Question

我的目的是拥有两个音乐曲目，它们在性质上相似，在不同时间之间相互淡化。当发生这样的淡入淡出时，一个音乐曲目应该在短时间内从全音量淡入淡出，同时，另一个曲目应该从0渐变到100并继续从同一时间指数播放。他们必须能够随时动态 - 当某个动作发生时，淡入淡出将发生并且新曲目将开始在同一位置播放一个人离开了。

通过使用音量操作或启动和停止音乐，这可能是合理的（但是，似乎只存在“淡出”选项，而且缺少“fadein”选项）。我怎样才能做到这一点？存在的最佳方法是什么？如果使用Pygame是不可能的， Pygame的替代品是可以接受的。

Answer 1

这不是问题的答案，但对于未来的googlers，我写了一个脚本，在早上从第0卷淡入我的音乐，这就是我使用的：

max_volume = 40 
current_volume = 0

# set the volume to the given percent using amixer
def set_volume_to(percent):
    subprocess.call(["amixer", "-D", "pulse", "sset", "Master", 
                     str(percent) + "%", "stdout=devnull"])

# play the song and fade in the song to the max_volume 
def play_song(song_file):
    global current_volume
    print("Song starting: " + song_file)
    pygame.mixer.music.load(song_file)
    pygame.mixer.music.play()

    # gradually increase volume to max
    while pygame.mixer.music.get_busy():
        if current_volume < max_volume: 
            set_volume_to(current_volume)
            current_volume += 1

        pygame.time.Clock().tick(1)

 play_song("foo.mp3")

Answer 2

伪代码：

track1 = ...
track2 = ...

track1.play_forever()
track1.volume = 100
track2.play_forever()
track2.volume = 0

playing = track1
tracks = [track1, track2]


def volume_switcher():
    while True:
        playing.volume = min(playing.volume + 1, 100)

        for track in tracks:
            if track != playing:
                track.volume = max(track.volume - 1, 100)

        time.sleep(0.1)

Thread(target=volume_switcher).start()

Answer 3

所以看起来你想在pygame中做的是创建两个'Sound'对象，并在它们之间的音量上创建一个线性插值。

我会创建两个向量，每个向量来自[0,100]，并将它们与某个常量相反。因此，当声音A为100时，声音b为0.然后当动作发生时，修改常量。

t = 0时
答：[0 ... 100 ]
B：[ 0 ... 100]

T = 1
行动

T = 1.1
答：[0 .. 50 .. 100]
B：[0 .. 50 .. 100]

T = 2
答：[ 0 ... 100]
B：[0 ... 100 ]

现在有些代码了。我不熟悉pygame，但这应该会让你走上正轨。

class Song(object):
    def __init__(self, songfilename):
        self.song = pygame.mixer.Sound(songfilename)

    def setVolume(self, somenumber):
        #number validation
        #possibly do some volume curve here if you wanted
        self.song.set_volume(somenumber)

class SongFader(object):
    def __init__(self, song1, song2):
        self.song1 = song1
        self.song2 = song2
        self.__xAxisMax = 100
        self.__xAxisMin = 0

    def fade(self, xaxis):
        assert(self.__xAxisMin <= xaxis <= self.__xAxisMax) 
          #could be any numbers you want. 
          #i chose 0-100 for convenience
        self.song1.setVolume(xaxis)
        self.song2.setVolume(self.__xAxisMax-xaxis)

song1 = Song('Song1.wav')
song2 = Song('Song2.wav')
fader = SongFader(song1, song2)

#Inside some event loop when you action is triggered
fader.fade(100) #Only song2 is playing
fader.fade(50)  #Songs are evenly split
fader.fade(0)   #Only left song is playing

修改

线性插值可能是这里更重要的概念，所以我修改了推子类，灵感来自Eric的线程理念。

class SongFader(object):
    def __init__(self, song1, song2):
        self.song1 = song1
        self.song2 = song2
        self.lefttoright = False
        self.starttime = 0
        self.endtime = 0


    def fade(self, starttime, fadeleft):
        self.lefttoright = fadeleft == True #Being verbose here
        self.starttime = starttime #assuming time is in millis
        self.endtime = starttime + 1000
        Thread(target = self.fadeHelper).start()

    #this is where you define how the two songs are faded
    def fadeHelper(self):
        #if using thread, make sure you mutex the 'self.' variables
        starttime = self.starttime
        endtime = self.endtime
        lefttoright = self.lefttoright
        while starttime < endtime:
            fadevalue = (starttime - endtime) / 1000 #a val between [0,1]
            if lefttoright:
                self.song1.setVolume(fadevalue)
                self.song2.setVolume(1-fadevalue)
            else:
                self.song1.setVolume(1-fadevalue)
                self.song2.setVolume(fadefalue)
            starttime = getGameTimeFromSomewhere()

Answer 4

试试这个，这很直接......

import pygame

pygame.mixer.init()
pygame.init()

# Maybe you can subclass the pygame.mixer.Sound and
# add the methods below to it..
class Fader(object):
    instances = []
    def __init__(self, fname):
        super(Fader, self).__init__()
        assert isinstance(fname, basestring)
        self.sound = pygame.mixer.Sound(fname)
        self.increment = 0.01 # tweak for speed of effect!!
        self.next_vol = 1 # fade to 100 on start
        Fader.instances.append(self)

    def fade_to(self, new_vol):
        # you could change the increment here based on something..
        self.next_vol = new_vol

    @classmethod
    def update(cls):
        for inst in cls.instances:
            curr_volume = inst.sound.get_volume()
            # print inst, curr_volume, inst.next_vol
            if inst.next_vol > curr_volume:
                inst.sound.set_volume(curr_volume + inst.increment)
            elif inst.next_vol < curr_volume:
                inst.sound.set_volume(curr_volume - inst.increment)

sound1 = Fader("1.wav")
sound2 = Fader("2.wav")
sound1.sound.play()
sound2.sound.play()
sound2.sound.set_volume(0)

# fading..
sound1.fade_to(0)
sound2.fade_to(1)


while True:
    Fader.update() # a call that will update all the faders..

Pygame中两首音乐曲目之间的淡入淡出

4 个答案:

修改