Maintaining video signals.

摘要

A video signal with pre-emphasis is applied via an input (1) to an encoder (2), such as that for HD-MAC, the encoded output being applied over a first path to an input (3) of an adder (4). The encoded signal is also applied via a decoder (5) to a further path comprising a de-emphasis circuit (6), a mean value estimator (7) and a pre-emphasis circuit (8) to an input of a difference circuit (10). The video signal from input (1) is also applied to a reference path comprising components (11, 12 and 13) which correspond to the components (6, 7 and 8) in the further path. The difference in the pre-emphasised mean values obtained from circuit (10) is applied via a shuffler (15) and added at adder (4) to the video signal in the first path.