RNNoise Noise Reduction

This project vendors RNNoise source code in libs/librnnoise and builds it as a static library (rnnoise) through CMake.

Goal

• Keep RNNoise integrated in the main build system.
• Keep architecture-specific files separated by CPU target.
• Keep the ARM64 section prepared for future Raspberry Pi 5 optimization work.

Source Layout

• Library root: libs/librnnoise
• Core C sources: libs/librnnoise/src
• x64 optimized sources: libs/librnnoise/src/x86
• C++ wrapper used by the app: libs/librnnoise/RNNoise.cpp

CMake Integration

The RNNoise build definition is in:

• libs/librnnoise/CMakeLists.txt

Current behavior:

• Core RNNoise sources are always compiled.
• x64-only files are compiled only in if(DEFINED TARGET_CPU_X64).
• ARM64-only files must be added only in if(DEFINED TARGET_CPU_ARM64).
• config_rnnoise.h is copied to generated config.h for upstream-compatible includes that expect #include "config.h".

Architecture Policy

x64

• Keep x64 SIMD files only in the x64 section.
• Per-file compile options are set for SIMD files:
  • SSE4.1 for nnet_sse4_1.c
  • AVX2 for nnet_avx2.c

ARM64

• The ARM64 section is intentionally a placeholder today.
• Add ARM/NEON optimized files there later.
• Do not mix ARM64 files into the generic source list.

Build Notes

• RNNoise currently builds as C/C++ in this project.
• HAVE_CONFIG_H is enabled for RNNoise sources.
• Runtime CPU dispatch is enabled for x64 with RNN_ENABLE_X86_RTCD.

Quick Verification

From repository root:

cmake -S libs/librnnoise -B /tmp/nlc-rnnoise-check -DTARGET_CPU_X64=ON -DTARGET_OS_LINUX=ON
cmake --build /tmp/nlc-rnnoise-check -j

If ARM64 flags/sources are added in the future, use the corresponding target defines/toolchain for ARM64 and verify the same way.