Run Both Applications Simultaneously#

Both Live Video Captioning and Loitering Detection can run in parallel on the same camera from the same Nx Witness integration.

Prerequisite — avoid container name and port conflicts#

The Loitering Detection (LD) and Live Video Captioning (LVC) stacks share some service names and host ports by default. Update the Loitering Detection docker-compose.yml file with the following changes to avoid clashes:

Service

Change

broker

Host port changed from 1883 to 1884 ("1884:1883")

dlstreamer-pipeline-server

Container name changed to dlstreamer-pipeline-server-ld

coturn

Container name changed to coturn-ld; host port changed to 3479

metrics-manager

Container name changed to metrics-manager-ld

Run applications simultaneously#

  1. Start the LVC stack (its broker occupies host port 1883):

    cd metro-ai-suite/live-video-analysis/live-video-captioning
docker compose up -d

  2. Start the LD stack (its broker now occupies host port 1884):

    cd metro-ai-suite/metro-vision-ai-app-recipe
docker compose up -d

  3. Update .env in the VAP directory so the LD MQTT subscriber uses the LD broker on port 1884:

    # metro-ai-suite/vms-adapter-plugin/.env
MQTT_PORT=1884

  4. Start VAP (already configured with both apps in config.yaml):

    cd metro-ai-suite/vms-adapter-plugin
docker compose up -d

  5. In the Nx Witness desktop client, close any open camera visualizer window. Navigate to the left panel, and under the server, find the camera you wish to run analytics on and right-click to open context menu. open Camera Settings → Integrations → VAP Analytics Integration. There are two checkboxes: Live Video Captioning and Loitering Detection. Enable the checkboxes for both.

VAP starts both pipelines independently within 5 seconds.

View results in Nx Witness#

Both pipelines run in parallel, but Nx Witness displays only one type of analytics output at a time:

  • Bookmarks tab (or press Ctrl+B) — shows LVC captions, each pushed as a timestamped bookmark.

  • Object Search (or press Alt+O) — shows Loitering Detection bounding boxes (vap.pedestrian, vap.vehicle, etc.) overlaid on the live feed.

This is an Nx Witness limitation: the client cannot overlay detection boxes and bookmarks simultaneously in the same camera panel, even though both pipelines produce results concurrently.