# FFmpeg WebAssembly Corresponding Source

This archive accompanies the exact `@ffmpeg/core` and `@ffmpeg/core-mt`
0.12.10 object code distributed by av-tools 0.1.0.

`SOURCE_LOCK.json` records the immutable Git commit for ffmpeg.wasm, FFmpeg and
every external library selected by the upstream v12.15 build. The source trees
are stored under `sources/`. In particular, the upstream branch names
`4-cores` and `master` have been resolved to the commits from which the
published core was built; neither branch changed between its recorded commit
and the upstream core release.

The original build-control files are in `sources/ffmpeg.wasm/`, including:

- `Dockerfile`;
- `Makefile`;
- `build/ffmpeg.sh`;
- `build/ffmpeg-wasm.sh`;
- the other dependency scripts under `build/`.

The upstream build selects Emscripten SDK 3.1.40 and FFmpeg n5.1.4. av-tools
does not modify the five published JavaScript/WebAssembly core assets. Their
exact sizes, hashes and embedded configure arguments are recorded in the
application's `SOURCE.md` and `docs/FFMPEG_BUILD.md`.

The source archive preserves each component's own licence and copyright
notices. av-tools itself is distributed separately under
GPL-3.0-or-later. Codec patent permissions, where required, are separate from
copyright licences.

To fetch and verify an identity:

```sh
git init source-check
git -C source-check fetch --depth 1 <repository> <revision>
test "$(git -C source-check rev-parse FETCH_HEAD)" = "<revision>"
```

The included ffmpeg.wasm Dockerfile documents the historical upstream build,
but still names remote tags and branches. It is not a turnkey offline or
byte-for-byte reproducible build recipe. To reconstruct a pinned build,
adapt each remote `ADD` to use the corresponding bundled source tree. Replace
the zimg `git clone -b ... --recursive` step with the bundled `sources/zimg/`
tree, which already contains its pinned GoogleTest submodule at
`test/extra/googletest/`. Keep the included build scripts and Emscripten
version unchanged. The upstream targets are `make prd` for single-thread and
`make prd-mt` for multithread.

General-purpose build tooling such as Git, Docker/BuildKit and the Emscripten
3.1.40 container image is not copied into this archive.