MPMoviePlayerController cannot play some 3gp format video - objective-c

Question

I use MPMoviePlayerViewController to play a video with format 3gp. some video can played,but others cannot be played. MPMoviePlayerViewController will loading and end immediately,just like the video is 0 second duration.
i thought there must be sty wrong with the video. but i use the iphone's video player inside the album, it can play the video!
So i think maybe MPMoviePlayerViewController is not powerful.and i wanna try to use avfoundation framework avplayer to play video. add a sublayer into my content view. failed..
that drive me crazy! does anyone met the some problem?
here is my code
-(void) playMovieWithSDK: (NSURL*) movieUrl
{
if ([[[UIDevice currentDevice] systemVersion] doubleValue] >= 3.2) {
MPMoviePlayerViewController *mSdk4Player = [[MPMoviePlayerViewController alloc] initWithContentURL:movieUrl];
mSdk4Player.navigationController.navigationBar.tag = 1000;
if (mSdk4Player) {
[self presentMoviePlayerViewControllerAnimated:mSdk4Player];
mSdk4Player.moviePlayer.scalingMode= MPMovieScalingModeAspectFit;
mSdk4Player.moviePlayer.movieSourceType = MPMovieSourceTypeFile;
mSdk4Player.moviePlayer.shouldAutoplay = YES;
[mSdk4Player release];
[[NSNotificationCenter defaultCenter]addObserver: self
selector: #selector(movieFinishedCallback:)
name: MPMoviePlayerPlaybackDidFinishNotification
object: mSdk4Player.moviePlayer];
}
}
else if ([[[UIDevice currentDevice] systemVersion] doubleValue] < 3.2) { // sdk 3.0 播放器
MPMoviePlayerController* mSdk3player = [[MPMoviePlayerController alloc] initWithContentURL: movieUrl];
mSdk3player.scalingMode = MPMovieScalingModeAspectFit;
[[NSNotificationCenter defaultCenter]addObserver: self
selector: #selector(movieFinishedCallback:)
name: MPMoviePlayerPlaybackDidFinishNotification
object: mSdk3player];
[mSdk3player play];
}
}

Answer 1

The video you are trying to play might not be compatible with the basic Codecs supported by MPMoviePlayerController.
According to the documentation:
This class plays any movie or audio file supported in iOS. This includes both streamed content and fixed-length files. For movie files, this typically means files with the extensions .mov, .mp4, .mpv, and .3gp and using one of the following compression standards:
H.264 Baseline Profile Level 3.0 video, up to 640 x 480 at 30 fps.
(The Baseline profile does not support B frames.)
MPEG-4 Part 2 video (Simple Profile)
If you use this class to play audio files, it displays a white screen with a QuickTime logo while the audio plays. For audio files, this class supports AAC-LC audio at up to 48 kHz, and MP3 (MPEG-1 Audio Layer 3) up to 48 kHz, stereo audio.