media/formats/mp4/aac.h

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