How to play an audiofile with pyaudio?

Question

I do not understand the example material for pyaudio. It seems they had written an entire small program and it threw me off.

How do I just play a single audio file?

Format is not an issue, I just want to know the bare minimum code I need to play an audio file.

Solution 1

The example seems pretty clear to me. You simply save the example as playwav.py call:

python playwav.py my_fav_wav.wav

The wave example with some extra comments:

import pyaudio
import wave
import sys

# length of data to read.
chunk = 1024

# validation. If a wave file hasn't been specified, exit.
if len(sys.argv) < 2:
    print "Plays a wave file.\n\n" +\
          "Usage: %s filename.wav" % sys.argv[0]
    sys.exit(-1)

'''
************************************************************************
      This is the start of the "minimum needed to read a wave"
************************************************************************
'''
# open the file for reading.
wf = wave.open(sys.argv[1], 'rb')

# create an audio object
p = pyaudio.PyAudio()

# open stream based on the wave object which has been input.
stream = p.open(format =
                p.get_format_from_width(wf.getsampwidth()),
                channels = wf.getnchannels(),
                rate = wf.getframerate(),
                output = True)

# read data (based on the chunk size)
data = wf.readframes(chunk)

# play stream (looping from beginning of file to the end)
while data != '':
    # writing to the stream is what *actually* plays the sound.
    stream.write(data)
    data = wf.readframes(chunk)

# cleanup stuff.
stream.close()    
p.terminate()

Solution 2

May be this small wrapper (warning: created on knees) of their example will help you to understand the meaning of code they wrote.

import pyaudio
import wave
import sys

class AudioFile:
    chunk = 1024

    def __init__(self, file):
        """ Init audio stream """ 
        self.wf = wave.open(file, 'rb')
        self.p = pyaudio.PyAudio()
        self.stream = self.p.open(
            format = self.p.get_format_from_width(self.wf.getsampwidth()),
            channels = self.wf.getnchannels(),
            rate = self.wf.getframerate(),
            output = True
        )

    def play(self):
        """ Play entire file """
        data = self.wf.readframes(self.chunk)
        while data != '':
            self.stream.write(data)
            data = self.wf.readframes(self.chunk)

    def close(self):
        """ Graceful shutdown """ 
        self.stream.close()
        self.p.terminate()

# Usage example for pyaudio
a = AudioFile("1.wav")
a.play()
a.close()

Comments

[JShoe]

But I the print stuff necessary?

[JShoe]

And this is all I need? I don't has to have any example saved etc...? Just Pyaudio right? This is standalone?

[Mikhail Churbanov]

@JShoe: Of course you need to save it to some *.py file (e.g. "somefile.py") and then run it with your python. And of course you need to have an audio file "1.wav" in your working dir.

[JShoe]

Well right. By the way, what is the default working dir for both mac and windows?

[Mikhail Churbanov]

@JShoe: Usually it is the place from where you call python. But you can specify absolute path to the file. That depends on what you really need to achieve.

[Jonathan]

I get Cannot connect to server request channel jack server is not running or cannot be started

[Jonathan]

Does this take in account speed of the file?

[cwallenpoole]

@JonathanLeaders You may wat to make that a new question

[Jonathan]

Apparently it plays regardless of the error, just at the wrong speed, so i went with pygame.mixer

[SwiftStudier]

With Python 3 I had to replace the condition to if len(data) > 0; otherwise this loop turns to infinite

[mazunki]

@SwiftStudier With Python you can solve the issue with while data != b"" as well, following the original answer's method. Apparently, in Python 3, a binary string is a sequence of octets, while a standard string is a sequence of Unicode characters. Python2 ignores the b in front of a string, so I would suggest OP to edit his answer. tl, dr: b""=="" returns False.

[Gringo Suave]

while data: works correctly, also needs wf.close()

[Gringo Suave]

self.wf not closed.

[jotadepicas]

data is not ascii, while should be != b'', with "b" prefix, otherwise it loops forever