ios - 在 iOS 中使用 AVFoundation Framework 来自相机的视频帧？

Question

我从未使用过 AVFoundation Framework，我想从后置摄像头获取视频帧并处理这些帧。任何人帮助我，您的经验将不胜感激。谢谢

Answer 1

您可以使用以下代码启动与 AVFoundation 的相机 session 以捕获静态图像:

AVCaptureSession *session;
AVCaptureStillImageOutput *stillImageOutput;

session = [[AVCaptureSession alloc] init];
[session setSessionPreset:AVCaptureSessionPresetPhoto];

AVCaptureDevice *inputDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSError *error;
AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:&error];

if ([session canAddInput:deviceInput]) {
    [session addInput:deviceInput];
}

AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
[previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
CALayer *rootLayer = [[self view] layer];
[rootLayer setMasksToBounds:YES];
CGRect frame = self.frameForCapture.frame;
[previewLayer setFrame:frame];
[rootLayer insertSublayer:previewLayer atIndex:0];

stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG, AVVideoCodecKey, nil];
[stillImageOutput setOutputSettings:outputSettings];
[session addOutput:stillImageOutput];

[session startRunning];

然后，为了实际捕获图像，您可以使用带有以下代码的按钮:

- (IBAction)takePhoto:(id)sender {
    AVCaptureConnection *videoConnection = nil;
    for (AVCaptureConnection *connection in stillImageOutput.connections) {
        for (AVCaptureInputPort *port in [connection inputPorts]) {
            if ([[port mediaType] isEqual:AVMediaTypeVideo]) {
                videoConnection = connection;
                break;
            }
        }
        if (videoConnection) {
            break;
        }
    }
    [stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection
                                                  completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
                                                      if (imageDataSampleBuffer != NULL) {
                                                          NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
                                                          UIImage *image = [UIImage imageWithData:imageData];
                                                      }
                                                  }];
}

然后，您可以对保存的图像做任何您想做的事情。