I have a movie with an .mp4 extension that will only play silently with a black screen with QT 7.1.3 and Perian.

Container : mp4
Video : avc / h.264 [x264 at crf=18] VLC describes it as avc1
Video resolution : 720x304
Audio : He-AAC 5.1

It plays perfectly well with VLC but I'd prefer to use QT if at all possible. Am I missing some components or just out of luck ?