如何 link 带有滑块的 mp3 文件，以便滑块根据 mp3 文件长度移动？

Question

如何 link 带有滑块的 mp3 文件，以便滑块根据 mp3 文件的长度移动？在我的代码中，只有当我将鼠标放在滑块槽上时，滑块才会移动。如何在不一直按住鼠标的情况下完成这项工作？

#using python3.6
from tkinter import *
from pygame import mixer
root = Tk()

from mutagen.mp3 import MP3
fLen =MP3('A Message to you Bit.mp3')
FileLength = fLen.info.length * 1000
mixer.init()

#load & play an mp3 file from root dir
def Play():
    mixer.music.load('A Message to you Bit.mp3')
    mixer.music.set_volume(.25)
    mixer.music.play()

#set slider to mp3 file position
def ProgressBar(event):
    slider.set(mixer.music.get_pos())

#create widgets
playBut = Button(text='Play',command = Play)
playBut.pack()

slider = Scale(to=FileLength, orient=HORIZONTAL, command=ProgressBar)
slider.pack()

Answer 1

我已经修改了您的代码以演示如何 link 您的滑块到轨道。见下文。要更新滑块的位置，您需要熟悉 :

tkinter 的 .get() 和 .set() 方法（参见 here) and use the variable option of the tkinter Scale widget (see here）。
tkinter 的 .after() 方法（参见 here）创建一个事件循环来跟踪 mp3 文件的播放。我创建的 .PlayTrack() 函数演示了如何执行此操作。
正在阅读Pygame的混音器文档, 我意识到 .get_pos() 和 .set_pos() 以毫秒为单位运行并且秒分别，因此你需要小心转换。

第 1 点： 请注意，修改后的代码中存在问题。该代码能够从一开始就播放音乐文件。但是，如果幻灯片不在起点，按播放按钮将引发 exception/error

line 24, in Play mixer.music.set_pos( playtime ) pygame.error: set_pos unsupported for this codec。

我不确定为什么 .set_pos 不起作用。我会让你解决这个问题。请在解决问题后分享您的答案。祝一切顺利。

第 2 点： 我将 mixer.init() 放在 Play() 函数中而不是放在主代码中，因为我注意到一旦它被激活，整个CPU 已消耗。我认为在按下播放按钮后激活它可以帮助您节省计算资源。

修改后的代码：

#using python3.6
from tkinter import *
from pygame import mixer

root = Tk()

from mutagen.mp3 import MP3
#fLen =MP3('A Message to you Bit.mp3')
musicfile='Test.mp3'
fLen =MP3( musicfile )
FileLength = fLen.info.length
print('FileLength = ', FileLength, ' sec')

#load & play an mp3 file from root dir
def Play():
    print('\ndef Play():')
    mixer.init()
    mixer.music.load( musicfile )
    mixer.music.set_volume( .25 )
    playtime = slider_value.get()
    if playtime > 0:            
        print( 'playtime = ', playtime, type(playtime) )
        mixer.music.rewind()
        mixer.music.set_pos( playtime )
    mixer.music.play()
    TrackPlay()

def TrackPlay():
    if mixer.music.get_busy():
        current = mixer.music.get_pos() #.get_pos() returns integer in milliseconds
        print( 'current = ', current, type(current) )
        slider_value.set( current/1000 ) #.set_pos() works in seconds
        print( 'slider_value = ', slider_value.get(), type(slider_value.get()) )
        root.after(1000, lambda:TrackPlay() ) # Loop every sec


#set slider to mp3 file position
def ProgressBar( value ):
    print('\ndef ProgressBar( value ):')
    print('value = ', value, type(value))
    slider_value.set( value )
    print('slider_value.get() = ', slider_value.get(), type(slider_value.get()) )
    print('value = ', value, type(value) )
    #slider.configure(from_=slider_value.get())


#create widgets
playBut = Button(text='Play',command=Play)
playBut.pack()

slider_value = DoubleVar()
slider = Scale( to=FileLength, orient=HORIZONTAL, length=500, resolution=1,
                showvalue=True, tickinterval=30, variable=slider_value,
                command=ProgressBar)
slider.pack()

root.mainloop()

更新 1：

我花时间仔细研究了未解决的问题。在这样做的同时，我意识到了一些等待我们的问题。

要在定义的时间播放曲目，我们可以使用pygame.mixer.music.play( start=time )。 time 是我们需要提供的参数。不需要使用给我们带来问题的 pygame.mixer.music.set_pos() 方法。
Pygame's advice:

Be aware that MP3 support is limited. On some systems an unsupported format can crash the program, e.g. Debian Linux. Consider using OGG instead.

MP3 与 pygame 不兼容，所以我们应该考虑使用 OGG。
要使音乐跟踪器有用，它应该允许用户在播放曲目时重新定位滑块，播放将从新的滑块位置开始。为此，我们必须取消由 .after 方法创建的回调。为了解决这个问题，以面向对象的方式编写 python 应用程序将使我们的事情变得更容易。
我们需要一种在整个 Tk window 被销毁之前退出 pygame.mixer 的方法。如果不是，它将继续在后台运行并消耗整个 CPU 核心。

基于以上，我写了一个新的脚本。我发现它非常适用于 ogg vorbis 音轨，但不适用于 mp3 音轨。我已将 python 脚本评论为我在脚本中所做的事情。希望它能帮助您学习如何使用 tkinter 和 python 做您想做的事。这是我第一次使用 pygame，所以如果我对 pygame 的回答不充分，请原谅我。

