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165 lines
4.0 KiB
Python
165 lines
4.0 KiB
Python
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# patWalk.py
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"""
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This module is an integeral part of the program
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MMA - Musical Midi Accompaniment.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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Bob van der Poel <bvdp@xplornet.com>
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"""
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import random
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from MMA.harmony import harmonize
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from MMA.notelen import getNoteLen
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import gbl
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from MMA.common import *
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from MMA.pat import PC
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class Walk(PC):
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""" Pattern class for a walking bass track. """
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vtype = 'WALK'
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walkChoice = 0
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def getPgroup(self, ev):
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""" Get group for walking bass pattern.
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Fields - start, length, volume
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"""
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if len(ev) != 3:
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error("There must be at exactly 3 items in each group in "
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"a Walking Bass definition, not <%s>." % ' '.join(ev))
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a = struct()
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a.offset = self.setBarOffset(ev[0])
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a.duration = getNoteLen(ev[1])
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a.vol = stoi(ev[2], "Type error in Walking Bass definition")
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return a
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def restart(self):
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self.ssvoice = -1
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self.walkChoice = 0
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def trackBar(self, pattern, ctable):
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""" Do a waling bass bar.
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Called from self.bar()
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"""
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sc=self.seq
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dir = self.direction[sc]
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unify = self.unify[sc]
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for p in pattern:
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tb = self.getChordInPos(p.offset, ctable)
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if tb.walkZ:
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continue
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root = tb.chord.rootNote # root note of chord
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""" Create a note list from the current scale. We do
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this for each beat, but it's pretty fast. The note
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list is simply notes 0..6 of the scale PLUS notes
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1..5 reversed. So, a Cmajor chord would result in
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the note list (0,2,4,5,7,9,7,5,4,2).
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Note that we deliberately skip the 7th. Too often
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the chord is a Major but the melody note will be
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the dom. 7th and the M7 will sound off. So, just
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err on the side of caution.
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If DIR is UP or DOWN we don't append the 2nd half
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of the scale.
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If DIR is DOWN we reverse the order as well.
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"""
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wNotes = list(tb.chord.scaleList[0:6])
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if dir not in ('UP', 'DOWN'):
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b = list(tb.chord.scaleList[1:5])
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b.reverse()
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wNotes += b
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if dir == 'DOWN':
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wNotes.reverse()
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# Ensure that the offset is in range.
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if self.walkChoice >= len(wNotes) or self.walkChoice < 0:
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self.walkChoice = 0
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""" Even with a walking bass it's nice to have the chord root on
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beat 1 ... not all the time, but most. This bit of code ensures
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that more that 50% of beat ones will have the root.
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"""
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if p.offset == 0 and random.choice((0,1)):
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self.walkChoice=0
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note = wNotes[self.walkChoice]
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""" Adjust offset for NEXT TIME. If the direction is
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up/down we just increment the pointer. If we have
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direction set to RANDOM then we select either -1,
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0 or 1 with equal change for moving up, down or
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not-at-all. With BOTH we have a preference to move up.
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"""
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if dir in ('UP', 'DOWN'):
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self.walkChoice += 1
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elif dir == 'RANDOM':
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self.walkChoice += random.choice((0,1,-1))
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else: # BOTH
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self.walkChoice += random.choice( (-1,0,0,2,2,1,1,1,1,1,1,1))
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if not self.harmonyOnly[sc]:
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self.sendNote(
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p.offset,
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self.getDur(p.duration),
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self.adjustNote(note),
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self.adjustVolume(p.vol, p.offset) )
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if self.harmony[sc]:
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ch = self.getChordInPos(p.offset, ctable).chord.noteList
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h = harmonize(self.harmony[sc], note, ch)
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for n in h:
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self.sendNote(
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p.offset,
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self.getDur(p.duration),
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self.adjustNote(n),
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self.adjustVolume(p.vol * self.harmonyVolume[sc], -1) )
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