Failing harness repro: setOutputSettings({ codec }) crashes (uncatchable) when a targetBitRate is set

[radko93]

This PR is a reproduction: it adds a failing harness test only, so the AWS Device Farm run shows the crash. A proposed fix is in the collapsible section — but note it is reasoned, not yet verified (see below).

What

On iOS, videoOutput.setOutputSettings({ codec }) called after a targetBitRate was configured aborts the whole process with an uncatchable Objective-C NSInvalidArgumentException (SIGTRAP). No JS try/catch can prevent it.

Why

HybridCameraVideoOutput.setOutputSettings (ios/.../HybridCameraVideoOutput.swift) does a read-modify-write of the fully-expanded settings dict:

var currentSettings = self.output.outputSettings(for: connection)   // expanded dict
currentSettings[AVVideoCodecKey] = try codec.toAVVideoCodecType()
self.output.setOutputSettings(currentSettings, for: connection)     // writes whole dict back

When targetBitRate is set, setBitRate(...) has already populated the connection, so outputSettings(for:) returns a dict containing AVVideoCompressionPropertiesKey plus width/height/color keys. AVCaptureMovieFileOutput.setOutputSettings:forConnection: rejects the non-codec keys with an ObjC exception that Swift can't catch → abort.

(It doesn't bite without targetBitRate because the expanded dict is then minimal enough.)

Test

Adds an it(...) to apps/simple-camera/__tests__/visioncamera.video.harness.ts: configure a targetBitRate, then call setOutputSettings({ codec: 'h264' }) and expect it to resolve. On current main the harness app crashes rather than the assertion failing cleanly — that crash is the reproduction. I haven't run the harness locally (no signed device build), so the Device Farm run is the verification.

Observed on iPhone18,1 / iOS 26.5.1, com.margelo.camera.video queue.

Proposed fix (reasoned, NOT verified — we worked around it by not calling setOutputSettings)

Don't round-trip the expanded outputSettings(for:). Write only the keys AVCaptureMovieFileOutput accepts — the codec, and the existing compression properties if present (which setBitRate already writes successfully):

var currentSettings = self.output.outputSettings(for: connection)
if let codec = settings.codec {
  if codec.isRawCodec {
    guard self.options.targetBitRate == nil else {
      throw RuntimeError.error(withMessage:
        "Cannot set bit-rate when recording in a RAW codec! (\(codec.stringValue))")
    }
  }
  currentSettings[AVVideoCodecKey] = try codec.toAVVideoCodecType()
}

// Only forward keys AVCaptureMovieFileOutput accepts; the expanded dict's
// width/height/color keys raise an uncatchable NSInvalidArgumentException.
var safeSettings: [String: Any] = [:]
if let codec = currentSettings[AVVideoCodecKey] {
  safeSettings[AVVideoCodecKey] = codec
}
if let compression = currentSettings[AVVideoCompressionPropertiesKey] {
  safeSettings[AVVideoCompressionPropertiesKey] = compression
}
self.output.setOutputSettings(safeSettings, for: connection)

This mirrors what setBitRate already does (it builds a minimal [AVVideoCodecKey, AVVideoCompressionPropertiesKey] dict and ships without crashing). I have not verified this exact patch on a device — our production workaround was simply to stop calling setOutputSettings — so treat it as a starting point for discussion. The maintainer may know the precise set of keys AVCaptureMovieFileOutput permits.

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