JMR-devandClaude Opus 5
da6f2807e9
Four corrections to the harness, none of which changes what a successful sweep does. R17 / #26 -- no trap. Ctrl-C during a sweep (now up to five boots long) left headless qemu on console port 5560 and an lmc_e2e_apiNN AVD behind. The next run's `emulator -port` then collides with the orphan and `emu_adb` can resolve to it -- on a workstation with the Pixel plugged in, exactly the ambiguity the ANDROID_SERIAL pinning exists to prevent. `cleanup` (stop_emulator + delete_created_avds, KEEP_AVD honoured) is now on EXIT, INT and TERM. It is idempotent and the normal path calls it explicitly before the summary, so cleanup output cannot land after the summary and the EXIT trap finds nothing to redo. The interrupt path passes a 6-second grace rather than 30: Ctrl-C has already reached the emulator through the foreground process group, so that wait is only for it to finish writing, and `kill -9` follows regardless. `exit "$overall"` stays the last line, so the exit code an EXIT trap could have swallowed is still the one that escapes. The emulator logs in $LOG_DIR are deliberately kept -- they are the only evidence a failed boot leaves. R31 / #40 -- `kill -9 "${EMU_PID:-0}"`. EMU_PID is empty, not unset, if the background launch never produced a job, so `:-0` converted "nothing to kill" into pid 0, which POSIX reads as the sender's whole process group. The `kill -0` wait loop had the same shape and would have spent its full grace period testing the group. All three sites now take a bare `$EMU_PID` behind one `[ -n ... ] || return 0` guard. boot_emulator's own `kill -0` is left alone: it runs only after the assignment and cannot reach the group form. R33 / #42 -- ensure_avd wrote CI's RAM and disk pins to a hardcoded $HOME/.android/avd/... path and checked nothing. With ANDROID_AVD_HOME (or ANDROID_USER_HOME, or ANDROID_SDK_HOME) set, the sed failed and the level ran on at default RAM and userdata, which surfaces much later as "not enough space" and reads as a device problem. `avd_config_path` now looks in every directory avdmanager honours -- no precedence is asserted, the existence check decides -- and a level that cannot be found or written fails instead of running unpinned. R34 / #43 -- disable_region_sampling's "one blocking wait on the device" did not wait: `adb shell stop` does not clear sys.boot_completed, so the property still read 1 and the loop returned at once. Deleted, and the comment now names the service-check loop below it as the actual wait -- which polls the better thing anyway, since `Can't find service: package` is the failure it exists to prevent. That loop also says so when it gives up after 150 s instead of proceeding silently. Deliberately not doing the `setprop sys.boot_completed 0` variant: the loop tested for an empty value, so a 0 would not have made it wait either, and the `!= 1` form it would need is an unbounded loop inside `adb shell` with no timeout. Checked with `bash -n` and with two stub harnesses in place of a device (shellcheck is not installed here): one drives the extracted lifecycle functions against fake binaries and asserts pid 0 really does hit the sender's process group, that an empty EMU_PID now signals nothing and returns at once, that SIGINT cleans up once and exits 130 within seconds, that KEEP_AVD survives the trap path, and that an explicit exit status survives the EXIT trap; the other runs the real script end to end on the boot-failure path, which stops short of e2e-run.sh, and checks the pins land in config.ini, the created AVD is removed, a misplaced config.ini fails the level, and `set -u` is not tripped anywhere. No emulator was booted. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
LibreMediaConverter
A free and open-source media converter for Android — batch video transcoding and compression, audio extraction and conversion, GIF and frame export, and file merging.
Android 13+ (API 33). Built with Jetpack Compose and Material 3.
Status: working, unreleased. Both conversion engines, the router, the background job queue and the join flow are implemented and building. The FFmpeg format tests have been written but not yet executed on a device.
Licensing at a glance
- Source code: MIT
- Distributed APK: GPL-3.0 — because it bundles FFmpeg built with x264/x265
That split is deliberate, not an oversight. See LICENSES/README.md
for the reasoning and the corresponding-source obligations.
Architecture
Two conversion engines behind an explicit router, because neither one covers the job alone.
AndroidX Media3 Transformer — the hardware path
Handles the common cases: H.264/HEVC, resolution and frame-rate changes, rotation, overlays, and audio to AAC. Fully hardware accelerated end to end — MediaCodec decodes to a GL surface and MediaCodec re-encodes, so frames never round-trip through the CPU. Roughly 7–8× realtime on 720p.
It writes MP4 and nothing else. media3-muxer ships WebM, Ogg, WAV and AAC muxers too,
but none can be driven by Transformer — they throw from addMetadataEntry, which the muxer
wrapper calls for every metadata entry a real recording carries. It reads far more than it
writes, Matroska included, which is what makes MKV → MP4 a hardware remux.
