1// Copyright (c) 2010 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "webkit/glue/media/audio_decoder.h"
6
7#include <vector>
8#include "base/basictypes.h"
9#include "base/string_util.h"
10#include "base/time.h"
11#include "media/filters/audio_file_reader.h"
12#include "third_party/WebKit/Source/WebKit/chromium/public/WebAudioBus.h"
13
14using media::AudioFileReader;
15using media::InMemoryDataReader;
16using std::vector;
17using WebKit::WebAudioBus;
18
19namespace webkit_glue {
20
21// Decode in-memory audio file data.
22bool DecodeAudioFileData(
23    WebKit::WebAudioBus* destination_bus,
24    const char* data, size_t data_size, double sample_rate) {
25  DCHECK(destination_bus);
26  if (!destination_bus)
27    return false;
28
29  // Uses the FFmpeg library for audio file reading.
30  InMemoryDataReader data_reader(data, data_size);
31  AudioFileReader reader(&data_reader);
32
33  if (!reader.Open())
34    return false;
35
36  size_t number_of_channels = reader.channels();
37  double file_sample_rate = reader.sample_rate();
38  double duration = reader.duration().InSecondsF();
39  size_t number_of_frames = static_cast<size_t>(reader.number_of_frames());
40
41  // TODO(crogers) : do sample-rate conversion with FFmpeg.
42  // For now, we're ignoring the requested 'sample_rate' and returning
43  // the WebAudioBus at the file's sample-rate.
44  // double destination_sample_rate =
45  //   (sample_rate != 0.0) ? sample_rate : file_sample_rate;
46  double destination_sample_rate = file_sample_rate;
47
48  DLOG(INFO) << "Decoding file data -"
49      << " data: " << data
50      << " data size: " << data_size
51      << " duration: " << duration
52      << " number of frames: " << number_of_frames
53      << " sample rate: " << file_sample_rate
54      << " number of channels: " << number_of_channels;
55
56  // Change to destination sample-rate.
57  number_of_frames = static_cast<size_t>(number_of_frames *
58      (destination_sample_rate / file_sample_rate));
59
60  // Allocate and configure the output audio channel data.
61  destination_bus->initialize(number_of_channels,
62                              number_of_frames,
63                              destination_sample_rate);
64
65  // Wrap the channel pointers which will receive the decoded PCM audio.
66  vector<float*> audio_data;
67  audio_data.reserve(number_of_channels);
68  for (size_t i = 0; i < number_of_channels; ++i) {
69    audio_data.push_back(destination_bus->channelData(i));
70  }
71
72  // Decode the audio file data.
73  return reader.Read(audio_data, number_of_frames);
74}
75
76}  // namespace webkit_glue
77