With regard to audio, analog audio formats always contain the electronic equivalent of the frequencies of human hearing and are differentiated mostly by their transport systems, such as 1/8" cassette tapes and 1/4" reel-to-reel tapes. See analog audio, audio cassette and sampling. With regard to video, analog formats mostly deal with resolution and frame rates that were dictated by the NTSC, PAL and SECAM television standards. From time to time, high-definition analog TV formats were developed, most notably the MUSE system in Japan, but all were superseded by digital formats. See video format.