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// 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.
#ifndef MEDIA_MP4_AAC_H_
#define MEDIA_MP4_AAC_H_
#include <vector>
#include "base/basictypes.h"
#include "media/base/channel_layout.h"
#include "media/base/media_export.h"
namespace media {
class BitReader;
namespace mp4 {
// This class parses the AAC information from decoder specific information
// embedded in the esds box in an ISO BMFF file.
// Please refer to ISO 14496 Part 3 Table 1.13 - Syntax of AudioSpecificConfig
// for more details.
class MEDIA_EXPORT AAC {
public:
AAC();
~AAC();
// Parse the AAC config from the raw binary data embedded in esds box.
// The function will parse the data and get the ElementaryStreamDescriptor,
// then it will parse the ElementaryStreamDescriptor to get audio stream
// configurations.
bool Parse(const std::vector<uint8>& data);
// Gets the output sample rate for the AAC stream.
// |sbr_in_mimetype| should be set to true if the SBR mode is
// signalled in the mimetype. (ie mp4a.40.5 in the codecs parameter).
// Returns the samples_per_second value that should used in an
// AudioDecoderConfig.
int GetOutputSamplesPerSecond(bool sbr_in_mimetype) const;
ChannelLayout channel_layout() const;
// This function converts a raw AAC frame into an AAC frame with an ADTS
// header. On success, the function returns true and stores the converted data
// in the buffer. The function returns false on failure and leaves the buffer
// unchanged.
bool ConvertEsdsToADTS(std::vector<uint8>* buffer) const;
// Size in bytes of the ADTS header added by ConvertEsdsToADTS().
static const size_t kADTSHeaderSize = 7;
private:
bool SkipDecoderGASpecificConfig(BitReader* bit_reader) const;
bool SkipErrorSpecificConfig() const;
bool SkipGASpecificConfig(BitReader* bit_reader) const;
// The following variables store the AAC specific configuration information
// that are used to generate the ADTS header.
uint8 profile_;
uint8 frequency_index_;
uint8 channel_config_;
// The following variables store audio configuration information that
// can be used by Chromium. They are based on the AAC specific
// configuration but can be overridden by extensions in elementary
// stream descriptor.
int frequency_;
int extension_frequency_;
ChannelLayout channel_layout_;
};
} // namespace mp4
} // namespace media
#endif // MEDIA_MP4_AAC_H_
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