发现自己真的很懒，很久都不想写文章（主要是不知道写什么，太难的不会，太简单的又感觉没必要😔）
这篇文章的初衷是为了获取涉嫌头取到的视频buffer以和本地视频的buffer通过OpenGL混合叠加，跟上一篇是姊妹篇：AVPlayer实现播放视频和AVFoundation获取视频的buffer
还是先上效果图：
效果图.gif
1、创建session
// 1 创建session
_captureSession = [[AVCaptureSession alloc]init];
// 设置视频质量，这里根据自己需要设置；
_captureSession.sessionPreset = AVCaptureSessionPreset640x480;
2、拿到设备的摄像头
// 2 device
_device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
_device = [self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];
/**
取得摄像头的方向
@param position 摄像头方向
@return 摄像头
*/
-(AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition )position{
NSArray *cameras = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *camera in cameras) {
if ([camera position]==position) {
return camera;
}
}
return nil;
}
3、创建并添加input
// 3 input
NSError *deviceError = nil;
AVCaptureDeviceInput *input = [[AVCaptureDeviceInput alloc]initWithDevice:_device error:&deviceError];
// 4 add input
if ([_captureSession canAddInput:input]) {
[_captureSession addInput:input];
}else{
NSLog(@"创建失败了,%@",deviceError);
return;
}
4、添加Video Out
// 5 video out
dispatch_queue_t queue = dispatch_queue_create("cameraQueue", NULL);
AVCaptureVideoDataOutput *videoOut = [[AVCaptureVideoDataOutput alloc]init];
[videoOut setSampleBufferDelegate:self queue:queue];
videoOut.alwaysDiscardsLateVideoFrames = NO;
5、设置视频格式
可以根据自己的需要设置，视频设置是一个字典形式的设置
// 6 视频格式设置
// [videoOut setVideoSettings:@{(id)kCVPixelBufferPixelFormatTypeKey:@(kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange)}];
[videoOut connectionWithMediaType:AVMediaTypeVideo];
6、添加输出 并显示预览
这里将_prevLayer设置成属性是为了后续调节Frame，我是在viewDidLoad中加载的摄像头，所以View的frame可能还不准确，frame我在
// 7 添加输出
if ([_captureSession canAddOutput:videoOut]) {
[_captureSession addOutput:videoOut];
}
// self.mGLView.isFullYUVRange = YES;
AVCaptureConnection *connection = [videoOut connectionWithMediaType:AVMediaTypeVideo];
[connection setVideoOrientation:AVCaptureVideoOrientationPortraitUpsideDown];
[_captureSession startRunning];
// 8 预览的layer
_prevLayer = [AVCaptureVideoPreviewLayer layerWithSession: _captureSession];
// _prevLayer.frame = self.view.bounds;
_prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer: _prevLayer];
// 不要忘了在viewDidLayoutSubviews中给prevLayer的frame赋值
-(void)viewDidLayoutSubviews{
_prevLayer.frame = self.view.bounds;
}
实现AVCaptureVideoDataOutputSampleBufferDelegate的代理方法拿到buffer做进一步处理
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
// int width1 = (int)CVPixelBufferGetWidth(pixelBuffer);
//
// int height1 = (int)CVPixelBufferGetHeight(pixelBuffer);
//
// NSLog(@"video width: %d height: %d", width1, height1);
// 拿到某一帧可以转换为图片保存起来，跟直接照相功能相似，也可以拿到某段时间内的视频帧，保存成视频
// 或者做一些其他美颜之类的处理等待；
// NSLog(@"在这里获得video sampleBuffer，做进一步处理（编码H.264）");
// [self.mGLView displayPixelBuffer:pixelBuffer];
// [pool drain];
}
