iOS镜头录制

镜头录制最简单，最基本的流程，还可以输出视频和音频buffer

//  ViewController.m
//  CoreMLVision
//
//  Created by admin on 27/12/17.
//  Copyright © 2017年 Yanyx. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()
{
    // 会话
    AVCaptureSession            *captureSession_;
    AVCaptureDevice             *captureDevice;
    AVCaptureDeviceInput *videoCaptureDeviceInput;
    AVCaptureDeviceInput *audioCaptureDeviceInput;
    
    AVCaptureVideoDataOutput *captureVideoDataOutput;
    AVCaptureAudioDataOutput *captureAudioDataOutput;
    dispatch_queue_t myQueue;
    AVCaptureConnection *videoConnection;
    AVCaptureConnection *audioConnection;
    AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;    
}
@end
@implementation ViewController

#pragma mark - AVCaptureDataOutputSampleBufferDelegate
- (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
  
}

- (void)createCamera{
    captureSession_ = [[AVCaptureSession alloc] init];
    if ([captureSession_ canSetSessionPreset:AVCaptureSessionPresetPhoto]) {
        [captureSession_ setSessionPreset:AVCaptureSessionPresetPhoto];
    }
    
    captureDevice = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInWideAngleCamera mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionBack];
    AVCaptureDevice *audioCaptureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
    
    audioCaptureDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:audioCaptureDevice error:nil];
    
    //视频输入
    videoCaptureDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:nil];
    
    if ([captureSession_ canAddInput:videoCaptureDeviceInput]) {
        [captureSession_ addInput:videoCaptureDeviceInput];
    }
    if ([captureSession_ canAddInput:audioCaptureDeviceInput]) {
        [captureSession_ addInput:audioCaptureDeviceInput];
    }
   
    captureVideoDataOutput = [[AVCaptureVideoDataOutput alloc] init];
    captureVideoDataOutput.videoSettings =  [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey];
    if ([captureSession_ canAddOutput:captureVideoDataOutput]) {
        [captureSession_ addOutput:captureVideoDataOutput];
    }
    
    myQueue = dispatch_queue_create("myQueue", NULL);
    [captureVideoDataOutput setSampleBufferDelegate:self queue:myQueue];
    captureVideoDataOutput.alwaysDiscardsLateVideoFrames = YES;
    
    //音频输出
    captureAudioDataOutput = [[AVCaptureAudioDataOutput alloc] init];
    [captureAudioDataOutput setSampleBufferDelegate:self queue:myQueue];
    if ([captureSession_ canAddOutput:captureAudioDataOutput]) {
        [captureSession_ addOutput:captureAudioDataOutput];
    }
    
    // 视频连接
    videoConnection = [captureVideoDataOutput connectionWithMediaType:AVMediaTypeVideo];
    
    videoConnection.videoOrientation = AVCaptureVideoOrientationPortrait;
    
    /// 音频连接
    
    audioConnection = [captureAudioDataOutput connectionWithMediaType:AVMediaTypeAudio];
    
    //初始化预览图层
    captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:captureSession_];
    [captureVideoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    captureVideoPreviewLayer.frame = self.view.frame;
    [self.view.layer addSublayer:captureVideoPreviewLayer];
    
}

- (void)changeCmaera{
    AVCaptureDevicePosition position = [[videoCaptureDeviceInput device] position];
    if (position == AVCaptureDevicePositionBack) {
        captureDevice = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInWideAngleCamera mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionFront];
    } else {
        captureDevice = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInWideAngleCamera mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionBack];
    }
    AVCaptureDeviceInput *newInput = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:nil];
    if (newInput) {
        [captureSession_ beginConfiguration];
        [captureSession_ removeInput:videoCaptureDeviceInput];
        if ([captureSession_ canAddInput:newInput]) {
            [captureSession_ addInput:newInput];
            videoCaptureDeviceInput = newInput;
            
        } else {
            [captureSession_ addInput:videoCaptureDeviceInput];
        }
        [captureSession_ commitConfiguration];
    }
    
}

#pragma mark - samplebuffer 转 cgimage
// 通过抽样缓存数据创建一个UIImage对象
- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer
{
    // 为媒体数据设置一个CMSampleBuffer的Core Video图像缓存对象
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    
    // 锁定pixel buffer的基地址
    CVPixelBufferLockBaseAddress(imageBuffer, 0);
    
    // 得到pixel buffer的基地址
    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
    
    // 得到pixel buffer的行字节数
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    
    // 得到pixel buffer的宽和高
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);
    if (width == 0 || height == 0) {
        return nil;
    }
    
    // 创建一个依赖于设备的RGB颜色空间
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    
    // 用抽样缓存的数据创建一个位图格式的图形上下文（graphics context）对象
    CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8,
                                                 bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    CGAffineTransform transform = CGAffineTransformIdentity;
    CGContextConcatCTM(context, transform);
    
    // 根据这个位图context中的像素数据创建一个Quartz image对象
    CGImageRef quartzImage = CGBitmapContextCreateImage(context);
    
    // 裁剪 图片
    struct CGImage *cgImage = CGImageCreateWithImageInRect(quartzImage, CGRectMake(0, 0, height, height));
    
    // 解锁pixel buffer
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
    
    // 释放context和颜色空间
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);
    
    // 用Quartz image创建一个UIImage对象image
    UIImage *image = [UIImage imageWithCGImage:cgImage];
    
    // 释放Quartz image对象
    CGImageRelease(cgImage);
    CGImageRelease(quartzImage);
    return (image);
    
}

- (void)dealloc{
    [captureSession_ stopRunning];
}

- (void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    [captureSession_ startRunning];
}

@end