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// Copyright (c) 2011 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/media/audio_decoder.h"
#include <vector>
#include "base/basictypes.h"
#include "base/string_util.h"
#include "base/time.h"
#include "media/base/limits.h"
#include "media/filters/audio_file_reader.h"
#include "media/filters/in_memory_url_protocol.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebAudioBus.h"
using media::AudioFileReader;
using media::InMemoryUrlProtocol;
using std::vector;
using WebKit::WebAudioBus;
namespace webkit_media {
// 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.
InMemoryUrlProtocol url_protocol(reinterpret_cast<const uint8*>(data),
data_size, false);
AudioFileReader reader(&url_protocol);
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());
// Apply sanity checks to make sure crazy values aren't coming out of
// FFmpeg.
if (!number_of_channels ||
number_of_channels > static_cast<size_t>(media::limits::kMaxChannels) ||
file_sample_rate < media::limits::kMinSampleRate ||
file_sample_rate > media::limits::kMaxSampleRate)
return false;
// 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_media
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