> For the complete documentation index, see [llms.txt](https://docs.caf.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.caf.io/caf-sdk/flutter/standalone-modules/documentdetector/start-sdk.md).

# Start Liveness Verification

## Calling `start`

To start document detection, initialize `DocumentDetector` with the necessary configurations, then call `start()` and handle events using a listener:

```dart
void startDocumentDetector(List<DocumentCaptureFlow> captureFlow) async {
  String personId = personIdController.text;
  String mobileToken = mobileTokenController.text;

  DocumentDetector documentDetector =
  DocumentDetector(mobileToken: mobileToken, captureFlow: captureFlow);

  // Configure Android-specific settings
  AndroidSettings androidSettings = AndroidSettings(
      securitySettings: SecuritySettings(
          useAdb: true,
          useDebug: true,
          useDeveloperMode: true,
          useEmulator: true,
          useRoot: true));

  documentDetector.setAndroidSettings(androidSettings);
  documentDetector.setNetworkSettings(20);
  documentDetector.setStage(isBeta ? CafStage.beta : CafStage.prod);
  documentDetector.setPersonId(personId);
  documentDetector.setPreviewSettings(PreviewSettings(show: true));

  try {
    DocumentDetectorEvent event = await documentDetector.start();
    // Handle the result
    if (event is DocumentDetectorEventSuccess) {
      print("SUCCESS: ${event.documentType}");
    } else if (event is DocumentDetectorEventFailure) {
      print("FAILURE: ${event.errorMessage}");
    } else if (event is DocumentDetectorEventClosed) {
      print("User closed document capture flow");
    }
  } catch (e) {
    print("Error starting DocumentDetector: ${e}");
  }
}
```


---

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