Post Sound 1.2 | Video Sync Offset

Overview

This tutorial explains how to measure and correct audio/video synchronization in Avid Pro Tools (Video Sync Offset) before importing production assets.

Why Sync Offset Matters

When you press play in Pro Tools, there’s an inherent playback/display delay before the video appears. This delay can range from milliseconds to several frames and may be increased by studio hardware and routing, such as:

• Network routing
• Video switchers
• Other hardware in the signal path

If you don’t calibrate now, later sync issues won’t be clear—making it hard to distinguish between:

• System delay
• Timeline/audio issues

Pre-flight Configuration in Pro Tools

1. Create a blank test session

   • Example session name: “video sync”
   • Sample rate: 48 kHz

2. Open Session Setup (Command/Ctrl + 2) and set:

   • Timecode rate / frame rate: 23,976 (matching the test clip, and likely the project)
   • Clock Master (the running clock for audio/video sync)
     • Home setups: Internal
     • Studios: set the correct external hardware clock (e.g., Sync HD)
   • Additional hardware-specific sync fields may appear, such as:
     • Clock reference
     • Positional reference
     • Video ref format

3. Import the sync check video

   • Go to: File → Import → Video
   • Use a sync check clip (referenced as available via a session template; also available online)
   • In the import dialog:
     • Select New Track
     • Set track location to Session Start
     • Enable Import audio from file
   • Route playback to the correct output (example: Main 51 bus)

Choosing Where to View Video

• Pro Tools can display video in the internal video window.
• For lower latency, the tutorial recommends routing video out through a dedicated output video card (e.g., DeckLink 4K) using:
  • Setup → Video Hardware Control Panel
• With multiple monitors, each may introduce different delay, so:
  • Choose one monitor as the main calibration monitor

Measuring the Offset (Catch and Sync Workflow)

1. Take a screen recording and compare the beep audio waveform to the visual sync indicator.
2. iPhone recommendation: “Catch and Sync” app.
3. Workflow:
   • In the app: start recording (film icon → record video)
   • In Pro Tools:
     • Enable loop on a selected transport-bar play segment
     • Play the loop while recording
   • In the app:
     • Scrub the waveform until the video indicates it’s in sync
     • Unlock to adjust audio independently from video
     • Move the beep to align with the red line
     • Read the resulting offset in milliseconds
4. Example result: 98 ms

Applying the Offset in Pro Tools

• Enter the measured value:
  • Setup → Video Sync Offset
  • Type in 98 milliseconds (or your measured number)

Verification

• Record another clip and confirm the beep waveform aligns perfectly with the video sync indicator.

Important Behavior of the Setting

Video Sync Offset is system-level, not session-specific:

• New sessions on the same system keep the same offset
• Moving a session to another system will change behavior based on that system’s offset

Next Step

After trusting the hardware sync, proceed to import assets into the session.

Sources / Speakers

• Primary speaker: the instructor/author of “Post Sound 1.2 | Video Sync Offset”
• Referenced external content/clip sources: Photo Joseph (sync check video used in the example)
• Referenced app developer: Catch and Sync