Apparatus for providing dropout compensation and error concealment in a

Abstract

Apparatus is disclosed for providing error compensation of a video information signal having a format. Sampling of the analog PAL format video information signal is done at a rate of four times the chrominance subcarrier frequency and is done in a precise manner whereby the samples are taken along orthogonal vector axes that are oriented at 45.degree. relative to the U and V vector axis. When samples are taken at the prescribed locations, substitute samples in the form of multi-bit digital words can be used as replacements for defective or missing sample words, which replacement samples exhibit the same vector phase as the defective sample, but which are taken from either the preceding or succeeding line relative to the line in which the defective sample is located. The apparatus of the present invention obviates the necessity of performing any arithmetic computation to derive the value for the sample to be substituted. Moreover, the sample is spatially closely related to the defective sample, i.e., it is merely spatially removed one horizontal line from the line of interest and is vertically aligned relative to the defective sample. The detection of a defective sample activates the apparatus to automatically substitute the proper digital data word sample for the defective sample. If part of or an entire line is missing or defective, the system automatically inserts an average of the preceding and succeeding line during the period of time when the missing or defective information is detected.