AudioEncoder WIP

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

@@ -8,16 +8,35 @@ import android.content.ComponentName;
 import android.content.Intent;
 import android.media.AudioFormat;
 import android.media.AudioRecord;
+import android.media.AudioTimestamp;
+import android.media.MediaCodec;
+import android.media.MediaFormat;
 import android.media.MediaRecorder;
 import android.os.Build;
+import android.os.Handler;
+import android.os.HandlerThread;
 import android.os.SystemClock;
 
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.atomic.AtomicBoolean;
+
 public final class AudioEncoder {
 
+    private static final String MIMETYPE = MediaFormat.MIMETYPE_AUDIO_OPUS;
     private static final int SAMPLE_RATE = 48000;
     private static final int CHANNELS = 2;
+    private static final int BIT_RATE = 128000;
 
-    private Thread thread;
+    private static int BUFFER_MS = 15; // milliseconds
+    private static final int BUFFER_SIZE = SAMPLE_RATE * CHANNELS * BUFFER_MS / 1000;
+
+    private AudioRecord recorder;
+    private MediaCodec mediaCodec;
+    private HandlerThread thread;
+    private final AtomicBoolean interrupted = new AtomicBoolean();
+    private final Semaphore endSemaphore = new Semaphore(0); // blocks until encoding is ended
 
     private static AudioFormat createAudioFormat() {
         AudioFormat.Builder builder = new AudioFormat.Builder();
@@ -41,34 +60,136 @@ public final class AudioEncoder {
         return builder.build();
     }
 
-    public void start() {
-        AudioRecord recorder = createAudioRecord();
+    private static MediaFormat createFormat() {
+        MediaFormat format = new MediaFormat();
+        format.setString(MediaFormat.KEY_MIME, MIMETYPE);
+        format.setInteger(MediaFormat.KEY_BIT_RATE, BIT_RATE);
+        format.setInteger(MediaFormat.KEY_CHANNEL_COUNT, CHANNELS);
+        format.setInteger(MediaFormat.KEY_SAMPLE_RATE, SAMPLE_RATE);
+        return format;
+    }
 
-        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();
-            }
-        });
+
+    @TargetApi(Build.VERSION_CODES.M)
+    public void start() throws IOException {
+        mediaCodec = MediaCodec.createEncoderByType(MIMETYPE); // may throw IOException
+
+        recorder = createAudioRecord();
+
+        MediaFormat format = createFormat();
+        mediaCodec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
+
+        recorder.startRecording();
+
+        thread = new HandlerThread("AudioEncoder");
         thread.start();
+
+        class AudioEncoderCallbacks extends MediaCodec.Callback {
+
+            private final AudioTimestamp timestamp = new AudioTimestamp();
+            private long nextPts;
+            private boolean eofSignaled;
+            private boolean ended;
+
+            private void notifyEnded() {
+                assert !ended;
+                ended = true;
+                endSemaphore.release();
+            }
+
+            @TargetApi(Build.VERSION_CODES.N)
+            @Override
+            public void onInputBufferAvailable(MediaCodec codec, int index) {
+                if (eofSignaled) {
+                    return;
+                }
+
+                ByteBuffer inputBuffer = codec.getInputBuffer(index);
+                int r = recorder.read(inputBuffer, BUFFER_SIZE);
+
+                long pts;
+
+                int ret = recorder.getTimestamp(timestamp, AudioTimestamp.TIMEBASE_MONOTONIC);
+                if (ret == AudioRecord.SUCCESS) {
+                    pts = timestamp.nanoTime / 1000;
+                } else {
+                    if (nextPts == 0) {
+                        Ln.w("Could not get any audio timestamp");
+                    }
+                    // compute from previous timestamp and packet size
+                    pts = nextPts;
+                }
+
+                long durationMs = r * 1000 / CHANNELS / SAMPLE_RATE;
+                nextPts = pts + durationMs;
+
+                int flags = 0;
+                if (interrupted.get()) {
+                    flags = flags | MediaCodec.BUFFER_FLAG_END_OF_STREAM;
+                    eofSignaled = true;
+                }
+
+                codec.queueInputBuffer(index, 0, r, pts, flags);
+            }
+
+            @Override
+            public void onOutputBufferAvailable(MediaCodec codec, int index, MediaCodec.BufferInfo bufferInfo) {
+                if (ended) {
+                    return;
+                }
+
+                ByteBuffer codecBuffer = codec.getOutputBuffer(index);
+                try {
+                    boolean isConfig = (bufferInfo.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0;
+                    long pts = bufferInfo.presentationTimeUs;
+                    Ln.i("Audio packet: pts=" + pts + " " + codecBuffer.remaining() + " bytes");
+                } finally {
+                    codec.releaseOutputBuffer(index, false);
+                }
+
+                boolean eof = (bufferInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0;
+                if (eof) {
+                    notifyEnded();
+                }
+            }
+
+            @Override
+            public void onError(MediaCodec codec, MediaCodec.CodecException e) {
+                Ln.e("MediaCodec error", e);
+                if (!ended) {
+                    notifyEnded();
+                }
+            }
+
+            @Override
+            public void onOutputFormatChanged(MediaCodec codec, MediaFormat format) {
+                // ignore
+            }
+        }
+
+        mediaCodec.setCallback(new AudioEncoderCallbacks(), new Handler(thread.getLooper()));
+        mediaCodec.start();
+    }
+
+    private void waitEnded() {
+        try {
+            endSemaphore.acquire();
+        } catch (InterruptedException e) {
+            // ignore
+        }
     }
 
     public void stop() {
+        Ln.i("==== STOP");
         if (thread != null) {
+            interrupted.set(true);
+            waitEnded();
             thread.interrupt();
             thread = null;
+            mediaCodec.stop();
+            mediaCodec.release();
+            recorder.stop();
+            Ln.i("==== STOPPED");
         }
     }
 }