Liveness with your own camera - deepidv

If you must keep your own camera screen, you can still run deepidv’s movement liveness check. You capture frames as the user moves closer; deepidv scores them.

The light challenge (flashing colors) needs the SDK’s own screen. If the workflow step is set to it, checkMovementLiveness throws .validation. Use CustomFaceLivenessView instead.

1. Time the capture with `faceProbe`

faceProbe reads one camera frame on the device (no network) and tells you where the face is.

let probe = client.faceProbe(pixelBuffer)   // CVPixelBuffer from your AVCaptureVideoDataOutput

if probe.faceCount != 1 {
    show("Only your face, please")
} else if probe.centerOffset > FaceProbe.centeredMaxOffset {
    show("Center your face")
} else if probe.widthRatio < FaceProbe.centeredMinWidth {
    show("Move closer")
} else {
    // Centered and close enough: capture frames as widthRatio rises
    // toward FaceProbe.closeTargetWidth.
}

Property	Meaning
`faceCount`	Faces in the frame. Capture only with exactly 1.
`widthRatio`	Face width ÷ frame width, 0 to 1. Larger is closer.
`centerOffset`	Distance of the face from the center, 0 to 1. 0 is centered.
`FaceProbe.centeredMaxOffset`	`0.20`: at or below counts as centered.
`FaceProbe.centeredMinWidth`	`0.25`: close enough to start the move-closer capture.
`FaceProbe.closeTargetWidth`	`0.55`: fully close.

2. Score it with `checkMovementLiveness`

let recorder = client.makeMovementReplayRecorder()   // optional
// For every camera frame: recorder.append(pixelBuffer)

let result = try await client.checkMovementLiveness(
    sessionID: sessionID,          // a workflow session at its face liveness step
    frames: capturedJPEGs.map(FileInput.data),
    clip: await recorder.finish()  // optional replay for reviewers
)
print(result.passed, result.confidence ?? 0)

Pass 3 to 8 frames in capture order. Fewer than 3 throws .validation; more than 8 are evenly reduced to 8.
passed is decided by deepidv against the workflow step’s threshold.
The replay clip is shown to reviewers in the Admin Console. MovementReplayRecorder.append(_:) can be called from any queue.

Returns FaceLivenessResult.