Audio Video Sync Dock 0.1.0

Introduction
Using a special pattern video, this plugin helps you measure the latency between audio and video.

If the latency is large, viewers will notice the lips is not synchronized to what they hear, and feel uncomfortable.

Idea

The pattern video consists of 3 types of frames:

• QR code -- Metadata describing the index number, audio frequency, etc., also helping to locate the following pattern in the frame.
• Pattern 1 -- Pattern consisting of white and black tiles.
• Pattern 2 -- Inverted pattern to identify the accurate timing of the transition.

The audio of the video consists of pulses of a sine wave with the index number encoded by quadrature amplitude modulation. The pulse starts at the timing that the transition from the pattern 1 to the pattern 2 happens. The index number helps to find the corresponding video pattern even if the latency is huge.

In many setup, the audio and video travel differently. For example, the video goes through a camera and a capture card, the audio goes through another audio interface. It causes the difference of the timing of arrival at OBS. This plugin checks which is slower and how much the delay is.

Demonstration
You can find a demonstration video on YouTube.

Usage

Please follow steps below.

1. Install this plugin.
2. Configure your microphone and your camera on OBS Studio.
3. Play the video containing the synchronization pattern on a player like a mobile phone. See table here.
4. Use your camera to shoot the display of the video.
5. Open Audio Video Sync Dock and start measuring. When the pattern is recognized, latency will be displayed.
6. Adjust the latency of your audio and/or video to make the latency close to 0 ms.

Slightly positive latency, such as +10 ms (equivalent to 3.3 m) or +20 ms (6.7 m), would be acceptable since the audio travels slower than the light in nature.