下图为本博文写作思路：
AVCaptureDevice博文写作思维导图.png
AVCaptureDevice
AVCaptureDevice 在这个采集过程中相当于在发电过程中“发电设备”，提供实现摄像头和麦克风相关初始化。而且可以对摄像头进行一些基本设置，例如：闪光灯、手电筒、聚焦、曝光、白平衡等一些基本设置。
AVCaptureDevice 实现摄像头初始化
在 AVCaptureDevice 初始化前需要对镜头申请权限，具体实现如下：
switch ([AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo]) { case AVAuthorizationStatusAuthorized:
{ //获取授权成功
break;
} case AVAuthorizationStatusNotDetermined:
{ //目前用户为选择
dispatch_suspend(self.sessionQueue);//self.seaaionQueue 是串行线程
[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) { if (!granted) { self.setupResult = FYCameraCaptureSetupResultNotAuthorized;
}
dispatch_resume(self.sessionQueue);
}]; break;
} default:
{ //处理其余情况
break;
}
}请求硬件的获取状态，如下：
AVAuthorizationStatusNotDetermined = 0,//用户暂时没有做相关选着 AVAuthorizationStatusRestricted = 1,//没有改媒体类型 AVAuthorizationStatusDenied = 2,//用户拒绝 AVAuthorizationStatusAuthorized = 3,//用户允许
在获取对 AVCaptureDevice 使用允许的情况中，可以获取上面四中情况。可以依次对上面三种情况进行处理。下面列出初始方法。
1） AVCaptureDevice基本初始方法
//方法(1)AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];//方法(2)AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInDuoCamera mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionBack];
2）AVCaptureDevice 实现镜头自动变焦
NSArray<AVCaptureDeviceType> *deviceType = @[AVCaptureDeviceTypeBuiltInWideAngleCamera, AVCaptureDeviceTypeBuiltInDualCamera];AVCaptureDeviceDiscoverySession *videoDeviceDiscoverySession = [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:deviceType mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionUnspecified];//获取 devices NSArray<AVCaptureDevice *> *devices = videoDeviceDiscoverySession.devices;
在使用 AVCaptureDeviceDiscoverySession 获取 AVCaptureDevice 过程中，使用 AVCaptureDeviceType。
下面列出 AVCaptureDeviceType 种类：
//AVCaptureDeviceType 种类AVCaptureDeviceTypeBuiltInMicrophone //创建麦克风AVCaptureDeviceTypeBuiltInWideAngleCamera //创建广角相机AVCaptureDeviceTypeBuiltInTelephotoCamera //创建比广角相机更长的焦距。只有使用 AVCaptureDeviceDiscoverySession 可以使用AVCaptureDeviceTypeBuiltInDualCamera //创建变焦的相机，可以实现广角和变焦的自动切换。使用同AVCaptureDeviceTypeBuiltInTelephotoCamera 一样。AVCaptureDeviceTypeBuiltInDuoCamera //iOS 10.2 被 AVCaptureDeviceTypeBuiltInDualCamera 替换
注释：
iOS 10.2之后添加自动变焦功能, 而且在查找自动变焦镜头时需要采用AVCaptureDeviceDiscoverySession进行查找。
AVCaptureDevice实现的通知
下面列出通知的类型：
// Notification type AVCaptureDeviceWasConnectedNotification//设备被链接时发出通知AVCaptureDeviceWasDisconnectedNotification//设备被去去除时发出通知AVCaptureDeviceSubjectAreaDidChangeNotification//设备中场景改变时发出通知，既预览发生变化
AVCaptureDevice的位置
AVCaptureDevicePositionUnspecified = 0, //不确定AVCaptureDevicePositionBack = 1,//后置AVCaptureDevicePositionFront = 2,//前置// 如果初始的 AVMediaType 是 AVMediaTypeVideo 表示前置和后置摄像头
AVCaptureDeviceFlash(闪光灯)
在光线不足的情况下，需要开启屏幕的闪光灯来进行补光。便于镜头可以捕捉更好的场景，拍摄出好的照片和视频。
iOS 10_0之前闪光灯设置
AVCaptureDevice *device = nil; NSArray *inputs = self.session.inputs; for (AVCaptureDeviceInput *input in inputs) { if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
} NSError *errorProperty = nil; if ([device hasFlash]) { if ([device isFlashAvailable]) { if ([device isFlashModeSupported:AVCaptureFlashModeOn]) { BOOL result = NO;
result = [device lockForConfiguration:&errorProperty]; if (result) {
[device setFlashMode:AVCaptureFlashModeOn];
}else { NSLog(@"ERROR : CONFIGURATION CAPTURE DEVICE FLASH FAILURE, ERROR CODE:%ld", (long)errorProperty.code);
}
[device unlockForConfiguration];
}else{ NSLog(@"ERROR : FLASH IS UNAVAILABLE BECAUSE THE DEVCICE OVERHEATS");
}
}else { NSLog(@"ERROR : SOFTWARE DEVICE HAVE NO FLASH");
}
}iOS 10_0之后设置
NSArray *outputs = self.session.outputs; for (AVCaptureOutput *output in outputs) { if ([output isMemberOfClass:[AVCapturePhotoOutput class]]) { AVCapturePhotoOutput *photoOutput = (AVCapturePhotoOutput *)output; BOOL flashSupported = [[photoOutput supportedFlashModes] containsObject:@(AVCaptureFlashModeAuto)]; if (flashSupported) { AVCapturePhotoSettings *photoSettings = photoOutput.photoSettingsForSceneMonitoring;
photoSettings.flashMode = AVCaptureFlashModeAuto;
}else { NSLog(@"ERROR : PHOTOOUTPUT CAN NOT SUPPORT AVCAPTUREMODE TYPE");
}
}
}下面列出闪光灯类型：
AVCaptureFlashModeOff = 0,//闪光灯关闭 AVCaptureFlashModeOn = 1,//闪光灯开启 AVCaptureFlashModeAuto = 2,//闪光灯自动
太困了，晚上跑 10 公里。目前都睁不开。
在 iPhone 6s 开始，如果是前置摄像头并且开启闪光灯，可以实现屏幕闪光灯补光。
AVCaptureDeviceTorch(手电筒)
在光线不是很暗的情况下我们可以用手机的 LED 灯当做手电筒使用，具体实现如下：
AVCaptureDevice *device = nil; NSArray *inputs = self.session.inputs; for (AVCaptureDeviceInput *input in inputs) { if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
} NSError *error = nil; if ([device hasTorch]) { if ([device isFlashAvailable]) { if ([device isTorchModeSupported:AVCaptureTorchModeOn]) { BOOL result = NO;
result = [device lockForConfiguration:&error]; if (result) {
[device setTorchMode:AVCaptureTorchModeOn];
}else { NSLog(@"ERROR : CONFIGURATION DEVICE TORCH FAIL AND ERROR CODE %ld", (long)error.code);
}
error = nil; // Torch light
result = [device setTorchModeOnWithLevel:0.5 error:&error]; if (!result) { NSLog(@"ERROR : DEVICE SET TORCH FAILURE AND ERROR CODE %ld", error.code);
}
[device unlockForConfiguration];
}else { NSLog(@"ERROR : DEVICE CAN NO SUPPORT TORCH");
}
}else { NSLog(@"ERROR : SOFTHARE DEVICE TORCH IS UNAVAILABLE BECAUSE OVERHEATS");
}
}else { NSLog(@"ERROR : SOFFHARE DEVICE HAS NO TORCH");
}下面列出 Torch 类型，使用方法和闪关灯类型：
AVCaptureTorchModeOff = 0,//关闭 AVCaptureTorchModeOn = 1,//打开 AVCaptureTorchModeAuto = 2,//自动
AVCaptureDeviceFocus(聚焦)
实现摄像头聚焦有两种情况：
镜头位置(AVCaptureFocusMode)
范围烧苗(AVCaptureAutoFocusRangeRestriction)
1）镜头位置(AVCaptureFocusMode)
