Overview
In live video workflows, it's common for audio and video to arrive slightly out of sync. This happens because audio and video signals travel through different processing paths — encoding delays, signal path differences, hardware conversion, or sync drift can all cause timing mismatches. Iris provides tools to correct this so your audio lines up precisely with your video.
There are two ways to adjust audio delay in Iris:
Audio Offset (software-level) — A delay you apply to any audio source within Iris. This adds a configurable delay in milliseconds to the audio stream.
Audio Delay (on-camera) — A hardware-level setting available on certain supported cameras. This tells the camera itself to delay its audio output, useful when the camera's built-in microphone or audio input is arriving ahead of its video signal.
What You'll Need
For Audio Offset (software):
At least one audio source added to your room
The audio source must be connected and active
For Audio Delay (on-camera):
A supported camera connected to Iris (certain Lumens, Datavideo, and VISCA-compatible models)
Access to the camera's Advanced Settings
Adjusting Audio Offset (Software-Level)
This is the most common way to fix audio-video sync issues.
In the Source Tray on the left side, locate the audio source you want to adjust.
Right-click the source or click the settings icon to open its settings panel.
Scroll to the Audio Offset section.
Toggle on "Enable to Adjust Latency."
In the Audio latency (milliseconds) field that appears, enter the number of milliseconds you want to delay the audio. For example, enter 200 for a 200ms delay.
Save your changes.
The offset is applied to the audio stream, shifting it forward in time to align with the video.
Range and Limits
Minimum: 0 ms (no delay)
Maximum: 5,000 ms (5 seconds)
If you enter a value outside this range, it's automatically adjusted to the nearest boundary (e.g., entering -100 becomes 0, entering 9999 becomes 5,000)
Toggling Off
When you toggle Audio Offset off, the input field becomes disabled and appears empty. Your previously entered value is preserved — if you toggle it back on, the value reappears.
Adjusting Audio Delay (On-Camera)
Some cameras have a built-in audio delay setting that Iris can control directly:
Open Advanced Settings for your supported camera.
Go to the Audio Settings section.
Find the Audio Delay toggle and switch it on.
Use the Audio Delay Time slider to set the desired delay (between 1 and 500 milliseconds).
Changes are sent to the camera in real time.
To turn it off, toggle the Audio Delay switch off. The camera reverts to its default behavior (no delay).
Supported Cameras
This feature only appears for cameras that support it. If your camera doesn't, the controls simply won't be in Advanced Settings.
Using Both Together
You can have both Audio Offset (software) and Audio Delay (on-camera) active at the same time, but be aware that the delays stack. If you set 200ms in Audio Offset and 100ms on the camera, the total audio delay will be approximately 300ms. Use caution to avoid over-correcting.
Calculating Audio Offset in Frames
To align audio delay with your video frame rate:
Take your frame rate (e.g., 30 fps).
Divide 1000 milliseconds by the frame rate to find the duration of a single frame.
Example:
30 fps → 1000 ÷ 30 = 33.33 ms per frame
To delay by 2 frames: 33.33 × 2 = 66.66 ms
Enter that value into the Audio Offset field for an approximate 2-frame delay.
Testing and Verifying Audio Sync
To fine-tune your delay:
Send your Iris output to a known output destination — a local monitor, external switcher, or remote viewer.
Play a sync reference video with both visual and audio indicators (a "beep and flash" countdown works well).
Observe whether the flash and beep line up.
Adjust the Audio Offset in Iris until they occur simultaneously on your output.
Save or document the offset value for repeatable future use.
Tips for testing:
Test on your output destination, not just the preview inside Iris.
Use a low-latency monitor to avoid introducing confusion.
Some streaming platforms apply their own buffering — don't rely solely on final stream playback for sync decisions.
Tips and Best Practices
Apply offset only to the source that's out of sync — avoid globally adjusting unless all signals are misaligned.
Label your sources with delay settings if you're operating in a multi-mixer or multi-encoder environment.
Audio Offset is per source — each audio source has its own independent setting, so you can fine-tune each one individually.
You can't make audio arrive earlier — Iris only adds delay. If audio is arriving too late, the issue is upstream and needs to be addressed at the source or network level.
Test before critical productions — offset adjustments may affect how audio is synchronized in recordings and live streams.
What Happens If…
…you enter a value outside the allowed range? It's automatically adjusted to the nearest boundary. -100 becomes 0, 9999 becomes 5,000.
…you toggle Audio Offset off? The input field becomes disabled and appears empty. Your value is preserved and reappears if you toggle it back on.
…your camera doesn't support Audio Delay? The Audio Delay controls simply don't appear in Advanced Settings. No error — they're only shown for supported cameras.
…you use both Audio Offset and on-camera Audio Delay at the same time? Both apply, and the total delay is the sum of both values. Be careful not to over-correct.
Troubleshooting
What's happening | Likely cause | What to do |
Audio is ahead of video | Audio arriving before video due to processing differences | Increase the Audio Offset value until audio and video sync up |
Audio is behind video | Too much delay applied, or video arriving faster than audio | Decrease the Audio Offset, or set to 0 and check your source configuration |
Audio Delay controls not visible in camera settings | Camera model doesn't support on-camera audio delay | Use the software-level Audio Offset instead |
Changes to Audio Offset don't take effect | Changes may not have been saved | Make sure you save your audio source settings after making changes |
Audio Delay slider won't move | The Audio Delay toggle may be off | Make sure the toggle is switched on before adjusting the slider |
FAQs
What's the difference between Audio Offset and Audio Delay? Audio Offset is a software-level delay applied within Iris to any audio source. Audio Delay is a hardware-level setting sent directly to supported cameras. Both sync audio with video, but operate at different levels.
What unit is Audio Offset measured in? Milliseconds. A value of 500 means a half-second delay.
What's the maximum Audio Offset? 5,000 milliseconds (5 seconds).
Is Audio Offset enabled by default? No. The default is 0 (no delay) and the toggle is off.
Can I use both at the same time? Yes, but the delays stack. If you set 200ms in software and 100ms on the camera, total delay is approximately 300ms.
Which cameras support on-camera Audio Delay? If your camera supports it, the controls appear automatically.
Can I apply delay to a video source instead of audio? No. Iris only applies manual latency adjustments to audio inputs.
Will this affect recordings? The offset adjusts the audio stream's latency in the pipeline, which may affect how audio is synchronized in recordings and live streams. Test before critical productions.
Can I set a different offset for each audio source? Yes. Each audio source has its own independent Audio Offset setting.
Use Cases
Aligning network audio with IP video — RTSP or NDI video streams may buffer and arrive later than audio from a Dante interface or USB device. Add delay to the audio source to compensate.
Correcting USB audio interface latency — When using an external USB audio interface alongside HDMI video capture, audio often arrives first. Delay by 2-3 frames to align.
Matching mixer output to switcher preview — When sending Iris output into a live switcher, use a beep-and-flash reference to find the exact offset needed.
Camera-embedded audio arriving early — On supported cameras, use the on-camera Audio Delay to push the camera's audio output to match its own video signal.