1സെഗ് is a mobile terrestrial digital audio/video and data broadcasting service in Japan, അർജന്റീന, ബ്രസീൽ, ചിലി, ഉറുഗ്വേ, പരാഗ്വേ, പെറു, and the Philippines.

1 seg is designed as a component of ISDB-ടി, the terrestrial digital broadcast system used in those countries, as each channel is divided into 13 സെഗ്‌മെന്റുകൾ, with a further segment separating it from the next channel; an HDTV broadcast signal occupies 12 സെഗ്‌മെന്റുകൾ, leaving the remaining (13th) segment for mobile receivers, hence the name, “1സെഗ്” അഥവാ “ഒരു സെഗ്”. See full seg.