AVCaptureDevice *device = nil; NSArray *inputs = self.session.inputs; for (AVCaptureDeviceInput *input in inputs) { if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
} if ([device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) { NSError *error; if ([device lockForConfiguration:&error]) {
[device setFocusMode:AVCaptureFocusModeAutoFocus]; //设置聚焦在设备坐标的中点
if (device.focusPointOfInterestSupported) {
device.focusPointOfInterest = CGPointMake(0.5, 0.5);
}
}
[device unlockForConfiguration];
}上述代码实现聚焦在设备坐标 中心位置。
下面列出实现聚焦设置类型：
AVCaptureFocusModeLocked = 0,//锁定当前镜头位置 AVCaptureFocusModeAutoFocus = 1,//镜头自动调焦 AVCaptureFocusModeContinuousAutoFocus = 2,//镜头连续自动调焦
AVCaptureDeviceExposure(曝光)
AVCaptureDevice *device = nil; NSArray *inputs = self.session.inputs; for (AVCaptureDeviceInput *input in inputs) { if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
} if ([device isExposureModeSupported:AVCaptureExposureModeAutoExpose]) { NSError *error; if ([device lockForConfiguration:&error]) {
[device setExposureMode:AVCaptureExposureModeAutoExpose];
}
[device unlockForConfiguration];
}上述代码实现自动调节曝光。
下面列出相关曝光设置类型：
AVCaptureExposureModeLocked = 0,//锁定 AVCaptureExposureModeAutoExpose = 1,//自动对焦 AVCaptureExposureModeContinuousAutoExposure = 2,//实现连续自动对焦 AVCaptureExposureModeCustom NS_ENUM_AVAILABLE_IOS(8_0) = 3,//通过 ISO 和 曝光时间实现
AVCaptureDeviceWhiteBalance(白平衡)
类型设置(AVCaptureWhiteBalanceMode)
RGB具体值(AVCaptureWhiteBalanceGains)
1）类型设置白平衡
AVCaptureDevice *device = nil; NSArray *inputs = self.session.inputs; for (AVCaptureDeviceInput *input in inputs) { if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
} if ([device isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeAutoWhiteBalance]) { NSError *error; if ([device lockForConfiguration:&error]) {
[device setWhiteBalanceMode:AVCaptureWhiteBalanceModeAutoWhiteBalance];
}
[device unlockForConfiguration];
}上述实现白平衡自动调整设置，下面列出白平衡类型：
AVCaptureWhiteBalanceModeLocked = 0, AVCaptureWhiteBalanceModeAutoWhiteBalance = 1, AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance = 2,
2）RGB 值设置白平衡
AVCaptureDevice *device = nil; NSArray *inputs = self.session.inputs; for (AVCaptureDeviceInput *input in inputs) { if ([device.deviceType isEqual:AVMediaTypeVideo]) {
device = input.device;
}
} float maxWhiteBalance = device.maxWhiteBalanceGain; float redGain = MIN(2.0, maxWhiteBalance); float greenGain = MIN(2.0, maxWhiteBalance); float blueGain = MIN(2.0, maxWhiteBalance); AVCaptureWhiteBalanceGains whiteBalanceGains = {
redGain,
greenGain,
blueGain
};
[device setWhiteBalanceModeLockedWithDeviceWhiteBalanceGains:whiteBalanceGains completionHandler:nil];额外附加功能
附加功能：可以获取 AVCaptureDevice 一些相关的参数。
例如：
视频录制过程中
min和max的帧率和帧时间间隔。曝光
ISO的min和max值和曝光时间的min和max值等。输入的独一的
ID和输入源的设备 名字（localizedName）。
作者：JackJin
链接：https://www.jianshu.com/p/9809760654ea