Timecode and Show Synchronisation
When a show must repeat identically — backing tracks, timed lighting, video and effects all locked together — a single master clock drives everyone through timecode. SMPTE LTC (linear timecode, an audio-like signal carried on a cable) and MTC (MIDI timecode) both count hours:minutes:seconds:frames, and every department chases that same running clock, so each cue fires at the exact same instant on every performance rather than depending on a human hitting GO.
Timecode only holds a show together if everyone agrees on the fine print. The frame rate must match across the whole system — 24, 25, 29.97 or 30 — and drop-frame versus non-drop must agree, or departments that started in step drift apart over a long show. Genlock is the related discipline for video: locking every video device to a common reference (black burst or tri-level sync) so their frames are physically in step and cuts stay clean. The two answer different questions — timecode says WHEN a cue happens, genlock says the frames themselves are aligned — and a big show usually needs both.
The trade-off is repeatability against flexibility. Timecode gives you a show that runs identically every night, which is exactly what a tightly-produced sequence needs — and exactly what a live caller cannot have, because the clock will not wait for a held moment. So hybrid shows run timecode for the locked musical or video sequences and hand control back to a live caller for the parts that need to breathe. Decide early who is master — who generates the clock and who chases it — because two devices each convinced they are the master is a show that fights itself.
One master clock, one frame rate — everyone chases, nobody guesses.