In the known color stripe process for preventing recording of video
signals, the color burst present on each line of active video is modified
so that any subsequent video tape recording of the video signal shows
variations in the color fidelity that appear as undesirable bands or
stripes of color error. This color stripe process is improved by a
combination of modifying the phase of the color burst on only part of the
color burst. Additional improvements were obtained by incorporating
techniques of widening the normal color burst envelope towards the
trailing edge of horizontal sync and towards the beginning of active
video. These techniques are useful in improving the performance of the
color stripe process in both the NTSC and PAL color systems. However,
additional improvements are described in the PAL system whereby the phase
modifications are controlled so as to avoid disturbing the so-called PAL
ID pulse. Such avoidance of the PAL ID pulse improves the playability of
the color stripe signal in the PAL format.