Calibrating Audio Delay
Typically video latency is higher than audio latency, so if you notice that lip sync appears off with your switcher's program output, we recommend an audio delay box for your recordings, to get the audio and video in sync.
If you have the SE-2800 or SE-2850, it has built-in audio delay, please refer to the product manuals for more information. We will add a section to this guide in the future.
Our
AD-100M delay unit and
AD-200 mixer/delay unit allow you to delay the audio from your analog mixer before the switcher embeds it.
Some mixers may have this feature built-in as well, but there may be limitations on which outputs support it, which can be an issue if you have a PA system as well.
It's important to do this test in front of the primary camera for your production at the standard distance, assuming you have multiple cameras that are the same brand and model. If you are using multiple model cameras and sync is critical, you may still have delay issues, and need a more complex system to manage it.
The threshold of noticeable delay varies depending on the viewer, but some guidelines are available
here, and the goal should be to make it close to zero as possible.
Here are two ways to determine the sync offset:
- The iOS app Catchin' Sync uses the iPhone's high speed camera and mic to determine the offset by recording a short video of a slate, or hand clap. More information is on their website.
- Recording a slate or hand clap, and manually calculating the offset after analyzing it in video editing software.
For the second method:
- Record a slate or hand clap in front of your primary camera at the standard distance for talent. Run the signal through your switcher and out to your recorder.
- Import the recorded video into editing software, and look at the audio and video track. Measure how many frames the audio is apart from the video.
- Determine your recording's frame rate. If the switcher is set to 1080i it is 30 frames per second, and 720p and 1080p is typically 60 frames per second.
Some recorders will convert 1080p60 to 1080p30, please confirm that in the recorded file settings.
Your frame rate is likely 29.97 or 59.94 and not 30 or 60, so make sure to account for that in your calculation.
- Our audio delay units allow you to enter the delay value in milliseconds.
The formula is ([frame offset] divided by [frames per second]) multiplied by 1000.
- Example: If the video is 3 frames after the audio, set the delay on the AD-100M to 100ms for 1080i, or 50ms for 720p.
