15

我正在制作一个应用程序，我想从前置摄像头捕获图像，而不显示任何类型的捕获屏幕。我想在没有任何用户交互的情况下完全用代码拍照。我将如何为前置摄像头执行此操作？

4

5 回答 5

41

如何使用 AVFoundation 前置摄像头捕捉图像：

开发注意事项：

  • 仔细检查您的应用程序和图像方向设置
  • AVFoundation 及其相关框架是令人讨厌的庞然大物，很难理解/实现。我已经使我的代码尽可能精简，但请查看这个优秀的教程以获得更好的解释（网站不再可用，通过 archive.org 链接）： http ://www.benjaminloulier.com/posts/ios4-和直接访问相机

视图控制器.h

// Frameworks
#import <CoreVideo/CoreVideo.h>
#import <CoreMedia/CoreMedia.h>
#import <AVFoundation/AVFoundation.h>
#import <UIKit/UIKit.h>

@interface CameraViewController : UIViewController <AVCaptureVideoDataOutputSampleBufferDelegate>

// Camera
@property (weak, nonatomic) IBOutlet UIImageView* cameraImageView;
@property (strong, nonatomic) AVCaptureDevice* device;
@property (strong, nonatomic) AVCaptureSession* captureSession;
@property (strong, nonatomic) AVCaptureVideoPreviewLayer* previewLayer;
@property (strong, nonatomic) UIImage* cameraImage;

@end

视图控制器.m

#import "CameraViewController.h"

@implementation CameraViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self setupCamera];
    [self setupTimer];
}

- (void)setupCamera
{    
    NSArray* devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for(AVCaptureDevice *device in devices)
    {
        if([device position] == AVCaptureDevicePositionFront)
            self.device = device;
    }

    AVCaptureDeviceInput* input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];
    AVCaptureVideoDataOutput* output = [[AVCaptureVideoDataOutput alloc] init];
    output.alwaysDiscardsLateVideoFrames = YES;

    dispatch_queue_t queue;
    queue = dispatch_queue_create("cameraQueue", NULL);
    [output setSampleBufferDelegate:self queue:queue];

    NSString* key = (NSString *) kCVPixelBufferPixelFormatTypeKey;
    NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
    NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
    [output setVideoSettings:videoSettings];

    self.captureSession = [[AVCaptureSession alloc] init];
    [self.captureSession addInput:input];
    [self.captureSession addOutput:output];
    [self.captureSession setSessionPreset:AVCaptureSessionPresetPhoto];

    self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
    self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

    // CHECK FOR YOUR APP
    self.previewLayer.frame = CGRectMake(0, 0, self.view.frame.size.height, self.view.frame.size.width);
    self.previewLayer.orientation = AVCaptureVideoOrientationLandscapeRight;
    // CHECK FOR YOUR APP

    [self.view.layer insertSublayer:self.previewLayer atIndex:0];   // Comment-out to hide preview layer

    [self.captureSession startRunning];
}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CVPixelBufferLockBaseAddress(imageBuffer,0);
    uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    CGImageRef newImage = CGBitmapContextCreateImage(newContext);

    CGContextRelease(newContext);
    CGColorSpaceRelease(colorSpace);

    self.cameraImage = [UIImage imageWithCGImage:newImage scale:1.0f orientation:UIImageOrientationDownMirrored];

    CGImageRelease(newImage);

    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
}

- (void)setupTimer
{
    NSTimer* cameraTimer = [NSTimer scheduledTimerWithTimeInterval:2.0f target:self selector:@selector(snapshot) userInfo:nil repeats:YES];
}

- (void)snapshot
{
    NSLog(@"SNAPSHOT");
    self.cameraImageView.image = self.cameraImage;  // Comment-out to hide snapshot
}

@end

将它连接到带有 UIImageView 的 UIViewController 用于快照，它会起作用！快照以 2.0 秒的间隔以编程方式拍摄，无需任何用户输入。注释掉选定的行以删除预览层和快照反馈。

如有更多问题/意见，请告诉我！

于 2012-12-28T00:27:49.257 回答
5

将上述代码转换为 Swift 4

import UIKit
import AVFoundation

class CameraViewController: UIViewController, AVCaptureVideoDataOutputSampleBufferDelegate {

@IBOutlet weak var cameraImageView: UIImageView!

var device: AVCaptureDevice?
var captureSession: AVCaptureSession?
var previewLayer: AVCaptureVideoPreviewLayer?
var cameraImage: UIImage?

override func viewDidLoad() {
    super.viewDidLoad()

    setupCamera()
    setupTimer()
}

func setupCamera() {
    let discoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera],
                                                            mediaType: AVMediaType.video,
                                                           position: .front)
    device = discoverySession.devices[0]

    let input: AVCaptureDeviceInput
    do {
        input = try AVCaptureDeviceInput(device: device!)
    } catch {
        return
    }

    let output = AVCaptureVideoDataOutput()
    output.alwaysDiscardsLateVideoFrames = true

    let queue = DispatchQueue(label: "cameraQueue")
    output.setSampleBufferDelegate(self, queue: queue)
    output.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable as! String: kCVPixelFormatType_32BGRA]

    captureSession = AVCaptureSession()
    captureSession?.addInput(input)
    captureSession?.addOutput(output)
    captureSession?.sessionPreset = AVCaptureSession.Preset.photo

    previewLayer = AVCaptureVideoPreviewLayer(session: captureSession!)
    previewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
    previewLayer?.frame = CGRect(x: 0.0, y: 0.0, width: view.frame.width, height: view.frame.height)

    view.layer.insertSublayer(previewLayer!, at: 0)

        captureSession?.startRunning()
    }

    func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
        let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
    CVPixelBufferLockBaseAddress(imageBuffer!, CVPixelBufferLockFlags(rawValue: 0))
        let baseAddress = UnsafeMutableRawPointer(CVPixelBufferGetBaseAddress(imageBuffer!))
        let bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer!)
        let width = CVPixelBufferGetWidth(imageBuffer!)
        let height = CVPixelBufferGetHeight(imageBuffer!)

