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#1 Posted : Wednesday, February 14, 2018 12:25:49 PM(UTC)

Hadi  
Hadi

Groups: Manager, Tech Support, Administrators
Posts: 197

Was thanked: 9 time(s) in 9 post(s)

Attached is a LEADTOOLS V20 .NET C# demo application that uses the LEADTOOLS Multimedia SDK alongside the LEADTOOLS Barcode SDK and the newly released AAMVAID class.

This demo shows how to use the LEADTOOLS Callback Filter to grab frames from a video device (webcam) and attempt to parse a Drivers License Barcode found within.

The demo takes advantage of the .NET 4+ System.Threading.Tasks Namespace to process multiple frames at once. There is a hard-coded 'MaxConcurrentTasks' property that tracks the total number of tasks being run at the same time to limit the application's use of threads. This is handled like so:

Code:

   private List<Task> Runningtasks = new List<Task>();
   private const int MaxConcurrentTasks = 8;
   private TimeSpan Timeout = TimeSpan.FromSeconds(2);


   //Check to see if we are at max concurrency
   if (Runningtasks.Count <= MaxConcurrentTasks)
   {
      //Start a new task here
      Task processFrame = Task.Factory.StartNew(() =>
      {
         //start the barocde read process in a new task
         var task = Task.Factory.StartNew(() => ProcessBarcode(pData, lWidth, lHeight, lBitCount, lSize, bTopDown));
         //if we are unable to find a barcode in 2 seconds, kill the task
         if (!task.Wait(Timeout))
            return;
      });

      // add the task to the list of running tasks
      Runningtasks.Add(processFrame);

      //once the task is complete (either through timeout or normal completion) remove it from the list of running tasks
      processFrame.ContinueWith(s =>
      {
         Runningtasks.Remove(processFrame);
      });
   }


The demo implements a custom event for when it finds a barcode in one of the threads to stop the other threads and notify the main program like so:

Code:

   public delegate void BarcodeFoundHandler(object sender, BarcodeFoundEventArgs e);
   public event BarcodeFoundHandler OnBarcodeFound;

   public class BarcodeFoundEventArgs : EventArgs, IDisposable
   {
      public AAMVAID AAMVAID { get; private set; }
      public BarcodeFoundEventArgs(AAMVAID aamvaid)
      {
         AAMVAID = aamvaid;
      }

      public void Dispose()
      {
         AAMVAID.Dispose();
      }
   }


When a barcode is found, the AAMVAID is then parsed and displayed to the user like so:
screenshot of demo

In order to run the demo, you need to have the LEADTOOLS Multimedia SDK installed as well as the LEADTOOLS Main Evaluation.

The demo can be downloaded from here:
File Attachment(s):
BarcodeLiveCaptureDemo.zip (20kb) downloaded 298 time(s).
Hadi Chami
Developer Support Manager
LEAD Technologies, Inc.

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Try the latest version of LEADTOOLS for free for 60 days by downloading the evaluation: https://www.leadtools.com/downloads

Wanna join the discussion? Login to your LEADTOOLS Support accountor Register a new forum account.

#2 Posted : Monday, February 19, 2018 3:58:41 PM(UTC)

Walter  
Walter

Groups: Tech Support, Administrators
Posts: 368

Thanks: 1 times
Was thanked: 4 time(s) in 4 post(s)

This demo has been updated with UI changes to show when the user has selected a device to capture from. The demo also releases that device when the application is closed.

The callback has also been updated to only grab one out of ever 6 frames. This is necessary to achieve better performance through lower CPU usage and keep the application responsive while attempting to find a barcode in the video stream.
File Attachment(s):
BarcodeLiveCaptureDemo.zip (280kb) downloaded 275 time(s).
Walter Bates
Senior Support Engineer
LEAD Technologies, Inc.
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#3 Posted : Friday, March 30, 2018 10:55:14 AM(UTC)
Anthony Northrup

Groups: Registered, Tech Support, Administrators
Posts: 199

Was thanked: 27 time(s) in 27 post(s)

Added simple image processing to aid the recognition (AutoColorLevel and DynamicBinary):
Code:

AutoColorLevelCommand autoColorLevelCommand = new AutoColorLevelCommand();
autoColorLevelCommand.Run(editted);
DynamicBinaryCommand dynamicBinaryCommand = new DynamicBinaryCommand();
dynamicBinaryCommand.Dimension = 13;
dynamicBinaryCommand.LocalContrast = 25;
dynamicBinaryCommand.Run(editted);

And if it still doesn't read (BarCodeReadPreprocess):
Code:

BarCodeReadPreprocessCommand barCodeReadPreprocessCommand = new BarCodeReadPreprocessCommand();
barCodeReadPreprocessCommand.Options = BarCodeReadPreprocessOptions.UseAutoDocumentBinarization;
barCodeReadPreprocessCommand.Run(editted);

Then using the location found by the preprocess command:
Code:

if (!barCodeReadPreprocessCommand.BarcodeLocation.IsEmpty)
    data = engine.Reader.ReadBarcode(editted, barCodeReadPreprocessCommand.BarcodeLocation, BarcodeSymbology.PDF417, options);

File Attachment(s):
BarcodeLiveCaptureDemo.zip (21kb) downloaded 237 time(s).
Anthony Northrup
Developer Support Engineer
LEAD Technologies, Inc.

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