METHOD AND APPARATUS FOR REPRODUCING AT A SELECTED SPEED VIDEO SIGNALS RECORDED ON MAGNETIC TAPE

摘要

The magnetic tape video playback apparatus for a digital video signal regenerates the sample rate from the playback to operate a counter and detects the video data block numbers to permit an address generator to derive the more significant bits of addresses for a picture memory in which the video data signal is temporarily stored. The counter provides the less significant bits of the write addresses. The separated vertical sync pulses are counted in a second counter to provide time information for storage in a time data memory which is operated in parallel with the picture memory, using the write addresses from the already mentioned address generator. A reference sample rate generator operates a third counter which provides the read out addresses for the picture and time data memories. The memory input and output time data are compared and the time difference is evaluated with reference to a threshold for providing an error flag to an error concealment unit to which the video data read out from the picture memory is supplied for concealing errors resulting from overage video data in the picture memory which may be stored there during playback at high speeds. At low speeds the minimum time difference designates an error.