Play audio on Raspberry Pi with Snapstream Firefly RF remote

#!/usr/bin/python

import sys
import subprocess
import threading
import evdev
import os

class Keys:
    KEY_MAXI = 44
    KEY_CLOSE = 2

    KEY_1 = 13
    KEY_2 = 14
    KEY_3 = 15
    KEY_4 = 16
    KEY_5 = 17
    KEY_6 = 18
    KEY_7 = 19
    KEY_8 = 20
    KEY_9 = 21

    KEY_BACK = 22
    KEY_0 = 23
    KEY_ENTER = 24

    KEY_VOL_UP = 9
    KEY_VOL_DOWN = 8
    KEY_MUTE = 10
    KEY_CH_UP = 11
    KEY_CH_DOWN = 12

    KEY_INFO = 46
    KEY_VENDOR = 0
    KEY_OPTION = 47

    KEY_UP = 26
    KEY_LEFT = 29
    KEY_OK = 30
    KEY_RIGHT = 31
    KEY_DOWN = 34

    KEY_MENU = 28
    KEY_EXIT = 32

    KEY_REW = 36
    KEY_PLAY = 37
    KEY_FWD = 38
    KEY_REC = 39
    KEY_STOP = 40
    KEY_PAUSE = 41
    KEY_NEXT = 42
    KEY_PREV = 43

    KEY_TV = 3
    KEY_DVD = 4
    KEY_PHOTOS = 5
    KEY_MUSIC = 6
    KEY_VIDEO = 7

    KEY_HELP = 1
    KEY_MOUSE = 45

    KEY_A = 25
    KEY_B = 27
    KEY_C = 33
    KEY_D = 35

# The map of files to play when something is pressed
map = {}
map[Keys.KEY_OK] = '/home/pi/torture.mp3'
map[Keys.KEY_LEFT] = '/home/pi/torture.mp3'
map[Keys.KEY_RIGHT] = '/home/pi/torture.mp3'
map[Keys.KEY_UP] = '/home/pi/torture.mp3'
map[Keys.KEY_DOWN] = '/home/pi/torture.mp3'

FNULL = open(os.devnull, 'w')

def play(path):
    # -o local causes the output to play through the audio jack (to pipe to the amp) rather than the HDMI cable
    subprocess.Popen(['omxplayer', '-o', 'local', '--no-osd', '--no-keys', path], stdout=FNULL, stderr=subprocess.STDOUT)

# The raspberry pi has an issue with playing sounds described here:
# http://raspberrypi.stackexchange.com/a/3633
# A workaround is to have an audio file playing in a loop. Here we play silence repeatedly
# Not sure how to end this, though. i.e. when terminating the script we should end the looped playback.
def loop_silence():
    # no-keys prevents interpretation of keys as commands to modify volume and such
    # no-osd prevents the on screed display showing seeking to the beginning of the file as it looops
    # loop causes the audio to loop forever
    subprocess.Popen(['omxplayer', '--loop', '--no-osd', '--no-keys', 'silence.wav'], stdout=FNULL, stderr=subprocess.STDOUT)

# Main worker loop
t = threading.Thread(target=loop_silence)
t.start()
devices = [evdev.InputDevice(fn) for fn in evdev.list_devices()]
firefly = None
for device in devices:
    if device.name == "X10 WTI RF receiver":
        firefly = device
        break

if not firefly:
    sys.exit()

for event in firefly.read_loop():
    if event.type == evdev.ecodes.EV_MSC:
        press = event.value
        if press == 2:
            print("You pressed <close>, exiting...")
            break

        if press in map:
            print("Key " + str(press) + ": Playing " + map[press] + " ...")
            play(map[press])
        else:
            print("Nothing to do for [" + str(press) + "]")