FFmpeg — the long tail
Everything Media3 structurally cannot do:
- Containers outside MP4/WebM/Ogg/WAV/AAC — MKV, MOV, AVI, FLV, MPEG-TS, WMV/ASF
- MP3 output — Android has no MP3 encoder at any version; this is a platform gap
- GIF and image sequences
- Input codecs with no platform decoder on the device
- CRF and 2-pass rate control, for the quality tier
- Codecs Media3's muxers decline even on a stream copy — its MP4 muxer carries AAC, Opus, Vorbis and PCM, but neither MP3 nor FLAC
Quality tiers
The router is surfaced to users as a quality choice rather than hidden:
| Tier | Engine | Rate control | Trade-off |
|---|---|---|---|
| Fast (default) | Media3 / MediaCodec | bitrate-targeted | ~7–8× realtime, low battery cost |
| Best quality | FFmpeg + x264/x265 | CRF or 2-pass | ~realtime or slower, better quality per byte |
A note on "GPU acceleration"
Android has no GPU video codec path. There are three distinct tiers, and conflating them causes a lot of confusion:
- Fixed-function video codec silicon — reached through
MediaCodec. This is what "hardware accelerated" means for encode and decode. It is not the GPU. - GPU shader cores — genuinely used, but only for filters, scaling, and color effects on already-decoded frames, via OpenGL ES. Never for entropy coding.
- CPU — x264, x265, and software decoders.
FFmpeg's -hwaccel is meaningful on Android only as mediacodec, and even then it
targets direct-to-Surface playback rather than file-to-file transcoding. Vulkan Video
exists in FFmpeg 8.0+ but no shipping Android GPU driver exposes it — no VK_KHR_video_*
extension appears in any Android Vulkan Profile tier.
So this app is hardware accelerated via MediaCodec, and GPU accelerated for effects via GL shaders. Both are real; neither is "the GPU decoding video."
Remuxing
Changing the container without touching the streams. Copying an H.264 track from MKV into MP4 moves the same samples into a different wrapper: it finishes in seconds instead of minutes, costs no quality, and needs no encoder — which is why it stays on the hardware path even on a device that cannot encode the codec in question.
Copy is a codec choice like any other, so it can be mixed: copy the video and re-encode
only the audio, or the reverse. Picking a codec the source already uses is upgraded to a
copy automatically when the container is changing — if container and codec both already
match, the only reason to run the job is to re-encode it, so it does.
A copy is never attempted on a stream whose codec could not be identified. A needless re-encode costs time; a wrong stream copy costs a file that will not play.
Features
| Formats | |
|---|---|
| Video out | MP4, MOV, MKV, WebM, MPEG-TS, AVI, FLV, WMV/ASF |
| Video codecs | H.264, H.265, VP9, or copy the source stream |
| Audio out | MP3, AAC/M4A, FLAC, Opus, WAV, MKA |
| Audio codecs | AAC, Opus, MP3, FLAC, PCM, or copy the source stream |
| Images | GIF, PNG frame sequences |
| Other | Remux without re-encoding; join several files into one |
Presets cover the common combinations in one tap. The Advanced picker exposes the full container × codec matrix — including combinations that cannot work, which it explains and offers alternatives for rather than hiding.
Conversions run as durable background work, so they survive leaving the app and are restored after a restart.
Building
Requires JDK 17+ (AGP 9 will not run on older) and the Android SDK with API 37.
FFmpeg is committed as a prebuilt archive under bin/, so a clone
builds without a cross-compile. That is deliberate: rebuilding it per CI run made test
results ambiguous, because a red build could mean broken code or a build that hiccuped.
See bin/README.md for its provenance and how to regenerate it.
./gradlew :app:assembleDebug # debug APK
./gradlew :app:testDebugUnitTest # JVM tests
./gradlew :app:connectedDebugAndroidTest # device tests, needs a running device
./gradlew :app:assembleRelease # R8-minified release
See tools/ffmpeg/README.md for why the build is
containerised and which flags matter. That recipe remains the authority — the committed
archive is its output, and is also what satisfies the GPL corresponding-source
obligation.
Testing
Unit tests cover the parts that decide correctness without needing hardware: the routing matrix, the container × codec capability matrix, the FFmpeg argument builder, and both stream-copy-versus-re-encode planners. They run against fabricated device profiles, so branches like "this device cannot encode HEVC" are reachable regardless of what the test machine is.
Instrumented tests cover the parts that only a device can prove: real hardware
transcoding, the foreground service type, and each FFmpeg output format asserted against
the produced file rather than the exit code. The remux tests additionally assert which
engine ran — a stream copy produces an identical file either way, so an output-only
assertion cannot tell a hardware transmux from FFmpeg's -c copy.
Privacy
The app has no INTERNET permission, so it cannot open a network connection at all.
Nothing is uploaded, and there is no analytics or advertising. See PRIVACY.md,
which also explains the permissions WorkManager adds automatically.
Contributing
Contributions are welcome. Note that contributions to the source are under MIT, while
the distributed binary remains GPL-3.0 for the reasons described in LICENSES/README.md.