Multimedia Detector Overview

The multimedia detector service, mm-detect, keeps track of which devices are attached to a car's infotainment system and triggers the synchronization of device metadata with QDB databases.

The mm-detect service ensures that HMI applications can display up-to-date media information to the end user, while relieving those applications from having to constantly monitor devices and synchronize databases.

Detecting devices, retrieving their media information, and delivering that information to HMI applications involves several low-level device management and data publishing tasks. However, mm-detect doesn't perform most of these tasks. Instead, the service relies on the following components:

Device publishers

Inform mm-detect through the Persistent Publish/Subscribe (PPS) service of device attachments and detachments.

Media content detector (mcd)

Mounts filesystems of attached devices so their contents can be read by multimedia services and other programs.

mm-sync

Synchronizes the contents of QDB databases with the latest media metadata on attached devices.

CAR HMI

Monitors PPS for synchronization statuses published by mm-detect and queries device databases to obtain up-to-date media information for displaying to the end user.