Simultaneous capture and fold transitions in a live-streaming app on iPhone Duo

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Created 4d

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I build Lumecast, a live-streaming app (custom AVCapture pipeline feeding WebRTC). Three questions:

1. Does iPhone Duo support AVCaptureMultiCamSession — specifically front + rear simultaneously? Our co-casting feature would let a solo host fill two panes with their face and what they're looking at.

How should a continuous capture session (live broadcast, can't pause) respond to camera direction changes as the device opens and closes? Is there a recommended pattern for swapping to the Virtual Front Camera mid-session without a visible gap for viewers?

3. Which cameras are available to third-party apps in each posture (folded / half-open / fully open), and does availability change at a specific hinge state?

Goal: a host folds or unfolds mid-broadcast and their audience never sees a dropped frame.

Answered by DTS Engineer in 906238022

Hey @Lumecast,

Have you seen Choosing a camera by the direction it faces?

I believe that article answers some of your questions here.

-- Greg

Answer 1

DTS Engineer OP

Apple

4d

Accepted Answer

Hey @Lumecast,

Have you seen Choosing a camera by the direction it faces?

I believe that article answers some of your questions here.

-- Greg

Answer 2

Lumecast OP

3d

Thanks Greg — that article answers my questions 2 and 3. The AVCaptureDeviceDirectionCoordinator + descriptor-swap-inside-beginConfiguration pattern is exactly what I needed for uninterrupted broadcasts, and the mirroring-from-the-direction-map note would have bitten me for sure.

One thing the article doesn't address is my question 1: is AVCaptureMultiCamSession supported on iPhone Duo — specifically streaming two cameras that face opposite directions simultaneously (e.g. .builtInInnerUltraWideCamera + .builtInOuterUltraWideCamera, or the Virtual Front Camera plus a backward-facing camera)? I noticed the article recommends single-input reconfiguration over multi-cam; is that a performance recommendation, or is opposite-direction multi-cam unavailable on this device? Our use case is a live co-cast where one host fills two video panes: their face and what they're looking at.

Answer 3

Media Engineer OP

Apple

3d

Yes, AVCaptureMultiCamSession is supported on iPhone Duo. .builtInInnerUltraWideCamera + .builtInOuterUltraWideCamera, or the Virtual Front Camera plus a backward-facing camera

All of these combinations should work.