HTC One M8 - Control the Music app without unlocking your phone
In this FAQ you will learn how to add the Music widget to the lockscreen of theHTC One M8. Once enable you will be able to control music playback and change tracks without unlocking your smartphone, follow the below procedure:
Go to Settings > Personal > Security.
Go the the Lockscreen section and check "Unlock Music automatically - Bypass security screen when launching Music".