Support (E)AC3 passthrough

media/base/android/java/src/org/chromium/media/AudioTrackOutputStream.java

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.media;
+
+import android.annotation.SuppressLint;
+import android.media.AudioFormat;
+import android.media.AudioManager;
+import android.media.AudioTrack;
+import android.os.Build;
+
+import org.chromium.base.Log;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+import java.nio.ByteBuffer;
+
+@JNINamespace("media")
+class AudioTrackOutputStream {
+    private static final String TAG = "AudioTrackOutput";
+
+    class WorkerThread extends Thread {
+        private boolean mDone = false;
+
+        public void finish() {
+            mDone = true;
+        }
+
+        public void run() {
+            while (!mDone) {
+                if (!readMoreData()) {
+                    msleep(10);
+                }
+            }
+        }
+
+        private void msleep(int msec) {
+            try {
+                Thread.sleep(msec);
+            } catch (InterruptedException e) {
+            }
+        }
+    }
+
+    private AudioTrack mAudioTrack;
+    private long mNativeAudioTrackOutputStream;
+    private int mBufferSizeInBytes;
+
+    private ByteBuffer mAudioBuffer;
+    private WorkerThread mWorkerThread;

[DaleCurtis, 2016/11/01 23:05:13]

What's the point of this? Using a thread instead of callbacks is going to lead
to being out of sync with playback and is not as efficient as using callbacks.

https://chromiumcodereview.appspot.com/1525033003/

This one piece is complicated enough to separate into its own code review with
unittests. We should also consider the question of whether it's worth it to
continue using OpenSLES or if we should always use AudioTrack instead.

[AndyWu, 2016/11/04 18:04:24]

I did try to use callback, but it failed. Please see:
http://androidxref.com/7.0.0_r1/xref/frameworks/av/media/libmedia/AudioTrack....

OK, I will create another CL for AudioTrackOutputStream.
I am not familiar with the differences between OpenSLES and AudioTrack. Will
update the comment once I have more information.

[DaleCurtis, 2016/11/04 19:48:29]

Ugh, no we wouldn't want to use a non-callback based stream for general audio
playback.

[chcunningham, 2017/06/14 20:03:08]

This is still unaddressed. Not sure what to do. AudioTrack seems push based.
When you say you tried before, what were the specifics of your approach and
where it went wrong? 

[chcunningham, 2017/06/14 20:27:21]

I think minimally you'll want to keep track of the delay between read frames and
played frames and basically stop asking for more data when the delay grows too
large. But more than that, you also might have a more dynamic sleep time? Dale
might hate these ideas, so wait for him. 

