AVCaptureSession 亮度

Question

我正在开发一个使用前置摄像头的镜像应用程序 AVFoundation。我已经完成向 UIView 显示相机屏幕。但是如何调整亮度？代码是这样的：

-(void)AVCaptureInit {   
    mCameraAVSession = [[AVCaptureSession alloc] init];
    [mCameraAVSession setSessionPreset:AVCaptureSessionPresetPhoto];

    mCaptureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *device in devices) {
        if ([device position] == AVCaptureDevicePositionFront) {
            mCaptureDevice = device;
            break;
        }
    }

    //if ([mCaptureDevice hasTorch] && [mCaptureDevice hasFlash])
    {
        [mCaptureDevice lockForConfiguration:nil];
        // [mCaptureDevice setTorchMode:AVCaptureTorchModeOn];
        //[mCaptureDevice setExposurePointOfInterest:0.5];

        [mCaptureDevice setExposureMode:AVCaptureExposureModeManual];

        [mCaptureDevice unlockForConfiguration];
    }



    // [inputDevice setTorchModeOnWithLevel:0.5 error:NULL];

    NSError *error;
    AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:mCaptureDevice error:&error];

    if ([mCameraAVSession canAddInput:deviceInput]) {
        [mCameraAVSession addInput:deviceInput];
    }

    AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:mCameraAVSession];
    [previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    CALayer *rootLayer = [mCameraView layer];
    [rootLayer setMasksToBounds:YES];
    CGRect frame = mCaptureView.frame;
    [previewLayer setFrame:frame];
    [rootLayer insertSublayer:previewLayer atIndex:0];

    mCameraImageOutput = [[AVCaptureStillImageOutput alloc] init];
    NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG, AVVideoCodecKey, nil];
    [mCameraImageOutput setOutputSettings:outputSettings];


    [mCameraAVSession addOutput:mCameraImageOutput];

    [mCameraAVSession startRunning];

    [self setVisible:mCaptureImage IsVisible:NO];
}

有人说可以通过曝光调节亮度，但是我不知道怎么用。特别是，我想在捏合时调整相机亮度。

Answer 1

WWDC2014 Session 508 and the Manual AVCam Sample Code 中描述了手动（自定义）相机曝光。

通过运行 AVCamManual 自行尝试，点击“曝光”>“自定义”并拖动“曝光”滑块。

在代码中，归结为将 AVCaptureDevice exposureMode 设置为 AVCaptureExposureModeCustom 并调用

if ([mCaptureDevice lockForConfiguration:&error]) {
    [mCaptureDevice setExposureModeCustomWithDuration:exposureDuration ISO:AVCaptureISOCurrent completionHandler:nil];
    [mCaptureDevice unlockForConfiguration];
}

p.s。我不确定你从哪里得到 AVCaptureExposureModeManual。好像不存在。

AVCaptureSession 亮度

AVCaptureSession Brightness

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