Crash when using external camera on iPad (unsupported frame rate)

[noho501]

Question

Could you please help take a look and let me know if there might be anything incorrect in my setup? The app crashes when setting the frame rate for an external camera, even though HaishinKit already checks isFrameRateSupported.

These crashes are observed in Firebase Crashlytics and occur quite frequently. I’ve included one representative example above, but there are many similar cases with different supported FPS ranges.

Fatal Exception: NSInvalidArgumentException
*** -[AVCaptureDevice setActiveVideoMinFrameDuration:]
Unsupported frame duration - Supported ranges: ( "<AVFrameRateRange: 30 - 30>" ),
tried to set maxFrameRate to 24.000000

0  CoreFoundation   __exceptionPreprocess
1  libobjc.A.dylib  objc_exception_throw
2  AVFCapture       -[AVCaptureFigVideoDevice setActiveVideoMinFrameDuration:]
3  myliveapp          VideoDeviceUnit.setFrameRate(_:) (VideoDeviceUnit.swift:117)
4  myliveapp          CameraLiveStreamVC.setupCamera()
5  myliveapp          MediaMixer.configuration(video:)

Here is my code:

do {
    // Sets to input frameRate.
    try? await mixer.configuration(video: 0) { video in
        do {
            try video.setFrameRate(Float64(videoFrame.fps))
        } catch {
            logger.error(error)
        }
        
        guard let device = video.device else { return }
        try device.lockForConfiguration()
        device.ramp(toVideoZoomFactor: zoomFactor, withRate: 5.0)
        device.unlockForConfiguration()
    }
    
    // Sets to output frameRate.
    try await mixer.setFrameRate(Float64(videoFrame.fps))
} catch {
    DispatchQueue.main.async {
        let alertController = UIAlertController(title: "Errror", message: error.localizedDescription, preferredStyle: .alert)
        alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
        self.present(alertController, animated: true, completion: nil)
    }
    logger.error(error)
}

Background / Tried Steps

• Connected an external camera to an iPad via a Type-C capture card
• The camera might to support fixed frame rates such as 30, 50, or 59 FPS
• The app is configured to set a different frame rate (e.g., 24 or 60 FPS)
• In these cases, the app sometimes crashes when applying the frame rate

Environment

Device: iPad mini (A17 Pro)
OS: iPadOS 26.3.1
External Camera (Type-C)
Crash log: Firebase Crashlytics
Haishinkit 2.2.5

[shogo4405]

This happens because the external camera only supports 30 FPS, yet it is being configured to 24 FPS.
An NSInvalidArgumentException cannot be caught at the Swift layer and results in an application crash.

Unsupported frame duration - Supported ranges: ( "<AVFrameRateRange: 30 - 30>" ),
tried to set maxFrameRate to 24.000000

It is possible to guard against this by retrieving the supported range via video.device.activeFormat, but this should ideally be handled within HaishinKit.

https://developer.apple.com/documentation/avfoundation/avcapturedevice/activeformat

try? await mixer.configuration(video: 0) { video in
   // Check the range. 
   // video.device.activeFormat
}