Auto Sync

How Synclay synchronizes multiple camera angles and telemetry data.

Overview

After grouping videos, Synclay can automatically align them so the same moment in time plays simultaneously across all angles. Auto Sync uses two methods depending on what data is available.

Audio Cross-Correlation

When two videos have audio tracks, Synclay extracts audio fingerprints and uses cross-correlation to find the precise time offset where the audio waveforms align. This is the most accurate sync method.

  1. Create a video group with at least two videos that have audio.
  2. Click the "Auto Sync" button on the group card.
  3. Synclay extracts audio, computes cross-correlation, and applies the offset.
  4. The PiP video shifts to align with the main video.

First-Movement Sync (Telemetry)

When telemetry data (AIM or Alfano) is present, Synclay can detect the first moment of vehicle movement in both the video and the telemetry stream, then align them at that point.

  1. Place a telemetry file (.csv for AIM, .zip for Alfano) in the same folder as your videos.
  2. Create a group.
  3. Click "Auto Sync".
  4. Synclay detects first-movement in both streams and applies the telemetry offset.
Tip: For best results with first-movement sync, start your telemetry logger before you begin driving. A clear transition from stationary to moving gives Synclay the sharpest signal.
Alfano laptimers: Alfano devices typically start recording telemetry at the start of the first lap (when crossing the S/F line), not when the vehicle first moves. This means there is no stationary-to-moving transition for Synclay to detect, and first-movement sync may fail. A future release will include S/F line crossing detection to handle this case. For now, if auto sync fails with Alfano telemetry, use manual sync offset adjustment instead.

Synced Badge Tiers

After syncing, a badge appears on the group card indicating sync quality:

Synced (green)
Audio cross-correlation found a strong match. Offset is highly accurate.
Synced (yellow)
Sync was applied but with lower confidence. Consider reviewing the offset manually.
Manual
Offset was set manually by the user, not by Auto Sync.
Tip: Sync results are cached. Re-opening a project with previously synced groups skips the sync step and applies the cached offset instantly.