Android implementation of WebAudio audio file decoder

media/base/android/webaudio_media_codec_bridge.cc

+// Copyright (c) 2012 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.
+
+#include "media/base/android/webaudio_media_codec_bridge.h"
+
+#include <unistd.h>
+#include <vector>
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_array.h"
+#include "base/android/jni_string.h"
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "jni/WebAudioMediaCodecBridge_jni.h"
+
+
+using base::android::AttachCurrentThread;
+using base::android::DetachFromVM;

[felipeg, 2013/03/29 17:18:29]

this is not being used

+
+namespace media {
+
+void WebAudioMediaCodecBridge::RunWebAudioMediaCodec(
+    base::SharedMemoryHandle input_fd,
+    base::FileDescriptor output_fd) {
+  DVLOG(0) << "RunWebAudioMediaCodec";
+
+  WebAudioMediaCodecBridge bridge(input_fd, output_fd);
+  bool result = bridge.DecodeInMemoryAudioFile();
+  DVLOG(0) << "RunWebAudioMediaCodec returned " << result;
+}
+
+WebAudioMediaCodecBridge::WebAudioMediaCodecBridge(
+    base::SharedMemoryHandle input_fd,
+    base::FileDescriptor output_fd)
+    : input_fd_(input_fd.fd),
+      output_fd_(output_fd.fd) {
+

[felipeg, 2013/03/29 17:18:29]

drop blank

+  DVLOG(0) << "WebAudioMediaCodecBridge start **********************";
+  DVLOG(0) << "input fd = " << input_fd_
+           << " output fd = " << output_fd.fd;
+}
+
+WebAudioMediaCodecBridge::~WebAudioMediaCodecBridge() {
+  int rc = close(output_fd_);

[felipeg, 2013/03/29 17:18:29]

s/rc/result or something meaningful

+  if (rc)
+    VLOG(0) << "Couldn't close output fd " << output_fd_
+            << ": rc = " << rc;
+
+  rc = close(input_fd_);
+  if (rc)
+    VLOG(0) << "Couldn't close shared mem fd " << input_fd_
+            << ": rc = " << rc;
+}
+
+bool WebAudioMediaCodecBridge::DecodeInMemoryAudioFile() {
+  // Process the encoded data that is in shared memory given by the
+  // file descriptor encodedDataFD_.
+
+  JNIEnv* env = AttachCurrentThread();
+  CHECK(env);
+  jboolean decoded = Java_WebAudioMediaCodecBridge_decodeAudioFile(
+      env,
+      base::android::GetApplicationContext(),
+      reinterpret_cast<intptr_t>(this),
+      input_fd_);
+
+  DVLOG(0) << "decoded = " << static_cast<bool>(decoded);
+  return decoded;
+}
+
+void WebAudioMediaCodecBridge::InitializeDestination(
+    JNIEnv* env,
+    jobject /*java object*/,
+    jint number_of_channels,
+    jint sample_rate,
+    jlong duration_us,
+    jboolean is_vorbis) {
+

[felipeg, 2013/03/29 17:18:29]

Drop blank line

+  long info[4];
+  info[0] = number_of_channels;
+  info[1] = sample_rate;
+  info[2] = 0.5 + (duration_us *  0.000001 * sample_rate);

[felipeg, 2013/03/29 17:18:29]

add a comment regarding the math here (I already forgot)

and also a comment regarding the format you are using for passing the data
through the pipe.
In this case would be the 4 consecutive longs as a long info[4] array

+  info[3] = is_vorbis ? 1 : 0;
+
+  DVLOG(0) << "InitializeDestination:";
+  DVLOG(0) << "  number of channels = " << number_of_channels;
+  DVLOG(0) << "  rate     = " << sample_rate;
+  DVLOG(0) << "  duration = " << duration_us << " us";
+  DVLOG(0) << "  vorbis   = " << (is_vorbis ? "yes" : "no");
+
+  write(output_fd_, info, sizeof(info));
+}
+
+void WebAudioMediaCodecBridge::OnChunkDecoded(
+    JNIEnv* env,
+    jobject /*java object*/,
+    jobject buf,
+    jint buf_size) {
+

[felipeg, 2013/03/29 17:18:29]

drop blank

+  signed short* decoded_buffer =
+      static_cast<signed short*>(env->GetDirectBufferAddress(buf));
+  DCHECK((buf_size % sizeof(decoded_buffer[0])) == 0);
+
+  int bytes_left = buf_size;
+  signed short* buffer = decoded_buffer;
+
+  // Write out the data to the pipe atomically, in small chunks if

[felipeg, 2013/03/29 17:18:29]

what you mean by atomically ?

[Raymond Toy (Google), 2013/03/29 19:47:24]

Irrelevant here since we are the only writer of the pipe.  I'll remove this.

+  // necessary.
+  while (bytes_left > 0) {
+    int bytes_to_write = (bytes_left >= PIPE_BUF) ? PIPE_BUF : bytes_left;
+    int bytes_written = write(output_fd_, buffer, bytes_to_write);
+    if (bytes_written != bytes_to_write)
+      VLOG(0) << "Only wrote " << bytes_written
+              << " bytes but expected " << bytes_to_write;
+    bytes_left -= bytes_written;
+    buffer += bytes_written / sizeof(decoded_buffer[0]);
+  }
+}
+
+bool WebAudioMediaCodecBridge::RegisterWebAudioMediaCodecBridge(JNIEnv* env) {
+  bool ret = RegisterNativesImpl(env);
+  return ret;
+}
+
+} // namespace