JMR-devandClaude Opus 5
b082cea889
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>
34 lines
1.5 KiB
Docker
34 lines
1.5 KiB
Docker
# Reproducible FFmpeg build environment for ffmpeg-kit-next.
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#
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# ffmpeg-kit-next is Nix-only: the repository ships nix-android.sh and a flake, and
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# there is no plain android.sh. Rather than install Nix on a developer machine, the
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# whole toolchain lives in this image. It also serves as the reproducibility artifact
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# F-Droid expects.
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#
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# The flake pins Android NDK 27.3.13750724 (r27d) itself and applies
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# -Wl,-z,max-page-size=16384 for arm64-v8a and x86_64 in android/jni/Android.mk, so
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# the output is 16 KB page-size compliant without needing NDK r28+ on the host.
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#
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# The base image already provides git, bash, curl and tar. Compilers and build tools
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# (make, cmake, autotools, pkg-config) are supplied by the flake's devShell at build
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# time, so nothing further is installed here — `nix profile install` would in fact
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# collide with the base image's existing profile entries.
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FROM docker.io/nixos/nix:2.35.2
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# nix-android.sh points NIX_USER_CONF_FILES at the repo's own nix.conf, which enables
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# the flakes and nix-command experimental features. Set them here too so that plain
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# `nix` invocations behave the same way.
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RUN mkdir -p /etc/nix && \
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printf 'experimental-features = nix-command flakes\naccept-flake-config = true\nwarn-dirty = false\nmax-jobs = auto\n' \
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>> /etc/nix/nix.conf
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# Upstream's scripts/*.sh use `#!/bin/bash`, but this image provides only /bin/sh.
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RUN ln -sf /bin/sh /bin/bash
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WORKDIR /work
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COPY build-ffmpeg.sh /usr/local/bin/build-ffmpeg.sh
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RUN chmod +x /usr/local/bin/build-ffmpeg.sh
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ENTRYPOINT ["/usr/local/bin/build-ffmpeg.sh"]
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