How to sync audio and video: step by step in MultiSyncer Studio
Recorder audio is lined up with the picture by waveform, by timecode or by a slate. For a couple of clips the built-in sync of an editing app is enough. With several cameras, a shoot over more than one day and long takes, it is easier to sync the whole shoot at once in MultiSyncer Studio and open a ready project in the edit.
Where built-in sync falls short
Premiere Pro, DaVinci Resolve and Final Cut Pro can sync by audio and by timecode, and for a single scene that is enough. A multicam shoot over a whole day, with many camera and sound stops, is hard to sync there: the footage takes a long time to prepare by hand, it gets synced in parts, and you have to hunt for the errors yourself.
| Task | Built-in sync of an editing app | MultiSyncer Studio |
|---|---|---|
| The whole shoot at once | Clips are grouped by camera when their camera metadata is filled in; otherwise every file becomes its own angle and the labels are set by hand. On a day with many stops the footage is usually synced in parts. | One button for the whole shoot: cameras, recorders and phones land on their own tracks in one pass. |
| Long takes | Finds one offset for the whole clip and does not change the speed of the sound, so drift stays: if the camera and recorder clocks run differently, the sound slides away by the end of a long take. | Clock drift correction: the sound is resampled to the camera's speed into new WAV files. On a real shoot a 24–81 ppm mismatch went down to 2–4 ppm. |
| Clips with no shared sound | Without shared sound or timecode the clip is placed by hand, by in/out points or markers. | The clip is placed by timecode or by its camera's clock and clearly marked, so you can see which clip to check. |
| Several days and shoot days | Days and shoot days are laid out and checked by hand. | Days and shoot days line up in order, and every shooting day gets its own sequence. |
| How exact the result is | Sync errors happen, and you have to find them yourself: the app does not show them clearly. | The offset is measured to the sample; the log records it in milliseconds, samples and frames. |
| Camera names and QC notes | Which camera is which angle has to be set up and checked by hand. | Tracks get their names from the project setup (“A · wide”), and fails from the set arrive as markers. |
How to sync audio and video in MultiSyncer Studio
Add the footage
There are three ways in, pick the one that suits you:
- After the card offload. If the cards were copied in MultiSyncer, the footage is already in the project, sorted by camera.
- “In the edit room” mode. You only need sync: choose this mode and only “Sync” and “Export” remain. Drop the camera and sound folders into the window and they land on their tracks.
- A project already started in an editing app. Export it to XML, FCPXML, AAF or EDL and open it in MultiSyncer: the synchronized sequence comes back.
Choose the method
The method is chosen in the app; “Auto” fits almost every shoot:
- Auto: sound + recording time (recommended)
- Sound only
- Slate + sound
- Timecode
- Recording time
- File order
A slate and timecode are optional: the app finds shared sounds across all recordings. Sound is taken from every channel and track of the camera, and channels in opposite phase do not cancel each other.
Press “Synchronize”
The sound of every clip is compared with the others and the offset is measured to the sample. If there is timecode, the app uses it; if you shot with a slate, it finds the clap. Clips are found by sound even if the camera clock was reset during the day.
The “Synchronization complete” panel appears on the right: how many clips landed by sound, how many as continued recording, how many by file time, and how many warnings. Below are “Needs review” and “Different recording speed”. Each day's sequence is saved to the project folder on its own.
Synchronization complete
Needs review
F002 · IMG_0412.MOV · by file time
F002 · IMG_0415.MOV · by file time
Different recording speed
Recorder: 40 ppm, 96 ms by the end
Check and adjust if needed
A clip with no shared sound is placed by timecode or by its camera's clock and marked. Its position can be adjusted: nudge by a frame, lock, “Sync to…” another clip.
A/B listening plays the camera sound and the recorder sound together. If you hear an echo or doubling, the sync is off; if it sounds like one source, it lines up.
How accuracy is tested. Every version of the app is tested on real shoots: clip positions are compared with a sync an editor made by hand.
Long takes: clock drift correction
The clocks in a camera and in a recorder run at slightly different speeds. On a forty-minute interview the sound is several frames late by the end, even when the start is exact.
MultiSyncer measures the speed of every device and resamples the sound to the camera's speed into new WAV files next to the export. The start of a long clip is taken from the drift line, not from the first match. The original files are not touched.
Hand the project to the edit
Every device is on its own track named from the project setup, and the sound is synced to the cameras. On export you set:
- the sequence frame rate and frame size, the sound, the track names;
- pauses: keep them, shorten them, or join the clips where no camera is rolling;
- takes of one line stacked, or a sequence for each take;
- templates: “Interview / podcast”, “Course / lecture”, “Event / concert”, “Fiction / commercial”, “Shoot without a sound recorder”, “Quick rough cut”, “Shorts / Reels”;
- which QC issues to bring in as markers: everything found, fail and not decided, or fail only.
A handover note on how to open the project in the edit is placed next to it.
Clips by file time
Which formats it reads and where the project goes
| What | Formats |
|---|---|
| Video | MOV, MP4, MXF, MTS, MKV, AVI, camera RAW formats, 360° camera files, action camera low-res copies |
| Audio | WAV and BWF, RF64, AIFF, FLAC, MP3, AAC and more; over 30 video and audio formats in all |
| Timecode | Camera and recorder timecode, LTC recorded as audio on a track |
| Project import | XML, FCPXML, AAF, EDL from an editing app |
| Premiere Pro and Vegas | XML |
| DaVinci Resolve | FCPXML 1.9 |
| Final Cut Pro | FCPXML 1.10 with a multicam clip (Final Cut Pro does not open Blackmagic RAW, so those files are left out of its export) |
| Avid Media Composer, EDIUS, Pro Tools | AAF and ALE |
| Any other app | EDL |