plexamp-lite/README.md

Plexamp Lite

A small Plexamp-style music player for Plex, built for the Samsung Galaxy Mini (GT-S5570: Android 2.2/2.3, 240×320 ldpi screen, 600 MHz ARMv6, 384 MB RAM). Runs on any Android 2.2+ phone, and comes in a second build for Android 4.1 and later (Xperia J, Galaxy S II…) that uses what those phones can do: see Android 4.1 build. Formerly Minamp (the package name, com.minamp, stays so updates install over it).

Language

The interface is in Galician by default, whatever language the phone is set to. English is available under Axustes → Idioma. All text lives in tools/strings.py (key → English, Galician), which generates res/values/strings.xml (Galician) and res/values-en/strings.xml; the connection log stays in English since it's meant for troubleshooting.

Install

1. On the phone: Settings → Applications → Unknown sources (tick it).
2. Copy PlexampLite.apk (Android 4.1+: PlexampLite-api16.apk; Tenda picks the right one by itself) to the SD card (USB cable, or download it in the browser) and open it with a file manager, or from a computer: adb install PlexampLite.apk.
3. Plexamp Lite installs to internal storage (about 1 MB): an app on the SD card is killed whenever the phone shares its SD card over USB, which stopped the music.

Sign in

Open Plexamp Lite → Sign in with Plex. It shows a 4-character code; on any other device go to plex.tv/link and type it in. Plexamp Lite then lists your servers (owned and shared) and music libraries.

Connect to a server address is the manual fallback: an IP/hostname plus an optional X-Plex-Token.

Streaming from anywhere

After sign-in Plexamp Lite knows every address Plex advertises for your server and picks the best working one, re-checking whenever the phone switches network:

Order	Connection	When it's used
1	Whatever worked last time	Tried alone first, so a normal start costs one request (if that was a remote address, the home addresses get 2 s first)
2	Home network, plain HTTP	On your Wi-Fi (fast: no encryption work for the phone)
3	Home network, HTTPS (*.plex.direct)	On your Wi-Fi if plain HTTP is refused, or if Settings → Encrypt at home too is on
4	Remote, HTTPS	Away, if Remote Access is set up on the server
5	Plex Relay	Away, when the server isn't reachable directly (bandwidth-capped; Plexamp Lite caps itself at 192 kbps)

Secure addresses are tried one at a time: on a 600 MHz phone a TLS handshake takes seconds, and several at once make each of them time out. Plexamp Lite uses TLS 1.2 with session resumption, so only the first connection to each server pays the full cost; later ones resume in a fraction of it.

For the best remote experience enable Settings → Remote Access on your Plex Media Server. Without it, Relay still works.

Android 2.x can't do modern TLS, so Plexamp Lite bundles its own TLS 1.2/1.3 stack (Bouncy Castle, renamed to com.minamp.bc so it doesn't clash with the old copy inside Android) and verifies certificates against Mozilla's root store (from certifi). A tiny loopback proxy feeds the phone's media player, so HTTPS streams and relay work the same as local ones. If the phone's clock has been reset to before 2024 the certificate date check is skipped rather than failing.

