| 摘要 |
PURPOSE:To attain YC separation and sequential scanning conversion even for a video signal which does not exist in a standard system by fixing a YC separation circuit and a sequential scanning conversion circuit in an animation mode when a fact that a composite video signal does not exist in the standard system is discriminated. CONSTITUTION:At first the separation circuit 10 separates a chrominance subcarrier, a horizontal synchronizing signal and a vertical synchronizing signal are separated from a composite video signal. Then whether or not the horizontal scanning frequency and the chrominance subcarrier frequency of the horizontal synchronizing signal are in a prescribed relation is discriminated by the 1st discrimination circuit 12 and the 2nd discrimination circuit 13 discriminates whether or not a frame frequency and a horizontal scanning frequency of a vertical synchronizing signal are in a prescribed relation is discriminated. Only when the frequency relations are satisfied at the same time, a 3rd discrimination circuit 14 discriminates the composite video signal is in accordance with the standard system, and if the signal is not in accordance with the standard system, the separation of the YC separation circuit 3 and the operation converting the scanning line of the sequential scanning conversion circuit 4 into double density are fixed respectively to the animation mode.
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