Kodierung und Dekodierung von MAC-Videosignalen

摘要

A MAC signal encoder (10), for encoding a video signal (Y/Pb/Pr) into MAC format, includes vertical sub-samplers (20, 24) for vertically sub-sampling colour difference signals (Pb/Pr) of the video signal, vertical filters (18, 22) that vertically filter the colour difference signals prior to their vertical sub-sampling so as to limit their spectra to a band below the vertical Nyquist frequency of the sub-sampled colour difference signals, a multiplexer (14) that multiplexes together the filtered and sub-sampled colour difference signals and luminance information (Y) of the video signal to produce a signal in MAC format, and a marker detector (28) responsive to the video signal containing marker information indicating that the signal has previously been MAC encoded to inhibit the vertical filtering of the colour difference signals (Pb, Pr) by the vertical filters (18, 22).