Txtset HEIC decoder — source and licence
========================================

/heic-converter/ does not ship a decoder inside this repository. On the first
conversion of a visit the page fetches one from a pinned address:

  https://cdn.jsdelivr.net/npm/libheif-js@1.19.8/libheif-wasm/libheif-bundle.js

That file is loaded with Subresource Integrity —

  sha384-HXIRij9wEcFbMeYe8lcO83/544aNPhd8574RnlD/cQVbNPdq5iBkjgGPpxtsycNv

— so a browser refuses to run it if a single byte differs from the version this
site was built against. The WebAssembly is embedded in that one file as base64,
so there is no second, unpinned fetch behind it.

What it is
----------

  libheif-js 1.19.8 — an Emscripten build of libheif for browsers and Node.
  https://github.com/catdad-experiments/libheif-js
  Package licence: LGPL-3.0

  libheif — the HEIF/HEIC/AVIF decoder itself, by Dirk Farin / struktur AG.
  https://github.com/strukturag/libheif
  Licence: LGPL-3.0 (the library), with the bundled HEVC decoder carrying its
  own terms; see that project's COPYING and README.

Why the LGPL is satisfied here
------------------------------

The library is used unmodified, as a separate file, loaded at runtime by name
and version. Nothing in this repository is linked into it or derived from it,
and the exact build a visitor runs is identified above, so anyone can obtain
the corresponding source from the projects named and substitute their own build
of the library.

What this does NOT mean
-----------------------

Downloading a decoder is not uploading a photo. The file travels TO the
visitor; the photo is decoded and re-encoded on the visitor's own device and is
never sent anywhere. That distinction is the whole reason this page exists —
nearly every other HEIC converter works the other way round.