| 摘要 |
A playback permits two or more recordings associated with time codes to be retrieved synchronously at variable relative speeds. A master playback unit retrieves a master video recording and the associated master time code and a slave playback unit retrieves a slave audio recording and the associated slave time code. A microprocessor scales the slave audio time code to produce virtual slave time code, and the master and virtual slave time codes are compared to produce a virtual offset which is maintained substantially constant with speed control thereby synchronizing the operation of the master and slave playback units. An operator can select the magnitude of the virtual offset, and can also select the scaling factor used to produce the virtual slave code thereby varying the retrieval speed of the slave playback unit relative to the master playback unit, effectively compressing or expanding the slave recording relative to the master recording. The operator can also advance the master tape to a required position and then advance the slave tape in response to the virtual offset to a corresponding position either manually or automatically. Accordingly, both variable speed synchronization and convenient advancing of master and slave tapes to corresponding positions are possible.
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