MPMoviePlayerController audio/video out of sync - objective-c

Question

In my iPad App, I create an MPMoviePlayerController that plays an MP4 off of a website. In the MP4 there are people talking. In the App, I have noticed that the audio and video are out of sync by half a second or a quarter-second, perhaps. (I can tell this because I view the video in a web browser and there is no lag.)
The only clue that I have to this is that when the MPMoviePlayerController first loads up, the audio starts playing, but the video doesn't--then the video starts playing and it seems to skip a couple of frames to "catch up" to the audio...but it doesn't quite sync.
Seeing as how this class is a "black box" per the Apple Documentation, and none of the existing methods or properties come across as helpful to this problem, I'm a bit stumped. I may have to leave it how it is with the slight lag, rather than face weird workarounds. I wanted to see if anyone has experienced this before or could suggest a solution.
I'm running on Mountain Lion, latest XCode, iPad 2 with iOS 6.
The code I use to generate the controller is:
-(void) startVideoPlaying {
if (!self.theMoviePlayer) {
self.theMoviePlayer = [[MPMoviePlayerController alloc] initWithContentURL: movieURL];
[self.bgView addSubview: self.theMoviePlayer.view];
[self.theMoviePlayer.view setFrame: movieContainer.frame]; // player's frame must match parent's
} else {
[self.theMoviePlayer setContentURL:movieURL];
}
self.theMoviePlayer.shouldAutoplay = YES;
[self.theMoviePlayer play];
}
Thanks for any help.

Answer 1

After a variety of tests, I must conclude that there is something wrong with the encoding on the MP4s that I have been playing. I am not a video codec guru, but I made the following tests, which tell me this:
1) Downloading the MP4, placing it into the app and loading it into the MPMoviePlayerController via a file URL. Audio still out of sync, so not a connectivity issue.
2) Finding another MP4 on the web (something off Vimeo) and streaming it into the Player. Audio synced properly, potentially something wrong with the MP4s I was attempting to play.
3) Downloading the MP4, and using Handbrake to convert it into M4V with a variety of different settings (including the iPad preset). The Audio was synced fine.
Based on this, it seems to me like there's something wrong with the file I was attempting to play rather than the player (or the player can't handle it). Unfortunately, the files I am attempting to play cannot simply be converted, they are part of a large website system and many hundreds of files would have to change, and so on. So, while I have answered my own question, I haven't solved the problem.