Android implementation of WebAudio audio file decoder

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

Index: media/base/android/java/src/org/chromium/media/WebAudioMediaCodecBridge.java
diff --git a/media/base/android/java/src/org/chromium/media/WebAudioMediaCodecBridge.java b/media/base/android/java/src/org/chromium/media/WebAudioMediaCodecBridge.java
new file mode 100644
index 0000000000000000000000000000000000000000..281290365f565f544337ab09ef536aaf8bea5003
--- /dev/null
+++ b/media/base/android/java/src/org/chromium/media/WebAudioMediaCodecBridge.java
@@ -0,0 +1,191 @@
+// Copyright (c) 2013 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.content.Context;
+import android.media.AudioFormat;
+import android.media.MediaCodec;
+import android.media.MediaCodec.BufferInfo;
+import android.media.MediaExtractor;
+import android.media.MediaFormat;
+import android.util.Log;
+
+import java.nio.ByteBuffer;
+import android.os.ParcelFileDescriptor;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+
+@JNINamespace("media")
+class WebAudioMediaCodecBridge {
+    private static native void nativeOnChunkDecoded(

[bulach, 2013/03/28 13:39:25]

nit: move these native declarations to the bottom of this file

+        int nativeWebAudioMediaCodecBridge, ByteBuffer buf, int size);
+
+    private static native void nativeInitializeDestination(
+        int nativeWebAudioMediaCodecBridge,
+        int channelCount,
+        int sampleRate,
+        long duration_us,
+        boolean is_vorbis);
+
+    @CalledByNative
+    private static boolean decodeAudioFile(Context ctx, int nativeMediaCodecBridge, int inputFD) {
+        MediaCodec codec;
+        ByteBuffer[] codecInputBuffers;
+        ByteBuffer[] codecOutputBuffers;
+        String LOG_TAG = "WebAudioMediaCodec";

[bulach, 2013/03/28 13:39:25]

nit: LOG_TAG is normally a private static final member

+        Log.d(LOG_TAG,
+              "decodeAudioFile start =======================================");

[bulach, 2013/03/28 13:39:25]

nit: remove the ==== decoration, saves some bytes. :) but more to the point, are
all of these logs really needed? there's plenty of them here..

+
+
+        // Todo(rtoy): What is the correct timeout value for reading

[bulach, 2013/03/28 13:39:25]

nit: s/Todo/TODO/

+        // from a file in memory?
+        long TIMEOUT_US = 500;
+
+        MediaExtractor extractor;
+        extractor = new MediaExtractor();
+
+        ParcelFileDescriptor encodedFD;
+        try {
+            encodedFD = ParcelFileDescriptor.adoptFd(inputFD);
+            extractor.setDataSource(encodedFD.getFileDescriptor());
+        } catch (Exception e) {
+            // TODO Auto-generated catch block

[bulach, 2013/03/28 13:39:25]

nit: remove?

+            e.printStackTrace();
+            return false;
+        }
+
+        Log.d(LOG_TAG, String.format("TRACKS #: %d", extractor.getTrackCount()));
+
+        if (extractor.getTrackCount() <= 0) {
+            encodedFD.detachFd();
+            return false;
+        }
+
+        MediaFormat format = extractor.getTrackFormat(0);
+        String mime = format.getString(MediaFormat.KEY_MIME);
+        Log.d(LOG_TAG, String.format("MIME TYPE: %s", mime));
+
+        int sampleRate = format.getInteger(MediaFormat.KEY_SAMPLE_RATE);
+        Log.d(LOG_TAG, String.format("Sample rate: %d", sampleRate));
+
+        int channelCount = format.getInteger(MediaFormat.KEY_CHANNEL_COUNT);
+        Log.d(LOG_TAG, String.format("Channel count: %d", channelCount));
+
+        long duration_us = 0;
+        if (format.containsKey(MediaFormat.KEY_CHANNEL_MASK)) {
+            Log.d(LOG_TAG,
+                  String.format(
+                      "Channel mask: %d",
+                      format.getInteger(MediaFormat.KEY_CHANNEL_MASK)));
+        }
+        if (format.containsKey(MediaFormat.KEY_DURATION)) {
+            try {
+                duration_us = format.getLong(MediaFormat.KEY_DURATION);
+                Log.d(LOG_TAG, "Duration : " + duration_us + " us");
+            } catch (Exception e) {
+                Log.d(LOG_TAG, "Cannot get duration");
+            }
+        }
+
+        int channelConfig;
+
+        if (channelCount == 2) {
+            channelConfig = AudioFormat.CHANNEL_OUT_STEREO;
+        } else {
+            channelConfig = AudioFormat.CHANNEL_OUT_MONO;
+        }

