| 摘要 |
A composite video input signal is delayed by a delay element and the delayed composite signal is applied to luminance and chrominance inputs of a picture processor for received signals of an NTSC format. For received signals of a PAL format, the delayed composite signal is applied only to the luminance input of the picture processor and the chrominance component of the received signal is transcoded to the NTSC format and applied, without passing through the composite signal delay element, to the chrominance input of the picture processor. The delay of the delay element for the composite video signal is selected to be equal to the transcoding delay whereby luminance and chrominance components of received signals of either NTSC or PAL format are delay compensated. Advantageously, the delay applied to the luminance component is constant and of the same value for signals of either format and so there is no need for switching of delay elements in the luminance path when changing from one format to the other and so undesirable switching artifacts (e.g., DC offset or transient effects) are avoided. |
