JMR-devandClaude Opus 5
a79ff62b61
API 37 was the only red job in the matrix, and the last two fixes each corrected a real problem only to reveal the next one. This is the cause of the third failure. The emulator raises an undersized guest to 2560M on its own, but only for API levels it recognises, and it does not recognise "37.0". Comparing the two CI logs from the same emulator binary (37.1.11.0) shows the asymmetry directly: the API 36 job logs "Increasing RAM size to 2560MB" and the API 37 job has no such line. So four levels were quietly running at 2560M while API 37 ran at the pixel_6 default of 1536M, lost system_server partway through installing the 82 MB APK, and surfaced it as "Can't find service: package". 2560M is not a guess at a sufficient value -- it is the value the other four levels already pass at, so this makes the matrix uniform rather than introducing a fifth configuration. Verified that the setting actually lands: the action appends hw.ramSize to a config.ini that already has one from the profile, so the fix only works if the later key wins. Appending a distinctive 3072M to an API 36 AVD produced MemTotal 3047924 kB and suppressed the automatic bump, confirming it does. This failure cannot be reproduced locally -- API 37 will not boot on a workstation under either GPU mode, aborting surfaceflinger in the goldfish mapper under -gpu host and segfaulting the emulator under swiftshader_indirect -- so the job now reports guest memory on every run and dumps OOM kills and native crashes on failure. That makes the next run conclusive either way instead of producing another bare "Can't find service: package". 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: MP4/MOV in and out, H.264/HEVC, resolution and frame-rate changes, rotation, overlays, audio to AAC, and stream-copy transmuxing. 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.
FFmpeg — the long tail
Everything Media3 structurally cannot do:
- Containers outside MP4/WebM/Ogg/WAV/AAC — MKV, AVI, FLV, MPEG-TS
- 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
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."
Features
| Formats | |
|---|---|
| Video out | MP4 (H.264/H.265), MKV (H.264/H.265), WebM (VP9) |
| Audio out | MP3, AAC/M4A, FLAC, Opus, WAV |
| Images | GIF, PNG frame sequences |
| Other | Join several files into one |
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 FFmpeg argument builder, and the stream-copy-versus-re-encode planner. 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.
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.