Multi-Camera Production: Genlock, Timecode Jamming & Sync

1. The Fundamental Difference: Timecode vs. Genlock

Many video creators confuse Timecode with Genlock. They solve two completely different physical problems:

• Timecode (SMPTE 12M / LTC): An electronic metadata clock that stamps every video frame and audio buffer with a unique address (Hours : Minutes : Seconds : Frames). Timecode tells editing software which frames match in post-production. However, timecode does not control when the camera's physical sensor starts exposing a frame.
• Genlock (Generator Locking / Tri-Level Sync): An electronic synchronization pulse sent via coaxial BNC cable that forces every camera sensor to start reading its scan lines at the exact same microsecond. In live broadcasting, switching between two cameras without genlock causes picture rolling, frame stutter, and switcher frame buffer lag.

2. Timecode Modes: Free Run vs. Rec Run

Modern cinema cameras and multi-track audio recorders provide several timecode generator run modes:

3. Dedicated TC vs. Auxiliary Audio Timecode

Professional cinema bodies (ARRI ALEXA, RED V-Raptor, Sony FX6/FX9, Canon C70/C300) have dedicated 5-pin LEMO or BNC Timecode In ports that inject timecode directly into the raw video container metadata.

Mirrorless hybrid cameras (Sony A7IV, Canon R5, Panasonic Lumix) lack dedicated TC ports. Filmmakers use wireless timecode boxes (such as Tentacle Sync E mkII or Deity TC-1) to output timecode audio pulses into the 3.5mm microphone input (Aux TC). Editing software converts this scratch audio buzz into real frame timecode with a single click.

4. Temperature Drift & Crystal Oscillators (PPM)

Camera internal clocks rely on quartz crystal oscillators that drift when ambient temperatures change. A clock that is 20 PPM (parts per million) fast or slow gains or loses about 144 ms in 2 hours, which is 3.5 frames at 24 fps. Real crystals vary with temperature and age, so the figure moves with the camera and the room.

Modern timecode transceivers incorporate Temperature-Compensated Crystal Oscillators (TCXO) with drift rates of about 0.5 PPM, which is roughly 43 ms over 24 hours, or about one frame at 24 fps. Bluetooth mesh systems constantly cross-jam and re-synchronize every unit over wireless RF to keep drift small.

5. NLE Automated Multi-Cam Grouping Workflow

Once footage is offloaded, building a synchronized multi-camera edit takes under 60 seconds:

1. DaVinci Resolve: Select all camera clips and separate production audio tracks in the Media Pool > Right-click > Create Multicam Clip Using Selected Clips > Set Angle Sync: Timecode and Angle Name: Camera Metadata.
2. Adobe Premiere Pro: Select clips in the bin > Right-click > Create Multi-Camera Source Sequence > Set Synchronize Point: Timecode and check Create single multicam source sequence.

Calculated: how much drift a given ppm figure means in frames

We recomputed section 4's figures on 2026-09-30. Drift is the clock error in parts per million times the time elapsed, and it is a number of frames when multiplied by the frame rate. Nothing was measured, and no camera or timecode box was involved.

The page used to say "a standard quartz clock drifts by roughly 1 frame every 2 hours (around 20 PPM)", and was corrected on 2026-10-06. Those two figures do not go together. 20 ppm over 2 hours is 144 ms, which is 3.5 frames at 24 fps and 4.3 at 29.97. One frame in 2 hours at 24 fps is about 5.8 ppm. Section 4 now gives the 20 ppm figure with its 144 ms. We did not check against a clock's specification what a standard quartz clock actually is.

The 0.5 ppm claim is close to right. Over 24 hours it is 43 ms, 1.04 frames at 24 fps and 1.3 at 29.97, so the page's earlier "less than 1 frame over 24 hours" held only below about 23 fps and was a frame or so over at 24 and 30. Section 4 now says about one frame at 24 fps. Over a shoot day of 12 hours it is half of that, under a frame at every rate here except 60 fps. The point of the section, that a temperature compensated clock is far steadier than a plain one, stands.

Reference. Recomputed 2026-09-30. The figures are for a constant clock error, and real crystals vary with temperature and age. No device was measured, and genlock, timecode modes and the NLE workflow were not tested.

Working Vocabulary

Key multi-camera and synchronization terms introduced in this guide:

• SMPTE 12M Timecode. The standard digital timing code protocol specifying hours, minutes, seconds, and frame numbers for audio and video synchronization.
• Genlock. An electronic synchronization signal that locks the frame rate and scan-line phase of multiple video cameras to a single master clock.
• Jam Sync. The process of synchronizing a secondary timecode device to a master clock by momentarily connecting them together or pairing over wireless mesh.
• Free Run. A timecode generator mode where the clock runs continuously regardless of whether the camera is actively recording.
• Aux Audio Timecode. Linear timecode recorded as an audible data signal onto an audio channel of a camera that lacks a dedicated timecode input port.
• TCXO (Temperature-Compensated Crystal Oscillator). A high-precision electronic quartz oscillator designed to resist temperature-induced timing drift.

Sources & Further Reading

• LTC Timecode Generator Audio Tool
• Timecode Calculator & Frame Rate Converter
• Wireless Video Systems & CRMX Lighting Control on Set
• SMPTE ST 2110 & NDI Broadcast Video Over IP Networks