OBS Audio/Video Sync Troubleshooting Guide
Problem
Audio and video desynchronize when streaming from Zoom to YouTube via OBS. Common symptom: lip-sync delay where audio arrives before or after video.
Phase 1: Diagnosis (The Clap Method)
- Start a local recording in OBS (don’t rely on live monitoring)
- Face camera, clap hands loudly 3 times
- Stop recording and watch back
- Analyze:
- Audio early (hear clap before hands touch) → need positive offset
- Audio late (hear clap after hands touch) → need negative offset
Phase 2: Quick Fix (Guess & Check)
- Open Audio Mixer dock in OBS
- Click gear icon next to audio source → Advanced Audio Properties
- Find Sync Offset (ms) column
- Enter value:
- Audio early: +100ms to +220ms (common range), up to +500ms for heavy delay
- Audio late: -100ms (negative value)
- Record another clap test, adjust in 50ms increments
Phase 3: Scientific Fix (Precise Calculation)
- Record clap test, import into video editor (Resolve, Premiere)
- Find exact frame where hands touch
- Find audio waveform spike for clap sound
- Count frames between visual and audio events
- Calculate:
(frames ÷ frame_rate) × 1000 = offset_ms- Example: 10 frames at 30fps = (10 ÷ 30) × 1000 = 333ms
- Example: 12 frames at 60fps = 200ms
- Enter exact value in OBS Sync Offset field
Phase 4: Troubleshooting
| Issue | Cause | Fix |
|---|---|---|
| Variable/drifting delay | High CPU/GPU usage | Reduce encoding preset or resolution |
| Capture card desync | Separate audio/video paths | Route mic through camera via HDMI to hardware-lock sync |
| Persistent offset | Video encoding slower than audio | Standard behavior — apply fixed offset per Phase 2/3 |
Capture Card Tip
If using a video capture card with separate audio input, check “Use Device Timestamps” in the audio source properties to let OBS manage sync automatically.
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