[python] Playing mp3 song on python

At this point, why not mentioning python-audio-tools:

• GitHub: https://github.com/tuffy/python-audio-tools
• docs: http://audiotools.sourceforge.net/programming/audiotools.html?highlight=seek#module-audiotools

It's the best solution I found.

(I needed to install libasound2-dev, on Raspbian)

Code excerpt loosely based on:
https://github.com/tuffy/python-audio-tools/blob/master/trackplay

#!/usr/bin/python

import os
import re
import audiotools.player


START = 0
INDEX = 0

PATH = '/path/to/your/mp3/folder'

class TracklistPlayer:
    def __init__(self,
                 tr_list,
                 audio_output=audiotools.player.open_output('ALSA'),  
                 replay_gain=audiotools.player.RG_NO_REPLAYGAIN,
                 skip=False):

        if skip:
            return

        self.track_index = INDEX + START - 1
        if self.track_index < -1:
            print('--> [track index was negative]')
            self.track_index = self.track_index + len(tr_list)

        self.track_list = tr_list

        self.player = audiotools.player.Player(
                audio_output,
                replay_gain,
                self.play_track)

        self.play_track(True, False)

    def play_track(self, forward=True, not_1st_track=True):
        try:
            if forward:
                self.track_index += 1
            else:
                self.track_index -= 1

            current_track = self.track_list[self.track_index]
            audio_file = audiotools.open(current_track)
            self.player.open(audio_file)
            self.player.play()

            print('--> index:   ' + str(self.track_index))
            print('--> PLAYING: ' + audio_file.filename)

            if not_1st_track:
                pass  # here I needed to do something :)

            if forward:
                pass  # ... and also here

        except IndexError:
            print('\n--> playing finished\n')

    def toggle_play_pause(self):
        self.player.toggle_play_pause()

    def stop(self):
        self.player.stop()

    def close(self):
        self.player.stop()
        self.player.close()


def natural_key(el):
    """See http://www.codinghorror.com/blog/archives/001018.html"""
    return [int(s) if s.isdigit() else s for s in re.split(r'(\d+)', el)]


def natural_cmp(a, b):
    return cmp(natural_key(a), natural_key(b))


if __name__ == "__main__":

    print('--> path:    ' + PATH)

    # remove hidden files (i.e. ".thumb")
    raw_list = filter(lambda element: not element.startswith('.'), os.listdir(PATH))

    # mp3 and wav files only list
    file_list = filter(lambda element: element.endswith('.mp3') | element.endswith('.wav'), raw_list)

    # natural order sorting
    file_list.sort(key=natural_key, reverse=False)

    track_list = []
    for f in file_list:
        track_list.append(os.path.join(PATH, f))


    TracklistPlayer(track_list)