Decoding of Dvb Digital Television Subtitles

The new subtitling system will be established along with the digital television broadcasting. The system uses MPEG-2 multiplexing and region-based bitmap graphics (with indexed pixel colors) technologies to transmit subtitle data to set-top box. It provides more interactivity than the existing analogue television although interactivity is limited. This paper gives a description of Digital Video Broadcasting (DVB) subtitle encoding and transmission technologies. A subtitle decoding process model in set-top box is designed. It describes demultiplexing and decoding procedures and memory organization and allocation of a software-based decoder. The means of user controlling via digital television Navigator (i.e., enable/disable subtitles in a program and language setting/selection) is presented. The two approaches for implementation based on the client-server model are proposed to ensure better performance and the interoperability. Finally, technical requirements are discussed in the paper.