Do I need timecode for a small shoot?

Not necessarily. Waveform sync works well when the camera records a scratch track, but timecode is much faster across many takes.

Why does my audio drift over a long take?

Usually a sample rate mismatch between camera audio and the recorder, or two free running clocks that were never rejammed.

Can I fix a 44.1 kHz recording for a 48 kHz timeline?

Yes, convert it with a proper sample rate converter before conforming, then verify the result in an inspector.

7 min read

Timecode sync and dual system sound, explained without the mystique

Two devices, one clock. Timecode is simple until sample rates disagree, and then it is the reason your dialogue drifts by the end of the take.

Dual system sound means the picture is recorded on the camera and the sound on a separate recorder. It is standard because camera preamps and microphone inputs are a compromise, and because the sound department needs to move independently of the lens.

What timecode actually is

Timecode is a running clock stamped into each file: hours, minutes, seconds and frames. When the camera and the recorder share the same clock, an editor can line up picture and sound automatically instead of clapping and eyeballing waveforms.

Ways to share the clock

Jam sync: a master box sets the camera and recorder clocks, then they free run.
Continuous feed: a cable or wireless box keeps feeding timecode all day.
Timecode over audio: the code is recorded onto a camera audio track as a scratch reference.
No timecode: sync by clapperboard and waveform matching in the edit.

Why sync still drifts

Two problems dominate. The first is clock drift: free running devices wander apart over hours, which is why crews rejam at lunch. The second is sample rate mismatch, and it is the one people miss.

If the sound is 48 kHz and a file somewhere in the chain is 44.1 kHz, the audio plays roughly nine percent long or short depending on how the timeline handles it. On a short take you hear a soft lip sync error. On a ten minute interview it is a disaster.

Checking before you blame the timecode

Inspect the files. Confirm the sample rate, bit depth, channel count and start timecode of both the camera audio and the recorder files. A mismatch is visible in seconds and explains most so called sync problems.

When the rate genuinely is wrong, resample deliberately with a converter that preserves length and quality, then reconform. Do not let an NLE silently stretch the file for you.

Practical habits

Jam at call time and again after lunch.
Slate every take even when timecode is running, as a visual backup.
Set the whole production to 48 kHz, cameras included.
Record a scratch track on camera, it costs nothing and saves days.