Capture most recent frame from remote livestream

I'm trying to use AVPlayer to capture frames from a livestream that is remotely playing. Eventually I want to convert these frames to UIImages to be displayed. The code I have right now is not working because pixel_buffer doesn't have an actual value for some reason. When I print itemTime its value is continuously 0, which I think might be a potential cause of this issue. Would appreciate any help with getting this to work.

import RealityKit
import RealityKitContent
import AVFoundation
import AVKit

class ViewController: UIViewController {
    let player = AVPlayer(url: URL(string: {webrtc stream link})!)
    let videoOutput = AVPlayerItemVideoOutput(pixelBufferAttributes: [String(kCVPixelBufferPixelFormatTypeKey): NSNumber(value: kCVPixelFormatType_32BGRA)])

    override func viewDidLoad() {
        print("doing viewDidLoad")
        super.viewDidLoad()
        player.currentItem!.add(videoOutput)
        player.play()
        

        let displayLink = CADisplayLink(target: self, selector: #selector(displayLinkDidRefresh(link:)))
        displayLink.add(to: RunLoop.main, forMode: RunLoop.Mode.common)
    }

    @objc func displayLinkDidRefresh(link: CADisplayLink) {
        let itemTime = videoOutput.itemTime(forHostTime: CACurrentMediaTime())
        if videoOutput.hasNewPixelBuffer(forItemTime: itemTime) {
            if let pixelBuffer = videoOutput.copyPixelBuffer(forItemTime: itemTime, itemTimeForDisplay: nil) {
                print("pixelBuffer \(pixelBuffer)") // yay, pixel buffer
                let image = CIImage(cvImageBuffer: pixelBuffer) // or maybe CIImage?
                print("CIImage \(image)")
            }
        }
    }
}


struct ImmersiveView: View {
    var body: some View {
        RealityView { content in
            if let scene = try? await Entity(named:"Immersive", in: realityKitContentBundle) {
                content.add(scene)
            }
            let viewcontroller = ViewController()
            viewcontroller.viewDidLoad()
}