RotationCoordinator returns angles 90 degrees lower on iPhone 17 Pro front camera — clarification on contract with AVSampleBufferDisplayLayer

To clarify the issue, our preview pipeline rotates the sample-buffer display layer by applying the RotationCoordinator angle as a transform on the layer itself, while leaving the data-output connection's rotation unset — a pattern that worked on every iPhone before 17 Pro because the buffer always arrived in the same default orientation. On the iPhone 17 Pro front cam the same code renders 90° off: RC still returns correct values, but the buffer's default orientation is itself 90° offset from every earlier device, so "RC's angle applied as a layer transform" no longer lands upright. The hidden dependency that broke is exactly this — applying RC's angle on the layer only works when the buffer's default orientation is fixed across devices, and since we never set the connection's rotation, we were silently relying on that default, which shifted on this one camera. The supported fix (driving connection.videoRotationAngle directly) corrects orientation but causes the emitted buffer's pixel dimensions to swap between portrait and landscape(1920x1080 to 1080x1920, which then breaks the preview aspect-ratio layout and the AVAssetWriter transform that were both built around stable buffer dimensions.

Hi, thank you for mentioning this.

Yes, the Center Stage front camera on iPhone 17 and iPhone 17 Pro is mounted differently compared to front cameras on previous iPhone generations.

However, to maintain backwards compatibility, AVCaptureVideoDataOutput continues to output buffers in the same orientation/rotation as previous generations by default. This means that the AVCaptureVideoDataOutput's connection's videoRotationAngle is non-0 by default for the Center Stage front camera.

To compensate for this difference, you can do something like the following:

let videoRotationAngleForHorizonLevelPreview = rotationCoordinator.videoRotationAngleForHorizonLevelPreview
let videoConnectionVideoRotationAngle = videoOutputConnection.videoRotationAngle

// Subtract how much we should apply (videoRotationAngleForHorizonLevelPreview) by how much is already applied (videoConnectionVideoRotationAngle)
let rotationAngleToApply = videoRotationAngleForHorizonLevelPreview - videoConnectionVideoRotationAngle

// Use rotationAngleToApply for your AVSampleBufferDisplayLayer or AVAssetWriter video input's transform

Alternatively, you could set the videoRotationAngle on your AVCaptureVideoDataOutput to 0 and solely rely on the rotation coordinator's videoRotationAngleForHorizonLevelPreview. This will yield better performance for AVFoundation as it will no longer output "physically rotated" buffers.

Is there an easy way in code to tell if a center-stage front camera is present on a device or not?