A visitor approaches an exhibit and hears a narration without a single tap. Or scans a QR code on the plaque. Or manually enters the number. All three scenarios must work offline—museum Wi-Fi often fails. According to research, over 60% of visitors use mobile devices in museums, but an unstable network undermines the experience. That's why developing a mobile audio guide for a museum must account for autonomy, reliable detection, and resource efficiency. A well-designed architecture can reduce support and licensing costs—for instance, dropping commercial maps saves money. Our team builds audio guides for museums from scratch: from beacon selection to store publishing. Over the years, we've delivered dozens of projects, including large state museums. In this article, we'll dive into technical details: how we build a reliable offline system that never lets visitors down.
Contact us to discuss your project and get a preliminary estimate.
How Automatic Exhibit Detection Works
The most interesting scenario is a proximity trigger with no user action.
iBeacon / Bluetooth LE. Beacons near each exhibit (Estimote, Kontakt.io). iOS: CLLocationManager.startRangingBeacons(satisfying:) obtains a list of beacons with proximity (.immediate / .near / .far) and rssi. We pick the closest with .immediate and start audio. Important: we don't react to every proximity change—apply a 2-3 second debounce to avoid switching audio due to random signal fluctuations.
Android: BluetoothLeScanner with a filter by beacon manufacturer UUID. The AltBeacon library simplifies ranging. A Foreground Service is needed for background scanning—while the app is active, normal scanning suffices. Bluetooth LE — official Android documentation.
QR scanning. Fallback method. iOS: VNDetectBarcodesRequest (Vision) — faster than AVMetadataOutput for single scans. Android: ML Kit Barcode Scanning. Flutter: mobile_scanner.
Manual number entry. Always as a fallback—in case Bluetooth is off or beacons are missing.
Comparison of Detection Methods
| Method | Accuracy | Offline Capability | Implementation Cost |
|---|---|---|---|
| iBeacon | High (up to 1 m) | Full (offline) | Medium (beacons $10–30 each) |
| QR code | High (camera-dependent) | Full (offline) | Low (paper labels) |
| Manual entry | Low (input errors) | Full (offline) | Zero |
| NFC tags | Medium (contact) | Full (offline) | Medium (tags $1–5 each) |
Offline Content and Data Structure
A museum with 200 exhibits means 200 audio files, images, and texts. Total 300–500 MB. Update strategy:
- On first launch, download a 'lightweight' package: texts, 200px previews, metadata (beacon UUIDs, exhibit numbers)
- Audio downloaded on demand or in batches with caching
Storage structure: CoreData/Room for exhibit metadata (id, title, beacon_uuid, qr_code, languages). Audio files in Application Support/filesDir with id→path mapping. SQLite query 'find exhibit by beacon UUID' is instantaneous.
Multilingualism: user selects language at start. Audio and texts stored with language suffix. Only the selected language is downloaded—saving space.
Audio caching details
For streaming playback, we use AVAssetResourceLoader (iOS) and CacheDataSource (ExoPlayer). Cache is stored up to 1 GB, evicted LRU when full. Only the current session's audio is guaranteed to be cached. Users can preload all audio via settings.Exhibit Audio Player
AVPlayer (iOS) / ExoPlayer Media3 (Android) / just_audio (Flutter). Features specific to audio guides:
- Auto-stop when moving away from exhibit (proximity returns to far)
- Progress saved: returning to exhibit resumes from pause point
- Playback speed: 0.8x for elderly visitors, 1.5x for quick ones
- Lock screen controls via MPNowPlayingInfoCenter (iOS) / MediaSession (Android)
Interactive Exhibition Map
A hall map with exhibit markers. Not Google Maps—museums want no external dependencies or fees. We use an SVG hall map: rendered in a WKWebView with interactive SVG (iOS), WebView (Android), or flutter_svg with GestureDetector (Flutter).
Alternatively, a native implementation with Canvas/CustomPainter: load a PNG map as a base, draw exhibit points on top with pinch-to-zoom scaling.
Visitor's current location on the map is determined via the same iBeacon ranging: we identify the hall by the set of visible strong-signal beacons. No GPS—it doesn't work indoors. Dropping commercial maps saves up to several hundred dollars a year in licensing.
Why a CMS for the Museum Is Essential
Administrators update texts and audio without releasing a new app version. Backend: simple REST API + S3 for media files. On launch, the app checks the manifest version—if changed, it downloads the delta. This saves moderation time and allows quick updates to tour content.
How to Implement an Offline Audio Guide: Process
- Analysis and design. Gather requirements: number of exhibits, halls, languages, budget. Choose stack: native or cross-platform.
- Development. Backend (CMS, API), mobile app (player, map, detection), beacon integration.
- Testing. Real-world testing with beacons, offline mode, load testing.
- Deployment. Publish to App Store and Google Play, configure Code Signing, Provisioning Profile, TestFlight.
- Maintenance. 3-month warranty, then contract.
Timeline Comparison
| Phase | Duration (basic version) | Duration (extended version) |
|---|---|---|
| Analysis | 3-5 days | 5-7 days |
| Development | 2-3 weeks | 4-5 weeks |
| Testing | 1 week | 1.5 weeks |
| Deployment | 3-5 days | 5-7 days |
What's Included
- Architecture documentation and API description
- App source code (Git repository)
- Operating manual for staff
- Staff training (1-2 days)
- Test run and tuning with real beacons
- Support during warranty period
Timeline and Cost Estimation
Basic version (QR + offline + player + map) — 4-6 weeks. Version with iBeacon and CMS — 7-9 weeks. Exact cost is calculated after requirements analysis. We'll assess your project for free—contact us for a consultation.
Certified developers with 5+ years of experience guarantee quality. We've built 10+ audio guides for museums in Russia and the CIS. iBeacon is the standard for proximity solutions.
Get a free project estimate: contact us, and we'll prepare a commercial proposal.