我希望使用QTKit.framework将摄像头输入的所有帧写入磁盘。但是,我得到的所有图像都是半透明的,而且缺少一些颜色,可能是颜色空间问题? ;( 在预览视图中它们看起来不错,但当我将它们写入时,“某些事情”发生了。 我想知道那是什么。
-(void)savePNGImage:(CGImageRef)imageRef path:(NSString *)path {
NSURL *outURL = [[NSURL alloc] initFileURLWithPath:path];
CGImageDestinationRef dr = CGImageDestinationCreateWithURL ((CFURLRef)outURL, (CFStringRef)@"public.png" , 1, NULL);
CGImageDestinationAddImage(dr, imageRef, NULL);
CGImageDestinationFinalize(dr);
[outURL release];
}
-(void)saveJPEGImage:(CGImageRef)imageRef path:(NSString *)path {
CFMutableDictionaryRef mSaveMetaAndOpts = CFDictionaryCreateMutable(nil, 0,
&kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
CFDictionarySetValue(mSaveMetaAndOpts, kCGImageDestinationLossyCompressionQuality,
[NSNumber numberWithFloat:1.0]); // set the compression quality here
NSURL *outURL = [[NSURL alloc] initFileURLWithPath:path];
CGImageDestinationRef dr = CGImageDestinationCreateWithURL ((CFURLRef)outURL, (CFStringRef)@"public.jpeg" , 1, NULL);
CGImageDestinationAddImage(dr, imageRef, mSaveMetaAndOpts);
CGImageDestinationFinalize(dr);
[outURL release];
}
- (void)captureOutput:(QTCaptureOutput *)captureOutput
didOutputVideoFrame:(CVImageBufferRef)videoFrame
withSampleBuffer:(QTSampleBuffer *)sampleBuffer
fromConnection:(QTCaptureConnection *)connection{
CVPixelBufferLockBaseAddress(videoFrame,0);
uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(videoFrame);
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(videoFrame);
size_t width = CVPixelBufferGetWidth(videoFrame);
size_t height = CVPixelBufferGetHeight(videoFrame);
CVPixelBufferUnlockBaseAddress(videoFrame,0);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef newContext = CGBitmapContextCreate(baseAddress,
width, height, 8,
bytesPerRow,
colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
CGImageRef frame = CGBitmapContextCreateImage(newContext);
CGContextRelease(newContext);
CGColorSpaceRelease(colorSpace);
[self savePNGImage:frame path:[NSString stringWithFormat:@"/Users/nacho4d/Desktop/framesCam/frame%003d.png", frameNum++]];
[self saveJPEGImage:frame path:[NSString stringWithFormat:@"/Users/nacho4d/Desktop/framesCam/frame%003d.jpeg", frameNum++]];
CGImageRelease(frame);
}
Capturer的属性只有帧大小和像素格式,例如:
[NSNumber numberWithUnsignedInt:kCVPixelFormatType_32ARGB], (id)kCVPixelBufferPixelFormatTypeKey
更新:我也尝试了使用JPEG,我得到了同样类型的图像,就像图片中缺少一些渠道,而且所有的写入帧都有一个白色的背景。(因为JPEG不允许透明度?)
原始图像和写入(JPEG)的图像如下所示:
![alt text](https://istack.dev59.com/8DX1H.webp)
![alt text](https://istack.dev59.com/loFZh.webp)
提前感谢。