I have some songs which have a bit rate of 96 Kbps which I want to convert to 320 Kbps. Do we have any software which will do this? Will there be any change in the quality of the song? Generally we observe that if we go from higher to lower it will be ok but if we go from lower to higher then there may be loss of quality. Why is that the most of the older songs are at lesser bit rate like the ones before 90's? Do we have anything like Constant Bit rate and Variable bit rate?