1సెగ్ is a mobile terrestrial digital audio/video and data broadcasting service in Japan, అర్జెంటీనా, బ్రెజిల్, చిలీ, ఉరుగ్వే, పరాగ్వే, పెరు, 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 విభాగాలు, with a further segment separating it from the next channel; an HDTV broadcast signal occupies 12 విభాగాలు, leaving the remaining (13th) segment for mobile receivers, hence the name, “1సెగ్” లేదా “ఒక Seg”. See full seg.