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      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_MPEG_AUDIO_STREAM_PARSER_BASE_H_
      6 #define MEDIA_FORMATS_MPEG_MPEG_AUDIO_STREAM_PARSER_BASE_H_
      7 
      8 #include <set>
      9 #include <vector>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/callback.h"
     13 #include "media/base/audio_decoder_config.h"
     14 #include "media/base/audio_timestamp_helper.h"
     15 #include "media/base/bit_reader.h"
     16 #include "media/base/byte_queue.h"
     17 #include "media/base/media_export.h"
     18 #include "media/base/stream_parser.h"
     19 
     20 namespace media {
     21 
     22 class MEDIA_EXPORT MPEGAudioStreamParserBase : public StreamParser {
     23  public:
     24   // |start_code_mask| is used to find the start of each frame header.  Also
     25   // referred to as the sync code in the MP3 and ADTS header specifications.
     26   // |codec_delay| is the number of samples the decoder will output before the
     27   // first real frame.
     28   MPEGAudioStreamParserBase(uint32 start_code_mask,
     29                             AudioCodec audio_codec,
     30                             int codec_delay);
     31   virtual ~MPEGAudioStreamParserBase();
     32 
     33   // StreamParser implementation.
     34   virtual void Init(const InitCB& init_cb,
     35                     const NewConfigCB& config_cb,
     36                     const NewBuffersCB& new_buffers_cb,
     37                     bool ignore_text_tracks,
     38                     const NeedKeyCB& need_key_cb,
     39                     const NewMediaSegmentCB& new_segment_cb,
     40                     const base::Closure& end_of_segment_cb,
     41                     const LogCB& log_cb) OVERRIDE;
     42   virtual void Flush() OVERRIDE;
     43   virtual bool Parse(const uint8* buf, int size) OVERRIDE;
     44 
     45  protected:
     46   // Subclasses implement this method to parse format specific frame headers.
     47   // |data| & |size| describe the data available for parsing.
     48   //
     49   // Implementations are expected to consume an entire frame header.  It should
     50   // only return a value greater than 0 when |data| has enough bytes to
     51   // successfully parse & consume the entire frame header.
     52   //
     53   // |frame_size| - Required parameter that is set to the size of the frame, in
     54   // bytes, including the frame header if the function returns a value > 0.
     55   // |sample_rate| - Optional parameter that is set to the sample rate
     56   // of the frame if this function returns a value > 0.
     57   // |channel_layout| - Optional parameter that is set to the channel_layout
     58   // of the frame if this function returns a value > 0.
     59   // |sample_count| - Optional parameter that is set to the number of samples
     60   // in the frame if this function returns a value > 0.
     61   // |metadata_frame| - Optional parameter that is set to true if the frame has
     62   // valid values for the above parameters, but no usable encoded data; only set
     63   // to true if this function returns a value > 0.
     64   //
     65   // |sample_rate|, |channel_layout|, |sample_count|, |metadata_frame| may be
     66   // NULL if the caller is not interested in receiving these values from the
     67   // frame header.
     68   //
     69   // If |metadata_frame| is true, the MPEGAudioStreamParserBase will discard the
     70   // frame after consuming the metadata values above.
     71   //
     72   // Returns:
     73   // > 0 : The number of bytes parsed.
     74   //   0 : If more data is needed to parse the entire frame header.
     75   // < 0 : An error was encountered during parsing.
     76   virtual int ParseFrameHeader(const uint8* data,
     77                                int size,
     78                                int* frame_size,
     79                                int* sample_rate,
     80                                ChannelLayout* channel_layout,
     81                                int* sample_count,
     82                                bool* metadata_frame) const = 0;
     83 
     84   const LogCB& log_cb() const { return log_cb_; }
     85 
     86  private:
     87   enum State {
     88     UNINITIALIZED,
     89     INITIALIZED,
     90     PARSE_ERROR
     91   };
     92 
     93   void ChangeState(State state);
     94 
     95   // Parsing functions for various byte stream elements.  |data| & |size|
     96   // describe the data available for parsing.
     97   //
     98   // Returns:
     99   // > 0 : The number of bytes parsed.
    100   //   0 : If more data is needed to parse the entire element.
    101   // < 0 : An error was encountered during parsing.
    102   int ParseFrame(const uint8* data, int size, BufferQueue* buffers);
    103   int ParseIcecastHeader(const uint8* data, int size);
    104   int ParseID3v1(const uint8* data, int size);
    105   int ParseID3v2(const uint8* data, int size);
    106 
    107   // Parses an ID3v2 "sync safe" integer.
    108   // |reader| - A BitReader to read from.
    109   // |value| - Set to the integer value read, if true is returned.
    110   //
    111   // Returns true if the integer was successfully parsed and |value|
    112   // was set.
    113   // Returns false if an error was encountered. The state of |value| is
    114   // undefined when false is returned.
    115   bool ParseSyncSafeInt(BitReader* reader, int32* value);
    116 
    117   // Scans |data| for the next valid start code.
    118   // Returns:
    119   // > 0 : The number of bytes that should be skipped to reach the
    120   //       next start code..
    121   //   0 : If a valid start code was not found and more data is needed.
    122   // < 0 : An error was encountered during parsing.
    123   int FindNextValidStartCode(const uint8* data, int size) const;
    124 
    125   // Sends the buffers in |buffers| to |new_buffers_cb_| and then clears
    126   // |buffers|.
    127   // If |end_of_segment| is set to true, then |end_of_segment_cb_| is called
    128   // after |new_buffers_cb_| to signal that these buffers represent the end of a
    129   // media segment.
    130   // Returns true if the buffers are sent successfully.
    131   bool SendBuffers(BufferQueue* buffers, bool end_of_segment);
    132 
    133   State state_;
    134 
    135   InitCB init_cb_;
    136   NewConfigCB config_cb_;
    137   NewBuffersCB new_buffers_cb_;
    138   NewMediaSegmentCB new_segment_cb_;
    139   base::Closure end_of_segment_cb_;
    140   LogCB log_cb_;
    141 
    142   ByteQueue queue_;
    143 
    144   AudioDecoderConfig config_;
    145   scoped_ptr<AudioTimestampHelper> timestamp_helper_;
    146   bool in_media_segment_;
    147   const uint32 start_code_mask_;
    148   const AudioCodec audio_codec_;
    149   const int codec_delay_;
    150 
    151   DISALLOW_COPY_AND_ASSIGN(MPEGAudioStreamParserBase);
    152 };
    153 
    154 }  // namespace media
    155 
    156 #endif  // MEDIA_FORMATS_MPEG_MPEG_AUDIO_STREAM_PARSER_BASE_H_
    157