instead of a discrete sound processor, the rsp frequently performs audio functions, although the cpu can be tasked with this as well. it can play back most types of audio (dependent on software codecs) including uncompressed pcm, mp3, midi, and tracker music. the rsp is theoretically capable of a maximum of 100 channels of pcm at a time, but only in a case where all system resources are devoted to audio. it has a maximum sampling rate of 48 khz with 16-bit audio. in practice, however, storage limitations caused by the rom cartridge format limit the audio size and thus quality. some game titles are designed for higher quality audio when storage expansions are available, as with "f-zero x expansion kit".