我正在尝试从视频中获取图像，然后使用该图像生成静态电影 第一步运行良好，但第二步在我设置 applyPreferredTrackTransform=true 后生成格式错误的视频

从视频中提取的正常图像 从图像生成的格式错误的视频

这是怎么来的？正常图像生成畸形视频？ 此外，如果我将 GenerateMovieFromImage.generateMovieWithImage block 放在#2 该应用程序将在 CGContextDrawImage(context, CGRectMake(0, 0, frameSize.width, frameSize.height), image);

我做了如下( swift ):

    var asset: AVAsset  = AVAsset.assetWithURL(self.tmpMovieURL!) as AVAsset
    var imageGen: AVAssetImageGenerator =  AVAssetImageGenerator(asset: asset)
    var time: CMTime = CMTimeMake(0, 60)
    imageGen.appliesPreferredTrackTransform = true
    imageGen.generateCGImagesAsynchronouslyForTimes( [ NSValue(CMTime:time) ], completionHandler: {

        (requestTime, image, actualTime, result, error) -> Void in
            if result == AVAssetImageGeneratorResult.Succeeded {



                ALAssetsLibrary().writeImageToSavedPhotosAlbum(image, metadata: nil, completionBlock: {
                    (nsurl, error) in
                       // #2                    
                })

                 GenerateMovieFromImage.generateMovieWithImage(image, completionBlock:{
                        (genMovieURL) in
                        handler(genMovieURL)

                })

GenerateMovieFromImage.generateMovieWithImage 来自 This answer

+ (void)generateMovieWithImage:(CGImageRef)image completionBlock:(GenerateMovieWithImageCompletionBlock)handler
{

NSLog(@"%@", image);

NSString *path = [NSTemporaryDirectory() stringByAppendingPathComponent: [@"tmpgen" stringByAppendingPathExtension:@"mov"  ] ];

NSURL *videoUrl = [NSURL fileURLWithPath:path];

if ([[NSFileManager defaultManager] fileExistsAtPath:path] ) {
    NSError *error;
    if ([[NSFileManager defaultManager] removeItemAtPath:path error:&error] == NO) {
        NSLog(@"removeitematpath %@ error :%@", path, error);
    }
}


// TODO: image need to rotate programly, not in hand
int width = (int)CGImageGetWidth(image);
int height = (int)CGImageGetHeight(image);

NSError *error = nil;
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:videoUrl
                               fileType:AVFileTypeQuickTimeMovie
                                                          error:&error];
NSParameterAssert(videoWriter);

NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                               AVVideoCodecH264, AVVideoCodecKey,
                               [NSNumber numberWithInt:width], AVVideoWidthKey,
                               [NSNumber numberWithInt:height], AVVideoHeightKey,
                               nil];
AVAssetWriterInput* writerInput = [AVAssetWriterInput
                                    assetWriterInputWithMediaType:AVMediaTypeVideo
                                    outputSettings:videoSettings] ; //retain should be removed if ARC


NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
[videoWriter addInput:writerInput];

AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
                                                 assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
                                                 sourcePixelBufferAttributes:nil ];

//    2) Start a session:
NSLog(@"start session");

[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero]; //use kCMTimeZero if unsure


dispatch_queue_t mediaInputQueue = dispatch_queue_create("mediaInputQueue", NULL);
[writerInput requestMediaDataWhenReadyOnQueue:mediaInputQueue usingBlock:^{

     if ([writerInput isReadyForMoreMediaData]) {


         //    3) Write some samples:

         // Or you can use AVAssetWriterInputPixelBufferAdaptor.
         // That lets you feed the writer input data from a CVPixelBuffer
         // that’s quite easy to create from a CGImage.


         CVPixelBufferRef sampleBuffer = [self newPixelBufferFromCGImage:image];

         if (sampleBuffer) {
             CMTime frameTime = CMTimeMake(150,30);
            [adaptor appendPixelBuffer:sampleBuffer withPresentationTime:kCMTimeZero];
            [adaptor appendPixelBuffer:sampleBuffer withPresentationTime:frameTime];
             CFRelease(sampleBuffer);
         }
     }


    //    4) Finish the session:

    [writerInput markAsFinished];
    [videoWriter endSessionAtSourceTime:CMTimeMakeWithSeconds(5, 30.0) ] ; //optional can call finishWriting without specifiying endTime
    // [videoWriter finishWriting]; //deprecated in ios6
    NSLog(@"to finnish writing");

    [videoWriter finishWritingWithCompletionHandler:^{
        NSLog(@"%@",videoWriter);
        NSLog(@"finishWriting..");

        handler(videoUrl);

        ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
        [library writeVideoAtPathToSavedPhotosAlbum:[NSURL fileURLWithPath:path] completionBlock: ^(NSURL *assetURL, NSError *error){
            if( error != nil) {
                NSLog(@"writeVideoAtPathToSavedPhotosAlbum error: %@" , error);
            }

        }];
    }]; //ios 6.0+

}];





}


+ (CVPixelBufferRef) newPixelBufferFromCGImage: (CGImageRef)image
{
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                         [NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
                         [NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
                         nil];
CVPixelBufferRef pxbuffer = NULL;


CGSize frameSize = CGSizeMake(CGImageGetWidth(image), CGImageGetHeight(image) );

NSLog(@"width:%f", frameSize.width);
NSLog(@"height:%f", frameSize.height);



CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, frameSize.width,
                                      frameSize.height, kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef)options,
                                      &pxbuffer);
NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);

CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
NSParameterAssert(pxdata != NULL);

CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, frameSize.width,
                                             frameSize.height, 8, 4*frameSize.width, rgbColorSpace,
                                             (CGBitmapInfo)kCGImageAlphaNoneSkipFirst
                                             );

NSParameterAssert(context);



CGContextConcatCTM(context, CGAffineTransformIdentity);
CGContextDrawImage(context, CGRectMake(0, 0, frameSize.width, frameSize.height), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);

CVPixelBufferUnlockBaseAddress(pxbuffer, 0);

return pxbuffer;
}

最佳答案

试试这个:

NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, nil];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary ];

我发现你的问题:

(requestTime, image, actualTime, result, error) -> Void in
     if result == AVAssetImageGeneratorResult.Succeeded {

        let img : UIImage = UIImage(CGImage: image)! // retain 
        UIImageWriteToSavedPhotosAlbum(img,nil,nil,nil) // synchron

        GenerateMovieFromImage.generateMovieWithImage(image, completionBlock:{
                (genMovieURL) in
                        handler(genMovieURL)

         })

我检查所有作品。如果您仍然有问题，那么问题出在您的设备上。

关于ios - 在设置 applyPreferredTrackTransform 后从普通 CGImageRef 图像生成格式错误的视频，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27414437/