Volume service for VLC radio based on Arduino measuring potentiometer voltage

volume.py

#!/usr/bin/python

import atexit
import re
import socket
import subprocess
import time
import os
import sys
from datetime import datetime
from UUGear import *

VLC_HOST = "127.0.0.1"
VLC_PORT = 9294

LOG_LEVEL = 0

PIDFILE = "/var/run/uuvolume.pid"
LOGFILE = "/var/log/uuvolume.log"
ERRFILE = "/var/log/uuvolume.err"

SHUTDOWN_HOLD_TIME = 3

LOG_INFO = 0
LOG_WARN = 1
LOG_FAIL = 2
LOG_DEBUG = 3

def log(msg, level=LOG_INFO):
    if level < LOG_LEVEL: return

    sys.stdout.write(str(datetime.now()))
    sys.stdout.write(": ")
    sys.stdout.write(msg)
    sys.stdout.write("\n")
    sys.stdout.flush()

class VLC():

    def __init__(self, host="127.0.0.1", port=9294):
        self.host = host
        self.port = port
        self.current_stream = None
        self.current_state = None
        self.connecting = False
        self.socket = None

    def send(self, command):
        if self.connecting:
            return False

        log("Sending command: {}".format(command), level=LOG_INFO)
        command_string = command + "\n"

        if sys.version_info[0] >= 3:
            command_string = command_string.encode("utf-8")

        try:
            self.socket.send(command_string)

        except socket.error:
            log("Failed to send command to VLC", level=LOG_WARN)
            if self.connect():
                self.send(command)

    def recv(self, length):
        value = self.socket.recv(8192)

        if sys.version_info[0] >= 3:
            value = value.decode("utf-8")

        return value

    def communicate(self, command, response_length=8192):
        self.send(command)
        return self.recv(response_length)

    def get_current_stream(self):
        self.send("status")
        status = self.recv(8192)

        result = re.search("input:\ (.*)\ ", status)
        state = re.search("state\ (.*)\ ", status)

        if state is not None:
            self.current_state = state.group(1)

        if result is not None:
            self.current_stream = result.group(1)
        else:
            self.current_stream = None

        return self.current_stream

    def connect(self):
        if self.connecting:
            return

        self.connecting = True

        if self.socket is not None:
            self.socket.close()

        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

        for attempt in range(10):
            try:
                log("Attempting to connect to VLC on {host}:{port}".format(host=self.host, port=self.port))
                self.socket.connect((self.host, self.port))
                log("Connection successful!", level=LOG_INFO)
                self.connecting = False
                return True

            except socket.error:
                time.sleep(1)

        log("Connection failed!", level=LOG_FAIL)
        self.connecting = False
        return False

UUGearDevice.setShowLogs(0)
arduino = UUGearDevice('UUGear-Arduino-4923-9864')

voltage = 0
prevVolume = 0
vlc = VLC(host=VLC_HOST, port=VLC_PORT)

if vlc.connect():
    while True:
        measured = arduino.analogRead(3)
        print measured
        if int(measured) != -1:
            voltage = 0.8 * voltage + 0.2 * float(measured)
            volume = int(round(voltage / 5)) + 20
            print volume
            if volume != prevVolume:
                prevVolume = volume
                vlc.communicate("volume " + str(int(volume)))
        time.sleep(0.15)