How to Fix Audio That Is Out of Sync in a Video

Audio sync issues (also called A/V sync or lip-sync problems) occur when the audio track drifts out of alignment with the video. The audio may be early (you hear words before lips move) or late (lips move before you hear anything). Here are the most effective fixes.

Understanding Audio Sync Problems

Audio sync drift has several root causes:

• Constant offset — audio is always ahead/behind by a fixed amount (easiest to fix)
• Progressive drift — audio starts in sync but gradually drifts (harder — different frame rates)
• Variable frame rate (VFR) — common with screen recordings and some phone videos

Fix 1: VLC — Simple Delay Adjustment (Live Playback)

For checking and compensating during playback only:

1. Open the video in VLC
2. Press J to delay audio by 50ms per press (audio starts later)
3. Press K to advance audio by 50ms per press (audio starts earlier)

This is for viewing only — it does not save the fix to the file.

Fix 2: HandBrake — Encode with Audio Delay Offset

HandBrake can apply a permanent audio delay offset during re-encoding:

1. Open HandBrake → load your video
2. Go to the Audio tab
3. Find the audio track → set Audio Track Offset (ms) (positive = audio starts later, negative = audio starts earlier)
4. Encode the video

Fix 3: MKVToolNix — No-Re-encode Fix (MKV Files)

For MKV files, MKVToolNix can adjust audio delay without re-encoding (no quality loss):

1. Download MKVToolNix (free)
2. Open MKVMerge → drag in your MKV file
3. Select the audio track → in "Delay" field, enter the offset in milliseconds
4. Start muxing → creates a new MKV with the corrected sync

Fix 4: DaVinci Resolve — Precise Timeline Fix (Free)

1. Import your video into DaVinci Resolve (free version)
2. In the timeline, click the audio clip
3. Drag it left or right to align with video
4. Use the Inspector panel for precise millisecond control
5. Export to your desired format

Fix 5: FFmpeg (Command Line)

For a precise, lossless fix (MKV or MP4):

ffmpeg -i input.mp4 -itsoffset 0.5 -i input.mp4 -map 0:v -map 1:a -c copy output.mp4

Replace 0.5 with the number of seconds to delay the audio.

Diagnosing the Offset

If you're unsure how much offset to apply, look for a clear sync cue in the video (a hand clap, ball bounce, or door slam) and count frames between the visual event and the audio event.