1. A method for scheduling packet transmission, said method comprising: receiving a plurality of data packets, wherein at least a portion of said plurality of data packets is associated with a media unit and comprises different quality information; determining profit-to-size ratios or distortion-to-size ratios for said data packets; and determining a plurality of schedules of said data packets for a plurality of data rates based at least in part on said profit-to-size ratios or distortion-to-size ratios.