如何仅通过‘ReplayKit’iOS SWIFT获取视频流

我使用‘ReplayKit’获取视频流。回调是持续调用，但rpSampleType返回其他内容。我只想要视频缓冲区。

这是我的代码

RPScreenRecorder.shared().startCapture(handler: { (cmSampleBuffer, rpSampleType, error) in
    if CMSampleBufferDataIsReady(cmSampleBuffer){

    switch rpSampleType {

    case RPSampleBufferType.video:

        // create the CVPixelBuffer
        let pixelBuffer = CMSampleBufferGetImageBuffer(cmSampleBuffer)!
        let rtcpixelBuffer = RTCCVPixelBuffer(pixelBuffer: pixelBuffer)


    default:

        print("sample has no matching type")
    }

}


}) { (error) in
    print(error?.localizedDescription)
}