+
+    @CalledByNative
+    private static AudioTrackOutputStream create() {
+        return new AudioTrackOutputStream();
+    }
+
+    @SuppressWarnings("deprecation")
+    private int getChannelConfig(int channelCount) {
+        switch (channelCount) {
+            case 1:
+                return AudioFormat.CHANNEL_OUT_MONO;
+            case 2:
+                return AudioFormat.CHANNEL_OUT_STEREO;
+            case 4:
+                return AudioFormat.CHANNEL_OUT_QUAD;
+            case 6:
+                return AudioFormat.CHANNEL_OUT_5POINT1;
+            case 8:
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+                    return AudioFormat.CHANNEL_OUT_7POINT1_SURROUND;
+                } else {
+                    return AudioFormat.CHANNEL_OUT_7POINT1;
+                }
+            default:
+                return AudioFormat.CHANNEL_OUT_DEFAULT;
+        }
+    }
+
+    @CalledByNative
+    private boolean open(int channelCount, int sampleRate, int sampleFormat) {
+        int channelConfig = getChannelConfig(channelCount);
+        mBufferSizeInBytes =
+                2 * AudioTrack.getMinBufferSize(sampleRate, channelConfig, sampleFormat);
+
+        if (mAudioTrack != null) mAudioTrack.release();
+
+        try {
+            Log.d(TAG, String.format("Crate AudioTrack with sample rate:%d, channel:%d, format:%d ",
+                               sampleRate, channelConfig, sampleFormat));
+
+            mAudioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRate, channelConfig,
+                    sampleFormat, 4 * mBufferSizeInBytes, AudioTrack.MODE_STREAM);
+        } catch (IllegalArgumentException ile) {
+            Log.e(TAG, "Exception creating AudioTrack for playback: ", ile);
+            return false;
+        }
+
+        if (mAudioTrack.getState() == AudioTrack.STATE_UNINITIALIZED) {
+            Log.e(TAG, "Cannot create AudioTrack");
+            mAudioTrack = null;
+            return false;
+        }
+
+        return true;
+    }
+
+    @CalledByNative
+    private void start(long nativeAudioTrackOutputStream) {
+        Log.i(TAG, "AudioTrackOutputStream.start()");
+        if (mWorkerThread != null) return;
+
+        mNativeAudioTrackOutputStream = nativeAudioTrackOutputStream;
+
+        mAudioBuffer = ByteBuffer.allocateDirect(mBufferSizeInBytes);
+        mAudioTrack.play();
+
+        mWorkerThread = new WorkerThread();
+        mWorkerThread.start();
+    }
+
+    @CalledByNative
+    private void stop() {
+        Log.w(TAG, "AudioTrackOutputStream.stop()");
+        if (mWorkerThread != null) {
+            mWorkerThread.finish();
+            try {
+                mWorkerThread.interrupt();
+                mWorkerThread.join();
+            } catch (SecurityException e) {
+                Log.e(TAG, "Exception while waiting for AudioTrack worker thread finished: ", e);
+            } catch (InterruptedException e) {
+                Log.e(TAG, "Exception while waiting for AudioTrack worker thread finished: ", e);
+            }
+            mWorkerThread = null;
+        }
+
+        mAudioTrack.pause();
+        mAudioTrack.flush();
+        mNativeAudioTrackOutputStream = 0;
+    }
+
+    @SuppressWarnings("deprecation")
+    @CalledByNative
+    private void setVolume(double volume) {
+        Log.w(TAG, "AudioTrackOutputStream.setVolume()");
+        // Chrome sends the volume in the range [0, 1.0], whereas Android
+        // expects the volume to be within [0, getMaxVolume()].
+        float scaledVolume = (float) (volume * mAudioTrack.getMaxVolume());
+        mAudioTrack.setStereoVolume(scaledVolume, scaledVolume);
+    }
+
+    @CalledByNative
+    private void close() {
+        Log.w(TAG, "AudioTrackOutputStream.close()");
+        if (mAudioTrack != null) mAudioTrack.release();
+    }
+
+    public boolean readMoreData() {
+        if (mNativeAudioTrackOutputStream == 0) return false;
+
+        int position = mAudioTrack.getPlaybackHeadPosition();
+        int size = nativeOnMoreData(mNativeAudioTrackOutputStream, mAudioBuffer, position);
+        if (size <= 0) {
+            return false;
+        }
+
+        ByteBuffer readOnlyBuffer = mAudioBuffer.asReadOnlyBuffer();
+        int result = writeAudio(readOnlyBuffer, size);
+
+        if (result < 0) {
+            Log.e(TAG, "AudioTrack.write() failed. Error:" + result);
+            return false;
+        } else if (result != size) {
+            Log.e(TAG, "AudioTrack.write() incomplete. Data size:" + size + ", written size:"
+                            + result);
+            return false;
+        }
+
+        return true;
+    }
+
+    @SuppressLint("NewApi")
+    private int writeAudio(ByteBuffer buffer, int size) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            return mAudioTrack.write(buffer, size, AudioTrack.WRITE_BLOCKING);
+        } else {
+            if (buffer.hasArray()) {
+                return mAudioTrack.write(buffer.array(), buffer.arrayOffset(), size);
+            } else {
+                byte[] array = new byte[size];
+                buffer.get(array);
+                return mAudioTrack.write(array, 0, size);
+            }
+        }
+    }
+
+    private native int nativeOnMoreData(
+            long nativeAudioTrackOutputStream, ByteBuffer audioData, int totalPlayedFrames);
+    private native void nativeOnError(long nativeAudioTrackOutputStream);
+}