如何使用Music21制作音乐的实时音频输出？

Question

如何从Music21制作的音乐中产生实时音频输出。否则，我怎么能通过开放源代码软件生成任何音乐输出从Music21制作的音乐？谢谢您的帮助。

Answer 1

这就是我发现的。这是一个适用于Windows XP的Python脚本。除了music21，它还需要pygame。

# genPlayM21Score.py Generates and Plays 2 Music21 Scores "on the fly". 
# 
# see way below for source notes 

from music21 import * 

# we create the music21 Bottom Part, and do this explicitly, one object at a time. 

n1 = note.Note('e4') 
n1.duration.type = 'whole' 
n2 = note.Note('d4') 
n2.duration.type = 'whole' 
m1 = stream.Measure() 
m2 = stream.Measure() 
m1.append(n1) 
m2.append(n2) 
partLower = stream.Part() 
partLower.append(m1) 
partLower.append(m2) 

# For the music21 Upper Part, we automate the note creation procedure 

data1 = [('g4', 'quarter'), ('a4', 'quarter'), ('b4', 'quarter'), ('c#5', 'quarter')] 
data2 = [('d5', 'whole')] 
data = [data1, data2] 
partUpper = stream.Part() 

def makeUpperPart(data): 
    for mData in data: 
     m = stream.Measure() 
     for pitchName, durType in mData: 
      n = note.Note(pitchName) 
      n.duration.type = durType 
      m.append(n) 
     partUpper.append(m) 
makeUpperPart(data)   

# Now, we can add both Part objects into a music21 Score object. 

sCadence = stream.Score() 
sCadence.insert(0, partUpper) 
sCadence.insert(0, partLower) 

# Now, let's play the MIDI of the sCadence Score [from memory, ie no file write necessary] using pygame 

import cStringIO 

# for music21 <= v.1.2: 
if hasattr(sCadence, 'midiFile'): 
    sCadence_mf = sCadence.midiFile 
else: # for >= v.1.3: 
    sCadence_mf = midi.translate.streamToMidiFile(sCadence) 
sCadence_mStr = sCadence_mf.writestr() 
sCadence_mStrFile = cStringIO.StringIO(sCadence_mStr) 

import pygame 

freq = 44100 # audio CD quality 
bitsize = -16 # unsigned 16 bit 
channels = 2 # 1 is mono, 2 is stereo 
buffer = 1024 # number of samples 
pygame.mixer.init(freq, bitsize, channels, buffer) 

# optional volume 0 to 1.0 
pygame.mixer.music.set_volume(0.8) 

def play_music(music_file): 
    """ 
    stream music with mixer.music module in blocking manner 
    this will stream the sound from disk while playing 
    """ 
    clock = pygame.time.Clock() 
    try: 
     pygame.mixer.music.load(music_file) 
     print "Music file %s loaded!" % music_file 
    except pygame.error: 
     print "File %s not found! (%s)" % (music_file, pygame.get_error()) 
     return 
    pygame.mixer.music.play() 
    while pygame.mixer.music.get_busy(): 
     # check if playback has finished 
     clock.tick(30) 

# play the midi file we just saved 
play_music(sCadence_mStrFile) 

#============================ 

# now let's make a new music21 Score by reversing the upperPart notes 
data1.reverse() 
data2 = [('d5', 'whole')] 
data = [data1, data2] 
partUpper = stream.Part() 
makeUpperPart(data)   
sCadence2 = stream.Score() 
sCadence2.insert(0, partUpper) 
sCadence2.insert(0, partLower) 

# now let's play the new Score 
sCadence2_mf = sCadence2.midiFile 
sCadence2_mStr = sCadence2_mf.writestr() 
sCadence2_mStrFile = cStringIO.StringIO(sCadence2_mStr) 
play_music(sCadence2_mStrFile) 



## SOURCE NOTES 
## There are 3 sources for this mashup: 

# 1. Source for the Music21 Score Creation http://web.mit.edu/music21/doc/html/quickStart.html#creating-notes-measures-parts-and-scores 

# 2. Source for the Music21 MidiFile Class Behaviour http://mit.edu/music21/doc/html/moduleMidiBase.html?highlight=midifile#music21.midi.base.MidiFile 

# 3. Source for the pygame player: http://www.daniweb.com/software-development/python/code/216979/embed-and-play-midi-music-in-your-code-python 

Answer 2

如你所见，music21没有被设计成为一个音乐播放系统，但它被设计为嵌入到其他播放系统内或将它们从系统中调用。我们不打算在播放系统上投入太多工作（因为有硬件支持，我们是一个很小的研究实验室，还需要在音乐分析等方面完成这项工作），但是您的解决方案非常优雅，现在作为music21.midi.realtime模块包含在所有版本的music21（post v1.1）中。如下是music21对以模拟微音程回放（对于大多数MIDI播放的一个主要问题）动态地分配不同的弯音对象MIDI通道的能力的一个示例：

# Set up a detuned piano 
# (where each key has a random 
# but consistent detuning from 30 cents flat to sharp) 
# and play a Bach Chorale on it in real time. 

from music21 import * 
import random 
keyDetune = [] 
for i in range(0, 127): 
    keyDetune.append(random.randint(-30, 30)) 

b = corpus.parse('bach/bwv66.6') 
for n in b.flat.notes: 
    n.microtone = keyDetune[n.midi] 
sp = midi.realtime.StreamPlayer(b) 
sp.play() 

的StreamPlayer的.play（）函数也采用busyFunction和busyArgs和busyWaitMilliseconds参数，它们指定一个函数在每个busyWaitMilliseconds时使用参数进行调用（如果系统较慢，则可能更多）。还有一个endFunction和endArgs将在最后调用，以防您想设置某种线程播放。 - Myke Cuthbert（Music21的创造者）