这里就不谈理论了，这一块的理论是比较复杂的，看多了看的自己迷糊，这里就说说每个步骤。
步骤1：
创建AVCaptureSession，AVCaptureSession是AVFoundation的核心类,用于捕捉视频和音频,协调视频和音频的输入和输出流.
代码：
- (AVCaptureSession *)session {
if (!_session) {
_session = [[AVCaptureSession alloc] init];
_session.sessionPreset = AVCaptureSessionPresetHigh;//设置分辨率
}
return _session;
}
步骤2：
创建AVCaptureDevice，AVCaptureDevice主要用来获取iphone一些关于相机设备的属性。
如：
1. 前置和后置摄像头
enum {
AVCaptureDevicePositionBack = 1,
AVCaptureDevicePositionFront = 2
};
typedef NSInteger AVCaptureDevicePosition;
2. 闪光灯开关
enum {
AVCaptureFlashModeOff = 0,
AVCaptureFlashModeOn = 1,
AVCaptureFlashModeAuto = 2
};
typedef NSInteger AVCaptureFlashMode;
3. 手电筒开关
enum {
AVCaptureTorchModelOff = 0,
AVCaptureTorchModelOn = 1,
AVCaptureTorchModeAuto = 2
};
typedef NSInteger AVCaptureTorchMode;
4. 焦距调整
enum {
AVCaptureFocusModelLocked = 0,
AVCaptureFocusModeAutoFocus = 1,
AVCaptureFocusModeContinousAutoFocus = 2
};
typedef NSInteger AVCaptureFocusMode;
5. 曝光量调节
enum {
AVCaptureExposureModeLocked = 0,
AVCaptureExposureModeAutoExpose = 1,
AVCaptureExposureModeContinuousAutoExposure = 2
};
typedef NSInteger AVCaptureExposureMode;
6. 白平衡
enum {
AVCaptureWhiteBalanceModeLocked = 0,
AVCaptureWhiteBalanceModeAutoWhiteBalance = 1,
AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance = 2
};
typedef NSInteger AVCaptureWhiteBalanceMode;
用AVCaptureDevice获取摄像头代码：
AVCaptureDevice *device;
NSArray *devideArray = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *devides in devideArray) {
if ([devides position] == AVCaptureDevicePositionBack) {
device = devides;
}
}
步骤3：
创建AVCaptureDeviceInput，AVCaptureDeviceInput是输入流，用来捕获AVCaptureDevice捕获的数据。
代码：
//创建一个设备的输入设备,并将它添加到session上
AVCaptureDeviceInput *input = [[AVCaptureDeviceInput alloc] initWithDevice:device error:&error];
if ([self.session canAddInput:input]) {
[self.session addInput:input];
}
步骤4
创建AVCaptureVideoDataOutput，一个数据输出流对象，设置获取数据代理和输出数据样式都是在此步骤。
代码：
_videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];//创建一个视频数据输出流
[_videoDataOutput setSampleBufferDelegate:self queue:self.queue];
// Specify the pixel format
_videoDataOutput.videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:kCVPixelFormatType_32BGRA], kCVPixelBufferPixelFormatTypeKey,
[NSNumber numberWithInt: kScreenWidth], (id)kCVPixelBufferWidthKey,
[NSNumber numberWithInt: kScreenHeight], (id)kCVPixelBufferHeightKey,
nil];
if ([self.session canAddOutput:_videoDataOutput]) {
[self.session addOutput:_videoDataOutput];
}
//实现代理方法
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
fromConnection:(AVCaptureConnection *)connection {
}
步骤5：
创建显示画面图层AVCaptureVideoPreviewLayer
代码：
_preLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
//preLayer = [AVCaptureVideoPreviewLayer layerWithSession:session];
_preLayer.frame = [UIScreen mainScreen].bounds;
_preLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[_streamView.layer addSublayer:_preLayer];
步骤6：
开始录制
代码：
[self.session startRunning];
到此结束了，这里都是基本的步骤，其它细节以后在写出来。
