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AVDevice is ignoring 60fps
Hello, I try to get the Video from an HDMI USB capture card and show it in a PreviewLayer with 60fps. The device I am using (ShadowCast 2) is supporting 1080p with 60fps in "yuvs" and "420v". This is my code with stripped away uninteresting stuff and removed error handling to build the previewLayer. I am using the AVFrameRateRange because the capture device is not directly supporting 60.00 but <AVFrameRateRange: 0x600000875680 60.00 - 60.00 (1000000 / 60000240 - 1000000 / 60000240)> fps. @Observable final class AVFoundationService: AVService { // Live View private let session: AVCaptureSession = .init() var previewLayer: AVCaptureVideoPreviewLayer { let layer = AVCaptureVideoPreviewLayer(session: session) layer.videoGravity = .resizeAspect return layer } var activeVideoDevice: AVCaptureDevice? { // TODO: implement correct logic if let device = videoDevices.first(where: { $0.localizedName.contains("Shadow") }) { return device } return AVCaptureDevice.default(for: .video) } func setupStreamDemo(completion: @escaping (Error?) -> Void) { session.beginConfiguration() if let device = activeVideoDevice { do { let input = try AVCaptureDeviceInput(device: device) if session.canAddInput(input) { session.addInput(input) } else { print("explode") } for format in device.formats { let dimensions = CMVideoFormatDescriptionGetDimensions(format.formatDescription) if dimensions.width == 1920 && dimensions.height == 1080 && format.formatDescription.mediaSubType.description == "'yuvs'" { let foundFPS = format.videoSupportedFrameRateRanges.first { Int($0.minFrameRate) == 60 && Int($0.minFrameRate) == 60 } try device.lockForConfiguration() device.activeFormat = format device.activeVideoMinFrameDuration = foundFPS!.minFrameDuration device.activeVideoMaxFrameDuration = foundFPS!.minFrameDuration device.unlockForConfiguration() } } } catch { return completion(error) } } session.commitConfiguration() session.startRunning() completion(nil) } } I am using the following code in SwiftUI to show the AVCaptureVideoPreviewLayer. struct VideoPreviewView: NSViewRepresentable { private let previewLayer: AVCaptureVideoPreviewLayer func makeNSView(context: Context) -> NSView { let view = NSView() view.layer = self.previewLayer view.layer?.frame = view.bounds return view } func updateNSView(_ nsView: NSView, context: Context) { if let layer = nsView.layer as? AVCaptureVideoPreviewLayer { layer.session = self.previewLayer.session } } } When I now run my app, it will ignore whatever I set on device.activeVideoMinFrameDuration and/or device.activeVideoMaxFrameDuration. If I set it to 10 fps - it's running with 30, if I set 60 it is running with 30. If I start in parallel to my app QuickTime and start a "Recording" from my USB Capture Card, it will switch to 60fps mode. I am on Mac Sequoia 15.0 with Xcode 16.0. What I am doing wrong?
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Oct ’24