FIELD: processing of videosignal for protection against copying. SUBSTANCE: according to invention videosignal is so changed that copying is prevented or specular value of copied cassette is diminished. In correspondence with method signal of color synchronization in each line is changed so that changes in accuracy of color rendition should be visible in any subsequent recording of videosignal. Additional perfection of method is expansion of envelope of typical signal of color synchronization to rear front of line of synchronization pulse. Device changing videosignal to prevent formation of video record of acceptable quality has generator of gating pulses of color synchronization to generate gating signal of color synchronization, unit entering signal of protection against copying, unit processing subcarrier. Technical result of invention is change of phase of color synchronization of part of videosignal, substitution of some periods of videosignal to prevent copying and additional improvements of PAL system so that specified changes do not affect quality of color rendition in process of authorized reception. EFFECT: improved protection against unauthorized copying of videosignals. 19 cl, 33 dwg, 4 tbl
