Random sound bug when mixing two music modules


I’m trying to play two music modules in sync: a base track and a module that can fade in and out. For testing, I’ve simply added both to a sound cue and mixed them.

The problem: there is a maybe 20% chance that the sound “clips” at each beat. It’s hard to describe, so I made a video: http://www.anteevy.de/upload/qfu/Sound%20Mixer%20Bug.mp4

At the start, it works. Then I restart the cue a few times until the bug occurs (at 0:07). The next cue replay it is still there (0:17), and then it works as intended again (the last few seconds).

Does anyone have an idea what could cause this? I’ve tried this with several different music tracks (though they have a similar beat). The bug even occurs when I put both tracks in their own sound cues and start playing them together.


Hey anteevy,

I found a post that addresses this issue directly from our lead audio engineer. He basically mentions playing two sounds in sync is a limitation of the engine and has been since UE3. We are currently in the process of revamping our audio framework which will take a bit of time to implement.

Syncing Audio Cues/Waves

There are also workarounds that are provided to help you find a solution. Let me know if you are still at a loss or need further assistance.

Thank you,

Thanks for the reply!

I don’t think that’s my problem. The music stays in sync nicely (I always fade the unused modules to 0.01 volume so they don’t stop). Maybe the two modules randomly start with a minimal offset that causes the “clipping” sound, I’m not sure. As seen in the video, the bug already occurs in the sound cue editor itself and directly when pressing the play button.