CE detection

This setup detects complex events from live Android phones or from recorded videos. Both inputs follow the same path: YOLO/YAMNet detections are published through MQTT and evaluated against a YAML complex-event (CE) definition.

See Architecture and replay flow for the complete live and recorded-video design.

Quick start

Requirements:

• Docker with Docker Compose
• Video files, or Android phones running the collector app

Choose a CE and start the receiver stack:

./run ce3

This starts MQTT, MongoDB, the device registry, visualization, and the CE detector. ce3 is shorthand for ce_definitions/iobt_ce3.yaml. Run ./run list to see the other available definitions.

Open the visualization at http://localhost:5000.

Replay recorded videos

Put one or more synchronized videos in a folder:

convoy-recording/
├── outside_phone.mp4
├── building_phone.mp4
└── convoy_phone.mp4

Each filename, without the extension, becomes its device ID. These names must match the devices in the selected CE definition. All videos are assumed to start at the same time.

With the receiver running in Terminal 1, start replay in Terminal 2:

./run replay /path/to/convoy-recording

That is the complete replay setup. No replay manifest or network plan is needed. The folder may contain one video or many videos, and subfolders are searched automatically. Supported formats are MP4, MOV, MKV, AVI, M4V, and WebM.

Replay:

• processes video with the bundled YOLO model;
• processes each video's embedded audio with YAMNet;
• keeps all files on one synchronized timeline; and
• publishes detections through MQTT exactly as live phones do.

Replay does not require NetWaggle.

Use live phones

On each phone, configure:

• MQTT server: the laptop's LAN IP address
• MQTT port: 1883
• Device ID: a device name from the selected CE YAML

Do not use localhost on a physical phone. Start the receiver with ./run ce3, then press toggle record in the app. No replay terminal is needed for live phones.

Define a complex event

CE definitions live in ce_definitions/. A definition declares its device names, atomic detection triggers, ordering, and timing constraints.

For example:

./run gunshot

starts the stack with ce_definitions/gunshot.yaml. See the CE language guide for the YAML format.

Architecture

Live phones and video replay share one observation path:

live phones ─┐
             ├─> MQTT ─> CE detector ─> MongoDB + visualization
video replay ┘

The complete flow, replay synchronization, and five core implementation files are described in docs/architecture.md.

Repository layout

android-app/       Android camera and microphone collector
ce_definitions/    Complex-event YAML files
docs/              Architecture figure
event-detector/    Replay, CE detection, services, and language parser
docker-compose.yml Runtime services
mosquitto.conf     MQTT configuration
run                Start, replay, list, logs, or stop

Useful commands

./run list          # list CE definitions
./run logs          # follow detector output
./run stop          # stop the services

MongoDB data is retained between runs. The development MQTT configuration is unauthenticated and should only be used on a trusted local network.

Build the Android app

Building the app is optional. With Android SDK tools and JDK 17 installed:

cd android-app
./gradlew assembleDebug

The APK is written to android-app/app/build/outputs/apk/debug/app-debug.apk.