ProPresenter 21.4 exposes no timecode through any API, so read the LTC
where it actually lives — the audio feed:
- tools/ltc-reader.js: zero-dependency SMPTE LTC decoder (biphase-mark,
adaptive bit clock, envelope-scaled comparator) fed s16le PCM on stdin
from ffmpeg/sox; POSTs running/stopped/nosignal + timecode + frame rate
(incl. 29.97 drop-frame) to the module. --selftest runs an encoder→
decoder suite (24/25/30 fps, DF minute counting, low level + noise + DC,
dropout recovery); --demo synthesizes live LTC through the real decoder
and ingest path with no audio hardware.
- Module: POST /ltc ingest route (optional bearer token, validated body,
6 s staleness with automatic fallback to the API probe / stage source),
richer LTC state (status, fps, df, reader source), health messages.
- Client: LTC card shows Running · <rate> / Stopped (held frame) /
No signal; works LTC-only with no ProPresenter host configured; the
reader-fed card no longer grays out when only ProPresenter is down.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
