Procedure:

1.First install this app and choose permissive option in this app
link:http://forum.xda-developers.com/devdb/project/dl/?id=12506

2.Go to recovery mode
Select install from sdcard
flash this file xtreme music
Link: https://www.androidfilehost.com/?fid=24269982086996038

3.Wipe cache and delvic cache

4.Reboot the system

5.At last flash dolby
Link:http://forum.xda-developers.com/devdb/project/dl/?id=13100

Don't forget to wipe delvic cache

Credits:xda forum and developers of above posted links
            Ganesh Naik for suggesting above method
            All group mebers of CPN3 Facebook group

FAQ:  
1.what to do with selinux mode changer app after installing dolby?
A: Open app grant it supersu access , then set it to permissive.
2. Selinux have to set permissve all time or should I uninstall that app now?
A: Yes u can.
3. And what about other 2 xtreme and viper4 android?
A: No,don't uninstall extreme and viper.
4. Can I uninstall nu player?
A: Yes,you can.
5. It require su permission?
A: Yes.