Frame Rate Mismatch and Sync Issues

Mixing different frame rates is a common reason for gradual audio drift. This guide explains how to detect and fix it.

Common mismatches

• 29.97 vs 30 fps
• 24 vs 30 fps
• Variable frame rate (VFR) sources

Symptoms

• Audio starts in sync but drifts later
• The longer the video, the worse the offset

Fix strategy

• Re‑encode video to a standard frame rate (e.g., 30)
• Keep audio untouched when possible
• Test a short clip before full merge

Recommended workflow

1. Check the frame rate of your source video.
2. If it is VFR, re‑encode to CFR (constant frame rate).
3. Merge again using Copy for audio.