External cameras in HTTP-snapshot mode failed to load with a repeating
"connection lost" when the endpoint served PNG/WebP/BMP stills instead of
JPEG (common on IP cameras and reverse-proxied snapshot URLs). The URL
rendered fine directly in a browser, but Bambuddy's MJPEG stream wraps
every part in a hard-coded Content-Type: image/jpeg boundary, so a
non-JPEG payload labelled as JPEG made the browser reject the frame and
tear down the whole multipart/x-mixed-replace stream.
_capture_snapshot now transcodes non-JPEG stills to JPEG via OpenCV
(already a dependency). Genuine JPEG snapshots keep a byte-for-byte fast
path; truly undecodable responses (HTML error pages, auth redirects) fall
back to the previous raw-return behaviour with a single clear warning
instead of a per-frame log flood.
go2rtc and several IP cameras still emit a warm-up / black frame on every
fresh MJPEG connection — even with the v0.2.4b2 warm-up-skip fix it
slipped through intermittently for @nkm8's setup. His own bisect named
the clean solution: go2rtc exposes /api/frame.jpeg as a dedicated
single-frame endpoint that never returns the encoder's stale keyframe.
Adds an optional external_camera_snapshot_url column on printers. When
set, every single-frame capture path (snapshot endpoint, [SNAPSHOT]
notification thumbnails, [PHOTO-BG] finish photo, layer timelapse,
Obico ML, plate-detect / calibrate-plate) routes through _capture_snapshot
on the override URL via plain HTTP GET, bypassing the warm-up dance.
Live view stays on the configured stream URL — only single-frame
captures use the override. Override is camera-type-agnostic. SSRF guard
applies (existing _sanitize_camera_url allowlist). Empty string treated
as unset.
Settings UI: new "Snapshot URL (optional)" input + Test button under
External Cameras, hidden for camera_type=snapshot since the live URL is
already a single-frame source. en + de fully translated; 6 other locales
seeded with English copy.
5 backend tests pin the routing contract; 3 frontend tests pin the
input + debounced PATCH. Documented in
bambuddy-wiki/docs/features/camera.md with the go2rtc example.
_capture_mjpeg_frame returned the very first JPEG it found in the
bytes stream, but many MJPEG sources — go2rtc most notably, and
several IP cameras — emit a warm-up frame on the byte that follows
connection accept: usually the last keyframe held in the encoder,
typically black or stale until the encoder catches up to live
content. Subsequent frames on the same connection are fine.
Result: every code path that opened a fresh capture (snapshot UX,
finish photos in notifications, timelapse, plate-detection CV,
Obico ML inference, Settings → Test button) returned a black image
on go2rtc-fronted cameras.
Reporter's support log showed every black frame was 11095 bytes
(pure-black 1280x720 JPEG ≈ 10-15 KB) while real-content frames
from the same source were 30-45 KB.
Fix:
- Read past the first complete JPEG, return the second.
- Fall back to the first frame if the connection closes / times out /
hits the 5 MB buffer cap before a second arrives. Without that
fallback, slow / single-frame streams that pre-fix returned the
warm-up would post-fix return None — a regression. The fallback
guarantees we never do worse than current behaviour.
- Inner while-loop now drains every complete frame already in the
buffer before pulling the next chunk so high-FPS sources that
pack multiple frames per chunk are handled correctly.
Untouched: snapshot / rtsp / usb capture paths, generate_mjpeg_stream
(live-view fan-out).
7 new regression tests in TestCaptureMjpegFrameWarmupSkip cover
two-frames-in-two-chunks, two-frames-in-one-chunk, partial-frame-
split-across-chunks, single-frame fallback, timeout fallback, zero-
frame stream returns None, non-200 returns None.
Latency penalty: at most one frame interval (typically 50 ms - 1 s
on a steady stream), well within every caller's tolerance window.
- Remove 28 unused imports across 22 test files
- Prefix 4 unused local variables with _ in app code
(archives, bambu_mqtt, main) and remove 1 dead store
- Consolidate import/import-from in test_plate_detection.py
- Fix unreachable statement in test_archive_service.py
- Simplify redundant comparison in timelapse_processor.py
Resolves ~50 CodeQL py/unused-import, py/unused-local-variable,
py/import-and-import-from, py/unreachable-statement, and
py/redundant-comparison findings.
- Add USB camera type to external camera service
- Auto-detect available V4L2 devices on Linux
- New API endpoint: GET /api/v1/printers/usb-cameras
- Use ffmpeg for USB camera capture and streaming
- Add "USB Camera (V4L2)" option in Settings UI
- Debounce camera URL input to avoid saving on every keystroke
Closes#143
Add support for external network cameras (MJPEG, RTSP, HTTP snapshot)
that replace a printer's built-in camera when configured.
Features:
- Live streaming on printers page (replaces built-in camera)
- Finish photo capture from external camera on print complete
- Layer-based timelapse: captures frame on each layer change,
stitches to MP4 video on print completion
Backend changes:
- Add external_camera_url, external_camera_type, external_camera_enabled
fields to Printer model with database migration
- New external_camera.py service: MJPEG/RTSP/snapshot frame capture,
connection testing, MJPEG stream generation
- New layer_timelapse.py service: TimelapseSession management,
layer-by-layer frame capture, ffmpeg video stitching
- Add on_layer_change callback to MQTT client and printer manager
- Update camera routes with external camera streaming and tracking
- Update print lifecycle hooks for timelapse start/stitch/cancel
- Add external camera fields to backup/restore
- Rate limiting for external camera streams (prevents browser freeze)
Frontend changes:
- Add external camera configuration UI in Settings > Camera
- Per-printer enable toggle, URL input, type selector, test button
- Toast notification on save
Closes#143
maziggy