| 摘要 |
PURPOSE:To reduce the number of switching circuits and prevent deterioration of quality of a basic picture by providing a burst flag generating circuit, an oscillating circuit and a phase shifter in a circuit and switching after color encoding. CONSTITUTION:The first composite color video signal of a basic picture from an input terminal 10 of a video composing circuit is added to a synchronizing signal separation circuit 11, a BPF12 and a clamping circuit 13, and vertical and horizontal synchronizing signals Vs, Hs are outputted by the circuit 11. The signal Hs is added to a burst flag generating circuit 15, and color burst signal position of composite video signal is detected by the circuit 15, and burst flag is added to an oscillating circuit 16, and at the same time, the synchronizing signal Hs is added to a color encoder 17. Color subcarrier signal is taken out and added to the circuit 16 by the BPF12, and color subcarrier signal outputted by the circuit 16 is added to a phase shifter 19. Output of the phase shifter 19 is added to the encoder 17, color signals R, G, B of a color demodulation circuit 22 are encoded and the video signal is processed by a superimpose detecting circuit 24 and a switching circuit. |
