1seg
1seg is a mobile terrestrial digital audio/video broadcasting service in Japan. Service is planned to begin on April 1st 2006.
Terrestrial digital broadcast in Japan (ISDB-T) is designed so that each channel is divided into 13 segments. HDTV content occupies 12 segments, and the remaining channel is used for mobile receivers. Thus the name, '1seg'.
Technical information[edit | edit source]
1seg broadcasting uses H.264 video and AAC audio encapsulated in MPEG2 Transport Stream. 1seg, like ISDB-T also uses 64QAM for modulation, 1/2 FEC and 1/8 guard ratio. Maximum video resolution is 320x240 pixels, and maximum video bitrate is 128kbps. Audio conforms to AAC-LC profile, with max bitrate of 64kbps. Additional data broadcasting using ja:BML (EPG, interactive services, etc) occupies remaining 60kbps.
Conditonal access and copy control is not implemented in 1seg broadcast, however each receiver device manufacturer can limit recording function. For example, W33SA receiver only allows recording 1seg broadcasts to internal memory, and disallows copy or move to external miniSD card.