Playback and quality

• MP3, AAC (M4A) and Ogg Vorbis play directly. FLAC, ALAC etc. are transcoded to MP3 by the server (Android 2.2/2.3 can't decode FLAC).
• Menu → Settings: separate quality for home Wi-Fi (default Original) and for away/mobile data (default 192 kbps MP3); 320/256/192/128/96 kbps available. Quality over Bluetooth (default 192 kbps) caps both while the sound goes to a Bluetooth speaker: on the Mini, Wi-Fi and Bluetooth share one radio, and a lighter stream keeps the speaker from stuttering.
• Seeking in a transcoded track restarts the transcode at the new position.
• Read-ahead: while a track plays, the next two in the queue are fetched whole in the background (one at a time) and then played from the file; without an SD card only the next one is kept. Android 2.x's player keeps only a few seconds of stream buffer, so on weak Wi-Fi shared with a Bluetooth speaker it used to go silent for seconds at a time.
• One stream per account: Plex cuts an account's file stream when any device signed in to it starts another, so every request for a track's file (playing, read-ahead, downloads) asks for it as a download (?download=1), which Plex leaves out of that rule; otherwise the read-ahead and the player, or two phones playing at once, cut each other off. A server that refuses downloads gets the plain address.
• If a stream fails, Plexamp Lite re-picks the connection and resumes; if it fails again it downloads the whole track first and plays from the SD card. "Download tracks before playing" forces that mode (useful on flaky mobile data). Playback that stalls ("playing" but the time doesn't move for 10 s) is recovered the same way.
• A Bluetooth speaker that drops its link for a moment pauses Plexamp Lite, which resumes by itself if the speaker is back within 20 s. Why playback paused or stopped is written to the connection log, which also goes to logcat (tag PlexampLite, readable over USB with adb logcat).
• Plays are reported to Plex (Now Playing in the Plex dashboard, play counts, resume position). For testing against a real server, an empty file named PlexampLite-noreport at the top of the SD card turns that off (adb shell touch /sdcard/PlexampLite-noreport; delete it afterwards).

Features

• Home: Library radio, Loved radio (rated 4★+ / loved), Time-travel radio (pick a decade), Random album, Recently added and Recently played shelves.
• Artists / Albums (5 sort orders) / Playlists tabs with paging and fast scroll; Search.
• Artist page with Play all and Artist radio; album and playlist pages with Play/Shuffle.
• Long-press anything: Play next, Add to queue, Go to album/artist, Love.
• Now Playing: big art on a backdrop coloured from the cover, seek bar, shuffle, repeat (queue/track), love, sleep timer (15–90 min or end of track), where it's streaming from.
• Lyrics: the microphone button in Now Playing shows the track's lyrics from Plex in place of the art (as in the Mac app). It's a lasting setting: it stays on for the following tracks and after restarts. Timed (LRC) lyrics follow the song with the current line lit (tap a line to jump there; scrolling by hand pauses the follow for a few seconds); plain-text lyrics just scroll. With several versions, timed ones win, else the longest text (a local .txt can be a broken copy).
• Home-screen widget (4×1): art, title, artist, previous / play-pause / next; tap the art for Now Playing.
• Up Next queue: jump, play next, remove, clear; the queue and position survive restarts.
• Downloads for offline listening: long-press a track, album, artist or playlist -> Download; Menu -> Downloads shows progress, space used and free, play/shuffle, retry and remove. Files go to the SD card. MP3 originals are kept as they are (unless above a lower Download quality in Settings); everything else is transcoded to MP3, 320 kbps by default. Downloaded tracks play from the SD card, offline too, and plays made offline are reported to Plex later.
• Menu -> Close Plexamp Lite stops the music and closes every screen.
• Wired headset button: 1 click play/pause, 2 next, 3 previous; Bluetooth media keys; pauses for calls and when headphones are unplugged.

Android 4.1 build

One build per Android level, never per phone (the same pattern as Tenda): build/PlexampLite.apk for Android 2.2+ and build/PlexampLite-api16.apk for 4.1+, from the same source, package and key. versionCode is the manifest's × 100 + the level (15 → 1508 and 1516), so a phone that moves up a level gets the newer build as an ordinary update, and Tenda gives each phone the build for its Android. Everything is shared in src/; what only one level can do is in platform/api8/…/Platform.java and platform/api16/…/Platform.java (the same methods; keep them in step), plus platform/api16/res, which overrides a few resources. The Android 4.1 build adds:

