AVCapturePhotoOutput不接受AVCaptureDevice的ExposureDuration和iso

Question

问题：使用AVCaptureDevice.setExposureModeCustom设置快速的“快门速度”（exposureDuration）和高ISO，调用AVCapturePhotoOutput拍照，然后在生成的图像中看到未使用ExposureDuration / ISO（即使实时视频源显示了它使用持续时间/ ISO通过按预期方式变亮/变暗）

Answer 1

原来应该归咎于AVCapturePhotoSettings.isAutoStillImageStabilizationEnabled ：默认情况下为true，如果为true， 则可以忽略/重置曝光时间和ISO设置 。

解决方案是在使用自定义曝光设置时将其设置为false，如下所示：

        // self.customDuration is nil if we're on auto-exposure, non-nil if we are on manual exposure, ie. we called AVCaptureDevice.setExposureModeCustom
        let photoSettings: AVCapturePhotoSettings
        if self.photoOutput.availablePhotoCodecTypes.contains(.hevc), heicSupported {
            photoSettings = AVCapturePhotoSettings(format:
                [AVVideoCodecKey: AVVideoCodecType.hevc])
        } else {
            photoSettings = AVCapturePhotoSettings(format:
                [AVVideoCodecKey: AVVideoCodecType.jpeg])
        }
        // auto still image stabilization destroys our settings for custom exposure (iso, duration), so turn it off if we have any
        photoSettings.isAutoStillImageStabilizationEnabled = self.customDuration == nil ?
            self.photoOutput.isStillImageStabilizationSupported : false