libcm/cmMidiFile.h

#ifndef cmMidiFile_h
#define cmMidiFile_h

#ifdef __cplusplus
extern "C" {
#endif

  // MIDI file timing:
  // Messages in the MIDI file are time tagged with a delta offset in 'ticks'
  // from the previous message in the same track.
  // 
  // A 'tick' can be converted to microsends as follows:
  //
  // microsecond per tick = micros per quarter note / ticks per quarter note
  // 
  // MpT = MpQN / TpQN
  // 
  // TpQN is given as a constant in the MIDI file header.
  // MpQN is given as the value of the MIDI file tempo message.
  //
  // See cmMidiFileSeekUSecs() for an example of converting ticks to milliseconds.
  //
  // As part of the file reading process, the status byte of note-on messages 
  // with velocity=0 are is changed to a note-off message. See _cmMidiFileReadChannelMsg().



  typedef cmHandle_t cmMidiFileH_t;
  typedef unsigned   cmMfRC_t;

  typedef struct
  {
    cmMidiByte_t hr;
    cmMidiByte_t min;
    cmMidiByte_t sec;
    cmMidiByte_t frm;
    cmMidiByte_t sfr;
  } cmMidiSmpte_t;

  typedef struct
  {
    cmMidiByte_t num;
    cmMidiByte_t den;
    cmMidiByte_t metro;
    cmMidiByte_t th2s;
  } cmMidiTimeSig_t;

  typedef struct
  {
    cmMidiByte_t key;
    cmMidiByte_t scale;
  } cmMidiKeySig_t;

  typedef struct
  {
    cmMidiByte_t ch;
    cmMidiByte_t d0;
    cmMidiByte_t d1;
    unsigned     durTicks; // note duration calc'd by cmMidiFileCalcNoteDurations();
  } cmMidiChMsg_t;


  typedef struct cmMidiTrackMsg_str
  {
    unsigned                   uid;     // uid's are unique among all msg's in the file
    unsigned                   dtick;   // delta ticks
    unsigned                   atick;   // accumulated ticks
    cmMidiByte_t               status;  // ch msg's have the channel value removed (it is stored in u.chMsgPtr->ch)
    cmMidiByte_t               metaId;  //
    unsigned short             trkIdx;  //  
    unsigned                   byteCnt; // length of data pointed to by u.voidPtr (or any other pointer in the union)
    struct cmMidiTrackMsg_str* link;    // link to next record in this track

    union
    {
      cmMidiByte_t           bVal;
      unsigned               iVal;
      unsigned short         sVal;
      const char*            text;
      const void*            voidPtr;
      const cmMidiSmpte_t*   smptePtr;
      const cmMidiTimeSig_t* timeSigPtr;
      const cmMidiKeySig_t*  keySigPtr;
      const cmMidiChMsg_t*   chMsgPtr;
      const cmMidiByte_t*    sysExPtr;
    } u;
  } cmMidiTrackMsg_t;

  enum
  {
    kOkMfRC = cmOkRC,    // 0
    kFileFailMfRC,       // 1
    kNotAMidiFileMfRC,   // 7
    kMemAllocFailMfRC,   // 8
    kFileCorruptMfRC,    // 9
    kMissingEoxMfRC,     // 10 
    kUnknownMetaIdMfRC,  // 11
    kInvalidHandleMfRC,  // 12
    kMissingNoteOffMfRC, // 13
    kInvalidStatusMfRC   // 14
  };

  extern cmMidiFileH_t cmMidiFileNullHandle;

  cmMfRC_t              cmMidiFileOpen( const char* fn, cmMidiFileH_t* hPtr, cmCtx_t* ctx );
  cmMfRC_t              cmMidiFileClose( cmMidiFileH_t* hp );

  cmMfRC_t              cmMidiFileWrite( cmMidiFileH_t h, const char* fn );

  bool                  cmMidiFileIsValid( cmMidiFileH_t h );

  // Returns track count or kInvalidCnt if 'h' is invalid.
  unsigned              cmMidiFileTrackCount( cmMidiFileH_t h );

