Measured six recordings off a live P25 node and found two independent
defects causing lost audio at the end of calls:
- stop_recording() sliced the ring buffer immediately, so if the MP3
muxer had not yet delivered the tail the file was silently short.
Now waits (bounded, 2s) until buffered audio covers the end epoch.
- TGID-change closes used the new grant's epoch as the end with no pad
at all, guaranteeing truncation on every split. Tail pad is now a
setting, default raised 0.5s -> 1.0s.
The ring buffer also capped maximum call length: a call longer than the
buffer had its front silently clamped. The ring now serves the pre-roll
only, with a per-call accumulator for the rest, bounded at 4.8MB.
Clamping is loudly warned rather than silent.
Uploads averaged 63% silence, which inflates STT cost and is a known
Whisper hallucination trigger. Leading/trailing silence is now trimmed
conservatively (-40dB, 0.25s guard, internal pauses untouched).
started_at/ended_at still describe the call; new audio_* fields carry
the trimmed audio bounds so playback can map back to wall clock.
All-silence recordings are skipped and logged instead of uploaded.
Also: log measured control-channel idle on idle-timeout closes so
CALL_IDLE_TIMEOUT can be tuned from data, and quiet the httpx logger
which emitted ~170k lines/day of poll noise.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
op25-container/system.pa New PulseAudio config: auth-anonymous=1 so the edge-node can connect without group membership
op25-container/Dockerfile Copies system.pa into /etc/pulse/system.pa
drb-edge-node/Dockerfile Added libpulse0 — ffmpeg needs this runtime library to use -f pulse
drb-edge-node/app/internal/call_recorder.py Switched recording from Icecast (burst-buffer overlap) to PulseAudio monitor (zero-delay, exact call boundaries)
Logan Cusano