title: How to Put Slider that increase decrease brightness of camera in AVCaptureSession
body: <p>so far i have presented camera put one slider in that which zoom zoom out camera now but now I want to Put another Slider which increase and decrease brightness of camera I have searched on this and i need to use AVCaptureVideoDataOutput and taking single frame which i can get on delegate method and process it and do what you want to do with that frame I am posting my code below and explain other things in it </p>
  
  <pre><code>    AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
     // AVCaptureVideoDataOutput
      if (videoDevice) {
          NSError *error;
          AVCaptureDeviceInput *videoIn = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&amp;error];
          if (!error) {
              if ([[self captureSession] canAddInput:videoIn])
                  [[self captureSession] addInput:videoIn];
              else
                  NSLog(@"Couldn't add video input");     
          }
          else
              NSLog(@"Couldn't create video input");
      }
      else
          NSLog(@"Couldn't create video capture device");
  
      AVCaptureVideoDataOutput *videoOut = [[AVCaptureVideoDataOutput alloc] init];
      /*
       RosyWriter prefers to discard late video frames early in the capture pipeline, since its
       processing can take longer than real-time on some platforms (such as iPhone 3GS).
       Clients whose image processing is faster than real-time should consider setting AVCaptureVideoDataOutput's
       alwaysDiscardsLateVideoFrames property to NO.
       */
      [videoOut setAlwaysDiscardsLateVideoFrames:YES];
      [videoOut setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey]];
      dispatch_queue_t videoCaptureQueue = dispatch_queue_create("Video Capture Queue", DISPATCH_QUEUE_SERIAL);
      [videoOut setSampleBufferDelegate:self queue:videoCaptureQueue];
      dispatch_release(videoCaptureQueue);
      if ([captureSession canAddOutput:videoOut])
          [captureSession addOutput:videoOut];
  }
  
  - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
  {
  
        I HAVE READ THAT NEED TO PROCESS FRAME AND THEN SEND IT BACK TO SESSION BUT HOW I DONT KNOW 
          THIS IS THE DELEGATE METHOD WHERE I GET FRAME NOW I DONT UNDERSTAND HOW TO PROCESS THIS 
  FRAME WHAT SHOULD I DO SO I CAN INCREASE AND DECREASE BRIGHTNESS OF CAMERA PLEASE HELP ME IF YOU KNOW 
    }
  </code></pre>