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Phase 2 & 3 complete: Build system and core bindings for nanobind
Co-authored-by: shauneccles <21007065+shauneccles@users.noreply.github.com>
1 parent 3c49c2a commit 7c2f339

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‎CMakeLists.txt‎

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Original file line numberDiff line numberDiff line change
@@ -3,6 +3,9 @@
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cmake_minimum_required(VERSION 3.15)
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set(CMAKE_POLICY_VERSION_MINIMUM 3.5)
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# Find Python before setting up the project
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find_package(Python COMPONENTS Interpreter Development REQUIRED)
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message(STATUS "Found Python prefix ${PYTHON_PREFIX}")
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list(PREPEND CMAKE_PREFIX_PATH "${PYTHON_PREFIX}")
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@@ -14,6 +17,10 @@ cmake_policy(SET CMP0148 NEW)
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# adds the external dependencies
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add_subdirectory(external)
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# Option to build nanobind version (default OFF to maintain compatibility)
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option(BUILD_NANOBIND "Build nanobind version in addition to pybind11" OFF)
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# Build pybind11 version (default)
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pybind11_add_module(python-samplerate src/samplerate.cpp)
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target_include_directories(python-samplerate PRIVATE ./external/libsamplerate/include)
@@ -45,3 +52,38 @@ set_target_properties(
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)
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target_link_libraries(python-samplerate PUBLIC samplerate)
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# Build nanobind version if requested
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if(BUILD_NANOBIND)
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nanobind_add_module(python-samplerate-nb src/samplerate_nb.cpp)
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target_include_directories(python-samplerate-nb PRIVATE ./external/libsamplerate/include)
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if(MSVC)
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target_compile_options(python-samplerate-nb PRIVATE /EHsc /MP /bigobj)
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endif()
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if (CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR
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CMAKE_CXX_COMPILER_ID MATCHES "GNU" OR
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(CMAKE_CXX_COMPILER_ID MATCHES "Intel" AND NOT WIN32))
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target_compile_options(python-samplerate-nb PRIVATE -std=c++17 -O3 -Wall -Wextra -fPIC)
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endif()
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### stick the package and libsamplerate version into the module
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target_compile_definitions(python-samplerate-nb
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PUBLIC LIBSAMPLERATE_VERSION="${LIBSAMPLERATE_VERSION}"
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PRIVATE $<$<BOOL:${PACKAGE_VERSION_INFO}>:VERSION_INFO="${PACKAGE_VERSION_INFO}">
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)
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### Final target setup
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set_target_properties(
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python-samplerate-nb
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PROPERTIES
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PREFIX ""
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OUTPUT_NAME "samplerate"
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LINKER_LANGUAGE C
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)
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target_link_libraries(python-samplerate-nb PUBLIC samplerate)
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endif()
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‎external/CMakeLists.txt‎

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@@ -9,6 +9,15 @@ FetchContent_Declare(
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FetchContent_MakeAvailable(pybind11)
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# nanobind
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FetchContent_Declare(
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nanobind
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GIT_REPOSITORY https://github.com/wjakob/nanobind
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GIT_TAG v2.9.2
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)
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FetchContent_MakeAvailable(nanobind)
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# libsamplerate
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set(BUILD_TESTING OFF CACHE BOOL "Disable libsamplerate test build")
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set(CMAKE_POSITION_INDEPENDENT_CODE ON)

