1Seg is a mobile terrestrial digital audio/video and data broadcasting service in Japan, Arjantin, Brezilya, Şili, Uruguay, Paraguay, Peru, and the Philippines.

1 seg is designed as a component of ISDB-T, the terrestrial digital broadcast system used in those countries, as each channel is divided into 13 segmentler, with a further segment separating it from the next channel; an HDTV broadcast signal occupies 12 segmentler, leaving the remaining (13inci) segment for mobile receivers, dolayısıyla adı, “1Seg” veya “Bir Seg”. See full seg.