mikkeli
d438b516e5
Camera-agnostic (--camera auto finds any V4L2 capture device and finds it again after a replug; non-MJPEG cameras are encoded), says when the camera is unavailable, paced per decision 28. Python, standard library only. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz
36 lines
1.6 KiB
Markdown
36 lines
1.6 KiB
Markdown
---
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type: guidelines
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---
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# Vision guidelines
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## 1. Camera-agnostic
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- Any V4L2 capture device works. Never hard-code a node such as `/dev/video0`:
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numbering follows enumeration order. Take a `/dev/v4l/by-id/` path, or find
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the camera at runtime (`--camera auto`).
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- Use what the camera offers. MJPEG passes through untouched; anything else is
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encoded here. A requested size or rate the camera lacks falls back to its own
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default rather than failing.
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- UVC control names differ between cameras and kernels. Look them up on the
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device; reply that a control is missing rather than guessing.
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## 2. One process owns the camera
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- V4L2 capture is single-reader. This service opens the device; recording and
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inference take frames from it, never from the device.
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- UVC controls reset when the camera re-enumerates. Set them on open, not once.
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## 3. The tablet link is the constraint
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- Every socket to a display is paced (`SO_MAX_PACING_RATE`, project-yukart
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decision 28). Unpaced bursts stall the USB link for seconds.
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- Latest frame wins. A slow client skips frames; it never gets a queue of old ones.
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- Say when there is no camera. A client must be able to tell "unavailable" from
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"slow".
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## 4. Python, on purpose
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- Python 3.10 (the Orin's), standard library only; GStreamer and v4l-utils come
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from the host. The exception to Rust for Orin services is decision 29: camera
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pipelines and inference live in the Python ecosystem.
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- No pip installs on the car Orin until there is a reason; then a venv under
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`~/infra/svc-vision/`, never the system Python.
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## 5. To be added
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