Quick Answer
Timecode labels frames so systems can agree on where they are in time. Genlock aligns devices to a common timing reference so they capture or output frames in phase. In post workflows, timecode may be enough. In live switching, XR, and other timing-sensitive systems, a timing reference is usually needed as well.
Timecode and genlock are often grouped under “sync,” but they solve different problems. A timecode value identifies a position in a timeline. A genlock reference controls when compatible video devices generate or output frames. A workflow may need one, both, or a profile-based IP timing system.
What It Is: SMPTE Timecode
SMPTE timecode represents positions as Hours : Minutes : Seconds : Frames. LTC encodes those values as an audio-frequency signal that can travel on a suitable analog path. Timecode can also be carried or embedded in other ways, including ancillary data in digital video systems; the exact method depends on the equipment and format.
If you connect a Timecode generator like a Tentacle Sync or an Ambient Lockit to four different cameras, you give post-production a much better chance of aligning clips quickly by matching timecode values inside the NLE. That still depends on the devices holding sync well over the duration of the shoot.
Why Timecode Isn't Enough for Live Switching
Timecode alone does not phase-align camera scanning or video output. Two cameras can report matching timecode while their frame timing reaches the switcher at different phases.
A live system may accept asynchronous inputs through input frame synchronizers, but that processing can add delay and its behavior varies by device and format. If low and predictable latency matters, verify whether every source is referenced and whether any input or output stage is buffering the signal.
What It Is: Genlock
Genlock lets compatible cameras, switchers, graphics systems, and other video devices lock their output timing to a common reference. The exact reference may be analogue black burst or tri-level sync in baseband systems, while supported IP systems can derive timing from PTP profiles.
Black Burst vs. Tri-Level Sync
Depending on your video format, your genlock signal will take one of two forms:
- Black Burst (SD): A legacy composite video signal (NTSC/PAL) that includes a color burst and vertical sync. Used for SD and some 1080i productions.
- Tri-Level Sync (HD): A bipolar analogue timing reference defined for supported high-definition formats. Use the reference type and format documented by the receiving equipment rather than assuming one reference works for every HD or UHD mode.
Analogue reference paths require the impedance and termination described by the equipment manufacturer. On a supported loop-through chain, the final input is normally terminated at 75 Ω while intermediate loop-through inputs are not; a distribution amplifier is often the clearer design. Verify the exact connectors and termination behavior before patching.
How to Use It
If you are shooting for later editorial sync, timecode may be the main requirement. If you are switching live sources, feeding LED processors, or trying to avoid downstream frame-sync delays, a common timing reference is typically just as important as time stamping. In hybrid or all-IP systems, that timing role may be handled differently, but it still needs to be designed deliberately.
Summary: When Do I Need Which?
| Scenario | Requirement |
|---|---|
| Shooting documentary clips for later post-production editing | Often timecode. Use suitable generators or jam-sync-capable devices and verify drift over the intended record duration. |
| Live switching 3 cameras through a hardware vision mixer into a broadcast TX. | Typically Genlock First. Timecode is still useful for ISO and post alignment, but timing reference is what prevents avoidable switcher delay. |
| LED Volume / Virtual Production XR stage using Unreal Engine. | Often both. Timing reference helps keep capture and display stable, while timecode can support alignment and tracking workflows such as tracking latency compensation. |
Common Mistakes
- Assuming matching timecode means two cameras are phase-aligned.
- Treating genlock like metadata rather than a timing reference.
- Assuming all-IP timing replaces every SDI or baseband sync workflow automatically.
- Applying one rule from a camera chain to a switcher, XR, or replay system without checking the full pipeline.
Related Tools & Next Step
Use the Genlock vs Timecode visual tool for a quick comparison, and use the SMPTE Timecode Calculator when you need to convert, add, or verify actual timecode values.
Share the clean URL with the camera, engineering, or virtual-production team.