Improvements in helical scan recording and playback systems.

摘要

A helical scan magnetic recording and reproducing system is of the type where time compressed audio signals are recorded in extensions of the video tracks. In order to avoid a time delay of the reproduced audio relative to its original relationship to the video, additional audio playback heads (S1, S2) are located on the helical scanner so as to read the audio information sufficiently in advance of the video heads (P1, P2) to allow restoration of the original audio/video synchronism. The audio is recovered by a switch (26), de-interleaving circuit (28) and time expansion circuits (30, 32). The arrangement allows full flexibility in audio editing even when the recorded audio signals are digitally encoded and interleaved. In order to avoid a time delay of the reproduced audio relative to the video when played back, additional audio recording heads are located on the helical scanner so as to record the audio information on tracks that when played back are reproduced sufficiently in advance of the video to allow restoration of the original audio/video synchronism. The arrangement can thus can be employed to produce prerecorded tapes having time advanced audio such that synchronous audio/video is reproduced on conventional playback reproducing systems.