How to change the speed of video playback

问题

I'm wondering if it's possible to change the video playback speed in an iphone application. we want users to yell in the microphone to speed up the playback and get to the end.

回答1:

You have to use setCurrentPlaybackRate:

回答2:

There is a rate property for the AVPlayer.

If you take the example from Apple called "avPlayerDemo" in the resource section, you then simply have to set the mplayer.rate. It worked for me, I created a new slider in the xib files, implemented that slider in the AVPlayerDemoPlaybackViewController and simply set mPlayer.rate to the slider value.

回答3:

What about the MPMoviePlayerController?

setCurrentPlaybackRate 

Here's some code which does not work at that spot

-(IBAction)abspielen:(id)sender 
{
    NSString *titleOfButton = [sender titleForState:UIControlStateNormal];
    NSBundle *bundle = [NSBundle mainBundle];
    NSString *moviePath = [bundle pathForResource:titleOfButton ofType:@"mov"];
    NSURL *movieURL = [ NSURL fileURLWithPath:moviePath];

    MPMoviePlayerController *themovie = [[MPMoviePlayerController alloc]initWithContentURL: movieURL];  
    [themovie play];
    [themovie setCurrentPlaybackRate:2.f];    
    [themovie release];

    MPMoviePlayerViewController *moviePlayer = [[MPMoviePlayerViewController alloc] initWithContentURL:movieURL];
    [self presentMoviePlayerViewControllerAnimated:moviePlayer];
    [moviePlayer release];              
}

来源：https://stackoverflow.com/questions/2483783/how-to-change-the-speed-of-video-playback