Amazon Rekognition
Developer Guide

Reading Streaming Video Analysis Results

You can use the Amazon Kinesis Data Streams Client Library to consume analysis results that are sent to the Amazon Kinesis Data Streams output stream. For more information, see Reading Data from a Kinesis Data Stream. Amazon Rekognition Video places a JSON frame record for each analyzed frame into the Kinesis output stream. Amazon Rekognition Video doesn't analyze every frame that's passed to it through the Kinesis video stream.

A frame record that's sent to a Kinesis data stream contains information about which Kinesis video stream fragment the frame is in, where the frame is in the fragment, and faces that are recognized in the frame. It also includes status information for the stream processor. For more information, see Reference: Kinesis Face Recognition Record.

Amazon Rekognition Video streams Amazon Rekognition Video analysis information to the Kinesis data stream. The following is a JSON example for a single record.

{ "InputInformation": { "KinesisVideo": { "StreamArn": "arn:aws:kinesisvideo:us-west-2:nnnnnnnnnnnn:stream/stream-name", "FragmentNumber": "91343852333289682796718532614445757584843717598", "ServerTimestamp": 1510552593.455, "ProducerTimestamp": 1510552593.193, "FrameOffsetInSeconds": 2 } }, "StreamProcessorInformation": { "Status": "RUNNING" }, "FaceSearchResponse": [ { "DetectedFace": { "BoundingBox": { "Height": 0.075, "Width": 0.05625, "Left": 0.428125, "Top": 0.40833333 }, "Confidence": 99.975174, "Landmarks": [ { "X": 0.4452057, "Y": 0.4395594, "Type": "eyeLeft" }, { "X": 0.46340984, "Y": 0.43744427, "Type": "eyeRight" }, { "X": 0.45960626, "Y": 0.4526856, "Type": "nose" }, { "X": 0.44958648, "Y": 0.4696949, "Type": "mouthLeft" }, { "X": 0.46409217, "Y": 0.46704912, "Type": "mouthRight" } ], "Pose": { "Pitch": 2.9691637, "Roll": -6.8904796, "Yaw": 23.84388 }, "Quality": { "Brightness": 40.592964, "Sharpness": 96.09616 } }, "MatchedFaces": [ { "Similarity": 88.863960, "Face": { "BoundingBox": { "Height": 0.557692, "Width": 0.749838, "Left": 0.103426, "Top": 0.206731 }, "FaceId": "ed1b560f-d6af-5158-989a-ff586c931545", "Confidence": 99.999201, "ImageId": "70e09693-2114-57e1-807c-50b6d61fa4dc", "ExternalImageId": "matchedImage.jpeg" } } ] } ] }

In the JSON example, note the following:

  • InputInformation – Information about the Kinesis video stream that's used to stream video into Amazon Rekognition Video. For more information, see InputInformation.

  • StreamProcessorInformation – Status information for the Amazon Rekognition Video stream processor. The only possible value for the Status field is RUNNING. For more information, see StreamProcessorInformation.

  • FaceSearchResponse – Contains information about faces in the streaming video that match faces in the input collection. FaceSearchResponse contains a DetectedFace object, which is a face that was detected in in the analyzed video frame. For each detected face, the array MatchedFaces contains an array of matching face objects (MatchedFace) found in the input collection, along with a similarity score.

Mapping the Kinesis Video Stream to the Kinesis Data Stream

You might want to map the Kinesis video stream frames to the analyzed frames that are sent to the Kinesis data stream. For example, during the display of a streaming video, you might want to display boxes around the faces of recognized people. The bounding box coordinates are sent as part of the Kinesis Face Recognition Record to the Kinesis data stream. To display the bounding box correctly, you need to map the time information that's sent with the Kinesis Face Recognition Record with the corresponding frames in the source Kinesis video stream.

The technique that you use to map the Kinesis video stream to the Kinesis data stream depends on if you're streaming live media (such as a live streaming video), or if you're streaming archived media (such as a stored video).

Mapping When You're Streaming Live Media

To map a Kinesis video stream frame to a Kinesis data stream frame

  1. Set the input parameter FragmentTimeCodeType of the PutMedia operation to RELATIVE.

  2. Call PutMedia to deliver live media into the Kinesis video stream.

  3. When you receive a Kinesis Face Recognition Record from the Kinesis data stream, store the values of ProducerTimestamp and FrameOffsetInSeconds from the KinesisVideo field.

  4. Calculate the time stamp that corresponds to the Kinesis video stream frame by adding the ProducerTimestamp and FrameOffsetInSeconds field values together.

Mapping When You're Streaming Archived Media

To map a Kinesis video stream frame to a Kinesis data stream frame

  1. Call PutMedia to deliver archived media into the Kinesis video stream.

  2. When you receive an Acknowledgement object from the PutMedia operation response, store the FragmentNumber field value from the Payload field. FragmentNumber is the fragment number for the MKV cluster.

  3. When you receive a Kinesis Face Recognition Record from the Kinesis data stream, store the FrameOffsetInSeconds field value from the KinesisVideo field.

  4. Calculate the mapping by using the FrameOffsetInSeconds and FragmentNumber values that you stored in steps 2 and 3. FrameOffsetInSeconds is the offset into the fragment with the specific FragmentNumber that's sent to the Amazon Kinesis data stream. For more information about getting the video frames for a given fragment number, see Amazon Kinesis Video Streams Archived Media.