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CVPixelBuffer如何在每秒60帧中捕获每三帧?

apple-vision cvpixelbuffer arkit swift

1

Andy Jazz · 技术社区 · 7 年前

我只需要每秒60帧中的20帧进行处理( CVPixelBuffer

如何在ARKit会话中捕获每三个ARFrame ? 我需要大约20 fps的捕捉速度(我知道可能会有下降帧)。

func updateCoreML() {

    let pixelBuffer: CVPixelBuffer? = (sceneView.session.currentFrame?.capturedImage)

    if pixelBuffer == nil { return }
    let ciImage = CIImage(cvPixelBuffer: pixelBuffer!)
    let imageRequestHandler = VNImageRequestHandler(ciImage: ciImage, options: [:])

    do {
        try imageRequestHandler.perform(self.visionRequests)
    } catch {
        print(error)
    }
}

2 回复 | 直到 6 年前

1

Maxim Volgin 7 年前

我所知道的最简单的方法就是使用 RxARKit 申请 .throttle() session.rx.didUpdateFrame .节流阀() RxVision ,这将确保 CoreML .

import RxSwift
import RxARKit
import RxVision


let disposeBag = DisposeBag()
let mlRequest: RxVNCoreMLRequest<CVPixelBuffer> = VNCoreMLRequest.rx.request(model: model, imageCropAndScaleOption: .scaleFit)

mlRequest
    .observable
    .subscribe { [unowned self] (event) in
        switch event {
            case .next(let completion):       
                let cvPixelBuffer = completion.value
                if let result = completion.request.results?[0] as? VNClassificationObservation {
                    os_log("results: %@", type: .debug, result.identifier)
                }
            default:
                break
        }
    }
    .disposed(by: disposeBag)

session
    .rx
    .didUpdateFrame
    .throttle(1/20)
    .subscribe { event in
        switch event {
        case .next(let didUpdateFrame):
        let frame: ARFrame = didUpdateFrame.frame        
        let imageRequestHandler = VNImageRequestHandler(cvPixelBuffer: frame.capturedImage, orientation: .up, options: requestOptions)
        do {
            try imageRequestHandler.rx.perform([mlRequest], with: frame.capturedImage) } catch {
            print(error)
        }            
        break
        default:
            break
        }
    }
    .disposed(by: disposeBag)

2

0

Tahir Iqbal 7 年前

您可以设置自定义帧速率,以便只获得20帧,也可以接收所有帧,但只使用每三帧,方法是获取一个标志变量并将其递增。

  func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
       totalFrameCount += 1
       if totalFrameCount % 3 != 0{ return }
}

 lockForConfiguration()
 activeVideoMinFrameDuration = CMTimeMake(1, 20)
 activeVideoMaxFrameDuration = CMTimeMake(1, 20)
 unlockForConfiguration()