我一直在使用AVCaptureDevice
来实现自定义相机,这需要使用自动对焦功能。接触工作很好。我使用以下代码进行相机初始化
- (void) initializeCamera {
AVAuthorizationStatus status = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
if(status == AVAuthorizationStatusAuthorized) { // authorized
[self.captureVideoPreviewLayer removeFromSuperlayer];
self.captureSession = [[AVCaptureSession alloc] init];
self.captureSession.sessionPreset = AVCaptureSessionPresetPhoto;
[self removeDeviceObserverForFocus];
self.captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
[self addDeviceObserverForFocus];
NSError *error = nil;
[self.captureDevice lockForConfiguration:nil]; //you must lock before setting torch mode
[self.captureDevice setSubjectAreaChangeMonitoringEnabled:YES];
[self.captureDevice unlockForConfiguration];
//Capture layer
self.captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
self.captureVideoPreviewLayer.bounds = CGRectMake(0, 0, CGRectGetWidth([UIScreen mainScreen].bounds), CGRectGetHeight([UIScreen mainScreen].bounds));
self.captureVideoPreviewLayer.position = CGPointMake(CGRectGetMidX(self.captureVideoPreviewLayer.bounds), CGRectGetMidY(self.captureVideoPreviewLayer.bounds));
[self.captureVideoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
self.captureVideoPreviewLayer.connection.enabled = YES;
[self.viewCamera.layer insertSublayer:self.captureVideoPreviewLayer atIndex:0];
//Capture input
self.captureInput = [AVCaptureDeviceInput deviceInputWithDevice:self.captureDevice error:&error];
if (!self.captureInput) {
[self capturePhoto];
}
else {
if ([self.captureSession canAddInput:self.captureInput]) {
[self.captureSession addInput:self.captureInput];
}
}
self.captureOutput = [[AVCaptureStillImageOutput alloc] init];
[self.captureOutput setOutputSettings:@{AVVideoCodecKey : AVVideoCodecJPEG}];
[self.captureSession addOutput:self.captureOutput];
//THIS LINE
[self.captureSession setSessionPreset:AVCaptureSessionPresetPhoto];
// setup metadata capture
AVCaptureMetadataOutput *metadataOutput = [[AVCaptureMetadataOutput alloc] init];
CGRect visibleMetadataOutputRect = [self.captureVideoPreviewLayer metadataOutputRectOfInterestForRect:self.vwCamera.bounds];
metadataOutput.rectOfInterest = visibleMetadataOutputRect;
[self.captureSession addOutput:metadataOutput];
dispatch_async(dispatch_get_main_queue(), ^{
[self.captureSession startRunning];
});
}
else if(status == AVAuthorizationStatusNotDetermined){ // not determined
//Try for getting permission
[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
[self performSelectorOnMainThread:@selector(initializeCamera) withObject:nil waitUntilDone:NO];
}];
}
}
- (void)removeDeviceObserverForFocus {
@try {
while ([self.captureDevice observationInfo] != nil) {
[self.captureDevice removeObserver:self forKeyPath:@"adjustingFocus"];
}
}
@catch (NSException *exception) {
NSLog(@"Exception");
}
@finally {
}
}
- (void)addDeviceObserverForFocus {
[self.captureDevice addObserver:self forKeyPath:@"adjustingFocus" options:NSKeyValueObservingOptionNew context:nil];
}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if( [keyPath isEqualToString:@"adjustingFocus"] ){
BOOL adjustingFocus = [ [change objectForKey:NSKeyValueChangeNewKey] isEqualToNumber:[NSNumber numberWithInt:1] ];
if (adjustingFocus) {
[self showFocusSquareAtPoint:self.viewCamera.center];
}
}
}
要通过相机移动来监控焦点,我正在执行以下操作..
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(avCaptureDeviceSubjectAreaDidChangeNotification:) name:AVCaptureDeviceSubjectAreaDidChangeNotification object:nil];
#pragma mark - AVCaptureDeviceSubjectAreaDidChangeNotification
-(void)avCaptureDeviceSubjectAreaDidChangeNotification:(NSNotification *)notification{
CGPoint devicePoint = CGPointMake( 0.5, 0.5 );
[self focusWithMode:AVCaptureFocusModeContinuousAutoFocus exposeWithMode:AVCaptureExposureModeContinuousAutoExposure atDevicePoint:devicePoint monitorSubjectAreaChange:NO];
[self showFocusSquareAtPoint:self.vwCamera.center];
}
- (void)focusWithMode:(AVCaptureFocusMode)focusMode exposeWithMode:(AVCaptureExposureMode)exposureMode atDevicePoint:(CGPoint)point monitorSubjectAreaChange:(BOOL)monitorSubjectAreaChange
{
dispatch_async( dispatch_get_main_queue(), ^{
AVCaptureDevice *device = self.captureDevice;
NSError *error = nil;
if ( [device lockForConfiguration:&error] ) {
// Setting (focus/exposure)PointOfInterest alone does not initiate a (focus/exposure) operation.
// Call -set(Focus/Exposure)Mode: to apply the new point of interest.
if ( device.isFocusPointOfInterestSupported && [device isFocusModeSupported:focusMode] ) {
device.focusPointOfInterest = point;
device.focusMode = focusMode;
}
if ( device.isExposurePointOfInterestSupported && [device isExposureModeSupported:exposureMode] ) {
device.exposurePointOfInterest = point;
device.exposureMode = exposureMode;
}
device.subjectAreaChangeMonitoringEnabled = monitorSubjectAreaChange;
[device unlockForConfiguration];
}
else {
NSLog( @"Could not lock device for configuration: %@", error );
}
} );
}
当我使用 [self.captureSession setSessionPreset:AVCaptureSessionPresetPhoto];
如果我将相机预设更改为其他内容,例如AVCaptureSessionPresetHigh
自动对焦和曝光不能正常工作..
遇到过这种情况的人?
感谢您的帮助。
答案 0 :(得分:1)
您是想拍照还是录制视频?导致高预设用于视频,曝光和对焦的工作方式不同(我相信)。以下是有关文档中不同预设的信息 - AVCaptureSessionPresets