Opticast

Opticast is an Android application that captures the device camera and microphone and encodes them to a live video stream over RTMP or SRT. You point it at a server you control and it publishes there; the destination URL is the only thing that leaves the device.

It is built on RootEncoder for capture and muxing, with a Jetpack Compose UI. Minimum Android 8.0 (API 26).

What it does

• Output protocols: RTMP/RTMPS and SRT.
• Video: H.264 or H.265, hardware-encoded. Resolution, frame rate and bitrate are configurable.
• Audio: AAC from the device microphone, with a mute toggle.
• Connection profiles: save any number of targets. Each stores its protocol, host, port, stream path/key, optional SRT passphrase, and its own quality settings.
• Quality: presets from 480p30 up to 1080p60, or an Advanced mode for an explicit resolution / fps / bitrate / codec. The editor flags unusual or unencrypted configurations as warnings but does not block them.
• Adaptive bitrate: the encoder drops bitrate when the link is congested and recovers when it clears.
• Reconnect: automatic reconnection with capped exponential backoff on connection loss.
• Foreground service: streaming runs in a typed foreground service with a wake lock, so it continues with the screen off or the app backgrounded. Start/stop is exposed in the notification.
• Camera controls: front/back switch, pinch-to-zoom, torch, tap-to-focus, and a focus mode selector — Auto (continuous), Lock (freeze current), or Infinity (far-scene lock for fixed mounts where a near object would otherwise steal focus).
• Optional preview: the on-screen camera preview is off by default to reduce CPU and battery cost; the stream runs regardless.
• Credential storage: stream keys and passphrases are stored with Android Keystore-backed encryption.
• No network access beyond the configured server. No analytics, ads, or telemetry.

Screenshots

  

Usage

1. Run an RTMP/SRT server you control — for example MediaMTX — or use any compatible ingest endpoint.
2. Targets → New: choose RTMP or SRT, enter host, port and path (and a passphrase/key if the server requires one), then pick a quality preset or open Advanced. Tap the profile to select it.
3. Go Live. The status chip reports connection state, live bitrate and uptime. Pull the same path in OBS, VLC, or any compatible player.
4. While live: toggle the preview, flip the camera, mute, or switch on the torch. Stop from the on-screen button or the notification.

Install

• APK: download from Releases and sideload.
• Updates: add https://github.com/teop23/opticast to Obtainium to track releases.

Building

./gradlew testDebugUnitTest   # unit tests
./gradlew assembleDebug       # debug APK
./gradlew installDebug        # install to a connected device
./gradlew assembleRelease     # release build (signed if keystore.properties is present)

Toolchain: AGP 8.11.1, Gradle 8.13, Kotlin 2.3.21, compileSdk 36, JDK 17+.

Release signing reads keystore.properties from the repo root (git-ignored), with keys storeFile, storePassword, keyAlias, keyPassword. Without that file assembleRelease still produces an unsigned APK.

Privacy

Opticast collects nothing. See PRIVACY.md.

License

GPL-3.0. RootEncoder is Apache-2.0.

Roadmap

Possible future work, not yet implemented:

• Multiple simultaneous destinations.
• Local recording alongside the live stream.
• RTSP server output (pull instead of push).
• WebRTC / WHIP publishing for low-latency delivery.