1080p capture stutters on iPhone 12 Pro/Max

[CubitSpeed]

Describe the bug The 1080p capture stutters on the iPhone 12 Pro/Max. Stuttering affects preview, local recording, and stream.

To Reproduce Steps to reproduce the behavior:

1. Clone iOS Example
2. Change rtmpStream.captureSettings.sessionPreset to be AVCaptureSession.Preset.hd1920x1080
3. Run project on iPhone
4. Switch back/front camera until issue occurs.

Expected behavior Preview, local recording, and stream should be smooth. No stuttering

Screenshots Please see attached video with reproduction steps and the stutter: https://user-images.githubusercontent.com/67028273/106406758-23917180-63ef-11eb-936e-a7dfb66c179e.MP4

Smartphone

• Device: iPhone 12 Pro and iPhone 12 Pro Max
• OS: iOS14 (newest)
• Version: HaishinKit.swift Master

Additional context Does not happen on iPhone 12 (non Pro/Max). Or any other iPhone devices I have tried.

Very strange: sometimes zooming in will solve the issue. But will re-occur after zoom out.

[themaxsmith]

I have seen this issue on an iPhone 12 as well using RTMP. Happens on the High / Main profile. The baseline profile seems to be unaffected. If I use SRTHashinkit it is also unaffected even if on High / Main profile

[shogo4405]

Would you like to reproduce now? That may have been the cause AVCaptureDecice#activeFormat. If it doesn't reproduce, I will close it. Thank you.

[shogo4405]

Currently iOS16. It is hard to reproduce. I will close.