gst-nvmm-cpp¶

Zero-copy NVMM-native GStreamer elements for NVIDIA Jetson (Xavier, Orin): hardware-accelerated video processing, TensorRT inference graphs, and inter-process video sharing with no CPU copies on the data path. C++14 internals, C-ABI boundary to GStreamer, LGPL, no DeepStream dependency.

On Jetson the native buffer type is NvBufSurface (NVMM) — physically contiguous, DMA-coherent memory operated on by the Tegra VIC. The stock nvcodec plugin targets desktop GPUs and does not understand NVMM; DeepStream does, but is heavyweight and single-process. This suite provides small standalone elements for that memory model, including a cross-process zero-copy NVMM transport (nvmmsink → nvmmappsrc) for which NVIDIA ships no stock element. See Zero-copy IPC.

Elements¶

Memory & IPC — the allocator and the cross-process transport.

Element	Role
`nvmmalloc`	`GstAllocator` for `NvBufSurface`; underpins the suite's buffer pools
`nvmmsink`	Publish NVMM frames to a shared pool; pass DMA-buf fds to consumers
`nvmmappsrc`	Import a producer's pool fds and read GPU memory in place

Video processing — 2D operations on the VIC.

Element	Role
`nvmmconvert`	Crop / scale / format-convert / rotate-flip
`nvmmcompositor`	Composite multiple NVMM inputs into one frame (mosaic / PiP)

Inference & analytics — composable nodes for building inference graphs; each passes the frame through untouched and reads or attaches metadata.

Element	Role
`nvmminfer`	TensorRT object detection; attaches `GstNvmmDetMeta`
`nvmmtracker`	IOU multi-object tracking; assigns stable `tracker_id`s
`nvmmofa`	Dense optical flow on the Orin OFA engine; flow rides as metadata
`nvmmfusion`	Joins detector + flow branches by PTS; computes per-object motion
`nvmmsecondaryinfer`	Cascade classifier on detected objects, with per-track caching
`nvmmdrawdet`	Renders boxes, ids, motion and classification onto the frame

Where to start¶

Getting started — build and run the first pipeline.
Pipeline examples — transport, processing and encoding.
Inference graphs — combining the analytics elements.
Creating a new element — extend the suite with your own node.

Status¶

Validated on Jetson Xavier NX (JP5.1.2) and Orin NX (JP6); the unit/integration suite runs on x86 CI against a mock NvBufSurface and on-device against the real stack — see Validation & benchmarks.