Tlog playback speed inaccurate (video sync issue)

Hi all!
I’m trying to make a video of mission planner showing the telemetry data (HUD, map and so on) with a little window in the corner displaying the recorded onboard video. Actually a pretty simple task. The problem is, that the video can’t be synchronized with the telemetry data. At first I thought it’s a problem with my screen video recorder, fps rate or something, but it’s not. I started MissionPlanner, played back a mission (of course with the playback speed set to „1x“) and compared the „Time in Air“ clock with a stopwatch. There is a huge difference. MissionPlanner is playing back the mission too slow.

I had to speed up the video to 106.4 % to achieve a correct synchronization with the onboard video. But the voice sounds really funny now.

I’ve noticed the same sync problem some month ago with another log, another onboard video and even another computer. So it seems to occur every time on every PC. Does anybody have an idea, where the problem comes from and how we could fix it?