# StartFaceDetection


Starts asynchronous detection of faces in a stored video.

Amazon Rekognition Video can detect faces in a video stored in an Amazon S3 bucket. Use [Video](API_Video.md) to specify the bucket name and the filename of the video. `StartFaceDetection` returns a job identifier (`JobId`) that you use to get the results of the operation. When face detection is finished, Amazon Rekognition Video publishes a completion status to the Amazon Simple Notification Service topic that you specify in `NotificationChannel`. To get the results of the face detection operation, first check that the status value published to the Amazon SNS topic is `SUCCEEDED`. If so, call [GetFaceDetection](API_GetFaceDetection.md) and pass the job identifier (`JobId`) from the initial call to `StartFaceDetection`.

For more information, see [Detecting faces in a stored video](https://docs.aws.amazon.com/rekognition/latest/dg/faces-sqs-video.html).

## Request Syntax


```
{
   "ClientRequestToken": "string",
   "FaceAttributes": "string",
   "JobTag": "string",
   "NotificationChannel": { 
      "RoleArn": "string",
      "SNSTopicArn": "string"
   },
   "Video": { 
      "S3Object": { 
         "Bucket": "string",
         "Name": "string",
         "Version": "string"
      }
   }
}
```

## Request Parameters


For information about the parameters that are common to all actions, see [Common Parameters](CommonParameters.md).

The request accepts the following data in JSON format.

 ** [ClientRequestToken](#API_StartFaceDetection_RequestSyntax) **   <a name="rekognition-StartFaceDetection-request-ClientRequestToken"></a>
Idempotent token used to identify the start request. If you use the same token with multiple `StartFaceDetection` requests, the same `JobId` is returned. Use `ClientRequestToken` to prevent the same job from being accidently started more than once.   
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 64.  
Pattern: `^[a-zA-Z0-9-_]+$`   
Required: No

 ** [FaceAttributes](#API_StartFaceDetection_RequestSyntax) **   <a name="rekognition-StartFaceDetection-request-FaceAttributes"></a>
The face attributes you want returned.  
 `DEFAULT` - The following subset of facial attributes are returned: BoundingBox, Confidence, Pose, Quality and Landmarks.   
 `ALL` - All facial attributes are returned.  
Type: String  
Valid Values: `DEFAULT | ALL`   
Required: No

 ** [JobTag](#API_StartFaceDetection_RequestSyntax) **   <a name="rekognition-StartFaceDetection-request-JobTag"></a>
An identifier you specify that's returned in the completion notification that's published to your Amazon Simple Notification Service topic. For example, you can use `JobTag` to group related jobs and identify them in the completion notification.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 1024.  
Pattern: `[a-zA-Z0-9_.\-:+=\/]+`   
Required: No

 ** [NotificationChannel](#API_StartFaceDetection_RequestSyntax) **   <a name="rekognition-StartFaceDetection-request-NotificationChannel"></a>
The ARN of the Amazon SNS topic to which you want Amazon Rekognition Video to publish the completion status of the face detection operation. The Amazon SNS topic must have a topic name that begins with *AmazonRekognition* if you are using the AmazonRekognitionServiceRole permissions policy.  
Type: [NotificationChannel](API_NotificationChannel.md) object  
Required: No

 ** [Video](#API_StartFaceDetection_RequestSyntax) **   <a name="rekognition-StartFaceDetection-request-Video"></a>
The video in which you want to detect faces. The video must be stored in an Amazon S3 bucket.  
Type: [Video](API_Video.md) object  
Required: Yes

## Response Syntax


```
{
   "JobId": "string"
}
```

## Response Elements


If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

 ** [JobId](#API_StartFaceDetection_ResponseSyntax) **   <a name="rekognition-StartFaceDetection-response-JobId"></a>
The identifier for the face detection job. Use `JobId` to identify the job in a subsequent call to `GetFaceDetection`.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 64.  
Pattern: `^[a-zA-Z0-9-_]+$` 

## Errors


For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).

 ** AccessDeniedException **   
You are not authorized to perform the action.  
HTTP Status Code: 400

 ** IdempotentParameterMismatchException **   
A `ClientRequestToken` input parameter was reused with an operation, but at least one of the other input parameters is different from the previous call to the operation.  
HTTP Status Code: 400

 ** InternalServerError **   
Amazon Rekognition experienced a service issue. Try your call again.  
HTTP Status Code: 500

 ** InvalidParameterException **   
Input parameter violated a constraint. Validate your parameter before calling the API operation again.  
HTTP Status Code: 400

 ** InvalidS3ObjectException **   
Amazon Rekognition is unable to access the S3 object specified in the request.  
HTTP Status Code: 400

 ** LimitExceededException **   
An Amazon Rekognition service limit was exceeded. For example, if you start too many jobs concurrently, subsequent calls to start operations (ex: `StartLabelDetection`) will raise a `LimitExceededException` exception (HTTP status code: 400) until the number of concurrently running jobs is below the Amazon Rekognition service limit.   
HTTP Status Code: 400

 ** ProvisionedThroughputExceededException **   
The number of requests exceeded your throughput limit. If you want to increase this limit, contact Amazon Rekognition.  
HTTP Status Code: 400

 ** ThrottlingException **   
Amazon Rekognition is temporarily unable to process the request. Try your call again.  
HTTP Status Code: 500

 ** VideoTooLargeException **   
The file size or duration of the supplied media is too large. The maximum file size is 10GB. The maximum duration is 6 hours.   
HTTP Status Code: 400

## See Also


For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS Command Line Interface V2](https://docs.aws.amazon.com/goto/cli2/rekognition-2016-06-27/StartFaceDetection) 
+  [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/rekognition-2016-06-27/StartFaceDetection) 
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/rekognition-2016-06-27/StartFaceDetection) 
+  [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/rekognition-2016-06-27/StartFaceDetection) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/rekognition-2016-06-27/StartFaceDetection) 
+  [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/rekognition-2016-06-27/StartFaceDetection) 
+  [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/rekognition-2016-06-27/StartFaceDetection) 
+  [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/rekognition-2016-06-27/StartFaceDetection) 
+  [AWS SDK for Python](https://docs.aws.amazon.com/goto/boto3/rekognition-2016-06-27/StartFaceDetection) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/rekognition-2016-06-27/StartFaceDetection)