我正在尝试将CIFilter应用到实时相机输入（并且能够捕获过滤后的静止图像）。
我在StackOverflow上看到了一些与此问题有关的代码，但我还没有能够让它发挥作用。
我的问题是，在方法captureOutput中，过滤器似乎已正确应用（我在那里放了一个断点并快速查找它），但我在UIView中看不到它（我看到原始的Feed ，没有过滤器。）
另外我不确定我应该在会话中添加哪个输出：
[self.session addOutput: self.stillOutput]; //AVCaptureStillImageOutput
[self.session addOutput: self.videoDataOut]; //AVCaptureVideoDataOutput
在寻找连接时我应该迭代哪些（findVideoConnection）。
我完全糊涂了。
这里有一些代码：
viewDidLoad中
-(void)viewDidLoad {
[super viewDidLoad];
self.shutterButton.userInteractionEnabled = YES;
self.context = [CIContext contextWithOptions: @{kCIContextUseSoftwareRenderer : @(YES)}];
self.filter = [CIFilter filterWithName:@"CIGaussianBlur"];
[self.filter setValue:@15 forKey:kCIInputRadiusKey];
}
准备会议
-(void)prepareSessionWithDevicePosition: (AVCaptureDevicePosition)position {
AVCaptureDevice* device = [self videoDeviceWithPosition: position];
self.currentPosition = position;
self.session = [[AVCaptureSession alloc] init];
self.session.sessionPreset = AVCaptureSessionPresetPhoto;
NSError* error = nil;
self.deviceInput = [AVCaptureDeviceInput deviceInputWithDevice: device error: &error];
if ([self.session canAddInput: self.deviceInput]) {
[self.session addInput: self.deviceInput];
}
AVCaptureVideoPreviewLayer* previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession: self.session];
previewLayer.videoGravity = AVLayerVideoGravityResizeAspect;
self.videoDataOut = [AVCaptureVideoDataOutput new];
[self.videoDataOut setSampleBufferDelegate: self queue:dispatch_queue_create("bufferQueue", DISPATCH_QUEUE_SERIAL)];
self.videoDataOut.alwaysDiscardsLateVideoFrames = YES;
CALayer* rootLayer = [[self view] layer];
rootLayer.masksToBounds = YES;
CGRect frame = self.previewView.frame;
previewLayer.frame = frame;
[rootLayer insertSublayer: previewLayer atIndex: 1];
self.stillOutput = [[AVCaptureStillImageOutput alloc] init];
NSDictionary* outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil];
self.stillOutput.outputSettings = outputSettings;
[self.session addOutput: self.stillOutput];
//tried [self.session addOutput: self.videoDataOut];
//and didn't work (filtered image didn't show, and also couldn't take pictures)
[self findVideoConnection];
}
查找视频连接
-(void)findVideoConnection {
for (AVCaptureConnection* connection in self.stillOutput.connections) {
//also tried self.videoDataOut.connections
for (AVCaptureInputPort* port in [connection inputPorts]) {
if ([[port mediaType] isEqualToString: AVMediaTypeVideo]) {
self.videoConnection = connection;
break;
}
}
if (self.videoConnection != nil) {
break;
}
}
}
捕获输出，应用过滤器并将其放入CALayer
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
// Get a CMSampleBuffer's Core Video image buffer for the media data
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
// turn buffer into an image we can manipulate
CIImage *result = [CIImage imageWithCVPixelBuffer:imageBuffer];
// filter
[self.filter setValue:result forKey: @"inputImage"];
// render image
CGImageRef blurredImage = [self.context createCGImage:self.filter.outputImage fromRect:result.extent];
UIImage* img = [UIImage imageWithCGImage: blurredImage];
//Did this to check whether the image was actually filtered.
//And surprisingly it was.
dispatch_async(dispatch_get_main_queue(), ^{
//The image present in my UIView is for some reason not blurred.
self.previewView.layer.contents = (__bridge id)blurredImage;
CGImageRelease(blurredImage);
});
}