title: How to play mp3 file using QAudioOutput and QAudioDecoder?
body: <p>I want to play a audio file to a specified device using QAudioOutput. It's ok with .wav files. But there are just buzzing when playing .mp3 files (.mp3 files are compressed files as I known, so QAudioOutput can not play it directely).<br>
  I'm trying to decode the .mp3 files before playing with QAudioOutput but I don't know how.<br>
  Can you give me a sample code so that we can play mp3 file using QAudioOutput and QAudioDecoder?</p>