Audio & playback
Video and audio out of sync? Find the cause and fix it
Short answer
First test where the problem lives: play the same file in a second player (VLC) and on another device. If it is in sync there, your player, browser or Bluetooth headphones are the cause. If it is out of sync everywhere, look at how it drifts: a gap that grows over time points to variable frame rate or a frame-rate mismatch; a gap that stays the same from the first frame points to an offset in the edit.
Key takeaways
- Test the same file in a second player and on another device first: if it is in sync there, the player, browser, TV or Bluetooth is the cause.
- A gap that grows over time is drift, usually variable frame rate or a frame-rate mismatch; a constant gap from the start is an offset.
- Bluetooth headphones add delay; TVs and soundbars have an audio delay (lip sync) setting.
- YouTube recommends uploading at the frame rate you recorded; converting rates in the edit adds timing errors.
- Convert variable frame rate clips to a constant frame rate before editing or uploading.
Find your case
| What you see | What it usually means | Do this |
|---|---|---|
| In sync in VLC, out of sync in one app or browser | That player or browser | Player fixes (step 1) |
| Only with Bluetooth headphones | Wireless audio delay | Test on speakers (step 2) |
| Gap grows over the video | Variable frame rate or wrong frame rate on export | Constant frame rate, matched fps (step 3) |
| Same gap from start to end | Offset in the edit | Shift the audio track (step 4) |
| Out of sync only after uploading | Platform conversion of a variable-frame-rate file | Upload a constant-frame-rate export (step 5) |
| Only on a TV or soundbar | HDMI ARC or eARC processing delay | Adjust the TV's audio delay or lip-sync setting |
| Everywhere, growing over time | Drift in the file | Constant frame rate conversion |
Fix it step by step
Rule out the player
Play the file in VLC or another player. In a browser, disable extensions and toggle hardware acceleration; in VLC you can test an audio delay (Tools → Track Synchronization) to confirm the offset.
Rule out Bluetooth
Wireless headphones and speakers add delay. If sync is correct on the device speaker, the file is fine.
Fix drift: constant frame rate
Screen recordings and phone videos are often variable frame rate. Convert them to constant frame rate (HandBrake: Constant Framerate) before editing, keep the project at the source rate, and export at that rate.
Fix a constant offset
Move the audio track on the timeline by the offset (a few frames is often enough), or use your editor's sync-by-waveform feature for separate audio recordings.
Before uploading anywhere
Export H.264 MP4 with AAC audio at a constant frame rate. Platforms convert uploads, and constant-frame-rate files convert without drift.
Fix drift: convert to a constant frame rate
- Check for variable frame rate:
ffprobe -v error -select_streams v:0 -show_entries stream=r_frame_rate,avg_frame_rate -of csv=p=0 in.mp4. Different values usually mean variable frame rate. - Convert to a constant frame rate (30 here):
ffmpeg -i in.mp4 -vf fps=30 -c:v libx264 -crf 18 -pix_fmt yuv420p -c:a aac -b:a 160k out.mp4
Fix a constant offset
- Delay the audio by 0.2 seconds:
ffmpeg -i in.mp4 -itsoffset 0.20 -i in.mp4 -map 0:v -map 1:a -c copy out.mp4 - Make audio earlier by delaying the video instead:
ffmpeg -i in.mp4 -itsoffset 0.20 -i in.mp4 -map 1:v -map 0:a -c copy out.mp4 - In VLC, the J and K keys shift audio sync while you watch, to measure the offset before fixing the file.
Out of sync on a TV or soundbar
TVs and soundbars process audio and picture separately, and HDMI ARC or eARC links can add delay. Look for an audio delay, AV sync or lip-sync setting on the TV or soundbar, and set the TV's audio output format to PCM or auto to test. If only one app is out of sync, update that app.
Audio out of sync on Windows 11
- Settings → System → Sound: check the output device; try another output to rule out the device.
- Open the output device's properties and turn off audio enhancements or spatial sound for the test.
- Device Manager → Sound, video and game controllers → right-click your audio device → Update driver.
- Update the graphics driver as well; video playback timing depends on it.
- Try another player (VLC or Windows Media Player) to see whether one player is the cause.
Out of sync on a phone
iPhone
- Test with the speaker; Bluetooth headphones add delay.
- Screen recordings are variable frame rate: convert before editing.
- Restart the app or the phone if only one app is out of sync.
Samsung and other Android phones
- Disconnect Bluetooth and test with the speaker.
- Update the player app or try another player.
- Convert variable frame rate recordings before editing or uploading.
Out of sync on a Mac
- Test with the Mac's speakers; AirPods and other Bluetooth headphones add delay.
- System Settings → Sound → Output: pick the device you are using.
- Try another player (QuickTime Player or VLC) to see whether one app is the cause.
- For files from screen recordings or phones, convert to a constant frame rate before editing.
Prevent sync problems when recording
- Set your phone or camera to a fixed frame rate where it offers one; many phones only record variable frame rate, so convert before editing.
- Record external audio at 48 kHz and clap at the start of each take.
