My mp3player is supposed to have a battery life of 12 hours but mine runs out within like, 5 hours or something and I wondered why.

It turns out that my mp3 player can run for 12 hours when the bit rates of my songs are recorded at about 80 (i think) bit rate. Can anyone enlighten me what a "bit rate" is and if it's true that the lower the bit rate, the longer the battery life?

And also: i've heard that .wma files require a lower bit rate to produce a quality of songs equal to that of a 128 bit rate .mp3 song, is that true?