At ISDB-T дижитал ТВ, there is 1сег and full seg types program.

1сег is 720P SD for mobile phone or in-car monitor, full seg is 1080P HD for home digital tv.

Sometimes, if the signal is weak, the full seg digital tv box will auto switch one seg program to get the tv signal at the lower picture quality, but the tv program is total the same.