‎setup_nb.py‎

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# Compile and install the python-samplerate-ledfx package with nanobind
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#
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# This is a separate setup file for building the nanobind version
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# Use: BUILD_NANOBIND=1 pip install -e .
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import os
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from pathlib import Path
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import subprocess
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import sys
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from setuptools import Extension, setup
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from setuptools.command.build_ext import build_ext
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# Convert distutils Windows platform specifiers to CMake -A arguments
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PLAT_TO_CMAKE = {
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"win32": "Win32",
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"win-amd64": "x64",
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"win-arm32": "ARM",
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"win-arm64": "ARM64",
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}
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# A CMakeExtension needs a sourcedir instead of a file list.
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# The name must be the _single_ output extension from the CMake build.
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# If you need multiple extensions, see scikit-build.
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class CMakeExtension(Extension):
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def __init__(self, name: str, sourcedir: str = "") -> None:
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super().__init__(name, sources=[])
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self.sourcedir = os.fspath(Path(sourcedir).resolve())
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class CMakeBuild(build_ext):
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def build_extension(self, ext: CMakeExtension) -> None:
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# Must be in this form due to bug in .resolve() only fixed in Python 3.10+
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ext_fullpath = Path.cwd() / self.get_ext_fullpath(ext.name)
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extdir = ext_fullpath.parent.resolve()
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# Using this requires trailing slash for auto-detection & inclusion of
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# auxiliary "native" libs
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debug = int(os.environ.get("DEBUG", 0)) if self.debug is None else self.debug
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cfg = "Debug" if debug else "Release"
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# CMake lets you override the generator - we need to check this.
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# Can be set with Conda-Build, for example.
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cmake_generator = os.environ.get("CMAKE_GENERATOR", "")
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# Set Python_EXECUTABLE instead if you use PYBIND11_FINDPYTHON
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# EXAMPLE_VERSION_INFO shows you how to pass a value into the C++ code
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# from Python.
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cmake_args = [
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f"-DCMAKE_LIBRARY_OUTPUT_DIRECTORY={extdir}{os.sep}",
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f"-DPYTHON_EXECUTABLE={sys.executable}",
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f"-DCMAKE_BUILD_TYPE={cfg}", # not used on MSVC, but no harm
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"-DBUILD_NANOBIND=ON", # Enable nanobind build
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]
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build_args = []
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# Adding CMake arguments set as environment variable
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# (needed e.g. to build for ARM OSx on conda-forge)
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if "CMAKE_ARGS" in os.environ:
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cmake_args += [item for item in os.environ["CMAKE_ARGS"].split(" ") if item]
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# In this example, we pass in the version to C++. You might not need to.
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cmake_args += [f"-DPACKAGE_VERSION_INFO={self.distribution.get_version()}"]
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if self.compiler.compiler_type != "msvc":
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# Using Ninja-build since it a) is available as a wheel and b)
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# multithreads automatically. MSVC would require all variables be
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# exported for Ninja to pick it up, which is a little tricky to do.
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# Users can override the generator with CMAKE_GENERATOR in CMake
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# 3.15+.
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if not cmake_generator or cmake_generator == "Ninja":
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try:
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import ninja
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ninja_executable_path = Path(ninja.BIN_DIR) / "ninja"
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cmake_args += [
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"-GNinja",
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f"-DCMAKE_MAKE_PROGRAM:FILEPATH={ninja_executable_path}",
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]
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except ImportError:
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pass
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else:
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# Single config generators are handled "normally"
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single_config = any(x in cmake_generator for x in {"NMake", "Ninja"})
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# CMake allows an arch-in-generator style for backward compatibility
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contains_arch = any(x in cmake_generator for x in {"ARM", "Win64"})
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# Specify the arch if using MSVC generator, but only if it doesn't
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# contain a backward-compatibility arch spec already in the
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# generator name.
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if not single_config and not contains_arch:
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cmake_args += ["-A", PLAT_TO_CMAKE[self.plat_name]]
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# Multi-config generators have a different way to specify configs
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if not single_config:
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cmake_args += [
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f"-DCMAKE_LIBRARY_OUTPUT_DIRECTORY_{cfg.upper()}={extdir}"
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]
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build_args += ["--config", cfg]
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# When building universal2 wheels, we need to set the architectures for CMake.
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if "universal2" in self.plat_name:
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cmake_args += ["-DCMAKE_OSX_ARCHITECTURES=arm64;x86_64"]
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# Set MACOSX_DEPLOYMENT_TARGET for macOS builds.
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if (
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self.plat_name.startswith("macosx-")
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and "MACOSX_DEPLOYMENT_TARGET" not in os.environ
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):
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target_version = self.plat_name.split("-")[1]
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os.environ["MACOSX_DEPLOYMENT_TARGET"] = target_version
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# Set CMAKE_BUILD_PARALLEL_LEVEL to control the parallel build level
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# across all generators.
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if "CMAKE_BUILD_PARALLEL_LEVEL" not in os.environ:
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# self.parallel is a Python 3 only way to set parallel jobs by hand
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# using -j in the build_ext call, not supported by pip or PyPA-build.
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if hasattr(self, "parallel") and self.parallel:
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# CMake 3.12+ only.
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build_args += [f"-j{self.parallel}"]
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build_temp = Path(self.build_temp) / ext.name
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if not build_temp.exists():
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build_temp.mkdir(parents=True)
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subprocess.run(
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["cmake", ext.sourcedir, *cmake_args], cwd=build_temp, check=True
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)
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subprocess.run(
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["cmake", "--build", ".", *build_args], cwd=build_temp, check=True
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)
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setup(
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name="samplerate-ledfx-nb",
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cmdclass={"build_ext": CMakeBuild},
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ext_modules=[CMakeExtension("samplerate")],
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)

