2 Commits
Author SHA1 Message Date
JMR-devandClaude Opus 5 d45abe7409 Rebuild the FFmpeg AAR with libvorbis, and make Ogg Vorbis reachable (#254)
`FFmpegCommandBuilder` has emitted `-c:a libvorbis` since the day it was
written, and libvorbis was not in the AAR this app ships: the configure line
omitted `--enable-libvorbis`, and `strings` on both ABIs' `libavcodec.so`
named every other external encoder and not that one. The arm was unreachable
from both ends, so nobody ever hit it -- but the first user to pick Ogg
Vorbis would have got `Unknown encoder 'libvorbis'`. That is #238's shape
again: two individually-correct facts, a builder arm and a configure line,
that no test put together, and that no coverage number can see.

So the binary is rebuilt rather than the arm rewritten. FFmpeg's in-tree
`vorbis` encoder was already in there and was tried first; it is
experimental, stereo-only, and its quality knob spans 2x its floor against
libvorbis's 6x. Shipping it would have meant `-strict experimental`, a
forced `-ac 2` that silently upmixes every mono source, and a slider with
nowhere to go. What ships instead is the arm as originally written,
`-c:a libvorbis -q:a 5`, with `OGG_VORBIS` added to the presets, `VORBIS`
added to `ENCODABLE_AUDIO`, and Ogg's per-codec extension fixed so a Vorbis
file is not named `.opus`.

The flag is `--enable-libvorbis`, read out of ffmpeg-kit's
`get_library_name()` rather than guessed: the `--enable-lame` /
`--enable-opus` rule predicts `--enable-vorbis`, and that is not it. An
unrecognised `--enable-*` is ignored silently, so the artifact was checked
before `bin/README.md` was touched -- `libvorbis` present in both ABIs, the
configure line otherwise identical, FFmpeg still n8.1.2, 10 shared libraries
per ABI, every LOAD still `0x4000`.

Both mutations were run on API 34 rather than predicted. Pointing the arm at
`libopus` reddens the e2e test with `expected:<[audio/vorbis]> but
was:<[audio/opus]>` while its `OggS` assertion still passes, which is why
the track MIME is asserted and the container magic is not enough. Adding
`-ac 2` back reddens it with `expected:<[1]> but was:<[2]>`: this class's
own fixture is mono, so mono staying mono is an assertion rather than a
claim.

The unit test's load-bearing assertion inverts with this change and is
rewritten to say so. It used to assert that `libvorbis` was *absent*; it now
asserts the encoder name plus the two flags that must not be there. Nothing
on the JVM can tell a real encoder name from a fictional one -- which is
exactly how this survived four coverage waves -- so the e2e test is the only
thing that proves the positive.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-06 18:31:36 -05:00
JMR-devandClaude Opus 5 b082cea889 Add containerized FFmpeg build producing a 16 KB-aligned GPL AAR
There is no usable prebuilt FFmpeg for Android any more. arthenica/ffmpeg-kit
is archived and its binaries were deleted from Maven Central, so every
com.arthenica:ffmpeg-kit-* coordinate 404s and all of its release tags have
zero assets. Maven Central's search index still lists the old versions, which
misleads; the files behind those entries are gone. The successor,
ffmpeg-kit-next, is source-only by design. Building it ourselves is the only
remaining option, not a preference.

ffmpeg-kit-next is Nix-only -- there is no plain android.sh, only
nix-android.sh and a flake -- so the toolchain lives in a container rather
than on the developer's machine. The recipe doubles as the reproducibility
artifact F-Droid expects and as the GPL corresponding-source obligation.

Four problems this path hits, none of them documented upstream:

- The nixos/nix base image already ships bash, coreutils and git; installing
  them collides with the existing profile entries and fails the image build.
- Upstream scripts use #!/bin/bash but the image provides only /bin/sh, so
  start-android.sh dies with "cannot execute: required file not found" after
  the entire toolchain has been built.
- Gradle's AAPT2 comes from Maven as a prebuilt binary linked against FHS
  paths that do not exist under Nix, failing with "Daemon startup failed"
  after the whole native build succeeds. Nixpkgs' Android SDK ships an
  already-patched aapt2, so Gradle is pointed at that.
- A bare '*.aar' find also collects every AAR Gradle unpacked into its own
  caches, so the copy is scoped to the ffmpeg-kit outputs.

The NDK stays at r27d as the flake pins it. Do not "upgrade" to r28+:
android/jni/Android.mk applies -Wl,-z,max-page-size=16384 manually precisely
because r27 predates automatic alignment, and the result is verified 16 KB
compliant as-is.

Verified against the produced artifact: every .so on both ABIs reports LOAD
align 0x4000, libraries are separate rather than a static monolith as the
GPL relinking obligation requires, and the embedded configure line confirms
--enable-gpl --enable-version3 with x264, x265, SVT-AV1, LAME, libass and
the MediaCodec wrappers. Note that --enable-small and --enable-lto
internalize symbols, so absence from strings output proves nothing; check
the configure line instead.

The 35 MB AAR itself is gitignored. F-Droid strips checked-in prebuilt
native libraries, and the recipe is the artifact of record.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-19 21:19:01 -05:00