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

Question

我用AVPlayer播放视频.它工作正常.

现在我想UIImage从视频播放中获取一个(当我按下按钮的时候).

附在我身上AVPlayer有一个CALayer用于显示我的视频UIView.我的想法是让一个UIImage从CALayer视频中播放.

我使用另一个问题的代码执行此操作:

来自CALayer的UIImage - iPhone SDK

不过我UIImage是空的.分辨率很好,但它是完全白色的!

看来视频没有写出我的内容CALayer.

有人可以帮帮我吗？谢谢

Answer 1

我不能让Meet的解决方案为我工作,但它让我思考正确的方向.

下面是我最终在我的项目中使用的代码.该方法screenshotFromPlayer:maximumSize:接受AVPlayer从中截取屏幕截图的实例,并且该实例CGSize将是返回图像的最大大小.

- (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;
}

还要注意,可以使用该方法generateCGImagesAsynchronouslyForTimes:completionHandler:而不是copyCGImageAtTime:actualTime:error:(在实例上AVAssetImageGenerator)异步执行图像生成.

此代码示例在AVPlayers 处生成屏幕截图currentTime,但可以随时使用.

Answer 2

从avplayer获取图像的代码.

 - (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];
}

设置[imageGenerator setRequestedTimeToleranceBefore:kCMTimeZero],[imageGenerator setRequestedTimeToleranceAfter:kCMTimeZero]如果你需要精确的时间.

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 *生成器 = [[AVAssetImageGenerator 分配] initWithAsset:asset];
    生成器.appliesPreferredTrackTransform=TRUE;
    [资产释放]；
    CMTime 拇指时间 = CMTimeMakeWithSeconds(0,30);
    AVAssetImageGeneratorCompletionHandler 处理程序 = ^(CMTime requestsTime, CGImageRef im, CMTime effectiveTime, AVAssetImageGeneratorResult 结果, NSError *error){
    if (结果！= AVAssetImageGeneratorSucceeded) {

    }
    UIImage *thumbImg = [[UIImage imageWithCGImage:im] 保留];
    [发电机释放]；