DeepStream Pipeline Builder

Generate ready-to-run gst-launch-1.0 pipelines for NVIDIA DeepStream SDK by collecting pipeline requirements through an interactive questionnaire, then assembling the pipeline using a standalone BM25 retrieval backend with structural metadata boosting (similarity search over 270+ verified pipelines, zero external dependencies).

Prerequisites

• Python: 3.8+ (stdlib only — no pip packages required)
• DeepStream SDK: Installed at /opt/nvidia/deepstream/deepstream/ (for gst-inspect-1.0 validation and element verification)
• GStreamer: gst-launch-1.0 and gst-inspect-1.0 on PATH (installed with DeepStream)
• Platform: x86 dGPU (T4, A100, L40, RTX, etc.) or aarch64 — Jetson (Orin, Xavier, Nano) / SBSA (Grace, GH200)

Usage Examples

# Fully specified — skips most questions
detect and track on 4 rtsp streams and display on jetson

# Partially specified — asks remaining questions
give me a pipeline to infer on an image

# Minimal — asks all 7 questions
build a pipeline

Supported Configurations

Scripts

Workflow

Step 1 — Collect Pipeline Requirements

You MUST Read references/requirement-extraction.md before doing this step. It contains the query-inference table, compound-extraction examples, the full AskUserQuestion question bank (with the default-first ordering contract), the automatic-OSD and extras/flip-method rules, and the dynamic question-reduction examples that this step depends on. Apply them exactly.

Order of operations:

1. Infer everything you can from the query using the inference table in references/requirement-extraction.md. The goal is to identify which of the 7 parameters (input source, num sources, inference, tracker, sink, platform, extras) the user has already specified.
2. Ask the user about the unknowns via AskUserQuestion in a single call. Do not silently default tracker/sink/platform/extras — these are real choices the user should make explicitly (display vs save, no tracker vs NvDCF, x86 dGPU vs aarch64 Jetson/SBSA, etc.). Skip only the questions whose answer is already clear from the query.
3. Quote the inferred parameters back to the user in the lead-in to the question call so they can see what you already extracted. Example: "From your query I have: 3 mp4 videos, primary inference. Just need a few more details:"

Follow the inference table, question bank, and OSD/extras rules in references/requirement-extraction.md to decide which questions to ask and how to place transform elements, then proceed to Step 2.

Step 2 — Build the Natural Language Query

From the user's answers, construct a single descriptive query string. Follow this pattern:

Please provide a GStreamer pipeline that [operation] on [num_sources] [input_type] [input_detail] [tracker_detail] and [output_action] [platform_detail]

Examples of constructed queries:

Step 3 — Run the Pipeline Generator Script

Execute the backend script with the constructed query and user parameters:

python3 <skill-path>/scripts/generate_pipeline.py \
  --query "<constructed_query>" \
  --source-type "<Local video file|Local image file|RTSP stream|USB camera|Test pattern>" \
  --num-sources <N> \
  --inference "<None|primary|primary+secondary|primary+preprocess|primary+secondary+preprocess|primary-triton|primary+secondary-triton>" \
  --tracker "<none|NvDCF|IOU|NvSORT|DeepSORT>" \
  --sink "<display|display-jetson|save-jpg|save-png|save-mp4|save-h264|rtsp-out|fakesink>" \
  --platform "<dGPU|Jetson|SBSA>" \
  --extras "<none|resize|rotate|crop|color-convert|osd>" \
  --format compact

Always pass --format compact. The compact mode returns only confidence + the top retrieved pipeline (~25 lines), instead of dumping all 10 retrievals as ~150 lines of JSON in the chat. The json mode (default for backward compat) is only useful when debugging the retriever directly. A summary mode (single human-readable line) also exists for non-Claude callers.