[bulach, 2013/03/28 13:39:25]

this would be simpler as:
int channelConfig = channelCount == 2 ?  AudioFormat.CHANNEL_OUT_STEREO :
AudioFormat.CHANNEL_OUT_MONO;

+
+        nativeInitializeDestination(nativeMediaCodecBridge,
+                                    channelCount,
+                                    sampleRate,
+                                    duration_us,
+                                    mime.equals("audio/vorbis"));
+
+        // Create decoder
+        codec = MediaCodec.createDecoderByType(mime);
+        codec.configure(format, null /* surface */, null /* crypto */, 0 /* flags */);
+        codec.start();
+
+        codecInputBuffers = codec.getInputBuffers();
+        codecOutputBuffers = codec.getOutputBuffers();
+
+        // You must select a track. You will read samples from the

[bulach, 2013/03/28 13:39:25]

nit: a while ago there's a discussion about not using pronouns in comments. :)

// A track must be selected and will be used to read samples.

+        // media from this track!
+        extractor.selectTrack(0);
+
+        boolean sawInputEOS = false;
+        boolean sawOutputEOS = false;
+
+        // Keep processing until the output is done.
+        while (!sawOutputEOS) {
+            int sampleSize = 0;
+            if (!sawInputEOS) {
+                // Input side
+                int inputBufIndex = codec.dequeueInputBuffer(TIMEOUT_US);
+
+                if (inputBufIndex >= 0) {
+                    ByteBuffer dstBuf = codecInputBuffers[inputBufIndex];
+                    sampleSize = extractor.readSampleData(dstBuf, 0);
+                    long presentationTimeUs = 0;
+
+                    if (sampleSize < 0) {
+                        sawInputEOS = true;
+                        sampleSize = 0;
+                    } else {
+                        presentationTimeUs = extractor.getSampleTime();
+                    }
+
+                    codec.queueInputBuffer(inputBufIndex,
+                                           0, //offset

[bulach, 2013/03/28 13:39:25]

nit: 0 /* offset */, is more common as it avoids commenting the entire rest of
the line..

+                                           sampleSize,
+                                           presentationTimeUs,
+                                           sawInputEOS ? MediaCodec.BUFFER_FLAG_END_OF_STREAM : 0);
+
+                    if (!sawInputEOS) {
+                        extractor.advance();
+                    }
+                }
+            }
+            // Output side
+
+            MediaCodec.BufferInfo info = new BufferInfo();
+            final int res = codec.dequeueOutputBuffer(info, TIMEOUT_US);
+
+            if (res >= 0) {
+                int outputBufIndex = res;
+                ByteBuffer buf = codecOutputBuffers[outputBufIndex];
+
+                if (info.size > 0) {
+                    nativeOnChunkDecoded(nativeMediaCodecBridge, buf, info.size);
+                }
+
+                buf.clear();
+                codec.releaseOutputBuffer(outputBufIndex, false /* render */);
+
+                if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
+                    sawOutputEOS = true;
+                }
+            } else if (res == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
+                Log.d(LOG_TAG, "Output buffers changed");
+                codecOutputBuffers = codec.getOutputBuffers();
+            } else if (res == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
+                final MediaFormat oformat = codec.getOutputFormat();
+                Log.d(LOG_TAG, "Output format has changed to " + oformat);
+            }
+        }
+
+        Log.d(LOG_TAG,
+              "decodeAudioFile finish =======================================");
+
+        encodedFD.detachFd();
+
+        codec.stop();
+        codec.release();
+        codec = null;
+
+        return true;
+    }
+}