Source Code for Module jazzparser.taggers.segmidi.midi

 1  from __future__ import absolute_import 
 2  """Midi processing for segmented midi taggers. 
 3   
 4  """ 
 5  """ 
 6  ============================== License ======================================== 
 7   Copyright (C) 2008, 2010-12 University of Edinburgh, Mark Granroth-Wilding 
 8    
 9   This file is part of The Jazz Parser. 
10    
11   The Jazz Parser is free software: you can redistribute it and/or modify 
12   it under the terms of the GNU General Public License as published by 
13   the Free Software Foundation, either version 3 of the License, or 
14   (at your option) any later version. 
15    
16   The Jazz Parser is distributed in the hope that it will be useful, 
17   but WITHOUT ANY WARRANTY; without even the implied warranty of 
18   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
19   GNU General Public License for more details. 
20    
21   You should have received a copy of the GNU General Public License 
22   along with The Jazz Parser.  If not, see <http://www.gnu.org/licenses/>. 
23   
24  ============================ End license ====================================== 
25   
26  """ 
27  __author__ = "Mark Granroth-Wilding <mark.granroth-wilding@ed.ac.uk>"  
28   
29  from midi import NoteOnEvent 
30     
31 -def midi_to_emission_stream(segmidi, metric=True, remove_empty=True, unique_notes=False): 
32      """ 
33      Get a list of emissions from the midi stream's note on events. 
34       
35      Returns a 2-tuple of the list of emissions and their  
36      corresponding start times in midi ticks. 
37       
38      @type segmidi: L{jazzparser.data.input.SegmentedMidiInput} 
39      @param segmidi: midi input 
40      @type metric: bool 
41      @param metric: include a metrical model. Each observation has a metrical  
42          value associated with it. If this is False, the value will always be 0 
43      @type remove_empty: bool 
44      @param remove_empty: remove any chunks that have no observations in them  
45          (default True) 
46       
47      """ 
48      chunks = [] 
49      start_times = [] 
50      tick_unit = segmidi.tick_unit 
51       
52      for segment in segmidi: 
53          segment_start = segment.segment_start 
54          start_times.append(segment_start) 
55          note_ons = [ev for ev in segment.trackpool if isinstance(ev, NoteOnEvent)] 
56           
57          # Produce an observation for every event 
58          chunk = [] 
59          for ev in note_ons: 
60              if metric: 
61                  # Compute the metrical prominence value 
62                  bar_time = ev.tick - segment_start 
63                  if bar_time == 0: 
64                      rhythm = 0 
65                  elif bar_time == tick_unit/2: 
66                      rhythm = 1 
67                  elif bar_time == tick_unit/4 or bar_time == tick_unit*3/4: 
68                      rhythm = 2 
69                  else: 
70                      rhythm = 3 
71              else: 
72                  # No metrical values: always 0 
73                  rhythm = 0 
74              pc = ev.pitch % 12 
75              chunk.append((pc, rhythm)) 
76          chunks.append(chunk) 
77           
78      # Get rid of duplicate values in the chunks (octaves) 
79      if unique_notes: 
80          chunks = [list(set(c)) for c in chunks] 
81      if remove_empty: 
82          # Remove chunks that have no observations in them 
83          chunks = [ems for ems in chunks if len(ems) > 0] 
84      chunks_times = zip(chunks, start_times) 
85       
86      # Return a tuple of the chunks and the start times 
87      return zip(*chunks_times) 
88