Objective c 如何将 AVCaptureDevice 曝光重置为默认值

Question

我正在使用相机设置自定义曝光/iso：

AVCaptureDevice* cd = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
[cd setExposureModeCustomWithDuration:cmtime ISO:iso completionHandler:nil];

这很好用。但是，在应用程序会话期间，这些自定义设置仍然存在。有没有办法重置捕获设备的曝光/iso 设置？我尝试过类似的方法：

if([captureDevice lockForConfiguration:&error]){
    [captureDevice setExposureModeCustomWithDuration:captureDevice.activeFormat.minExposureDuration ISO:captureDevice.activeFormat.minISO completionHandler:nil];
    [captureDevice unlockForConfiguration];
}

但这不会将相机重置为默认设置。

Answer 1

您可以在自定义之前存储曝光模式

AVCaptureDevice* cd = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

self.defaultExposureMode = cd.exposureMode; // store in some property

if([cd lockForConfiguration:&error]){
    [cd setExposureModeCustomWithDuration:cmtime ISO:iso completionHandler:nil];
    [cd unlockForConfiguration];
}

然后在需要时恢复它

AVCaptureDevice* cd = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if([cd lockForConfiguration:&error]){
    cd.exposureMode = self.defaultExposureMode;
    [cd unlockForConfiguration];
}