- Screen recorders (OBS, Game Bar, QuickTime): choose a constant frame rate if there is an option, and record the microphone on the same device.
- Keep audio linked to video in your editor; detach only to fix it.
- Export at the project's frame rate and check the result before uploading.
Bluetooth delay, explained
Bluetooth audio is compressed, sent in packets and buffered by the headphones, which adds a delay that wired headphones and speakers do not have. Many video players and phones compensate for it, but not every app or device does, so the same video can be in sync on the speaker and late on headphones. If sync is only wrong on Bluetooth, the file is fine; try reconnecting the headphones, updating them, or using a player that offers an audio delay setting.
Out of sync in a browser
- Reload the page; sync problems after seeking or a network hiccup often clear.
- Toggle hardware acceleration in the browser settings and restart the browser.
- Disable extensions that modify video or audio.
- Try another browser to see whether one browser is the cause.
How much offset people notice
ITU-R BT.1359-1, a broadcast recommendation based on viewer tests, puts the threshold of detectability at about 45 ms with audio ahead of the picture and about 125 ms with audio behind it. It puts the limit of acceptability at about 90 ms early and 185 ms late. Audio that arrives early bothers viewers sooner than audio that arrives late.
Constant offset or drift
Check at the start and again near the end of the file. The same offset at both points is a constant shift; a gap that grows is drift.
| Frame rate mismatch | Drift per minute | Typical cause |
|---|---|---|
| 0.1% (29.97 vs 30 fps) | about 60 ms | A 30 fps project holding 29.97 fps footage |
| 1% | about 600 ms | A clip speed change applied only to the picture |
Fix the file with ffmpeg
- Constant shift, delay the audio by 0.25 s:
ffmpeg -i in.mp4 -itsoffset 0.25 -i in.mp4 -map 0:v -map 1:a -c copy out.mp4 - Constant shift, move the audio earlier by 0.25 s: use
-itsoffset -0.25. - Drift, stretch or squeeze the audio to match:
ffmpeg -i in.mp4 -af aresample=async=1 -c:v copy out.mp4
Test the result on the same device that showed the problem, because Bluetooth speakers add their own delay that no edit to the file can remove.
Frequently asked questions
Why does my audio get further out of sync as the video plays?
Variable frame rate or a frame-rate mismatch. Convert the source to constant frame rate and export at the same rate.
How do I fix audio delay in a video?
If the delay is constant, shift the audio track in an editor. If it grows, fix the frame rate first.
Why is my video out of sync only on YouTube or Instagram?
The platform converted a variable-frame-rate file. Upload a constant-frame-rate H.264 MP4.
Why is my video and audio out of sync on YouTube?
If only your upload is affected, the file is variable frame rate or was converted between rates; export at a constant, recorded frame rate. If every video is affected, check Bluetooth, the browser or the TV.
Why is my video and audio out of sync on iPhone?
Screen recordings and some camera clips are variable frame rate, and Bluetooth adds delay. Test with the speaker and convert the clip to a constant frame rate before editing.
Why is my video and audio out of sync on Instagram?
Instagram re-encodes uploads, and variable frame rate files drift after processing. Export a constant 30 fps file.
How do I fix audio out of sync on a Fire TV stick?
Settings → Display & Sounds → Audio → AV Sync Tuning, then move the slider until the tone matches the flash. Amazon says to use Lip Sync Tuning instead with a home theater setup.
How do I fix audio and video out of sync on a TV?
Look for the TV's or soundbar's audio delay, AV sync or lip-sync setting. If only one app is out of sync, update or reinstall that app.
How do I fix audio out of sync in OBS?
Open Advanced Audio Properties and set a Sync Offset for the microphone or capture source, in milliseconds, until speech matches the picture.
Why is my audio out of sync in Premiere Pro or DaVinci Resolve?
Variable frame rate phone and screen recordings drift in editors. Convert them to a constant frame rate before importing, and set the timeline to the footage's frame rate.
How do I fix audio out of sync in an MP4 file?
Measure the offset in VLC (J and K keys), then shift the audio with FFmpeg's -itsoffset or in an editor. If the gap grows over time, convert the file to a constant frame rate instead.
Why is video and audio out of sync on Netflix or Hulu?
Streaming apps are rarely the cause. Check Bluetooth, the TV's or soundbar's audio delay setting, then restart the streaming device and update the app.
Why is video and audio out of sync on my Samsung phone?
Most often Bluetooth delay or a variable frame rate recording. Test with the speaker; if the file itself drifts, convert it to a constant frame rate.
Why is my screen recording out of sync?
Screen recorders often save variable frame rate video, which drifts in editors and after upload. Convert the recording to a constant frame rate before editing.
Sources
- YouTube Help: Recommended upload encoding settings (official, checked 2026-10-05)
- Amazon Help: Audio is out of sync on your Fire TV device (official, checked 2026-10-06)
- ITU-R BT.1359-1: Relative timing of sound and vision for broadcasting (official, checked 2026-10-06)
Reviewed 2026-10-06. Steps not attributed to a source are general video practice or computed above.