iphone：尝试将图像导出为电影时，电影已损坏答案

【问题标题】：iphone: when trying to export a image as a movie, the movie is corruptediphone：尝试将图像导出为电影时，电影已损坏
【发布时间】：2012-04-16 07:20:47
【问题描述】：

我正在尝试从单个图像导出电影。类似于How do I export UIImage array as a movie?。

我尝试了许多变体，但我不断收到损坏的视频。（颜色和图像都是错误的）。有人知道吗？谢谢

代码：

- (void)writeImageAsMovie:(UIImage*)image toPath:(NSString*)path size:(CGSize)size duration:(int)duration 
{
NSFileManager *localFileManager=[[NSFileManager alloc] init];
NSError *error = nil;
[localFileManager removeItemAtPath:path error:&error];
NSLog(@"Write Started");

AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
                              [NSURL fileURLWithPath:path] fileType:AVFileTypeQuickTimeMovie
                                                          error:&error];
NSParameterAssert(videoWriter);

NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                               AVVideoCodecH264, AVVideoCodecKey,
                               [NSNumber numberWithInt:size.width], AVVideoWidthKey,
                               [NSNumber numberWithInt:size.height], AVVideoHeightKey,
                               nil];
AVAssetWriterInput* writerInput = [AVAssetWriterInput
                                    assetWriterInputWithMediaType:AVMediaTypeVideo
                                    outputSettings:videoSettings];

AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
                                                 assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
                                                 sourcePixelBufferAttributes:nil];
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
[videoWriter addInput:writerInput];

//Start a session:
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];

//Write samples:
CVPixelBufferRef buffer = [self newPixelBufferFromCGImage:image.CGImage andSize:image.size];
[adaptor appendPixelBuffer:buffer withPresentationTime:kCMTimeZero];
[adaptor appendPixelBuffer:buffer withPresentationTime:CMTimeMake(duration-1, 2)];

//Finish the session:
[writerInput markAsFinished];
[videoWriter endSessionAtSourceTime:CMTimeMake(duration, 2)];
[videoWriter finishWriting];

}

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

CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, size.width,
                                      size.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, size.width,
                                             size.height, 8, 4*size.width, rgbColorSpace, 
                                             kCGImageAlphaNoneSkipFirst);
NSParameterAssert(context);
//CGContextConcatCTM(context, frameTransform);
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image), 
                                       CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);

CVPixelBufferUnlockBaseAddress(pxbuffer, 0);

return pxbuffer;

}

【问题讨论】：

标签： ios iphone

【解决方案1】：

这里只是一个仅供参考，但是当正在编码的视频的宽度为奇数时，我在模拟器中看到了同样的错误。例如，在 16x16 图像上没有错误，但在 17x16 电影中会出现错误。它不会出现在 18x18 电影中，所以我认为它与 H264 编码的过程有关，期望输入是 4 的倍数。此外，这似乎只是模拟器中的问题。

【讨论】：