webkit/media/audio_decoder.cc

   1 // Copyright (c) 2011 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/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/base/limits.h"
  12 #include "media/filters/audio_file_reader.h"
  13 #include "media/filters/in_memory_url_protocol.h"
  14 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebAudioBus.h"
  15
  16 using media::AudioFileReader;
  17 using media::InMemoryUrlProtocol;
  18 using std::vector;
  19 using WebKit::WebAudioBus;
  20
  21 namespace webkit_media {
  22
  23 // Decode in-memory audio file data.
  24 bool DecodeAudioFileData(
  25     WebKit::WebAudioBus* destination_bus,
  26     const char* data, size_t data_size, double sample_rate) {
  27   DCHECK(destination_bus);
  28   if (!destination_bus)
  29     return false;
  30
  31   // Uses the FFmpeg library for audio file reading.
  32   InMemoryUrlProtocol url_protocol(reinterpret_cast<const uint8*>(data),
  33                                    data_size, false);
  34   AudioFileReader reader(&url_protocol);
  35
  36   if (!reader.Open())
  37     return false;
  38
  39   size_t number_of_channels = reader.channels();
  40   double file_sample_rate = reader.sample_rate();
  41   double duration = reader.duration().InSecondsF();
  42   size_t number_of_frames = static_cast<size_t>(reader.number_of_frames());
  43
  44   // Apply sanity checks to make sure crazy values aren't coming out of
  45   // FFmpeg.
  46   if (!number_of_channels ||
  47       number_of_channels > static_cast<size_t>(media::limits::kMaxChannels) ||
  48       file_sample_rate < media::limits::kMinSampleRate ||
  49       file_sample_rate > media::limits::kMaxSampleRate)
  50     return false;
  51
  52   // TODO(crogers) : do sample-rate conversion with FFmpeg.
  53   // For now, we're ignoring the requested 'sample_rate' and returning
  54   // the WebAudioBus at the file's sample-rate.
  55   // double destination_sample_rate =
  56   //   (sample_rate != 0.0) ? sample_rate : file_sample_rate;
  57   double destination_sample_rate = file_sample_rate;
  58
  59   DLOG(INFO) << "Decoding file data -"
  60       << " data: " << data
  61       << " data size: " << data_size
  62       << " duration: " << duration
  63       << " number of frames: " << number_of_frames
  64       << " sample rate: " << file_sample_rate
  65       << " number of channels: " << number_of_channels;
  66
  67   // Change to destination sample-rate.
  68   number_of_frames = static_cast<size_t>(number_of_frames *
  69       (destination_sample_rate / file_sample_rate));
  70
  71   // Allocate and configure the output audio channel data.
  72   destination_bus->initialize(number_of_channels,
  73                               number_of_frames,
  74                               destination_sample_rate);
  75
  76   // Wrap the channel pointers which will receive the decoded PCM audio.
  77   vector<float*> audio_data;
  78   audio_data.reserve(number_of_channels);
  79   for (size_t i = 0; i < number_of_channels; ++i) {
  80     audio_data.push_back(destination_bus->channelData(i));
  81   }
  82
  83   // Decode the audio file data.
  84   return reader.Read(audio_data, number_of_frames);
  85 }
  86
  87 }  // namespace webkit_media