承接上一篇博文小编讲述在镜头采集过程所需知识点和 AVCaptureSession 基本使用方法，本篇博文将要讲述 AVCaptureDevice 相关使用方法。
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）。
参考资料：
AVCaptureDevice
AVCaptureDevicePosition
AVCaptureTorchMode
AVCaptureFlashMode
AVCaptureFocusMode
AVCaptureExposureMode
AVCaptureWhiteBalanceMode
Advanced Camera Controls for iOS: Setting Manual White Balance
第一次发布：2017/8/15 23:16:32 星期二
第二次发布：2017/8/16 00:17:59 星期三
第三次发布：2017/8/16 20:53:56 星期三