• ExoPlayer 2.18 (platform/api16/…/ExoEngine.java) instead of Android's MediaPlayer, behind the small Engine interface the player service uses (MediaPlayerEngine on Android 2.x):
  • gapless playback: when the next track's file is already here (read ahead or downloaded), it's queued in the player and starts with no gap;
  • a buffer of up to 3 minutes instead of seconds, so Wi-Fi gaps don't silence it;
  • errors that say what failed. A track ExoPlayer can't decode is retried with Android's MediaPlayer. Read-ahead, the stream proxy, the transcodes and the recovery steps are the same in both builds.
• A notification with the art and ⏮ ⏯ ⏭ × (pull it down for a larger one); swiping it away while paused stops.
• Lock-screen controls with the art (RemoteControlClient).
• The widget can be resized; two rows or taller shows a larger layout.
• Android 4's Holo dialogs and text fields; a ⋮ button on phones without a Menu key.
• Metered networks: a phone's Wi-Fi hotspot counts as away, like mobile data.

The Galaxy Mini's build is unchanged in how it plays, and also got the widget and the lyrics.

Building (no Android SDK needed)

tools/setup_toolchain.sh      # once: fetches aapt2, the API 8 android.jar, builds dx, renames Bouncy Castle
tools/fetch_exoplayer.sh      # once: ExoPlayer 2.18.7 + Guava (checksums pinned) into ~/android-toolchain
./build.sh                    # -> build/PlexampLite.apk (Android 2.2+) and build/PlexampLite-api16.apk (4.1+)
./build.sh 16                 # one level only

Also needed for the Android 4.1 build: the API 16 android.jar in ~/android-toolchain/platforms/android-16/, R8 (d8.jar from build-tools 34, in ~/android-toolchain/calendar-tools/) and a JDK 11+ (build.sh finds Homebrew's openjdk@17). ExoPlayer 2.18.7 is the newest that needs only Guava; R8 (tools/r8-rules.pro) keeps the app whole and shrinks ExoPlayer and Guava to what it uses, in one dex.

Per level build.sh runs aapt2 (resources), javac (Java 8 bytecode checked against that level's android.jar), then for Android 2.x the Dalvik 2.x link check and dx (dex 035), for 4.1 R8; then tools/signapk.py, which writes the v1 signature in the classic Android SignApk format and aligns the APK. (Modern jarsigner output does not install on Android 4.2 and older: it names digests SHA-1-Digest and labels the PKCS#7 signer algorithm in a way old JarUtils can't read, so the phone treats the APK as unsigned.) The debug key in signing/ (password minamp123) is what this APK is signed with, so rebuilt APKs install over it.

Tests (desktop JVM, no device):

• test/PlexTest.java + test/mock_plex.py: PIN sign-in, server discovery, connection picking/fallback, TLS with a wildcard plex.direct-style certificate (ECDSA leaf, RSA root), untrusted-root rejection, browsing, search, artwork, and the stream proxy (Range requests over TLS, de-chunking transcodes, aborting).
• test/QueueTest.java: shuffle/unshuffle, repeat modes, play next, remove, move, clear.
• test/LyricsTest.java: LRC (several stamps a line, offsets, word stamps) and plain-text lyrics (javac -d /tmp/lt src/com/minamp/util/Lrc.java test/LyricsTest.java && java -cp /tmp/lt LyricsTest).
• test/PoolAbortTest.java (test/run_pool_abort.sh): aborting a response that's already finished leaves its pooled connection, now carrying another request, alone.
• test/PreferHomeTest.java + test/identity_server.py: after being away, the home address wins again as soon as it answers.
• test/NetTest.java: the bundled TLS + HTTP client against real servers; test/HandshakeProfile.java samples where handshake time goes (run with -Xint).

Limits

• Android 2.x build: no gapless playback (no API for it), and the notification has no playback buttons (pre-Android 3 can't): tap it to open Now Playing, or use the widget.
• Android 4.1 build: gapless only into a track whose file is already on the phone; FLAC is still transcoded (ExoPlayer has no FLAC decoder on Android 4.1).