| 摘要 |
A video processor produces video and key signals to be processed by a television production switcher for superimposing text or the like on a background image. The video processor has a key generator for receiving an input video signal and an input key signal and selecting one of these signals and shaping waveforms of the selected signal. Responsive to a first control signal, the input video signal is stored in a first frame memory and read during a later frame interval. Responsive to a second control signal, the output signal of the key generator is stored in a second frame memory and read during a later frame interval. A delay time corresponding to the processing time of the key generator is introduced to the input video signal. A first switch selects one of the outputs of the delay circuit and the first frame memory, and a second switch selects one of the outputs of the key generator and the second frame memory. A shadow insertion circuit is provided for receiving the output signals of the first and second switches for inserting a shadow to the received signals.
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