  // Return midi file format id (0,1,2) or kInvalidId if 'h' is invalid.
  unsigned              cmMidiFileType( cmMidiFileH_t h );

  // Returns ticks per quarter note or kInvalidMidiByte if 'h' is invalid or 0 if file uses SMPTE ticks per frame time base.
  unsigned              cmMidiFileTicksPerQN( cmMidiFileH_t h );

  // The file name used in an earlier call to midiFileOpen() or NULL if this 
  // midi file did not originate from an actual file.
  const char*           cmMidiFileName( cmMidiFileH_t h );

  // Returns SMPTE ticks per frame or kInvalidMidiByte if 'h' is invalid or 0 if file uses ticks per quarter note time base.
  cmMidiByte_t          cmMidiFileTicksPerSmpteFrame( cmMidiFileH_t h );

  // Returns SMPTE format or kInvalidMidiByte if 'h' is invalid or 0 if file uses ticks per quarter note time base.
  cmMidiByte_t          cmMidiFileSmpteFormatId( cmMidiFileH_t h );

  // Returns count of records in track 'trackIdx' or kInvalidCnt if 'h' is invalid.
  unsigned              cmMidiFileTrackMsgCount( cmMidiFileH_t h, unsigned trackIdx );

  // Returns base of record chain from track 'trackIdx' or NULL if 'h' is invalid.
  const cmMidiTrackMsg_t* cmMidiFileTrackMsg( cmMidiFileH_t h, unsigned trackIdx );

  // Returns the total count of records in the midi file and the number in the array returned by cmMidiFileMsgArray().
  // Return kInvalidCnt if 'h' is invalid.
  unsigned              cmMidiFileMsgCount( cmMidiFileH_t h );

  // Returns a pointer to the base of an array of pointers to each record in the file sorted in ascending time order.
  // Returns NULL if 'h' is invalid.
  const cmMidiTrackMsg_t** cmMidiFileMsgArray( cmMidiFileH_t h );

  // Return a pointer to the first msg at or after 'usecsOffs' or kInvalidIdx if no
  // msg exists after 'usecsOffs'.  Note that 'usecOffs' is an offset from the beginning
  // of the file.
  // On return *'msgUsecsPtr' is set to the actual time of the msg. 
  // (which will be equal to or greater than 'usecsOffs').
  unsigned              cmMidiFileSeekUsecs( cmMidiFileH_t h, unsigned usecsOffs, unsigned* msgUsecsPtr, unsigned* newMicrosPerTickPtr );

  double                cmMidiFileDurSecs( cmMidiFileH_t h );

  // Convert the track message 'dtick' field to delta-microseconds.
  void                  cmMidiFileTickToMicros( cmMidiFileH_t h );

  // Convert the track message 'dtick' field to samples.
  // If the absFl is set then the delta times are converted to absolute time.
  void                  cmMidiFileTickToSamples( cmMidiFileH_t h, double srate, bool absFl );

  // Calculate Note Duration 
  void                  cmMidiFileCalcNoteDurations( cmMidiFileH_t h );

  // Set the delay prior to the first non-zero msg.
  void                  cmMidiFileSetDelay( cmMidiFileH_t h, unsigned ticks );

  // This function packs a track msg into a single  consecutive 
  // block of memory buf[ bufByteCnt ]. Call cmMidiFilePackTracMsgBufByteCount()
  // to get the required buffer length for any given cmMidiTrackMsg_t instance.
  cmMidiTrackMsg_t*     cmMidiFilePackTrackMsg( const cmMidiTrackMsg_t* m, void* buf, unsigned bufByteCnt );
  unsigned              cmMidiFilePackTrackMsgBufByteCount( const cmMidiTrackMsg_t* m );

  void                  cmMidiFilePrint( cmMidiFileH_t h, unsigned trkIdx, cmRpt_t* rpt );
  bool                  cmMidiFileIsNull( cmMidiFileH_t h );
  void                  cmMidiFileTest( const char* fn, cmCtx_t* ctx );

#ifdef __cplusplus
}
#endif
 
#endif