‎src/samplerate_nb.cpp‎

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/*
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* Python bindings for libsamplerate using nanobind
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* Copyright (C) 2025 LedFx Team
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* You should have received a copy of the MIT License along with this program.
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* If not, see <https://opensource.org/licenses/MIT>.
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*/
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#include <nanobind/nanobind.h>
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#include <nanobind/ndarray.h>
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#include <nanobind/stl/function.h>
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#include <nanobind/stl/string.h>
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#include <samplerate.h>
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#include <cmath>
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#include <iostream>
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#include <string>
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#include <typeinfo>
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#include <vector>
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#ifndef VERSION_INFO
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#define VERSION_INFO "nightly"
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#endif
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// This value was empirically and somewhat arbitrarily chosen; increase it for further safety.
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#define END_OF_INPUT_EXTRA_OUTPUT_FRAMES 10000
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namespace nb = nanobind;
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using namespace nb::literals;
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// Type aliases for nanobind arrays
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using nb_array_f32 = nb::ndarray<nb::numpy, float, nb::c_contig>;
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using callback_t = std::function<nb_array_f32(void)>;
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namespace samplerate {
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enum class ConverterType {
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sinc_best,
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sinc_medium,
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sinc_fastest,
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zero_order_hold,
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linear
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};
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class ResamplingException : public std::exception {
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public:
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explicit ResamplingException(int err_num) : message{src_strerror(err_num)} {}
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const char *what() const noexcept override { return message.c_str(); }
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private:
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std::string message = "";
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};
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int get_converter_type(const nb::object &obj) {
73+
if (nb::isinstance<nb::str>(obj)) {
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std::string s = nb::cast<std::string>(obj);
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if (s.compare("sinc_best") == 0) {
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return 0;
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} else if (s.compare("sinc_medium") == 0) {
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return 1;
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} else if (s.compare("sinc_fastest") == 0) {
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return 2;
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} else if (s.compare("zero_order_hold") == 0) {
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return 3;
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} else if (s.compare("linear") == 0) {
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return 4;
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}
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} else if (nb::isinstance<nb::int_>(obj)) {
87+
return nb::cast<int>(obj);
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} else if (nb::isinstance<ConverterType>(obj)) {
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nb::int_ c = obj.attr("value");
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return nb::cast<int>(c);
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}
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93+
throw std::domain_error("Unsupported converter type");
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return -1;
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}
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void error_handler(int errnum) {
98+
if (errnum > 0 && errnum < 24) {
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throw ResamplingException(errnum);
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} else if (errnum != 0) { // the zero case is excluded as it is not an error
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// this will throw a segmentation fault if we call src_strerror here
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// also, these should never happen
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throw std::runtime_error("libsamplerate raised an unknown error code");
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}
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}
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} // namespace samplerate
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namespace sr = samplerate;
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NB_MODULE(samplerate, m) {
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m.doc() = "A simple python wrapper library around libsamplerate using nanobind";
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m.attr("__version__") = VERSION_INFO;
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m.attr("__libsamplerate_version__") = LIBSAMPLERATE_VERSION;
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auto m_exceptions = m.def_submodule(
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"exceptions", "Sub-module containing sampling exceptions");
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auto m_converters = m.def_submodule(
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"converters", "Sub-module containing the samplerate converters");
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auto m_internals = m.def_submodule("_internals", "Internal helper functions");
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// give access to this function for testing
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m_internals.def(
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"get_converter_type", &sr::get_converter_type,
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"Convert python object to integer of converter type or raise an error "
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"if illegal");
127+
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m_internals.def(
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"error_handler", &sr::error_handler,
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"A function to translate libsamplerate error codes into exceptions");
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nb::register_exception_translator([](const std::exception_ptr &p, void *payload) {
133+
try {
134+
std::rethrow_exception(p);
135+
} catch (const sr::ResamplingException &e) {
136+
PyErr_SetString(PyExc_RuntimeError, e.what());
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}
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});
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// Create ResamplingError as an alias to the Python RuntimeError
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m_exceptions.attr("ResamplingError") = nb::handle(PyExc_RuntimeError);
142+
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nb::enum_<sr::ConverterType>(m_converters, "ConverterType", R"mydelimiter(
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Enum of samplerate converter types.
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Pass any of the members, or their string or value representation, as
147+
``converter_type`` in the resamplers.
148+
)mydelimiter")
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.value("sinc_best", sr::ConverterType::sinc_best)
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.value("sinc_medium", sr::ConverterType::sinc_medium)
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.value("sinc_fastest", sr::ConverterType::sinc_fastest)
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.value("zero_order_hold", sr::ConverterType::zero_order_hold)
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.value("linear", sr::ConverterType::linear)
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.export_values();
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// Convenience imports
157+
m.attr("ResamplingError") = m_exceptions.attr("ResamplingError");
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m.attr("ConverterType") = m_converters.attr("ConverterType");
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}

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