# Third-Party Software Notice: MP3 Encoding

ZoneBuilder uses LAME for browser MP3 encoding, including durable Workbench and
Practice recording saves. The local worker loads the encoder on demand.

| Component | Version | License | Distributed form |
| --- | --- | --- | --- |
| LAME MP3 Encoder | 3.100, commit `98db548e8e851defbba3184125ce10725355c332` | GNU Library General Public License v2.0 or later | Encoder library statically linked into `mp3.wasm`; matching source download |
| wasm-media-encoders | 0.7.0, commit `4a45333baadbab312d1cc0911151dfad23157c51` | MIT | C bridge inside WASM; separate JavaScript wrapper; matching source/build inputs |

LAME is used under the GNU Library GPL; its use is covered by that license.
[Read the full Library GPL v2.0 text](licenses/LAME-GNU-Library-GPL-2.0.txt).
The source headers permit v2 or later. Do not substitute LGPL-2.1 wording for
this license. LAME project: <https://lame.sourceforge.io/>.

Attributions from the encoding-engine source include Copyright (c) 1999–2000
Mark Taylor, 2000–2005 Takehiro Tominaga, 2000–2017 Robert Hegemann, 2000–2005
Gabriel Bouvigne, and 2000–2004 Alexander Leidinger. Other contributors' original
copyright/author notices are preserved in the retained source files.
The wrapper/bridge is Copyright (c) 2020–2024 arseneyr:
[MIT license and warranty disclaimer](licenses/wasm-media-encoders-MIT.txt).
LAME's original [commercial-use notes](licenses/LAME-commercial-use-notes.txt)
are retained; the actual COPYING license governs the source/relink conditions.

## Obtain matching source and relink materials

[Download the source/build package](source/zonebuilder-mp3-source-0.7.0-lame-3.100-zb1.tar.gz)
from this same application deployment, or use **System → About → Third-Party
Software → Download MP3 source**. No login or request to the developer is needed.
See [download/build instructions](source/README.md), the
[SHA-256 manifest](source/manifest.json), and [build provenance](BUILD_PROVENANCE.md).

The package supplies the exact retained LAME source, the C bridge that links
against it, missing header/export graph and build/version inputs, original
licenses, and a documented MP3-only rebuild helper. The helper is separately
identified first-party build tooling. Upstream LAME/bridge source and the
published JavaScript wrapper are unchanged. The current WASM is built by
ZoneBuilder from this exact source package, using the documented recipe;
its SHA-256 is `a1d8ba08c80ec5e63d62ad30685e9656c9032126e9cd3b9c95991f8e17083b68`.
The archived published WASM is explicitly a historical comparison reference.

You may modify the encoder work for your own use and reverse engineer it for
debugging those modifications, as required by Library GPL section 6. Build and
replace the standalone WASM using the included instructions. Providing the
linked bridge in source form supports that relinking; no proprietary bridge
object is withheld. This notice does not assign a license to unrelated app code.

Materials are offered with equivalent download access alongside the binary
under sections 4 and 6(c), rather than the alternative section 6(b) written
offer. Distributors must retain matching materials and notices for each encoder
binary they make available. The download is outside application startup and is
not precached. An explicit download can be cached by the existing service worker.

The source package also retains distinct notices for source-only mpglib/hip
(Library GPL v2-or-later), TinyXML (zlib-style), GNU build helpers (their GPL
terms and distribution exceptions), and compiler/runtime support where noted.
They are not additional automatically loaded application modules.