Here's a bit of an odd one. I have CS6 on the Mac and have been happily encoding mp4's that play back fine on the Mac using Windows Media Encoder.

However today a client asked me why the audio was out of sync on a clip. Puzzled I checked the clip and it was fine. So then I tried it on a Windows PC using Windows Media Player (the default player in Windows) and the audio was out of sync. I tried another mp4 and this was also out of sync. However on the Mac it was fine and if played back on Quicktime on the PC it was also fine.

I tried 3 separate Windows PC's and on all of them mp4's encoded in Adobe Media Encoder all had audio sync issues.

I then re-encoded the clips using Handbrake and the resulting clips played back fine on every machine I tried.

So what's the issue then? What is it that Windows Media Player doesn't like about MP4 clips encoded in Adobe Media Encoder on the Mac? I've tried different profiles, resolutions, bitrates. All of them with the same problem. Yet the same clips encoded via Handbrake are always fine.

Any ideas?

Cheers.