I'm trying to use Windows Movie Maker to trim some .avi files while converting them to .mp4. Everything seemed good, the interface is noob-firendly (I just want to set new start time), it converts to mp4 etc. But I noticed that in the output video, the audio is out of sync (it is ahead of the video) by about 0.5 sec. Why does that happen? I'd rather not adjust it manually because it will never be as ideally synced as in the input video...