Here's a program that does what you want:

#!/usr/bin/env python

# coding: utf8



import time

import sys

import commands





USER = commands.getoutput("cat /var/log/auth.log | grep " +

    sys.argv[0]).split("sudo:")[1].split()[0].strip()





def is_idle():

    return int(commands.getoutput("xprintidle")) >= 10 * 60 * 1000



def is_night():

    return time.localtime().tm_hour in (22, 23, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9)



def is_stumm():

    return "RUNNING" not in commands.getoutput(("sudo -u %s pacmd " +

        "list-sinks | grep RUNNING") % USER)





def main():

    powersave = False

    while 1:

        if is_idle() and is_night() and is_stumm():

            if not powersave:

                print "going into powersave mode"

                commands.getoutput("echo powersave > " +

                    "/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor")

                powersave = True

        else:

            if powersave:

                print "going into ondemand mode"

                commands.getoutput("echo ondemand > " +

                    "/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor")

                powersave = False

        time.sleep(0.5)



if __name__ == '__main__':

    assert commands.getstatusoutput("xprintidle")[0] == 0, (

        "you need to `sudo apt-get install xprintidle`")

    assert commands.getoutput("whoami") == "root", (

        "you need to be root to run this program")

    main()

Note your preferences:

• ... >= 10 * 60 * 1000


• ... tm_hour in (22, 23, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
  and


• "RUNNING" not in ...

I'm using pulseaudio to find out if a movie is playing. This also affect music.