# third_party/ — vendored dependencies

Dependencies that are **not** consumed through vcpkg live here, copied verbatim into the tree.
Everything here is permissively licensed (no GPL/LGPL) per the house rule in
[`docs/tech-stack.md`](../docs/tech-stack.md) §5.

## rnnoise/

Real-time speech **noise suppression** (the DSP backend behind `ApmProcessor` —
see [`docs/voice.md`](../docs/voice.md) §10–11). Used by the receive-side per-stream NR
(`RemoteStream::recv_ns`) and the send-side mic NR (`vc_client::mic_ns_`).

- **Upstream:** https://github.com/xiph/rnnoise
- **Vendored at commit:** `70f1d256acd4b34a572f999a05c87bf00b67730d`
- **License:** BSD-3-Clause (code, see `rnnoise/COPYING`) + CC0-1.0 (model weights).
- **Why vendored, not vcpkg:** the vcpkg `rnnoise` port is marked `!windows !arm`, i.e.
  unavailable on our primary targets (Windows MinGW, Apple Silicon, iOS). RNNoise is small,
  self-contained C99 with no dependencies, so we vendor it directly.

### What was copied / changed
- Only the **library** sources + headers (`src/*.c`, `src/*.h`, `src/x86/*.h`, `include/`).
  The training/feature-dump tools (`dump_features.c`, `write_weights.c`, the `src/x86/*.c`
  RTCD kernels), build scaffolding (autotools, Meson) and `torch/` `training/` dirs are omitted.
- `src/rnnoise_data.c` is the **shrunk** model: upstream's `scripts/shrink_model.sh` strips the
  `#ifndef DISABLE_DEBUG_FLOAT` float-weight duplicates, taking the default model from ~78 MB to
  ~11.7 MB. We build with `-DDISABLE_DEBUG_FLOAT` so only the int8-quantized weights are used —
  this is exactly how upstream's default (non-debug) build behaves. The model is the built-in
  default loaded by `rnnoise_create(NULL)`; there is **no runtime model file**.

### Build
Built as a standalone static lib `rnnoise` in [`core/CMakeLists.txt`](../core/CMakeLists.txt)
(no RTCD; portable scalar path on x86, NEON on arm64), and linked into `libvoicecat` which
defines `VOICECAT_HAS_NS`. To refresh the model, re-run upstream `autogen.sh`/`download_model.sh`
+ `scripts/shrink_model.sh` and re-copy `src/rnnoise_data.{c,h}`.