Offline-First Playback: Why Internet Reliability Should Not Stop Your Screens

Every digital signage deployment eventually faces the same test: what happens when the internet goes down? If your screens go blank or freeze on the last fetched frame, you have a problem. If they continue playing the correct scheduled content without interruption, you have an offline-first architecture. Digipal is built to pass that test.

The Content Cache

When a player receives a content assignment, it downloads all media files to local storage. Images, videos, and design files are cached on the device. The cache is updated incrementally: when you change a design or assign new content, only the changed assets are downloaded. This keeps bandwidth usage low and ensures the device always has the latest approved content available locally.

The cache manager tracks which assets are referenced by active content assignments and removes unreferenced files to free up space. On devices with limited storage, currently scheduled content is always prioritised over content that is not active in any current schedule.

Schedule-Aware Local Playback

Schedules are also cached on the player. The player stores the full schedule configuration locally and evaluates it using the device clock. If the internet connection drops, the schedule continues to run as configured. Time-based entries, repeat modes, and playlist sequences all work without a cloud connection.

This means that a screen scheduled to show breakfast content until 11am and lunch content from 11am will make that transition correctly even if it has not had internet access since the previous day. The schedule was cached when it was last updated, and the local clock handles the timing.

The Connection Waterfall

Digipal players attempt to connect to the management server using a waterfall sequence: first the local network hub if one is configured, then a direct internet connection, then a relay connection, and finally the cloud. This means that in environments with a local Hub running on a Windows or Mac machine on the same network, players can continue to receive content updates and commands even without internet access.

LOCAL: connect to a Digipal Hub on the same local network via mDNS discovery
DIRECT: connect to the Digipal cloud over a standard internet connection
RELAY: connect through a relay server for networks with restrictive firewall rules
CLOUD: fall back to a cloud relay as a last resort

The Local Hub

The Local Hub is an Electron desktop application available for Windows and macOS. It runs a full clone of the management server locally, including content storage, schedule management, and the real-time WebSocket connection to players. In environments where internet connectivity is unreliable or restricted, the hub provides complete management capability without cloud dependency.

The hub syncs bidirectionally with the cloud when internet is available, so changes made locally are pushed to the cloud and changes made in the cloud are pulled down. Conflict detection handles cases where the same content was edited in both places during an outage.

Android Permanent Local Storage

Android TV players cache content to the device's internal storage. Content persists across reboots and app updates. On devices with limited storage, the cache manager prioritises currently scheduled content and removes assets that are no longer referenced by any active assignment.

When to Use the Local Hub

Most deployments run perfectly well without a local hub. The cache and schedule systems handle normal internet outages. The hub is recommended for environments with consistently unreliable internet, locations where content needs to update in real time (such as a live event venue), or deployments subject to data sovereignty requirements that prevent content from transiting cloud servers.