The script will (zero external dependencies — pure Python stdlib):

1. Load the pipeline dataset (270+ verified DeepStream pipelines)
2. Extract structural metadata from each pipeline (platform, source type, sink type, inference mode, tracker, stream count)
3. Score with BM25 (document-length-normalized) + domain-specific synonym expansion on both queries and documents
4. Apply structural boosting — results matching the user's platform/source/sink/inference get boosted, mismatches get penalized
5. Return the top-K results as JSON with a confidence field (high/medium/low) based on the top score
6. Claude uses these retrieved examples + the assembly rules below to construct the final pipeline

When confidence is low, rely more heavily on the assembly rules below rather than the retrieved examples.

Step 4 — Validate the Pipeline

Before presenting, run the validation script to catch syntax errors, unknown elements, and linking issues:

python3 <skill-path>/scripts/validate_pipeline.py "<assembled_pipeline>" --format summary

Always pass --format summary. Summary prints a single status line (e.g. valid · 11 elements · 0 warnings · live-parse skipped (multi-stream)), with errors/warnings indented underneath only if present. The default json mode emits ~40 lines of structured output and is only useful for programmatic callers.

The validator performs 4 checks:

1. Syntax check — unbalanced quotes, empty pipe segments, missing source/sink
2. Element check — verifies each element exists via gst-inspect-1.0
3. Property check — validates known properties for DeepStream elements
4. Live parse check — uses gst-launch-1.0 itself to construct the pipeline graph (with fakesrc/fakesink substituted), catching linking errors and pad mismatches. Automatically skipped for multi-stream pipelines (those with named pad refs like m.sink_0) since fakesrc cannot negotiate caps through named pads.

If validation fails ("valid": false), fix the errors and re-validate before presenting. Limit validation retries to a maximum of 2 attempts — if the pipeline still fails after 2 fixes, present it as-is (the remaining checks already cover syntax, element, property, and structural correctness). If there are only warnings, present the pipeline but mention the warnings to the user.

Step 5 — Present the Pipeline

5.1 — Output format (THE ONLY ACCEPTED FORM)

Your response must be exactly five blocks, in this order:

1. One-line status badge (validation + confidence)
2. Single bash code block containing the full gst-launch-1.0 -e … command with concrete absolute paths, on one line (no \ continuations, no shell variables, no shell wrapper)
3. Breakdown table grouped by stage
4. Suggestions bullet list
5. (only if pre-flight failed) a ⚠ line above the status badge stating which default path is missing

That is the ONLY accepted output shape for this step. The Section 5.3 template in references/output-format.md is the literal template — match it.

5.2 — Pre-flight check (run before composing the response)

Run one Bash ls over the default paths the pipeline will reference (sample video, PGIE config, tracker lib/config). The result tells you whether to mark the badge with ⚠ default path not found: <path> and bump the matching "Use your own …" suggestion to the top.

ls /opt/nvidia/deepstream/deepstream/samples/streams/sample_1080p_h264.mp4 \
   /opt/nvidia/deepstream/deepstream/samples/configs/deepstream-app/config_infer_primary.txt \
   2>&1

5.3 / 5.4 — Worked example & forbidden anti-patterns

You MUST Read references/output-format.md before composing this response. It contains the literal Section 5.3 template your output must match exactly, and the Section 5.4 gallery of forbidden output shapes (heredoc wrappers, shell-var indirection, \ line-continuations, stray "Run it" lines, Write-to-script). Mirror Section 5.3; never emit any Section 5.4 form.

5.5 — Self-check before sending the response

Before you emit your reply, mentally tick each box. If any check fails, rewrite the response.

• The pipeline is on exactly one line inside a single ```bash code block.
• The pipeline begins with gst-launch-1.0 -e and contains only literal absolute paths (e.g. /opt/nvidia/deepstream/...) — no $VAR, no ${VAR:-default}, no cat >, no EOF, no \ line continuations.
• The response does not contain any of: cat > /tmp/pipeline.sh, bash /tmp/pipeline.sh, <<'EOF', ${VAR:-.
• The response does not call the Write tool. (Save-to-file is offered as a suggestion bullet, not an action.)
• The breakdown table is grouped by stage (Source / Mux / Inference / Tracking / Composition / Render — adapt names to the pipeline's actual stages, e.g. add an Encode/Mux row for file sinks).
• The "Save it to a script?" line appears in the Suggestions list — never as a primary action.

