Speaker controller

Let's write a Python class (tone_player.py in downloads) that plays a musical tone indicating that the boot-up of your Raspberry Pi is complete. For this section, you will need a USB sound card and a speaker interfaced to the USB hub of the Raspberry Pi.

Let's call our class TonePlayer. This class should be capable of controlling the speaker volume and playing any file passed as an argument while creating an object:

class TonePlayer(object): 
    """A Python class to play boot-up complete tone""" 

    def __init__(self, file_name): 
        self.file_name = file_name

In this case, the file that has to be played by the TonePlayer class has to be passed an argument. For example:

       tone_player = TonePlayer("/home/pi/tone.wav")

We also need to be able to set the volume level at which the tone has to be played. Let's add a method to do the same:

def set_volume(self, value): 
    """set tone sound volume""" 
    subprocess.Popen(["amixer", "set", "'PCM'", str(value)], 
    shell...