> For clean Markdown of any page, append .md to the page URL. > For a complete documentation index, see https://docs.nvidia.com/holoscan/sdk-user-guide/llms.txt. > For full documentation content, see https://docs.nvidia.com/holoscan/sdk-user-guide/llms-full.txt. > For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.nvidia.com/holoscan/sdk-user-guide/_mcp/server. The units of work of Holoscan applications are implemented within Operators, as described in the [core concepts](/holoscan/sdk-user-guide/using-the-sdk/holoscan-core) of the SDK. The operators included in the SDK provide domain-agnostic functionalities such as IO, machine learning inference, processing, and visualization, optimized for AI streaming pipelines, relying on a set of [Core Technologies](/holoscan/sdk-user-guide/introduction/relevant-technologies). ## Operators The operators below are defined under the `holoscan::ops` namespace for C++ and CMake, and under the `holoscan.operators` module in Python. If you are new to Holoscan, a common starting pipeline is: `VideoStreamReplayerOp`/`V4L2VideoCaptureOp` -> `FormatConverterOp` -> `InferenceOp` -> `SegmentationPostprocessorOp` -> `HolovizOp`. ### Imaging and visualization | Class | Typical use | API reference | | --------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------- | | **BayerDemosaicOp** | Convert Bayer RAW camera input to RGB/BGR style images for downstream processing. | C++ (`holoscan::ops::BayerDemosaicOp`)/Python (`holoscan.operators.BayerDemosaicOp`) | | **FormatConverterOp** | Convert between tensor/image formats, memory layouts, and data types between operators. See [Byom Example](/holoscan/sdk-user-guide/using-the-sdk/holoscan-by-example/byom#byom-example). | C++ (`holoscan::ops::FormatConverterOp`)/Python (`holoscan.operators.FormatConverterOp`) | | **HolovizOp** | Visualize tensors, overlays, geometry, and results for debugging or runtime display. See [visualization](/holoscan/sdk-user-guide/operators/visualization). | C++ (`holoscan::ops::HolovizOp`)/Python (`holoscan.operators.HolovizOp`) | ### Inference and post-processing | Class | Typical use | API reference | | ------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------ | | **InferenceOp** | Run one or more AI models (including dependency-ordered pipelines) in streaming applications. See [Inference](/holoscan/sdk-user-guide/operators/operators-and-extensions#inference). | C++ (`holoscan::ops::InferenceOp`)/Python (`holoscan.operators.InferenceOp`) | | **InferenceProcessorOp** | Apply model-specific preprocessing/postprocessing around inference outputs. | C++ (`holoscan::ops::InferenceProcessorOp`)/Python (`holoscan.operators.InferenceProcessorOp`) | | **SegmentationPostprocessorOp** | Convert raw segmentation model outputs into masks/labels suitable for display or downstream logic. | C++ (`holoscan::ops::SegmentationPostprocessorOp`)/Python (`holoscan.operators.SegmentationPostprocessorOp`) | ### Source, replay, and recording | Class | Typical use | API reference | | ------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------ | | **V4L2VideoCaptureOp** | Capture live video frames from V4L2 devices on Linux systems. | C++ (`holoscan::ops::V4L2VideoCaptureOp`)/Python (`holoscan.operators.V4L2VideoCaptureOp`) | | **VideoStreamReplayerOp** | Replay recorded streams for deterministic development, benchmarking, and regression testing. See [Video Replayer Example](/holoscan/sdk-user-guide/using-the-sdk/holoscan-by-example/video-replayer#video-replayer-example). | C++ (`holoscan::ops::VideoStreamReplayerOp`)/Python (`holoscan.operators.VideoStreamReplayerOp`) | | **VideoStreamRecorderOp** | Record tensor streams to disk for offline replay and reproducible experiments. | C++ (`holoscan::ops::VideoStreamRecorderOp`)/Python (`holoscan.operators.VideoStreamRecorderOp`) | ### Basic networking | Class | Typical use | API reference | | ------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------- | | **PingTxOp** | Emit synthetic scalar data to test graph connectivity and scheduling behavior. See [native operator ping example](/holoscan/sdk-user-guide/operators/operators-and-extensions#ping-multi-port-cpp) and [native operator ping example](/holoscan/sdk-user-guide/operators/operators-and-extensions#ping-multi-port-python). | C++ (`holoscan::ops::PingTxOp`)/Python (`holoscan.operators.PingTxOp`) | | **PingRxOp** | Receive and inspect synthetic scalar data in tutorial or debugging pipelines. See [native operator ping example](/holoscan/sdk-user-guide/operators/operators-and-extensions#ping-multi-port-cpp) and [native operator ping example](/holoscan/sdk-user-guide/operators/operators-and-extensions#ping-multi-port-python). | C++ (`holoscan::ops::PingRxOp`)/Python (`holoscan.operators.PingRxOp`) | | **PingTensorTxOp** | Emit synthetic tensor payloads to validate tensor paths and operator interoperability. | C++ (`holoscan::ops::PingTensorTxOp`)/Python (`holoscan.operators.PingTensorTxOp`) | | **PingTensorRxOp** | Receive synthetic tensor payloads for debugging C++/Python tensor flow behavior. | C++ (`holoscan::ops::PingTensorRxOp`)/Python (`holoscan.operators.PingTensorRxOp`) | For complete, end-to-end application examples that combine these operators, see the [Holoscan SDK examples](https://github.com/nvidia-holoscan/holoscan-sdk/blob/main/examples#holoscan-sdk-examples) and the [Holohub repository](https://github.com/nvidia-holoscan/holohub). Given an instance of an operator class, you can print a human-readable description of its specification to inspect the inputs, outputs, and parameters that can be configured on that operator class: ```cpp std::cout << operator_object->spec()->description() << std::endl; ``` ```python print(operator_object.spec) ``` The Holoscan SDK uses meta-programming with templating and `std::any` to support arbitrary data types. Because of this, some type information (and therefore values) might not be retrievable by the `description` API. If more details are needed, we recommend inspecting the list of `Parameter` members in the operator [header](https://github.com/nvidia-holoscan/holoscan-sdk/blob/main/include/holoscan/operators) to identify their type. ### Holoscan UCX GXF Extension The `ucx_holoscan` extension includes `nvidia::holoscan::UcxHoloscanComponentSerializer` which is a `nvidia::gxf::ComponentSerializer` that handles serialization of `holoscan::Message` and `holoscan::Tensor` types for transmission using the Unified Communication X (UCX) library. UCX is the library used by Holoscan SDK to enable communication of data between fragments in distributed applications. For more details see the [Creating Holoscan Distributed Application](/holoscan/sdk-user-guide/using-the-sdk/create-a-distributed-application#creating-holoscan-distributed-application) page. The `UcxHoloscanComponentSerializer` is intended for use in combination with other UCX components defined in the GXF UCX extension. Specifically, it can be used by the `UcxEntitySerializer` where it can operate alongside the `UcxComponentSerializer` that serializes GXF-specific types (`nvidia::gxf::Tensor`, `nvidia::gxf::VideoBuffer`, etc.). This way both GXF and Holoscan types can be serialized by distributed applications. ### Holohub Holohub is an open collection of reusable Holoscan operators, applications, workflows, and supporting tools designed to accelerate Holoscan-based development. You can browse the full set of operators directly in the [Holohub repository](https://github.com/nvidia-holoscan/holohub/tree/main/operators) or explore them with detailed documentation and search features on the [Holohub documentation website](https://nvidia-holoscan.github.io/holohub/operators/). For a quick overview of Holohub, see the [Holohub Overview](/holoscan/sdk-user-guide/holo-hub/holo-hub-overview#holohub).