        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let newContext = CGContext(data: baseAddress, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo:
        CGBitmapInfo.byteOrder32Little.rawValue | CGImageAlphaInfo.premultipliedFirst.rawValue)

        let newImage = newContext!.makeImage()
         cameraImage = UIImage(cgImage: newImage!)

        CVPixelBufferUnlockBaseAddress(imageBuffer!, CVPixelBufferLockFlags(rawValue: 0))
    }

    func setupTimer() {
        _ = Timer.scheduledTimer(timeInterval: 2.0, target: self, selector: #selector(snapshot), userInfo: nil, repeats: true)
    }

    @objc func snapshot() {
        print("SNAPSHOT")
        cameraImageView.image = cameraImage
    }
}
于 2017-12-09T19:52:39.690 回答
3

您可能需要用于AVFoundation捕获视频流/图像而不显示它。与 不同UIImagePickerController，它不能“开箱即用”。以 AppleAVCam为例来帮助您入门。

于 2012-06-02T12:03:53.140 回答
2

如果有人在 2017 年仍在寻找解决方案，我将上面的代码从 Objc 转换为 Swift 3。

import UIKit
import AVFoundation

class CameraViewController: UIViewController, AVCaptureVideoDataOutputSampleBufferDelegate {

@IBOutlet weak var cameraImageView: UIImageView!

var device: AVCaptureDevice?
var captureSession: AVCaptureSession?
var previewLayer: AVCaptureVideoPreviewLayer?
var cameraImage: UIImage?

override func viewDidLoad() {
    super.viewDidLoad()

    setupCamera()
    setupTimer()
}

func setupCamera() {
    let discoverySession = AVCaptureDeviceDiscoverySession(deviceTypes: [.builtInWideAngleCamera],
                                                           mediaType: AVMediaTypeVideo,
                                                           position: .front)
    device = discoverySession?.devices[0]

    let input: AVCaptureDeviceInput
    do {
        input = try AVCaptureDeviceInput(device: device)
    } catch {
        return
    }

    let output = AVCaptureVideoDataOutput()
    output.alwaysDiscardsLateVideoFrames = true

    let queue = DispatchQueue(label: "cameraQueue")
    output.setSampleBufferDelegate(self, queue: queue)
    output.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable: kCVPixelFormatType_32BGRA]

    captureSession = AVCaptureSession()
    captureSession?.addInput(input)
    captureSession?.addOutput(output)
    captureSession?.sessionPreset = AVCaptureSessionPresetPhoto

    previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    previewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill

    previewLayer?.frame = CGRect(x: 0.0, y: 0.0, width: view.frame.width, height: view.frame.height)

    view.layer.insertSublayer(previewLayer!, at: 0)

    captureSession?.startRunning()
}

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
    let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
    CVPixelBufferLockBaseAddress(imageBuffer!, CVPixelBufferLockFlags(rawValue: .allZeros))
    let baseAddress = UnsafeMutableRawPointer(CVPixelBufferGetBaseAddress(imageBuffer!))
    let bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer!)
    let width = CVPixelBufferGetWidth(imageBuffer!)
    let height = CVPixelBufferGetHeight(imageBuffer!)

    let colorSpace = CGColorSpaceCreateDeviceRGB()
    let newContext = CGContext(data: baseAddress, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo:
        CGBitmapInfo.byteOrder32Little.rawValue | CGImageAlphaInfo.premultipliedFirst.rawValue)

    let newImage = newContext!.makeImage()
    cameraImage = UIImage(cgImage: newImage!)

    CVPixelBufferUnlockBaseAddress(imageBuffer!, CVPixelBufferLockFlags(rawValue: .allZeros))
}

func setupTimer() {
    _ = Timer.scheduledTimer(timeInterval: 2.0, target: self, selector: #selector(snapshot), userInfo: nil, repeats: true)
}

func snapshot() {
    print("SNAPSHOT")
    cameraImageView.image = cameraImage
}
}

另外，我找到了一个从 CMSampleBuffer 获取图像的更短的解决方案：

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
    let myPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
    let myCIimage = CIImage(cvPixelBuffer: myPixelBuffer!)
    let videoImage = UIImage(ciImage: myCIimage)
    cameraImage = videoImage
}
于 2017-08-11T11:11:05.927 回答
0

UIImagePickerController 类的文档中有一个名为 takePicture 的方法。它说：

将此方法与自定义叠加视图结合使用，以启动静止图像的编程捕获。这支持在不离开界面的情况下拍摄多张照片，但需要您隐藏默认的图像选择器控件。

于 2014-10-08T17:11:20.400 回答