aac.h revision 5d1f7b1de12d16ceb2c938c56701a3e8bfa558f7 
1// Copyright 2014 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#ifndef MEDIA_FORMATS_MP4_AAC_H_
6#define MEDIA_FORMATS_MP4_AAC_H_
7
8#include <vector>
9
10#include "base/basictypes.h"
11#include "media/base/channel_layout.h"
12#include "media/base/media_export.h"
13
14namespace media {
15
16class BitReader;
17
18namespace mp4 {
19
20// This class parses the AAC information from decoder specific information
21// embedded in the esds box in an ISO BMFF file.
22// Please refer to ISO 14496 Part 3 Table 1.13 - Syntax of AudioSpecificConfig
23// for more details.
24class MEDIA_EXPORT AAC {
25 public:
26  AAC();
27  ~AAC();
28
29  // Parse the AAC config from the raw binary data embedded in esds box.
30  // The function will parse the data and get the ElementaryStreamDescriptor,
31  // then it will parse the ElementaryStreamDescriptor to get audio stream
32  // configurations.
33  bool Parse(const std::vector<uint8>& data);
34
35  // Gets the output sample rate for the AAC stream.
36  // |sbr_in_mimetype| should be set to true if the SBR mode is
37  // signalled in the mimetype. (ie mp4a.40.5 in the codecs parameter).
38  // Returns the samples_per_second value that should used in an
39  // AudioDecoderConfig.
40  int GetOutputSamplesPerSecond(bool sbr_in_mimetype) const;
41
42  // Gets the channel layout for the AAC stream.
43  // |sbr_in_mimetype| should be set to true if the SBR mode is
44  // signalled in the mimetype. (ie mp4a.40.5 in the codecs parameter).
45  // Returns the channel_layout value that should used in an
46  // AudioDecoderConfig.
47  ChannelLayout GetChannelLayout(bool sbr_in_mimetype) const;
48
49  // This function converts a raw AAC frame into an AAC frame with an ADTS
50  // header. On success, the function returns true and stores the converted data
51  // in the buffer. The function returns false on failure and leaves the buffer
52  // unchanged.
53  bool ConvertEsdsToADTS(std::vector<uint8>* buffer) const;
54
55#if defined(OS_ANDROID)
56  // Returns the codec specific data needed by android MediaCodec.
57  std::vector<uint8> codec_specific_data() const {
58    return codec_specific_data_;
59  }
60#endif
61
62 private:
63  bool SkipDecoderGASpecificConfig(BitReader* bit_reader) const;
64  bool SkipErrorSpecificConfig() const;
65  bool SkipGASpecificConfig(BitReader* bit_reader) const;
66
67  // The following variables store the AAC specific configuration information
68  // that are used to generate the ADTS header.
69  uint8 profile_;
70  uint8 frequency_index_;
71  uint8 channel_config_;
72
73#if defined(OS_ANDROID)
74  // The codec specific data needed by the android MediaCodec.
75  std::vector<uint8> codec_specific_data_;
76#endif
77
78  // The following variables store audio configuration information that
79  // can be used by Chromium. They are based on the AAC specific
80  // configuration but can be overridden by extensions in elementary
81  // stream descriptor.
82  int frequency_;
83  int extension_frequency_;
84  ChannelLayout channel_layout_;
85};
86
87}  // namespace mp4
88
89}  // namespace media
90
91#endif  // MEDIA_FORMATS_MP4_AAC_H_
92