(Committing on behalf of Chris Rogers -- original CL http://codereview.chromium.org/5550006/ )

Implement WebKitClientImpl::loadAudioResource() to decode in-memory audio file data for use by WebKit.
Most of the interesting low-level code is being added in the media directory.

BUG=NONE
TEST=NONE (tested locally with web audio API loading files of format .wav .aif .mp3 .m4a 16bit 24bit
In the longer term, WebKit layout tests will comprehensively exercise this code)

Review URL: http://codereview.chromium.org/5880002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69458 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 96 insertions, 0 deletions

diff --git a/webkit/glue/media/audio_decoder.cc b/webkit/glue/media/audio_decoder.cc
new file mode 100644
index 0000000..3fc05c9
--- /dev/null
+++ b/webkit/glue/media/audio_decoder.cc
@@ -0,0 +1,76 @@
+// Copyright (c) 2010 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 "webkit/glue/media/audio_decoder.h"
+
+#include <vector>
+#include "base/basictypes.h"
+#include "base/string_util.h"
+#include "base/time.h"
+#include "media/filters/audio_file_reader.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebAudioBus.h"
+
+using media::AudioFileReader;
+using media::InMemoryDataReader;
+using std::vector;
+using WebKit::WebAudioBus;
+
+namespace webkit_glue {
+
+// Decode in-memory audio file data.
+bool DecodeAudioFileData(
+    WebKit::WebAudioBus* destination_bus,
+    const char* data, size_t data_size, double sample_rate) {
+  DCHECK(destination_bus);
+  if (!destination_bus)
+    return false;
+
+  // Uses the FFmpeg library for audio file reading.
+  InMemoryDataReader data_reader(data, data_size);
+  AudioFileReader reader(&data_reader);
+
+  if (!reader.Open())
+    return false;
+
+  size_t number_of_channels = reader.channels();
+  double file_sample_rate = reader.sample_rate();
+  double duration = reader.duration().InSecondsF();
+  size_t number_of_frames = static_cast<size_t>(reader.number_of_frames());
+
+  // TODO(crogers) : do sample-rate conversion with FFmpeg.
+  // For now, we're ignoring the requested 'sample_rate' and returning
+  // the WebAudioBus at the file's sample-rate.
+  // double destination_sample_rate =
+  //   (sample_rate != 0.0) ? sample_rate : file_sample_rate;
+  double destination_sample_rate = file_sample_rate;
+
+  DLOG(INFO) << "Decoding file data -"
+      << " data: " << data
+      << " data size: " << data_size
+      << " duration: " << duration
+      << " number of frames: " << number_of_frames
+      << " sample rate: " << file_sample_rate
+      << " number of channels: " << number_of_channels;
+
+  // Change to destination sample-rate.
+  number_of_frames = static_cast<size_t>(number_of_frames *
+      (destination_sample_rate / file_sample_rate));
+
+  // Allocate and configure the output audio channel data.
+  destination_bus->initialize(number_of_channels,
+                              number_of_frames,
+                              destination_sample_rate);
+
+  // Wrap the channel pointers which will receive the decoded PCM audio.
+  vector<float*> audio_data;
+  audio_data.reserve(number_of_channels);
+  for (size_t i = 0; i < number_of_channels; ++i) {
+    audio_data.push_back(destination_bus->channelData(i));
+  }
+
+  // Decode the audio file data.
+  return reader.Read(audio_data, number_of_frames);
+}
+
+}  // namespace webkit_glue
diff --git a/webkit/glue/media/audio_decoder.h b/webkit/glue/media/audio_decoder.h
new file mode 100644
index 0000000..57cc90b
--- /dev/null
+++ b/webkit/glue/media/audio_decoder.h
@@ -0,0 +1,20 @@
+// Copyright (c) 2010 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 WEBKIT_GLUE_MEDIA_AUDIO_DECODER_H_
+#define WEBKIT_GLUE_MEDIA_AUDIO_DECODER_H_
+
+#include "base/basictypes.h"
+
+namespace WebKit { class WebAudioBus; }
+
+namespace webkit_glue {
+
+// Decode in-memory audio file data.
+bool DecodeAudioFileData(WebKit::WebAudioBus* destination_bus, const char* data,
+                         size_t data_size, double sample_rate);
+
+}  // namespace webkit_glue
+
+#endif  // WEBKIT_GLUE_MEDIA_AUDIO_DECODER_H_