Android implementation of WebAudio audio file decoder

media/base/android/webaudio_media_codec_bridge.h

+// 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.
+
+#ifndef MEDIA_BASE_ANDROID_MEDIA_CODEC_BRIDGE_H_
+#define MEDIA_BASE_ANDROID_MEDIA_CODEC_BRIDGE_H_
+
+#include <jni.h>
+
+#include "base/file_descriptor_posix.h"
+#include "base/shared_memory.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+// This class serves as a bridge for native code to call Java
+// functions in the Android MediaCodec class. See
+// http://developer.android.com/reference/android/media/MediaCodec.html.
+class MEDIA_EXPORT WebAudioMediaCodecBridge {
+ public:
+  // Create the bridge with the given file descriptors.  We read from
+  // |encoded_audio_handle| to get the encoded audio data.  Audio file
+  // information and decoded PCM samples are written to |pcm_output|.
+  // We also take ownership of |pcm_output|.
+  WebAudioMediaCodecBridge(base::SharedMemoryHandle encoded_audio_handle,
+                           base::FileDescriptor pcm_output);
+  ~WebAudioMediaCodecBridge();
+
+  // Inform JNI about this bridge.  Returns true if registration
+  // succeeded.
+  static bool RegisterWebAudioMediaCodecBridge(JNIEnv* env);
+
+  // Start MediaCodec to process the encoded data in
+  // |encoded_audio_handle|.  The PCM samples are sent to

[qinmin, 2013/04/12 17:15:23]

nit: extra white space in lots of the comments after "."

+  // |pcm_output|.
+  static void RunWebAudioMediaCodec(
+      base::SharedMemoryHandle encoded_audio_handle,
+      base::FileDescriptor pcm_output);
+
+  void OnChunkDecoded(JNIEnv* env,
+                      jobject /*java object*/,
+                      jobject buf,
+                      jint buf_size);
+
+  void InitializeDestination(JNIEnv* env,
+                             jobject /*java object*/,
+                             jint channel_count,
+                             jint sample_rate,
+                             jlong duration_us,
+                             jboolean is_vorbis);
+
+ private:
+  // Handles MediaCodec processing of the encoded data in
+  // |encoded_audio_handle_| and sends the pcm data to |pcm_output_|.
+  // Returns true if decoding was successful.
+  bool DecodeInMemoryAudioFile();
+
+  // The encoded audio data is read from this file descriptor for the
+  // shared memory that holds the encoded data.
+  int encoded_audio_handle_;
+
+  // The audio file information and decoded pcm data are written to
+  // this file descriptor.  Owned.

[qinmin, 2013/04/12 17:15:23]

nit: what is Owned? extra white space before Owned.

+  int pcm_output_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebAudioMediaCodecBridge);
+};
+
+}  // namespace media
+#endif  // MEDIA_BASE_ANDROID_MEDIA_CODEC_BRIDGE_H_