| 摘要 |
An audio-visual editing system includes a universal slave driver (USD) coupled between a timecode-producing device, such as a video tape deck, and a digital audio workstation (DAW). The USD includes a sample counter for counting the audio samples for each timecode frame, and a timecode reader to interpret the tape's location. An audio board of the digital audio workstation includes an identical sample counter. Both counters are driven from a common clock. A serial interface connection couples the digital audio workstation to the universal slave driver. One of the handshaking pins of the serial interface connection is used as a dedicated reset pin. When the dedicated reset pin is pulsed, the running sample counters in both the USD and DAW are set to a common value, typically zero. Resetting the sample counters at precisely the same time ensures that the DAW and the USD are operating in synchronization. Once the sample counters are set to a common value, an efficient, binary protocol may be executed over the serial interface to determine the timing relationship between the sample counters and the beginning of a frame of the off-tape timecode from the videotape/audiotape recorder. The DAW need then only refer to it's own sample counter, and not to any timecode, to calculate a precise point to trigger playback. |
