Question

我用AVPlayer播放视频。它运作正常。

现在我想从视频播放中获得UIImage（当我暂时按下按钮时）。

我的AVPlayer附加了一个CALayer，用于在UIView上显示视频。我的想法是在播放视频时从UIImage获得CALayer。

我使用其他问题的代码执行此操作：

UIImage from CALayer - iPhone SDK

但是我的UIImage是空的。分辨率很好，但它完全是白色!!!

视频似乎没有写出CALayer的内容。

有人可以帮帮我吗？感谢

Answer 1

我无法让Meet的解决方案为我工作，但它让我思考正确的方向。

以下是我最终在项目中使用的代码。方法screenshotFromPlayer:maximumSize:接受从中获取屏幕截图的AVPlayer实例，以及将作为返回图像的最大大小的CGSize。

- (UIImage *)screenshotFromPlayer:(AVPlayer *)player maximumSize:(CGSize)maxSize {

    CMTime actualTime;
    NSError *error;

    AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:player.currentItem.asset];

    // Setting a maximum size is not necessary for this code to 
    // successfully get a screenshot, but it was useful for my project.
    generator.maximumSize = maxSize;

    CGImageRef cgIm = [generator copyCGImageAtTime:player.currentTime 
                                        actualTime:&actualTime 
                                             error:&error];
    UIImage *image = [UIImage imageWithCGImage:cgIm];
    CFRelease(cgIm);

    if (nil != error) {
        NSLog(@"Error making screenshot: %@", [error localizedDescription]);
        NSLog(@"Actual screenshot time: %f Requested screenshot time: %f", CMTimeGetSeconds(actualTime),
          CMTimeGetSeconds(self.recordPlayer.currentTime));
        return nil;
    }

    return image;
}

另请注意，可以使用方法generateCGImagesAsynchronouslyForTimes:completionHandler:代替copyCGImageAtTime:actualTime:error:（在AVAssetImageGenerator的实例上）以异步方式执行图像生成。

此代码示例在AVPlayer的{{1}}生成屏幕截图，但可以随时使用。

Answer 2

从avplayer获取图片的代码。

 - (UIImage *)currentItemScreenShot
{
    AVPlayer *abovePlayer = [abovePlayerView player];
    CMTime time = [[abovePlayer currentItem] currentTime];
    AVAsset *asset = [[[abovePlayerView player] currentItem] asset];
    AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
    if ([imageGenerator respondsToSelector:@selector(setRequestedTimeToleranceBefore:)] && [imageGenerator respondsToSelector:@selector(setRequestedTimeToleranceAfter:)]) {
        [imageGenerator setRequestedTimeToleranceBefore:kCMTimeZero];
        [imageGenerator setRequestedTimeToleranceAfter:kCMTimeZero];
    }
    CGImageRef imgRef = [imageGenerator copyCGImageAtTime:time
                                          actualTime:NULL
                                               error:NULL];
    if (imgRef == nil) {
        if ([imageGenerator respondsToSelector:@selector(setRequestedTimeToleranceBefore:)] && [imageGenerator respondsToSelector:@selector(setRequestedTimeToleranceAfter:)]) {
            [imageGenerator setRequestedTimeToleranceBefore:kCMTimePositiveInfinity];
            [imageGenerator setRequestedTimeToleranceAfter:kCMTimePositiveInfinity];
        }
        imgRef = [imageGenerator copyCGImageAtTime:time actualTime:NULL error:NULL];
    }
    UIImage *image = [[UIImage alloc] initWithCGImage:imgRef];
    CGImageRelease(imgRef);
    [imageGenerator release];

    return [image autorelease];
}

如果您需要精确的时间，请

设置[imageGenerator setRequestedTimeToleranceBefore:kCMTimeZero]和[imageGenerator setRequestedTimeToleranceAfter:kCMTimeZero]。

Answer 3

尝试使用AVAssetImageGenerator从指定实例的视频文件中获取图像：

    AVURLAsset *asset=[[AVURLAsset alloc] initWithURL:[NSURL fileURLWithPath:[info objectForKey:@"UIImagePickerControllerReferenceURL"]] options:nil];
    AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
    generator.appliesPreferredTrackTransform=TRUE;
    [asset release];
    CMTime thumbTime = CMTimeMakeWithSeconds(0,30);
    AVAssetImageGeneratorCompletionHandler handler = ^(CMTime requestedTime, CGImageRef im, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error){
    if (result != AVAssetImageGeneratorSucceeded) {

    }
    UIImage *thumbImg = [[UIImage imageWithCGImage:im] retain];
    [generator release];

从连接到AVPlayer的CALayer获取UIImage（从视频播放中提取帧）

3 个答案: