AGENTS.md — ByteTrack Counter C++

RKNN Dynamic Shape Requirement

The RKNN model (zenai_apc_cicalengka_20260609.rknn) is exported with dynamic input shapes (model inference type: dynamic_shape). The C API requires calling rknn_set_input_shapes() before rknn_inputs_set(). Without it, librknnrt.so crashes with:

std::out_of_range: vector::_M_range_check: __n (which is 18446744073709551615) >= this->size() (which is 1)

This is called in the constructor of RKNNYOLO at src/rknn_yolo.cpp:60, right after querying input attributes:

in_attr.dims[0] = 1;
in_attr.dims[1] = imgsz_;
in_attr.dims[2] = imgsz_;
in_attr.dims[3] = 3;
in_attr.n_dims = 4;
ret = rknn_set_input_shapes(rknn_ctx_, io_num.n_input, &in_attr);

Build

cd /opt/bytetrack-counter-cpp/build
cmake .. -DHAS_RKNN=ON
make -j$(nproc)

Service

systemctl restart bytetrack-counter
journalctl -u bytetrack-counter -f

Reset via .reset file

Place a .reset file in SHM_DIR (default /dev/shm/bytetrack-counter) to trigger a full state reset:

Startup: deleting .reset before service starts clears all state files on boot
Runtime: dropping .reset while service runs calls BatchStore::reset() — ends active batch, clears in-memory state, deletes STATE_FILE, clears live stream JPEG + writes blank frame on next write

touch /dev/shm/bytetrack-counter/.reset

Shared memory

SHM_DIR (/dev/shm/bytetrack-counter by default) stores:

LIVE_STREAM_FRAME_PATH JPEG snapshot
RECORD_SHM_DIR video recordings before move to disk
.reset trigger file

Directory auto-created at startup.

Video recordings

Recordings are written to SHM_DIR as batch_pending_*.mp4, confirmed when ayam detected, and moved via fork() (non-blocking) to OUTPUT_DIR/<batch counting_date>/batch_<num>_<YYYYMMDD>_<HHMMSS>.mp4.
The day folder uses the batch counting date (today before DAILY_CUTOFF_TIME, tomorrow after), forwarded from BatchStore through the batch-closed callback — matching the SQLite counting_date.
Retention cleanup compares day folders with std::localtime to match folder naming.
H.264 encode quality is set via RECORD_CRF (lower = better, default unset) and RECORD_PRESET — start_recording() writes OPENCV_FFMPEG_WRITE_OPTIONS (crf;<n>|preset;<p>) before writer_.open().

Source override

bytetrack-counter <config.env> --source /tmp/test.mp4      # local file (single pass)
bytetrack-counter <config.env> --source rtsp://cam:554/x   # live stream
bytetrack-counter <config.env> -s path  # or --source=path

Pause on first frame (file sources)

For local file input, hold the first frame as the live stream view until signalled:

Enable via --pause-on-first-frame (CLI, overrides env) or PAUSE_ON_FIRST_FRAME=true.
Frame 0 is fully processed (inference, tracking, HUD) then the loop idles: the annotated frame is re-written to LIVE_STREAM_FRAME_PATH while polling for SHM_DIR/.continue.
Resume by touch /dev/shm/bytetrack-counter/.continue (file is deleted on consume).
Ignored for live (rtsp/http) sources with a warning. A stale .continue is cleared at startup.

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