/src/echonest/support/midi/experimental/MidiOutStreamBase.py

  1class MidiOutStreamBase:
  2
  3
  4    """
  5
  6    MidiOutStreamBase is Basically an eventhandler. It is the most central
  7    class in the Midi library. You use it both for writing events to
  8    an output stream, and as an event handler for an input stream.
  9
 10    This makes it extremely easy to take input from one stream and
 11    send it to another. Ie. if you want to read a Midi file, do some
 12    processing, and send it to a midiport.
 13
 14    All time values are in absolute values from the opening of a
 15    stream. To calculate time values, please use the MidiTime and
 16    MidiDeltaTime classes.
 17
 18    """
 19
 20    def __init__(self):
 21        
 22        # the time is rather global, so it needs to be stored 
 23        # here. Otherwise there would be no really simple way to 
 24        # calculate it. The alternative would be to have each event 
 25        # handler do it. That sucks even worse!
 26        self._absolute_time = 0
 27        self._relative_time = 0
 28        self._current_track = 0
 29
 30    # time handling event handlers. They should overwritten with care
 31
 32    def update_time(self, new_time=0, relative=1):
 33        """
 34        Updates the time, if relative is true, new_time is relative, 
 35        else it's absolute.
 36        """
 37        if relative:
 38            self._relative_time = new_time
 39            self._absolute_time += new_time
 40        else:
 41            self._absolute_time = new_time
 42            self._relative_time = new_time - self._absolute_time
 43
 44    def rel_time(self):
 45        "Returns the relative time"
 46        return self._relative_time
 47
 48    def abs_time(self):
 49        "Returns the absolute time"
 50        return self._absolute_time
 51
 52    # track handling event handlers
 53    
 54    def set_current_track(self, new_track):
 55        "Sets the current track number"
 56        self._current_track = new_track
 57    
 58    def get_current_track(self):
 59        "Returns the current track number"
 60        return self._current_track
 61    
 62    
 63    #####################
 64    ## Midi events
 65
 66
 67    def channel_message(self, message_type, channel, data):
 68        """The default event handler for channel messages"""
 69        pass
 70
 71
 72    #####################
 73    ## Common events
 74
 75    def system_exclusive(self, data):
 76
 77        """The default event handler for system_exclusive messages"""
 78        pass
 79
 80
 81    def system_common(self, common_type, common_data):
 82
 83        """The default event handler for system common messages"""
 84        pass
 85
 86
 87    #########################
 88    # header does not really belong here. But anyhoo!!!
 89    
 90    def header(self, format, nTracks, division):
 91
 92        """
 93        format: type of midi file in [1,2]
 94        nTracks: number of tracks
 95        division: timing division
 96        """
 97        pass
 98
 99
100    def start_of_track(self, n_track=0):
101
102        """
103        n_track: number of track
104        """
105        pass
106
107
108    def eof(self):
109
110        """
111        End of file. No more events to be processed.
112        """
113        pass
114
115
116    #####################
117    ## meta events
118
119
120    def meta_event(self, meta_type, data, time):
121        
122        """The default event handler for meta_events"""
123        pass
124
125
126
127
128if __name__ == '__main__':
129
130    midiOut = MidiOutStreamBase()
131    midiOut.update_time(0,0)
132    midiOut.note_on(0, 63, 127)
133    midiOut.note_off(0, 63, 127)
134
135