Moonshine Voice C++ Example

This is a minimal, platform independent example of using the C++ interface to the Moonshine Voice Library.

To use this you'll first need to download a prebuilt version of the library, or build it yourself using cmake in core/ if you're on a platform without a prebuilt version.

Download

The easiest way to grab everything you need is the download-library.sh helper in this folder. It detects your platform, downloads the matching prebuilt library archive from our GitHub releases, and always extracts it into a folder named moonshine-voice here (regardless of operating system or architecture, so the build commands below never change). It also fetches the Medium Streaming English model into medium-streaming-en/ and a sample recording (two_cities.wav) so the transcriber example runs out of the box:

bash

cd examples/c++
./download-library.sh

On Linux the extracted moonshine-voice/lib folder is self-contained: it holds libmoonshine.so alongside the libonnxruntime.so.1 it depends on, and the library is built with an $ORIGIN rpath so it finds the ONNX Runtime next to itself with no LD_LIBRARY_PATH needed.

If you would rather download by hand, look for moonshine-voice-<platform>.tar.gz on the releases page and extract it into a moonshine-voice folder in this directory. For example, on MacOS:

bash

cd examples/c++
curl -O -L https://github.com/moonshine-ai/moonshine/releases/download/v0.0.71/moonshine-voice-macos-arm64.tar.gz
mkdir -p moonshine-voice
tar xzf moonshine-voice-macos-arm64.tar.gz -C moonshine-voice --strip-components=1

Build

The archive contains the Moonshine library inside the lib folder — a shared libmoonshine.so on Linux, a static libmoonshine.a on MacOS, or moonshine.lib on Windows. This is what you'll link against. There are also two headers, one for the low-level C API, and another for the higher-level C++ framework that's built on top of it. On Linux the lib folder also contains libonnxruntime.so.1, the ONNX Runtime shared library that libmoonshine.so loads at runtime.

Since this is a generic C++ example, I'll show the simplest possible build command lines on some common platforms. Because download-library.sh always extracts into a folder named moonshine-voice, the exact same command works on both x86_64 and 64-bit ARM within each operating system.

Linux

bash

g++ transcriber.cpp \
  -Imoonshine-voice/include \
  -Lmoonshine-voice/lib \
  -lmoonshine \
  -Wl,-rpath,'$ORIGIN/moonshine-voice/lib' \
  -o transcriber

The -Wl,-rpath,'$ORIGIN/...' flag records a runtime library search path relative to the compiled transcriber binary, so it finds libmoonshine.so (and, through that library's own $ORIGIN rpath, libonnxruntime.so.1) without any LD_LIBRARY_PATH. If you prefer, drop the rpath flag and instead export LD_LIBRARY_PATH=$(pwd)/moonshine-voice/lib before running.

You can build text-to-speech.cpp the same way (swap the source and -o output names). Note that it additionally needs the TTS voice and G2P data — pass its location with --asset-root (in a checkout of this repo that is ../../core/moonshine-tts/data).

MacOS

bash

g++ transcriber.cpp \
  -Imoonshine-voice/include \
  -Lmoonshine-voice/lib \
  -lmoonshine \
  -o transcriber \
  -framework CoreFoundation \
  -framework Foundation
g++ text-to-speech.cpp \
  -Imoonshine-voice/include \
  -Lmoonshine-voice/lib \
  -lmoonshine \
  -o text-to-speech \
  -framework CoreFoundation \
  -framework Foundation

Run

You should now have an executable called transcriber in this folder. Run it with:

bash

./transcriber

By default it transcribes the two_cities.wav sample using the Medium Streaming English model that download-library.sh placed in the medium-streaming-en/ folder, so you should see transcription results printed as it goes. You can point it at different models and inputs using --model-path, --model-arch, and --wav-path.