Table of Contents

Class OcrBlock

Namespace
VisioForge.Core.MediaBlocks.AI
Assembly
VisioForge.Core.AI.dll

An OCR (optical character recognition) media block that recognizes text in video frames using a multi-stage PaddleOCR (PP-OCR) ONNX pipeline. Implements the VisioForge.Core.MediaBlocks.MediaBlock. Implements the VisioForge.Core.MediaBlocks.IMediaBlockInternals.

public class OcrBlock : MediaBlock, IMediaBlock, IDisposable, IMediaBlockInternals

Inheritance

MediaBlock

Implements

IMediaBlock
IMediaBlockInternals

Inherited Members

MediaBlock._isBuilt
MediaBlock._pipeline
MediaBlock._pipelineCtx
MediaBlock.GetPipelineContext()
MediaBlock.SetPipelineContext(BlockPipelineContext)
MediaBlock.SetPipeline(MediaBlocksPipeline)
MediaBlock.Context
MediaBlock.Name
MediaBlock.IsBuilt
MediaBlock.Owner
MediaBlock.Type
MediaBlock.ID
MediaBlock.Input
MediaBlock.Inputs
MediaBlock.Output
MediaBlock.Outputs
MediaBlock.HasInputs
MediaBlock.HasOutputs
MediaBlock.Build()
MediaBlock.CreateElements()
MediaBlock.AddElementsToPipeline()
MediaBlock.RemoveElementsFromPipeline()
MediaBlock.DeepCopy(string)
MediaBlock.Reset()
MediaBlock.ToYAMLBlock()
MediaBlock.ClearPads()
MediaBlock.Dispose(bool)
MediaBlock.Dispose()

Remarks

Taps RGBA frames via an internal sample grabber, runs text detection → optional angle classification → recognition on each processed frame, optionally draws the recognized regions into the frame, and raises VisioForge.Core.MediaBlocks.AI.OcrBlock.OnTextDetected for every frame that yields at least one region. Inference runs on the pipeline's streaming thread; use VisioForge.Core.Types.X.AI.OcrSettings.FramesToSkip to reduce the OCR rate on live video.

Constructors

OcrBlock(OcrSettings)

Initializes a new instance of the VisioForge.Core.MediaBlocks.AI.OcrBlock class.

public OcrBlock(OcrSettings settings)

Parameters

settings OcrSettings

The OCR settings. Must specify valid detection and recognition model paths and a character dictionary.

Exceptions

ArgumentNullException

Thrown when settings is null.

Properties

ActiveProvider

Gets the execution provider that the OCR sessions actually engaged. Valid after the block has been built; reports VisioForge.Core.Types.X.AI.OnnxExecutionProvider.CPU otherwise.

public OnnxExecutionProvider ActiveProvider { get; }

Property Value

OnnxExecutionProvider

DroppedFrameCount

Gets the number of frames that arrived while the background OCR worker was still busy and were therefore skipped for recognition (the live video is unaffected). A high value relative to the frame rate means OCR cannot keep up; raise VisioForge.Core.Types.X.AI.OcrSettings.FramesToSkip or use a faster execution provider.

public long DroppedFrameCount { get; }

Property Value

long

Input

Gets the primary input pad.

public override MediaBlockPad Input { get; }

Property Value

MediaBlockPad

Inputs

Gets the array of all input pads.

public override MediaBlockPad[] Inputs { get; }

Property Value

MediaBlockPad[]

LastInferenceTimeMs

Gets the wall-clock time, in milliseconds, the most recent OCR run took (detection + optional angle classification + recognition). OCR runs on a background thread; use this to tune VisioForge.Core.Types.X.AI.OcrSettings.FramesToSkip to the hardware.

public float LastInferenceTimeMs { get; }

Property Value

float

Output

Gets the primary output pad.

public override MediaBlockPad Output { get; }

Property Value

MediaBlockPad

Outputs

Gets the array of all output pads.

public override MediaBlockPad[] Outputs { get; }

Property Value

MediaBlockPad[]

Type

Gets the type of the media block.

public override MediaBlockType Type { get; }

Property Value

MediaBlockType

Methods

Build()

Constructs the internal GStreamer elements and pads for this block.

public override bool Build()

Returns

bool

true if successful, false otherwise.

CleanUp()

Cleans up internal resources, specifically the GStreamer element.

public void CleanUp()

Dispose(bool)

Releases unmanaged and - optionally - managed resources.

protected override void Dispose(bool disposing)

Parameters

disposing bool

true to release both managed and unmanaged resources; false to release only unmanaged resources.

GetCore()

Gets the core GStreamer element wrapped by this block.

public BaseElement GetCore()

Returns

BaseElement

The VisioForge.Core.GStreamer.Base.BaseElement wrapper, or null if not built yet.

GetElement()

Gets the GStreamer element instance.

public Element GetElement()

Returns

Element

The Gst.Element, or null if not built yet.

IMediaBlockInternals.SetContext(MediaBlocksPipeline)

Sets the pipeline context for this block.

void IMediaBlockInternals.SetContext(MediaBlocksPipeline pipeline)

Parameters

pipeline MediaBlocksPipeline

The pipeline.

OnTextDetected

Event raised when one or more text regions are recognized in a video frame.

public event EventHandler<OcrTextDetectedEventArgs> OnTextDetected

Event Type

EventHandler<OcrTextDetectedEventArgs>

See Also

MediaBlock
IMediaBlockInternals