I've been playing around with playing MP3's on the Pi. What I noticed is that the sound with OmxPlayer is louder (better quality maybe too?) than mpg321. I believe they are using a different library each for playing the MP3's, been searching around but just not able to find any topics on this.
Does anyone here know how to get better sound on mpg321? The reason I want this, is because I'm developing a Qt program and the QMediaPlayer class uses the same library as mpg321, afaik.