5.6 — Pre-flight failure variant

If the Section 5.2 ls reported one or more missing default paths, prepend a ⚠ line above the status badge and bump the matching "Use your own …" suggestion to the top:

⚠ default path not found: `/opt/nvidia/deepstream/deepstream/samples/streams/sample_1080p_h264.mp4` — substitute your own video path before running
✓ Validated · 11 elements · 0 warnings · confidence: HIGH

```bash
gst-launch-1.0 -e filesrc location=/opt/nvidia/deepstream/deepstream/samples/streams/sample_1080p_h264.mp4 ! …
```

[breakdown + suggestions as in Section 5.3, with the "Use your own video" suggestion bumped to the top]

On length: 5–8 stream pipelines run long when on a single line. That is correct and intended — chat clients render bash code blocks faithfully and copy reproduces them correctly. Long ≠ split.

Step 6 — Offer Refinement

After presenting the pipeline, ask the user if they want to adjust anything:

Want me to modify anything? For example:

• Change the number of streams
• Add/remove tracker or secondary inference
• Switch between display and file output
• Change the platform (x86 dGPU / aarch64 Jetson / SBSA)

If the user requests changes, go back to Step 2 with updated parameters — do NOT re-ask all 7 questions. Only ask about the specific parameter that changed, or just apply the change directly if it's clear.

Step 6.5 — Optional: Save Pipeline to a Script

Only do this step when the user explicitly asks (e.g. "save it", "save to pipeline.sh", "write it to a file", "put it in ~/run.sh"). Do not create the file proactively — Step 5 always shows the concrete pipeline in chat for direct copy-paste; saving is a follow-up convenience.

1. Filename: Default to /tmp/pipeline.sh if the user just says "save it". Use the exact path the user named otherwise (e.g. ~/run.sh, scripts/demo.sh).

2. File contents: Two lines — shebang + the same single-line pipeline shown in chat (concrete absolute paths, no shell vars). Keep them in sync — what the user runs from the file is bit-for-bit identical to what they could have copy-pasted.

   #!/usr/bin/env bash
   gst-launch-1.0 -e filesrc location=/opt/nvidia/deepstream/deepstream/samples/streams/sample_1080p_h264.mp4 ! qtdemux ! h264parse ! nvv4l2decoder ! m.sink_0 … ! nvdsosd ! nveglglessink
   

   Use the Write tool to create the file.

3. Confirm to user with the run command:

   Saved to <path>. Run it with:

   bash <path>
   

Pipeline Assembly Rules

When the script is not available or fails, assemble the pipeline using the rules in references/assembly-rules.md. These rules cover source elements, multi-stream patterns, inference chains, tracker configs, sink elements, and extra operations. They also serve as validation for script output.

Error Handling

Testing

Run the test suite to verify retrieval quality and validator correctness:

python3 -m unittest discover -s <skill-path>/tests -v

The suite includes:

• Unit tests for the BM25 retriever (tokenizer, synonym expansion, metadata extraction, scoring)
• Unit tests for the validator (syntax, structure, property, named-pad checks)
• Golden regression tests — 20+ query→expected-result pairs ensuring retrieval quality doesn't regress
• Data quality linter — checks the CSV for duplicates, syntax issues, and structural bugs:

python3 <skill-path>/scripts/lint_data.py          # report issues
python3 <skill-path>/scripts/lint_data.py --fix     # auto-fix and overwrite

Security, Limitations & Notes

Security posture, known limitations, and operational notes are documented in references/security-and-limitations.md. Read that file when you need details on subprocess safety, input validation, platform/SDK requirements, the multi-stream dry-run caveat, or sample-path/config-file reminders.