要使用此文件，请对第 42、44 和 146 行进行必要的更改。

新代码：

#!/usr/bin/python3
# -*- coding: utf-8 -*-

from mutagen.mp3 import MP3
from mutagen.oggvorbis import OggVorbis
from mutagen import MutagenError
from pygame import mixer
import tkinter as tk
import tkinter.messagebox as tkMessageBox


class MusicPlayer( tk.Frame ):

    def __init__(self, master, tracktype='ogg', *args, **kwargs):

        super().__init__(master) #initilizes self, which is a tk.Frame
        self.pack()

        # MusicPlayer's Atrributes
        self.master = master     # Tk window
        self.track = None        # Audio file
        self.trackLength = None  # Audio file length
        self.player = None       # Music player
        self.playBut = None      # Play Button
        self.stopBut = None      # Stop Button
        self.slider = None       # Progress Bar
        self.slider_value = None # Progress Bar value

        # Call these methods
        self.get_AudioFile_MetaData( tracktype )
        self.load_AudioFile()
        self.create_Widgets()


    def get_AudioFile_MetaData( self, tracktype ):
        '''Get audio file and it's meta data (e.g. tracklength).'''
        print( '\ndef get_AudioFileMetaData( self, audiofile ):' )

        try:
            if tracktype == 'mp3':
                audiofile='Test.mp3' # In current directory
                f = MP3( audiofile )
            elif tracktype == 'ogg':
                audiofile='Test.ogg' # In current directory
                f = OggVorbis( audiofile )
            else:
                raise print( 'Track type not supported.' )
        except MutagenError:
            print( "Fail to load audio file ({}) metadata".format(audiofile) )
        else:
            trackLength = f.info.length
        self.track = audiofile
        self.trackLength = trackLength; print( 'self.trackLength',type(self.trackLength),self.trackLength,' sec' )


    def load_AudioFile( self ):
        '''Initialise pygame mixer, load audio file and set volume.'''
        print( '\ndef load_AudioFile( self, audiofile ):' )
        player = mixer
        player.init()
        player.music.load( self.track )
        player.music.set_volume( .25 )

        self.player = player
        print('self.player ', self.player)


    def create_Widgets ( self ):
        '''Create Buttons (e.g. Start & Stop ) and Progress Bar.''' 
        print( '\ndef create_Widgets ( self ):' )
        self.playBut = tk.Button( self, text='Play', command=self.Play )
        self.playBut.pack()

        self.stopBut = tk.Button( self, text='Stop', command=self.Stop )
        self.stopBut.pack()

        self.slider_value = tk.DoubleVar()
        self.slider = tk.Scale( self, to=self.trackLength, orient=tk.HORIZONTAL, length=700,
                                resolution=0.5, showvalue=True, tickinterval=30, digit=4,
                                variable=self.slider_value, command=self.UpdateSlider )
        self.slider.pack()


    def Play( self ):
        '''Play track from slider location.'''
        print('\ndef Play():')
        #1. Get slider location.
        #2. Play music from slider location.
        #3. Update slider location (use tk's .after loop)
        playtime = self.slider_value.get();       print( type(playtime),'playtime = ',playtime,'sec' )
        self.player.music.play( start=playtime ); print( 'Play Started' )
        self.TrackPlay( playtime )


    def TrackPlay( self, playtime ):
        '''Slider to track the playing of the track.'''
        print('\ndef TrackPlay():')
        #1.When track is playing
        #   1. Set slider position to playtime
        #   2. Increase playtime by interval (1 sec)
        #   3. start TrackPlay loop
        #2.When track is not playing
        #   1. Print 'Track Ended'
        if self.player.music.get_busy():
            self.slider_value.set( playtime ); print( type(self.slider_value.get()),'slider_value = ',self.slider_value.get() )
            playtime += 1.0 
            self.loopID = self.after(1000, lambda:self.TrackPlay( playtime ) );\
                                               print( 'self.loopID = ', self.loopID ) 
        else:
            print('Track Ended')


    def UpdateSlider( self, value ):
        '''Move slider position when tk.Scale's trough is clicked or when slider is clicked.'''
        print( '\ndef UpdateSlider():' );       print(type(value),'value = ',value,' sec')
        if self.player.music.get_busy():
            print("Track Playing")
            self.after_cancel( self.loopID ) #Cancel PlayTrack loop    
            self.slider_value.set( value )   #Move slider to new position
            self.Play( )                     #Play track from new postion
        else:
            print("Track Not Playing")
            self.slider_value.set( value )   #Move slider to new position


    def Stop( self ):
        '''Stop the playing of the track.'''
        print('\ndef Stop():')
        if self.player.music.get_busy():
            self.player.music.stop()
            print('Play Stopped')


def ask_quit():
    '''Confirmation to quit application.'''
    if tkMessageBox.askokcancel("Quit", "Exit MusicPlayer"):
        app.Stop()         #Stop playing track 
        app.player.quit()  #Quit pygame.mixer
        root.destroy()     #Destroy the Tk Window instance.

        # Note: After initialzing pygame.mixer, it will preoccupy an entire CPU core.
        #       Before destroying the Tk Window, ensure pygame.mixer is quitted too else
        #       pygame.mixer will still be running in the background despite destroying the 
        #       Tk Window instance.


if __name__ == "__main__":
    root = tk.Tk()                              #Initialize an instance of Tk window.
    app = MusicPlayer( root, tracktype='ogg' )  #Initialize an instance of MusicPlayer object and passing Tk window instance into it as it's master.
    root.protocol("WM_DELETE_WINDOW", ask_quit) #Tell Tk window instance what to do before it is destroyed.
    root.mainloop()                             #Start Tk window instance's mainloop.

如何 link 带有滑块的 mp3 文件，以便滑块根据 mp3 文件长度移动？

How do I link an mp3 file with a slider so that the slider moves in relation to the mp3 file length?

mp3

progress-bar

tkinter-scale