Sync, Timecode, Room Tone, Wild Tracks and Sound Reports — Matching Sound to Picture

The slate is the surest reference, and it needs no extra gear. Call out the scene, shot and take and clap the sticks once; in editing, you find the first frame where the sticks meet on the picture and the start of the clap on the audio, and line them up. If you missed the head slate, hold it upside down at the end for a tail slate, and mark takes with no sound as MOS.

Timecode is time information in hours:minutes:seconds:frames. Use the recorder or a timecode generator as the master clock, set the cameras and recorder to the same value and have them record at the same frame rate. Editing software can then read each file’s timecode and sync many takes at once. Device clocks can drift a little over time, so it’s safer to re-jam after battery changes or long breaks. Even with timecode, many crews still clap a slate as a backup reference.

• Camera scratch audio — Sound recorded on the camera’s built-in mic is low quality, but editing software can compare it with the recorder’s waveform to sync.
• Slating close-ups — Near an actor’s face, clap the sticks gently. Too loud startles the actor and clips the level.
• Multiple cameras — Have every camera see the same slate, or slate each camera separately, so no camera misses a reference.

• Sample rate and bit depth — 48kHz/24-bit is widely used for video work. Use the same settings for the whole project and confirm with the post team in advance.
• File format — Recorders usually record Broadcast WAV (BWF), which stores information like scene, take and track names inside the file.
• Multitrack — Keep a separate track for each mic, boom and lavs (ISO tracks), plus a mix track where the production sound mixer blends them.
• Mix track — Used for editorial previews and dailies. The final mix is redone in post from the ISO tracks.
• Track names — Name tracks on the recorder, like “1 Boom, 2 Lav Actor A, 3 Lav Actor B,” so post never gets confused.

Room tone is 30 seconds to a minute of just the location’s background sound, recorded while everyone stays still and silent. When editors cut or join dialogue, they fill the gaps with it so the scene doesn’t sound choppy. Keep the lights and gear the same as during the shot, and record it again when the location or situation changes.

• Wild lines — Re-record a line that had noise over it during the take, on the spot without camera. Because it’s the same space, it usually blends in more naturally than ADR.
• Wild effects — Capture sounds unique to the location, like a door opening and closing, a car starting or footsteps. They become reference or raw material for sound effects and Foley in post.
• Ambience — Record long stretches of background sound that sits under the whole scene, like a street, a forest or an office.

Fill out one sound report per sound roll. Post uses it to find sound files and to know in advance which tracks to use and which takes have problems. Use the same scene, shot and take labels as the camera report and the two can be cross-checked directly.