How to Jam Sync Timecode Between Camera and Sound

A step-by-step walkthrough for getting camera and sound recorder locked to the same timecode before the first take of the day.

True-Slate Guides · updated 30 September 2026

Jam syncing looks intimidating the first time someone explains it, but the actual process on set takes about a minute per device. Here's the full workflow, plus the mistakes that actually cause sync problems in the edit.

What you need

• A timecode source, this can be a dedicated LTC generator, or a slate app like True-Slate that generates real LTC.
• An audio cable from that source into each device you're jamming, usually via a USB-C or Lightning to 3.5mm adapter if you're jamming from a phone or iPad.
• A sound recorder and camera that both actually support external LTC jam sync. Check this before the shoot day, not on it.

Before you start: agree the settings

Get these three things matching across every device before you jam anything. Jamming devices that disagree on the basics just gives you confidently wrong timecode.

1. Frame rate. Camera, sound recorder, and your timecode source all need to be set to the same frame rate, 24fps and 23.976fps are not the same thing to a computer, even though they sound similar.
2. Drop-frame or non-drop. Pick one and set it everywhere. Mixing the two is one of the most common, entirely avoidable causes of drift in post.
3. Time of day, or free run from zero. Most crews jam to time of day, since it's easy to reconstruct later, but any convention works as long as everyone's using the same one.

The jam sync process

1. Set your master source. Decide what everything jams from, a dedicated timecode box, or a slate app generating LTC out.
2. Connect the cable from the source's audio output into the sound recorder's timecode input.
3. Trigger the jam on the recorder, this is usually a "jam sync" or "ext TC" option in its menu. Most recorders show a locked or synced indicator once it's taken.
4. Repeat for the camera. Move the same cable to the camera's timecode input (or its audio input, if that's how your slate app generates LTC) and jam it the same way.
5. Repeat again for any second camera. Every device that needs matching timecode gets its own jam from the same source, one at a time.
6. Do a test clap and check both files land with matching timecode before you roll on anything that matters.

Common mistakes

• Mismatched frame rates between camera and sound, the single most common cause of "sync that's almost right but not quite."
• Jamming the camera but forgetting the second camera on a multi-cam day.
• Mixing drop-frame and non-drop-frame across devices.
• Powering a device off and back on without re-jamming, some devices reset their timecode on restart.
• Assuming jam sync replaces the slate. It doesn't, always still clap. The slate mark is the editor's visual confirmation that the numbers actually lined up.

Doing this without a dedicated timecode box

A dedicated hardware LTC generator does one job well but costs several hundred pounds on its own. True-Slate reads and generates real LTC directly from an iPhone or iPad over a standard audio cable, so the same device that's slating the take can also be the timecode source everything else jams from, or can itself jam from an existing source and pass genuine, synced timecode into the shot log automatically.

Related reading

• What Is LTC Timecode? A Guide for Film Crews
• Digital Clapperboard vs Traditional Slate: What's the Difference?
• The Full True-Slate Feature Guide