Syncing cameras

Every camera hears the same room, so the same words and bumps appear in each file at slightly different times. EditAI finds that difference for each camera and puts them all on one timeline.

How it works

Each file's sound is decoded and compared with the others using GCC-PHAT cross-correlation. Weighting every frequency equally makes the match sharp and tolerant of different microphones, gain and reverb. The first camera with sound is the reference; the others are placed relative to it, falling back to the other cameras if the first match is weak. The first 15 minutes of each file are compared and offsets up to 10 minutes are found.

Check it

The Sync tab lists every camera with its offset and how strong the match was. Strong is a clear match, weak means check it by eye: play the timeline and watch the waveforms of the camera lanes line up on a clap or a loud word.

Fix a camera

• Nudge: −100 ms, −1 frame, +1 frame, +100 ms. A camera you nudge is marked "by hand" and is left alone by re-sync.
• Re-sync by sound: runs the match again for every camera not set by hand. Auto again on a camera hands it back to the matcher.
• Cameras with no sound cannot be matched. They are placed at 0; nudge them into place.

Adding a camera later

Click + above the camera list, or drop files on the editor. The new camera is matched against the existing ones and your edit is kept.