audioRecord.stop();
@@ -109,10 +110,7 @@ public class MonitorActivity extends Activity {
         final Object currentToken = new Object();
         connectionToken = currentToken;
 
-        new Thread(new Runnable() {
+        new Thread(() -> {
-            @Override
-            public void run()
-            {
             while(Objects.equals(connectionToken, currentToken)) {
                 try (ServerSocket serverSocket = new ServerSocket(currentPort)) {
                     currentSocket = serverSocket;
@@ -133,13 +131,12 @@ public class MonitorActivity extends Activity {
                         unregisterService();
                         serviceConnection(socket);
                     }
-                    } catch(IOException e) {
+                } catch(Exception e) {
                     // Just in case
                     currentPort++;
                     Log.e(TAG, "Failed to open server socket. Port increased to " + currentPort, e);
                 }
             }
-            }
         }).start();
 
         final TextView addressText = findViewById(R.id.address);

app/src/main/java/de/rochefort/childmonitor/VolumeView.java

@@ -56,7 +56,7 @@ public class VolumeView extends View {
         paint.setColor(Color.rgb(255, 127, 0));
     }
 
-    public void onAudioData(byte[] data) {
+    public void onAudioData(short[] data) {
         double sum = 0;
         for (int i = 0; i < data.length; i++) {
             double rel = data[i] / ((double)128);
@@ -94,7 +94,7 @@ public class VolumeView extends View {
         double margins = height * 0.1;
         double graphHeight = height - 2*margins;
         int leftMost = Math.max(0, volumeHistory.size() - width);
-        int yPrev = (int) (graphHeight - margins);
+        int yPrev = (int) (height - margins);
         for (int i = leftMost; i < volumeHistory.size() && i - leftMost < width; i++) {
             int xNext = i - leftMost;
             int yNext = (int) (margins + graphHeight - volumeHistory.get(i) / maxVolume * (graphHeight));

app/src/main/java/de/rochefort/childmonitor/audio/G711UCodec.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Taken from https://android.googlesource.com/platform/external/nist-sip/+/6f95fdeab4481188b6260041b41d1db12b101266/src/com/android/sip/media/G711UCodec.java
+ *
+ */
+package de.rochefort.childmonitor.audio;
+/**
+ * G.711 codec. This class provides u-law conversion.
+ */
+public class G711UCodec {
+    // s00000001wxyz...s000wxyz
+    // s0000001wxyza...s001wxyz
+    // s000001wxyzab...s010wxyz
+    // s00001wxyzabc...s011wxyz
+    // s0001wxyzabcd...s100wxyz
+    // s001wxyzabcde...s101wxyz
+    // s01wxyzabcdef...s110wxyz
+    // s1wxyzabcdefg...s111wxyz
+    private static byte[] table13to8 = new byte[8192];
+    private static short[] table8to16 = new short[256];
+    static {
+        // b13 --> b8
+        for (int p = 1, q = 0; p <= 0x80; p <<= 1, q+=0x10) {
+            for (int i = 0, j = (p << 4) - 0x10; i < 16; i++, j += p) {
+                int v = (i + q) ^ 0x7F;
+                byte value1 = (byte) v;
+                byte value2 = (byte) (v + 128);
+                for (int m = j, e = j + p; m < e; m++) {
+                    table13to8[m] = value1;
+                    table13to8[8191 - m] = value2;
+                }
+            }
+        }
+        // b8 --> b16
+        for (int q = 0; q <= 7; q++) {
+            for (int i = 0, m = (q << 4); i < 16; i++, m++) {
+                int v = (((i + 0x10) << q) - 0x10) << 3;
+                table8to16[m ^ 0x7F] = (short) v;
+                table8to16[(m ^ 0x7F) + 128] = (short) (65536 - v);
+            }
+        }
+    }
+    public int decode(short[] b16, byte[] ulaw, int count, int offset) {
+        for (int i = 0, j = offset; i < count; i++, j++) {
+            b16[i] = table8to16[ulaw[j] & 0xFF];
+        }
+        return count;
+    }
+    public int encode(short[] b16, int count, byte[] b8, int offset) {
+        for (int i = 0, j = offset; i < count; i++, j++) {
+            b8[j] = table13to8[(b16[i] >> 4) & 0x1FFF];
+        }
+        return count;
+    }
+    public int getSampleCount(int frameSize) {
+        return frameSize;
+    }
+}