LeanCast

English | 简体中文

A minimal, ad-free DLNA/UPnP cast receiver for Android TV. Open any video app with a cast button (Bilibili, iQiyi, Tencent Video, Youku, Quark, …), pick this receiver, and the video plays fullscreen with hardware decoding — no ads, no accounts, no cloud.

Phone app --SSDP--> discovers  Phone app --SOAP SetAVTransportURI--> LeanCast
                                                                    |
                                                        ExoPlayer + MediaCodec HW decode

• Standard UPnP AV MediaRenderer:1 — SSDP discovery, AVTransport / RenderingControl / ConnectionManager SOAP control, and real GENA eventing (initial LastChange on subscribe, then a notification per state change).
• Hardware decoding via Media3/ExoPlayer: HLS (.m3u8), progressive MP4, Matroska, HTTP-FLV (best effort), HTTP↔HTTPS redirects, cleartext LAN URLs.
• TV-native controls & OSD: OK = pause/resume, ◀ ▶ = seek with an escalating fast-forward ladder (10 s → 5 min while held), ▼ = cycle playback speed (0.75x / 1.0x / 1.25x / 1.5x / 2.0x), ▲ = reveal OSD, Back = exit; on-screen HUD with live progress bar, media title, and seek/speed feedback in English or Chinese.
• Lean & private: lighter than the stock TV launcher (see below); zero analytics, zero non-LAN network calls; pure-Kotlin APK with no native libs — one artifact runs on armeabi-v7a, arm64-v8a, x86, x86_64.
• Nothing hardcoded: the cast name defaults to LeanCast and is user-renamable; UUID is derived from the device id, so it survives reboots and reinstalls; UI language switchable between 简体中文 and English.
• Tested on an Amazon Fire TV (Fire OS 7 / Android 9, 32-bit MTK SoC) with minSdk 21 / targetSdk 28.

Requirements: JDK 17+, Android SDK (platform 34). Then:

./gradlew assembleDebug
# app/build/outputs/apk/debug/app-debug.apk

adb connect <TV-IP>:5555
adb install -r app/build/outputs/apk/debug/app-debug.apk
adb shell am start -n io.leancast/io.leancast.app.MainActivity

Launch the app once to start the receiver service; it then appears in every DLNA sender's device list under the receiver name (rename it in the app). Optional: enable Start on boot in the app.

LeanCast is a pure-Kotlin APK with no native libraries and minSdk 21 (Android 5.0, 2014), so a single artifact covers armeabi-v7a, arm64-v8a, x86 and x86_64. Decoding uses each device's platform MediaCodec, so codec coverage follows the device: H.264 everywhere, HEVC/4K on 2016+ TVs, AV1 only on newer boxes.

Notes:

• Phone "system cast" (Miracast) is out of scope — LeanCast is a DLNA/UPnP receiver, so use the [TV] button inside video apps.
• Tested an unlisted device? Open a Device compatibility report issue and help grow the matrix.

Measured on the primary test device (Fire TV, 1.6 GB RAM); idle = receiver waiting on the dashboard:

Lighter than the stock Fire TV launcher (83 MB PSS) on the same device.

Two GitHub Actions workflows ship with the repo:

• CI (.github/workflows/ci.yml) — runs domain unit tests + debug build on every push to main and every PR; uploads the debug APK as an artifact.
• Release (.github/workflows/release.yml) — triggered by pushing a v* tag (or manually via workflow_dispatch). Builds the release APK, runs the unit tests, creates a GitHub Release with auto-generated notes, and attaches LeanCast-<version>.apk.

To publish a release:

git tag v0.2.0
git push origin v0.2.0

By default the release APK falls back to the debug keystore (fine for personal sideloading). For a stable release signature across builds, add these repository secrets (Settings → Secrets and variables → Actions):

The workflow decodes the keystore to ci-release.keystore (git-ignored) and signs with it. Generate a keystore once with:

keytool -genkeypair -v -keystore release.keystore -alias leancast \
  -keyalg RSA -keysize 2048 -validity 10000

domain/          Pure-Kotlin protocol core (JVM-unit-tested, 90 tests)
  ssdp/          M-SEARCH parsing, target matching, USN, alive/byebye, MX delays
  upnp/          Device description + SCPDs, SOAP parser (prefix-tolerant DIDL),
                 response envelopes & faults, H:MM:SS time math, SOAP router
  cast/          AVTransport state machine, player port, volume math
app/             Android shell (thin adapters, E2E-verified on device)
  ControlServer  Minimal HTTP/1.1 server: /desc.xml, /scpd/*, /ctl/*, /evt/*
  SsdpAgent      Multicast UDP listener + advertiser (MulticastLock held)
  ExoPlayerPort  PlayerPort adapter (main-thread marshalled, cached position)
  ReceiverService Foreground service assembling everything
tools/
  e2e_control_point.py  Scripted UPnP control point for device E2E runs
openspec/        Spec-driven development artifacts (proposal/specs/design/tasks)

Development follows OpenSpec (openspec/) with strict TDD: every spec scenario maps to unit tests in domain; run them with ./gradlew :domain:test. End-to-end verification drives a real device from a dev box:

python3 tools/e2e_control_point.py http://<lan-host>/video.mp4

Apache-2.0. Dependencies: Media3 (Apache-2.0).