iphone ios取出视频的每一帧图片（关键帧，AVAssetImageGenerator）

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1. [mImageGenerator generateCGImagesAsynchronouslyForTimes:[NSArray arrayWithObject:[NSValue valueWithCMTime:CMTimeMakeWithSeconds(time, NSEC_PER_SEC)]] completionHandler:  
2.     ^(CMTime requestedTime, CGImageRef image, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error)  
3.     {  
4.    
5.         NSLog(@"actual got image at time:%f", CMTimeGetSeconds(actualTime));  
6.         if (image)  
7.         {  
8.             [CATransaction begin];  
9.             [CATransaction setDisableActions:YES];  
10.             [layer setContents:(id)image];  
11.    
12.             //UIImage *img = [UIImage imageWithCGImage:image];  
13.             //UIImageWriteToSavedPhotosAlbum(img, self, nil, nil);  
14.    
15.             [CATransaction commit];  
16.         }  
17.     }];  
18.    

    如何取得第一帧

    AVFoundationframework 

     CoreMediaframework
    
    
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    1. + (UIImage*) thumbnailImageForVideo:(NSURL *)videoURL atTime:(NSTimeInterval)time {  
    2.     AVURLAsset *asset = [[[AVURLAsset alloc] initWithURL:videoURL options:nil] autorelease];  
    3.     NSParameterAssert(asset);  
    4.     AVAssetImageGenerator *assetImageGenerator = [[[AVAssetImageGenerator alloc] initWithAsset:asset] autorelease];  
    5.     assetImageGenerator.appliesPreferredTrackTransform = YES;  
    6.     assetImageGenerator.apertureMode = AVAssetImageGeneratorApertureModeEncodedPixels;  
    7.   
    8.     CGImageRef thumbnailImageRef = NULL;  
    9.     CFTimeInterval thumbnailImageTime = time;  
    10.     NSError *thumbnailImageGenerationError = nil;  
    11.     thumbnailImageRef = [assetImageGenerator copyCGImageAtTime:CMTimeMake(thumbnailImageTime, 60) actualTime:NULL error:&thumbnailImageGenerationError];  
    12.   
    13.     if (!thumbnailImageRef)  
    14.         NSLog(@"thumbnailImageGenerationError %@", thumbnailImageGenerationError);  
    15.   
    16.     UIImage *thumbnailImage = thumbnailImageRef ? [[[UIImage alloc] initWithCGImage:thumbnailImageRef] autorelease] : nil;  
    17.   
    18.     return thumbnailImage;  
    
    本文转载，原文：http://blog.csdn.net/linzhiji/article/details/6751661