| 摘要 |
A caption decoder is provided to change a generation period of a timing signal according to a control signal and to convert a horizontal line signal into a binary signal according to the timing signal. A caption decoder includes a timing generator(251), a binary signal converter(221), a buffer unit(222), a caption data judging unit(240), a caption data extracting unit(223) and an error detector(252). The timing generator generates a timing signal every stored period, and the binary signal converter converts horizontal line signals into binary signals. The buffer unit stores the binary signals from the binary signal converter. The caption data judging unit judges whether caption data are present in the binary signal stored in the buffer unit. The caption data extracting unit extracts caption data from the binary signals. The error detector judges whether error occurs in the extracted caption data and changes a generation period of the timing signal from the timing generator.
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