iPhone 6 Plus Camera Performance Using AVCaptureStillImageOutput.CaptureStillImageAsynchronously Is Abysmal, Why?

Question

We have been using AVCaptureStillImageOutput.CaptureStillImageAsynchronously to capture on image on iOS in our application. On iPhone 5, 5c, 5s, and 6 this call takes about 300-400ms to return using the AVCaptureSession.PresetPhoto setting. On iPhone 6 Plus, this takes 800-1250ms. This camera problem only exists on the iPhone 6 Plus.

Why? We have looked at the settings and are unclear if there is something we are doing wrong.

We are also using the following pixel format: CVPixelFormatType.CV48RGB

Answer 1

The key difference between iPhone 6 Plus and the others is the OIS (optical image stabilisation). And a key feature of OIS is that it takes time to do its thing.

Consequently, given an AVCaptureStillImageOutput called stillImageOutput, you can add this to your setup in order to speed things up (although, obviously, you lose the image stabilisation...):

if (stillImageOutput.stillImageStabilizationSupported)
  stillImageOutput.automaticallyEnablesStillImageStabilizationWhenAvailable = FALSE;