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 inside

[palmer, 2013/04/02 18:01:08]

NIT: Capitalization and article: "...to call Java functions inside the Android
MediaCodec class."

Then, simply: "See http://developer..."

+// android MediaCodec class. For more information on android MediaCodec, check
+// 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
+  // |input_fd| to get the encoded audio data.  Audio file information
+  // and decoded pcm samples are written to |output_fd|.  We also take

[palmer, 2013/04/02 18:01:08]

NIT: Capitalize initialisms: PCM.

+  // ownership of |output_fd|.
+  WebAudioMediaCodecBridge(base::SharedMemoryHandle input_fd,

[palmer, 2013/04/02 18:01:08]

Use the same variable names for these objects here as you do elsewhere. In
particular, it's a bit confusing to call a SharedMemoryHandle an fd (even if it
is one underneath).

+                           base::FileDescriptor output_fd);
+  ~WebAudioMediaCodecBridge();
+
+  bool DecodeInMemoryAudioFile();
+  static bool RegisterWebAudioMediaCodecBridge(JNIEnv* env);
+  static void RunWebAudioMediaCodec(base::SharedMemoryHandle input_fd,
+                                    base::FileDescriptor output_fd);
+
+  void OnChunkDecoded(JNIEnv* env,
+                      jobject /*java object*/,
+                      jobject buf,
+                      jint buf_size);
+
+  void InitializeDestination(JNIEnv* env,
+                             jobject /*java object*/,
+                             jint number_of_channels,

[palmer, 2013/04/02 18:01:08]

NIT: |channel_count| is more concise.

+                             jint sample_rate,
+                             jlong duration_us,
+                             jboolean is_vorbis);
+
+private:
+  // The encoded audio data is read from this file descriptor for the
+  // shared memory that holds the encoded data.
+  int input_fd_;
+
+  // The audio file information and decoded pcm data are written to
+  // this file descriptor.  Owned.
+  int output_fd_;
+};
+
+}  // namespace media
+#endif  // MEDIA_BASE_ANDROID_MEDIA_CODEC_BRIDGE_H_