Why can't I capture a screenshot of MPMoviePla

Question

I need to capture a screen shot of a video playing in mpmovieplayer controller, but all I get is a red screen (I made the coverView with red background and 0.5 alpha).

Here is the code:

NSArray *windows = [[UIApplication sharedApplication] windows];
if ([windows count] > 1)
{
    UIWindow *moviePlayerWindow = [[UIApplication sharedApplication] keyWindow];


    UIView *coverView = [[UIView alloc] initWithFrame:moviePlayerWindow.bounds];
    [mainController.moviePlayer pause];  //Without that it won't work either!
    coverView.backgroundColor = [UIColor redColor];
    coverView.alpha = 0.5;
    [moviePlayerWindow addSubview:coverView];

    UIGraphicsBeginImageContext(coverView.bounds.size);
    [coverView.layer renderInContext:UIGraphicsGetCurrentContext()];

    UIImage *screenShot;

    screenShot = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    UIImageWriteToSavedPhotosAlbum(screenShot, self, nil, nil);
}

Any ideas???

Thanks

Answer 1

I was curious about his myself. I believe there are similar issues with taking screenshots of OpenGL stuff too.

If you look at this blog post http://getsetgames.com/2009/07/30/5-ways-to-take-screenshots-of-your-iphone-app/, they have a method that works for an EAGLView, it might be worth giving it a go for your issue.

Answer 2

Sounds like you're taking a shot of the video overlay mask http://en.wikipedia.org/wiki/Hardware_overlay

Answer 3

Follow up to the question:

Recently I have a project that requires the functionality that was asked in this thread again, and I am glad to say there is already an apple provided solution to this. I am posting this so that people that visit this thread can get an answer.

MPMoviePlayerController now has a method that return a UIImage of the moment you want to capture.

- (UIImage *)thumbnailImageAtTime:(NSTimeInterval)playbackTime timeOption:(MPMovieTimeOption)option

Just put in the playbackTime you want to capture, and bingo, UIImage.

---

Looking at your codes, I would like to advise that you should look for an alternative method of getting the image rather than from the mpmovieplayer itself. The reason being that the method you are using is a private framework code, and second, getting screenshots off a video is highly prone to crashes.

Instead of getting a screenshot from the video, how about tagging the video beforehand? The codes looks highly vulnerable to an app rejection by apple.