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LinuxPy Camera Controller (Example)

This LinuxPy-based controller is an example for generic V4L2 devices (/dev/video*). It is meant as a starting point for community contributions and quick experiments, not as a complete camera driver.

If you need extensive camera-specific behavior (custom controls, quirks, tuning, workarounds), it is usually cleaner to create a dedicated camera controller for your device (similar to Picamera2Controller) instead of growing the LinuxPy controller.

What it does

  • Preview uses a persistent VideoCapture session to avoid re-opening the device for each frame.
  • Photos are captured as JPEG from the V4L2 stream.
  • Fallback formats (RGB/YUV/pseudo-DNG) are derived from the JPEG stream.
  • EXIF orientation: CameraSettings.orientation_flag is embedded into JPEG EXIF (same idea as Picamera2).

Limitations

  • Many devices don't expose controls via LinuxPy (no set_control, empty controls), so settings like saturation/contrast/gain/JPEG quality may not have any effect.
  • No AF/AWB lock, no scaler cropping, no true RAW/DNG.

Where to start tweaking

  • openscan_firmware/controllers/hardware/cameras/linuxpy.py:
    • _CONTROL_MAP and _JPEG_QUALITY_CONTROL (control name mapping)
    • _apply_basic_controls() (where settings are applied)

Verifying your webcam

v4l2-ctl --list-devices
python - <<'PY'
from linuxpy.video.device import Device
dev = Device("/dev/videoX")  # replace with your device node
dev.open()
print("has set_control:", hasattr(dev, "set_control"))
print("controls:", dev.controls)
dev.close()
PY