Telecom ABC - D
Digital Multimedia Broadcasting (DMB) is the use of the Digital Audio Broadcasting (DAB) system for broadcasting of video, audio and other data services and not just for the broadcast of radio programs. DMB supplies a large number of contents (music, text, video etc) on handheld devices. Therefore, DMB is very well suited for mobile TV and other services on relative small terminals, such as a mobile telephone or a PDA.
DMB can be used in both a Terrestrial (T-DMB) and a Satellite version (S-DMB). The data capacity of T-DMB is about 1,5 Mbps per radio-channel of 1,5 MHz. In principle, about all compression techniques can be used. Not only the original DAB compression standard for audio (MP2: MPEG 1/2 Layer II) but also more modern compression standards can be used, such as AAC for audio and MPEG-4 for video.
The DMB standard defines a video service that is based om MPEG-4 (AVS/H.264) video compression combined with HE-AAC audio compression. Both information streams are combined in a MPEG-2 Transport Stream. The DMB standard supports the video formats QCIF (176×144), QVGA (320×240), CIF (352×288) and WDF (384×224).An additional error correction is added, because video is more vulnerable to errors than audio. This reduces the data capacity by 7.8%.
DMB started in Germany with not too much success. Later, South Korea started a more succesfull introduction of DMB, via both satellite and terrestrial stations.
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