| name | sahi-build-plugins |
| description | Rebuild and test the SAHI C++ plugins / nvinfer parser after editing them. Use when changing gst-nvsahipreprocess, gst-nvsahipostprocess, or libs/nvdsinfer_yolo, and you need to verify it compiles and the result is correct. |
Build & test the SAHI plugins
There is no host build — the plugins need the DeepStream SDK headers, so build inside the container.
Build (fast path)
docker exec ds-sahi bash -lc 'cd /apps/deepstream-sahi && ./install.sh --plugins-only'
--plugins-only rebuilds only nvsahipreprocess, nvsahipostprocess, and libnvds_infer_yolo.so
(≈1–2 min). Flags -Wall -Werror -O2, so warnings fail the build.- Outputs:
/opt/nvidia/deepstream/deepstream/lib/gst-plugins/libnvdsgst_sahi{pre,post}process.so,
/opt/nvidia/deepstream/deepstream/lib/libnvds_infer_yolo.so.
- Verify a parser symbol is exported:
nm -D .../libnvds_infer_yolo.so | grep NvDsInferYolo.
Correctness A/B (MANDATORY for postprocess/parser changes)
A perf change must NOT change detections. Compare obj/frame before vs after on a dense video:
docker exec ds-sahi bash -lc '... python3 deepstream_test_sahi.py --model <m> --no-display --csv -i ../videos/aerial_crowding_01.mp4'
To revert for the A/B: git stash push -- <file> → rebuild → run → git stash pop → rebuild.
A real example from this repo: the SahiSpatialGrid::query visited-stamp change was neutral (~23%
faster postprocess, identical results); a companion cell_size=median change altered results and was
rejected. Always isolate one change at a time when results move.
Profiling
- Postprocess time:
GST_DEBUG=nvsahipostprocess:4 → avg X ms/frame.
- The GST latency tracer does not give per-element times for DeepStream elements; instrument with
a 1 s counter like the one in
gstnvsahipostprocess.cpp if you need preprocess timing.
Gotchas
results/ and built .so/.engine are root-owned (container) — sudo chown on the host if needed.- Keep the container alive between edits so the engine cache + pyds build are reused.
