GetLabelDetection - Amazon Rekognition

GetLabelDetection

Gets the label detection results of a Amazon Rekognition Video analysis started by StartLabelDetection.

The label detection operation is started by a call to StartLabelDetection which returns a job identifier (JobId). When the label detection operation finishes, Amazon Rekognition publishes a completion status to the Amazon Simple Notification Service topic registered in the initial call to StartlabelDetection.

To get the results of the label detection operation, first check that the status value published to the Amazon SNS topic is SUCCEEDED. If so, call GetLabelDetection and pass the job identifier (JobId) from the initial call to StartLabelDetection.

GetLabelDetection returns an array of detected labels (Labels) sorted by the time the labels were detected. You can also sort by the label name by specifying NAME for the SortBy input parameter. If there is no NAME specified, the default sort is by timestamp.

You can select how results are aggregated by using the AggregateBy input parameter. The default aggregation method is TIMESTAMPS. You can also aggregate by SEGMENTS, which aggregates all instances of labels detected in a given segment.

The returned Labels array may include the following attributes:

  • Name - The name of the detected label.

  • Confidence - The level of confidence in the label assigned to a detected object.

  • Parents - The ancestor labels for a detected label. GetLabelDetection returns a hierarchical taxonomy of detected labels. For example, a detected car might be assigned the label car. The label car has two parent labels: Vehicle (its parent) and Transportation (its grandparent). The response includes the all ancestors for a label, where every ancestor is a unique label. In the previous example, Car, Vehicle, and Transportation are returned as unique labels in the response.

  • Aliases - Possible Aliases for the label.

  • Categories - The label categories that the detected label belongs to.

  • BoundingBox — Bounding boxes are described for all instances of detected common object labels, returned in an array of Instance objects. An Instance object contains a BoundingBox object, describing the location of the label on the input image. It also includes the confidence for the accuracy of the detected bounding box.

  • Timestamp - Time, in milliseconds from the start of the video, that the label was detected. For aggregation by SEGMENTS, the StartTimestampMillis, EndTimestampMillis, and DurationMillis structures are what define a segment. Although the “Timestamp” structure is still returned with each label, its value is set to be the same as StartTimestampMillis.

Timestamp and Bounding box information are returned for detected Instances, only if aggregation is done by TIMESTAMPS. If aggregating by SEGMENTS, information about detected instances isn’t returned.

The version of the label model used for the detection is also returned.

Note DominantColors isn't returned for Instances, although it is shown as part of the response in the sample seen below.

Use MaxResults parameter to limit the number of labels returned. If there are more results than specified in MaxResults, the value of NextToken in the operation response contains a pagination token for getting the next set of results. To get the next page of results, call GetlabelDetection and populate the NextToken request parameter with the token value returned from the previous call to GetLabelDetection.

Request Syntax

{ "AggregateBy": "string", "JobId": "string", "MaxResults": number, "NextToken": "string", "SortBy": "string" }

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

The request accepts the following data in JSON format.

AggregateBy

Defines how to aggregate the returned results. Results can be aggregated by timestamps or segments.

Type: String

Valid Values: TIMESTAMPS | SEGMENTS

Required: No

JobId

Job identifier for the label detection operation for which you want results returned. You get the job identifer from an initial call to StartlabelDetection.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 64.

Pattern: ^[a-zA-Z0-9-_]+$

Required: Yes

MaxResults

Maximum number of results to return per paginated call. The largest value you can specify is 1000. If you specify a value greater than 1000, a maximum of 1000 results is returned. The default value is 1000.

Type: Integer

Valid Range: Minimum value of 1.

Required: No

NextToken

If the previous response was incomplete (because there are more labels to retrieve), Amazon Rekognition Video returns a pagination token in the response. You can use this pagination token to retrieve the next set of labels.

Type: String

Length Constraints: Maximum length of 255.

Required: No

SortBy

Sort to use for elements in the Labels array. Use TIMESTAMP to sort array elements by the time labels are detected. Use NAME to alphabetically group elements for a label together. Within each label group, the array element are sorted by detection confidence. The default sort is by TIMESTAMP.

Type: String

Valid Values: NAME | TIMESTAMP

Required: No

Response Syntax

{ "JobStatus": "string", "LabelModelVersion": "string", "Labels": [ { "DurationMillis": number, "EndTimestampMillis": number, "Label": { "Aliases": [ { "Name": "string" } ], "Categories": [ { "Name": "string" } ], "Confidence": number, "Instances": [ { "BoundingBox": { "Height": number, "Left": number, "Top": number, "Width": number }, "Confidence": number, "DominantColors": [ { "Blue": number, "CSSColor": "string", "Green": number, "HexCode": "string", "PixelPercent": number, "Red": number, "SimplifiedColor": "string" } ] } ], "Name": "string", "Parents": [ { "Name": "string" } ] }, "StartTimestampMillis": number, "Timestamp": number } ], "NextToken": "string", "StatusMessage": "string", "VideoMetadata": { "Codec": "string", "ColorRange": "string", "DurationMillis": number, "Format": "string", "FrameHeight": number, "FrameRate": number, "FrameWidth": number } }

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.

JobStatus

The current status of the label detection job.

Type: String

Valid Values: IN_PROGRESS | SUCCEEDED | FAILED

LabelModelVersion

Version number of the label detection model that was used to detect labels.

Type: String

Labels

An array of labels detected in the video. Each element contains the detected label and the time, in milliseconds from the start of the video, that the label was detected.

Type: Array of LabelDetection objects

NextToken

If the response is truncated, Amazon Rekognition Video returns this token that you can use in the subsequent request to retrieve the next set of labels.

Type: String

Length Constraints: Maximum length of 255.

StatusMessage

If the job fails, StatusMessage provides a descriptive error message.

Type: String

VideoMetadata

Information about a video that Amazon Rekognition Video analyzed. Videometadata is returned in every page of paginated responses from a Amazon Rekognition video operation.

Type: VideoMetadata object

Errors

For information about the errors that are common to all actions, see Common Errors.

AccessDeniedException

You are not authorized to perform the action.

HTTP Status Code: 400

InternalServerError

Amazon Rekognition experienced a service issue. Try your call again.

HTTP Status Code: 500

InvalidPaginationTokenException

Pagination token in the request is not valid.

HTTP Status Code: 400

InvalidParameterException

Input parameter violated a constraint. Validate your parameter before calling the API operation again.

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

ResourceNotFoundException

The resource specified in the request cannot be found.

HTTP Status Code: 400

ThrottlingException

Amazon Rekognition is temporarily unable to process the request. Try your call again.

HTTP Status Code: 500

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: