MP4 files won't play nice in FCP

[mainstreetprod]

I make MP4's all the time in FCP but many of the ones I get from clients will not work- they will play back in QT but can't be converted (error message) or used in FCP in any way. MPEG streamclip can't convert them either. Anyone know the solution?

 

[Alex H.]

ClipWrap. The container is something that neither FCP nor MPEG StreamClip like, but the data under the hood is just fine. Change the wrapper and the problem goes away.