Our team is developing a web application that plays back recorded video stored in XProtect using the WebRTC API.
During playback, we overlay our video‑analysis results (bounding boxes and metadata) on top of the video frames.
However, we have noticed that the bounding boxes appear to move with a noticeable delay relative to the video displayed through WebRTC, which is causing issues for us.
As part of our investigation, we compared WebRTC playback with Smart Client VOD playback.
We found that even when both are displaying frames with the same timestamp, the WebRTC stream appears to be approximately one second ahead.
In contrast, the Smart Client video aligns correctly with our analysis results and bounding boxes.
Is this difference in playback timing expected behavior?
Additionally, is there any recommended way to compensate for or correct this timing offset when using WebRTC playback?
Any guidance or clarification would be greatly appreciated.
One possible explanation is that the Smart Client is applying a video buffer. Please test the following:
In Smart Client, open your test view.
Enter Setup mode (via the Setup button).
In the left‑hand pane, locate Properties → Video Buffering.
Disable “Use default video buffer” and set Video buffer to None.
Please check whether this changes the behavior.
If it does not, Milestone Development has created a new API Gateway build that includes a potential fix. Note that this is an experimental fix for 2025 R2, not an official release. Your feedback—whether the fix resolves the issue or not—is important.
You can download the experimental fix here: [link].
This fix was developed for a similar case reported on 2025 R2. If you are running 2025 R3, please let us know and we can provide a build for that version. In any case, please specify which XProtect VMS version you are using.
The XProtect VMS version we are using is 2024 R2.
Have you confirmed any similar cases occurring on 2024 R2?
If you have confirmed occurrences on 2024 R2, please provide a fix build for 2024 R2.
