Capture device audio WIP

Co-authored-by: Romain Vimont <rom@rom1v.com>
Signed-off-by: Romain Vimont <rom@rom1v.com>

server/src/main/java/com/genymobile/scrcpy/AudioEncoder.java

@@ -0,0 +1,74 @@
+package com.genymobile.scrcpy;
+
+import com.genymobile.scrcpy.wrappers.ServiceManager;
+
+import android.annotation.SuppressLint;
+import android.annotation.TargetApi;
+import android.content.ComponentName;
+import android.content.Intent;
+import android.media.AudioFormat;
+import android.media.AudioRecord;
+import android.media.MediaRecorder;
+import android.os.Build;
+import android.os.SystemClock;
+
+public final class AudioEncoder {
+
+    private static final int SAMPLE_RATE = 48000;
+    private static final int CHANNELS = 2;
+
+    private Thread thread;
+
+    private static AudioFormat createAudioFormat() {
+        AudioFormat.Builder builder = new AudioFormat.Builder();
+        builder.setEncoding(AudioFormat.ENCODING_PCM_16BIT);
+        builder.setSampleRate(SAMPLE_RATE);
+        builder.setChannelMask(CHANNELS == 2 ? AudioFormat.CHANNEL_IN_STEREO : AudioFormat.CHANNEL_IN_MONO);
+        return builder.build();
+    }
+
+    @TargetApi(Build.VERSION_CODES.M)
+    @SuppressLint({"WrongConstant", "MissingPermission"})
+    private static AudioRecord createAudioRecord() {
+        AudioRecord.Builder builder = new AudioRecord.Builder();
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+            // On older APIs, Workarounds.fillAppInfo() must be called beforehand
+            builder.setContext(FakeContext.get());
+        }
+        builder.setAudioSource(MediaRecorder.AudioSource.REMOTE_SUBMIX);
+        builder.setAudioFormat(createAudioFormat());
+        builder.setBufferSizeInBytes(1024 * 1024);
+        return builder.build();
+    }
+
+    public void start() {
+        AudioRecord recorder = createAudioRecord();
+
+        thread = new Thread(() -> {
+            recorder.startRecording();
+            try {
+                int BUFFER_MS = 15; // do not buffer more than BUFFER_MS milliseconds
+                byte[] buf = new byte[SAMPLE_RATE * CHANNELS * BUFFER_MS / 1000];
+                while (!Thread.currentThread().isInterrupted()) {
+                    int r = recorder.read(buf, 0, buf.length);
+                    if (r > 0) {
+                        Ln.i("Audio captured: " + r + " bytes");
+                    }
+                    if (r < 0) {
+                        Ln.e("Audio capture error: " + r);
+                    }
+                }
+            } finally {
+                recorder.stop();
+            }
+        });
+        thread.start();
+    }
+
+    public void stop() {
+        if (thread != null) {
+            thread.interrupt();
+            thread = null;
+        }
+    }
+}

server/src/main/java/com/genymobile/scrcpy/Server.java

@@ -69,10 +69,11 @@ public final class Server {
         int uid = options.getUid();
         boolean tunnelForward = options.isTunnelForward();
         boolean control = options.getControl();
+        boolean audio = Build.VERSION.SDK_INT >= Build.VERSION_CODES.R; // TODO option
         boolean sendDummyByte = options.getSendDummyByte();
 
         Workarounds.prepareMainLooper();
-        if (Build.BRAND.equalsIgnoreCase("meizu")) {
+
         // Workarounds must be applied for Meizu phones:
         //  - <https://github.com/Genymobile/scrcpy/issues/240>
         //  - <https://github.com/Genymobile/scrcpy/issues/365>
@@ -81,6 +82,14 @@ public final class Server {
         // But only apply when strictly necessary, since workarounds can cause other issues:
         //  - <https://github.com/Genymobile/scrcpy/issues/940>
         //  - <https://github.com/Genymobile/scrcpy/issues/994>
+        boolean mustFillAppInfo = Build.BRAND.equalsIgnoreCase("meizu");
+
+        // Before Android 11, audio is not supported.
+        // Since Android 12, we can properly set a context on the AudioRecord.
+        // Only on Android 11 we must fill app info for the AudioRecord to work.
+        mustFillAppInfo |= audio && Build.VERSION.SDK_INT == Build.VERSION_CODES.R;
+
+        if (mustFillAppInfo) {
             Workarounds.fillAppInfo();
         }
 
@@ -102,6 +111,12 @@ public final class Server {
                 device.setClipboardListener(text -> controllerRef.getSender().pushClipboardText(text));
             }
 
+            AudioEncoder audioEncoder = null;
+            if (audio) {
+                audioEncoder = new AudioEncoder();
+                audioEncoder.start();
+            }
+
             try {
                 // synchronous
                 VideoStreamer videoStreamer = new VideoStreamer(connection.getVideoFd(), options.getSendFrameMeta());
@@ -117,6 +132,9 @@ public final class Server {
                 if (controller != null) {
                     controller.stop();
                 }
+                if (audioEncoder != null) {
+                    audioEncoder.stop();
+                }
             }
         }
     }