media/formats/mpeg/mpeg1_audio_stream_parser.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_MPEG_MPEG1_AUDIO_STREAM_PARSER_H_
   6 #define MEDIA_FORMATS_MPEG_MPEG1_AUDIO_STREAM_PARSER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "media/base/media_export.h"
  10 #include "media/formats/mpeg/mpeg_audio_stream_parser_base.h"
  11
  12 namespace media {
  13
  14 // MPEG1AudioStreamParser handles MPEG-1 audio streams (ISO/IEC 11172-3)
  15 // as well as the following extensions:
  16 // - MPEG-2 audio (ISO/IEC 13818-3),
  17 // - and MPEG2.5 (not an ISO standard).
  18 class MEDIA_EXPORT MPEG1AudioStreamParser : public MPEGAudioStreamParserBase {
  19  public:
  20   // Size of an MPEG-1 frame header in bytes.
  21   enum {
  22     kHeaderSize = 4,
  23   };
  24
  25   // Versions and layers as defined in ISO/IEC 11172-3.
  26   enum Version {
  27     kVersion1 = 3,
  28     kVersion2 = 2,
  29     kVersionReserved = 1,
  30     kVersion2_5 = 0,
  31   };
  32
  33   enum Layer {
  34     kLayer1 = 3,
  35     kLayer2 = 2,
  36     kLayer3 = 1,
  37     kLayerReserved = 0,
  38   };
  39
  40   struct Header {
  41     Version version;
  42
  43     // Layer as defined in ISO/IEC 11172-3 bitstream specification.
  44     Layer layer;
  45
  46     // Frame size in bytes.
  47     int frame_size;
  48
  49     // Sample frequency.
  50     int sample_rate;
  51
  52     // Channel mode as defined in ISO/IEC 11172-3 bitstream specification.
  53     int channel_mode;
  54
  55     // Channel layout.
  56     ChannelLayout channel_layout;
  57
  58     // Number of samples per frame.
  59     int sample_count;
  60   };
  61
  62   // Parses the header starting at |data|.
  63   // Assumption: size of array |data| should be at least |kHeaderSize|.
  64   // Returns false if the header is not valid.
  65   static bool ParseHeader(const scoped_refptr<MediaLog>& media_log,
  66                           const uint8* data,
  67                           Header* header);
  68
  69   MPEG1AudioStreamParser();
  70   ~MPEG1AudioStreamParser() override;
  71
  72  private:
  73   // MPEGAudioStreamParserBase overrides.
  74   int ParseFrameHeader(const uint8* data,
  75                        int size,
  76                        int* frame_size,
  77                        int* sample_rate,
  78                        ChannelLayout* channel_layout,
  79                        int* sample_count,
  80                        bool* metadata_frame) const override;
  81
  82   DISALLOW_COPY_AND_ASSIGN(MPEG1AudioStreamParser);
  83 };
  84
  85 }  // namespace media
  86
  87 #endif  // MEDIA_FORMATS_MPEG_MPEG1_AUDIO_STREAM_PARSER_H_