Concurrent VHD_OpenBoardHandle calls from multiple capture sidecars
trigger delta_x300 BufMngr.c:781 array-index-out-of-bounds, wedging all
RX channels until the module is reloaded. The node-agent stagger only
delays container start — the bridge binary starts ~2s later and can still
race. This fix acquires an exclusive flock on /dev/shm/deltacast/bridge.lock
before VHD_OpenBoardHandle and holds it until signal lock succeeds (then
adds a 4s settle before releasing so the board's buffer queues stabilize).
Lock is released on signal failure too so the next bridge is never
permanently blocked. All 8 channels can now start safely by serializing
through the same lock file mounted into every sidecar.
ffmpeg opens all inputs before processing; input 1 is the audio FIFO. The
bridge previously opened the FIFO writer only after VHD_OpenStreamHandle +
VHD_StartStream succeeded, returning early on failure / no embedded audio and
never opening the FIFO -> ffmpeg blocked forever on input 1 -> 0 fps and an
empty HLS preview. Now the FIFO writer is opened unconditionally and first,
and the audio thread feeds a continuous, wall-clock-paced s16le stereo stream
(real samples when available, otherwise silence). SIGPIPE is ignored so a
dying ffmpeg returns EPIPE instead of killing the bridge.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
