User goal: ESP32-CAM live preview that works with any webcam,
regardless of resolution, brand, or scene complexity. The previous
fixed-quality 0.28 was fragile (intermittent decode errors on
moving/textured scenes) and capped visual quality unnecessarily.
Two-layer fix; either alone is insufficient:
LAYER A — Bounded JPEG encoder (frontend, this repo)
frontend/src/hooks/useWebcamFrames.ts:
encodeBoundedJpeg() walks a quality ladder [0.6, 0.5, ..., 0.1]
until the JPEG fits in MAX_FRAME_BYTES (23 000). If even q=0.1
overshoots — extreme HD/4K scenes — falls back to a 240×180
downscaled canvas at q=0.4. Guarantees every emitted frame fits
the deliverable budget regardless of webcam hardware.
The hook now exposes lastQualityUsed + lastDownscaled so UI can
surface when auto-tuning kicks in.
frontend/src/components/simulator/CameraToggle.tsx:
Tooltip shows "(auto-tuned to q=0.X)" or "(auto-downscaled, q=0.X)"
while streaming so users see what the encoder picked.
LAYER B — Multi-lap descriptor ring walker (qemu-lcgamboa, submodule)
Bumps the QEMU per-frame deliverable cap from 8 KiB to ~32 KiB by
letting the walker reset the descriptor ring up to 4 times per
VSYNC. Submodule pointer bumped to eb8b7a5d.
Combined, the demo now supports:
- Cheap 480p webcams: q=0.6, 5-10 KiB JPEGs, sharp
- Logitech mid-range: q=0.5-0.6, 8-15 KiB JPEGs, sharp
- HD 1080p webcams: q=0.4-0.6, 15-23 KiB JPEGs, sharp
- 4K complex scenes: downscaled, still readable
Documented as bug closure in:
test/test-esp32-cam/autosearch/15_universal_webcam_compat.md
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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