修改曝光持续时间后返回AVCaptureExposureModeContinuousAutoExposure后出现奇怪的行为 [英] Strange behaviour after modifying exposure duration and going back to AVCaptureExposureModeContinuousAutoExposure

问题描述

我正在开发一个应用程序，它使用iOS 8中引入的新API公开相机的手动控件，我正在使用示例应用作为参考。

I am working on an app that exposes manual controls for the camera with the new APIs introduced in iOS 8, and I am using this sample app from WWDC 2014 as a reference.

但是我注意到一个奇怪的行为（在我的5s和6上）：将曝光模式设置为自定义然后再返回自动后，图像继续滞后，就像曝光持续时间不受此更改影响一样。

However I noticed a strange bahaviour (on my 5s and on a 6): after setting the exposure mode to "custom" and then back to "auto" the image continues to lag as if the exposure duration was not affected by this change.

以下是每个步骤中涉及的代码（来自示例应用程序，未经任何修改）：

Here is the code involved in each step (from the sample app, without any modification):

- (IBAction)changeExposureMode:(id)sender
{
    UISegmentedControl *control = sender;
    NSError *error = nil;
    AVCaptureExposureMode mode = (AVCaptureExposureMode)[self.exposureModes[control.selectedSegmentIndex] intValue];

    if ([self.videoDevice lockForConfiguration:&error])
    {
        if ([self.videoDevice isExposureModeSupported:mode])
        {
            [self.videoDevice setExposureMode:mode];
        }
        else
        {
            NSLog(@"Exposure mode %@ is not supported. Exposure mode is %@.", [self stringFromExposureMode:mode], [self stringFromExposureMode:self.videoDevice.exposureMode]);
        }
    }
    else
    {
        NSLog(@"%@", error);
    }
}


- (IBAction)changeExposureDuration:(id)sender
{
    UISlider *control = sender;
    NSError *error = nil;

    double p = pow( control.value, EXPOSURE_DURATION_POWER ); // Apply power function to expand slider's low-end range
    double minDurationSeconds = MAX(CMTimeGetSeconds(self.videoDevice.activeFormat.minExposureDuration), EXPOSURE_MINIMUM_DURATION);
    double maxDurationSeconds = CMTimeGetSeconds(self.videoDevice.activeFormat.maxExposureDuration);
    double newDurationSeconds = p * ( maxDurationSeconds - minDurationSeconds ) + minDurationSeconds; // Scale from 0-1 slider range to actual duration

    if (self.videoDevice.exposureMode == AVCaptureExposureModeCustom)
    {
        if ( newDurationSeconds < 1 )
        {
            int digits = MAX( 0, 2 + floor( log10( newDurationSeconds ) ) );
            self.exposureDurationValueLabel.text = [NSString stringWithFormat:@"1/%.*f", digits, 1/newDurationSeconds];
        }
        else
        {
            self.exposureDurationValueLabel.text = [NSString stringWithFormat:@"%.2f", newDurationSeconds];
        }
    }

    if ([self.videoDevice lockForConfiguration:&error])
    {
        [self.videoDevice setExposureModeCustomWithDuration:CMTimeMakeWithSeconds(newDurationSeconds, 1000*1000*1000)  ISO:AVCaptureISOCurrent completionHandler:nil];
    }
    else
    {
        NSLog(@"%@", error);
    }
}

推荐答案

我尝试了相同的示例应用程序，并尝试重现该问题，但无法看起来他们现在已修复它。

I tried the same sample app and tried to reproduce the issue but was not able to it looks like they have fixed it now.

这篇关于修改曝光持续时间后返回AVCaptureExposureModeContinuousAutoExposure后出现奇怪的行为的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！