Android app (APK) — phone as the caster

[gluckdev]

Summary

An Android app so the phone is the remote and the media server — discover DLNA/Chromecast/AirPlay on Wi-Fi and cast files, web video (YouTube/Rutube/VK/any site), and radio with cover art, including multi-room. This is the ideal form factor (it's how BubbleUPnP / Web Video Cast / AllCast work), and Android — unlike a browser — can do the raw networking needed.

Why Android fits

Android apps have raw sockets (SSDP discovery + /24 scan), plus mature native pieces:

• DLNA: jUPnP / Cling (device discovery + AVTransport control).
• Chromecast: Google Cast SDK — first-class on Android.
• ffmpeg: ffmpeg-kit (transcode to dongle-safe baseline H.264, the same approach as the desktop app).
• yt-dlp: youtubedl-android (yt-dlp bundled via Chaquopy).
• The phone runs a small HTTP server and streams to the TVs (same model as the desktop HTTPServerThread/streamers).

Approaches

Primary — native Kotlin (recommended): Kotlin + jUPnP + Cast SDK + ffmpeg-kit + youtubedl-android. Fully standalone on the phone, best UX; ground-up rewrite (no Python reuse) but mirrors the proven cast apps. Port the logic (re-encode rules, play-once, DLNA OP/headers, radio cover-art compositing) from cast_to_tv.py.

Alt 1 — Python-on-Android: Kivy/BeeWare + Chaquopy reuses the existing engine, but packaging ffmpeg/yt-dlp and the native cast SDKs is rough (pychromecast/pyatv on Android are unreliable). Max code reuse, lower polish.

Alt 2 — thin client: a WebView/native shell over the web local-agent (#); fastest MVP but needs the backend running somewhere.

Scope (native path)

• DLNA discover + AVTransport cast (jUPnP); Chromecast via Cast SDK; AirPlay best-effort.
• Sources: local files, web URLs via youtubedl-android, radio with live cover art; transcode via ffmpeg-kit to baseline H.264; phone-hosted HTTP server.
• Multi-room fan-out; pause/seek/stop; protocol-tagged device list.
• APK build + release.

Acceptance

• Cast a local file and a YouTube/VK link from the phone to a DLNA dongle and a Chromecast.
• Radio with cover art plays; multi-room starts on 2+ devices.

Shares design with the desktop engine; the headless CastingController (#) is reusable if the Python-on-Android path is chosen.