# Face Recognition

Face Recognition identifies faces that are detected in media. Before using face recognition you must train Media Server to recognize faces, by providing images of people who you want to recognize.

Configuration Parameter | Description
--- | ---
Database | A face database to use to recognize faces. Media Server compares the detected faces to faces in this database.
GPUBatchingDuration | The maximum amount of time to wait, before sending a batch of video frames to the GPU for analysis.
GPUNumParallel | The maximum number of video frames to analyze concurrently using the GPU (per CPU thread).
Identifier | A comma-separated list of identifiers that specifies the faces to recognize.
Input | The track that you want to analyze.
MaxFaces | The maximum number of faces that you want to recognize.
MaxRecognitionResults | The maximum number of recognition results to return per face.
Metadata | A metadata field name and value that specifies the faces to recognize.
NumParallel | The maximum number of CPU threads to use for analysis.
OutputIdentities | The types of identities to include in the output (`all`, `known`, or `unknown`).
RecognitionThreshold | The minimum confidence score required to consider a face as a match.
SegmentDuration | The maximum duration of a record in the `SegmentedResult` or `SegmentedResultWithSource` track.
SyncDatabase | Specifies whether to synchronize with the training database before beginning the analysis task.
Type | The analysis engine to use. Set this parameter to `FaceRecognize`.

## Output Tracks

Output track | Description | Output1This column indicates whether the information contained in the track is included by default in the output created by an output task (when you don't set the Input parameter for the output task).
--- | --- | ---
`Data` | Contains records that describe a face recognition result for a single input record. | No
`DataWithSource` | The same as the `Data` track, but each record also includes the source frame. | No
`Result` | Contains zero or more records, each describing a face recognition result, for each detected face. (There can be multiple recognition results when there are several matches that exceed the recognition threshold. See the configuration parameters OutputIdentities, RecognitionThreshold, and MaxRecognitionResults). Face recognition results inherit their ID from the detected face, so all of the recognition results for the same detected face have the same ID. | Yes
`ResultWithSource` | The same as the `Result` track, but each record also includes the best source frame. | No
`SegmentedResult` | (Available only when processing video). The same as the `Result` track, except the duration of each record is limited by the parameter SegmentDuration. If a result exceeds the specified duration, Media Server begins a new record with the same ID. | Yes
`SegmentedResultWithSource` | (Available only when processing video). The same as the `ResultWithSource` track, except the duration of each record is limited by the parameter SegmentDuration. If a result exceeds the specified duration, Media Server begins a new record with the same ID. | No

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