1seg
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1seg (Katakana: ワンセグ) is a mobile terrestrial digital audio/video and data broadcasting service in Japan. Service began expertimentally during 2005 and officially on April 1, 2006. First mobile phone handsets for 1seg were sold by KDDI to consumers in autumn 2005.
Terrestrial digital broadcast in Japan (ISDB-T) is designed so that each channel is divided into 13 segments (plus one segment for separating channels). HDTV broadcast occupies 12 segments, and the remaining (13th) one segment is used for mobile receivers. Thus the name, '1seg'.
Technical information
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 128 kbit/s. Audio conforms to AAC-LC profile, with max bitrate of 64 kbit/s. Additional data broadcasting using BML (EPG, interactive services, etc) occupies the remaining 60 kbit/s.
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.
Receivers
- () [NTT DoCoMo P901iTV]
- () [KDDI/Sanyo W33SA]
- () [KDDI/Sanyo W33SAⅡ]
- () [KDDI/Hitachi W41H]
- () Nintendo DS (via [announced add-on])
- () [Pixela PC]
- () [Sanyo One-seg & car navigation system]
- [Vodafone 905SH] by SHARP
External links
- () [Association for promotion of Digital Broadcasting (Japanese)]
- () [1seg promotion site (Japanese)]
- () [one-seg.com (Japanese)]
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