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RapidSpeech.cpp

On-device speech AI runtime for ASR, TTS, VAD, and voice cloning. Python-simple, C++-native, GGUF-powered.

RapidSpeech.cpp runs speech recognition, text-to-speech, VAD, speaker embedding, and voice cloning on-device. It gives Python developers a simple API while keeping the runtime pure C/C++, backed by ggml and a unified GGUF model format. No cloud API, no speech server, no heavyweight Python model stack.

Python In 60 Seconds

Install

pip install rapidspeech

GPU wheels:

pip install rapidspeech-metal   # macOS / Apple Silicon
pip install rapidspeech-cuda    # Linux / NVIDIA

Text to speech

python python-api-examples/tts/tts-offline.py \
  --model /path/to/omnivoice-f16.gguf \
  --text "Hello, welcome to RapidSpeech." \
  --output output.wav

Speech to text

python python-api-examples/asr/asr-offline.py \
  --model /path/to/funasr-nano-fp16.gguf \
  --audio /path/to/audio.wav

Python API

import rapidspeech

tts = rapidspeech.tts_synthesizer("/path/to/omnivoice-f16.gguf")
tts.set_params(instruct="male, young adult", language="English", seed=42)
pcm = tts.synthesize("Hello from a native speech engine.")
sample_rate = tts.get_sample_rate()

import rapidspeech

asr = rapidspeech.asr_offline("/path/to/funasr-nano-fp16.gguf")
sample_rate = asr.get_model_meta()["audio_sample_rate"]
pcm = ...  # 1-D float32 mono PCM at sample_rate
asr.push_audio(pcm)
asr.process()
print(asr.get_text())

Why RapidSpeech.cpp

• Built for the edge: run speech models locally on laptops, servers, browsers, and device-class hardware.
• Python-simple, C++-native: write Python, run a C++/ggml engine underneath.
• One model format: ASR, TTS, VAD, and speaker models use GGUF.
• NumPy in, NumPy out: ASR takes float32 PCM; TTS returns float32 PCM.
• Edge-first backends: CPU, Metal, CUDA, Vulkan, CANN, OpenCL, and WebGPU.

Performance Snapshot

Test environment: Apple M1 Pro, funasr-nano-fp16.gguf, 15s audio.

RTF is processing time divided by audio duration. Lower is faster; RTF < 1 is faster than real time.

Supported Today

X-ASR — Chinese/English Zipformer2 transducer (icefall/k2). One GGUF serves both offline full-context decoding and true chunked streaming (per-layer left-context caches, sub-second partials, --chunk-len 16/32/48/96/192 fbank frames). Punctuation and casing, greedy transducer decode, runs on CPU / Metal / CUDA / Vulkan and quantizes to q4_k_m (99.5 MB).

IndexTTS-2 — expressive zero-shot voice-cloning TTS (GPT + S2Mel CFM + BigVGAN-v2 vocoder) with 4-mode emotion control (reference audio / vector / text / Qwen). See docs/index2tts.md.

In Progress

CosyVoice3, Qwen3-ASR, Qwen3-TTS.

Documentation

• Python examples
• Technical Notes: architecture, design tradeoffs, backends, model conversion, and binding surfaces.
• Model guides:
  • ASR — X-ASR (Zipformer2, streaming) · SenseVoice · FunASR-Nano
  • TTS — IndexTTS-2 (voice clone + emotion) · CosyVoice3 · OmniVoice · OpenVoice2 · Kokoro
  • VAD — Silero / FireRedVAD
  • Speaker — CAMPPlus
• Browser / WASM examples
• Node.js example

Native C++ CLI

Download Models

Models are available on:

• 🤗 Hugging Face: https://huggingface.co/RapidAI/RapidSpeech
• ModelScope: https://www.modelscope.cn/models/RapidAI/RapidSpeech

Build from Source

git clone https://github.com/RapidAI/RapidSpeech.cpp
cd RapidSpeech.cpp
git submodule sync && git submodule update --init --recursive
cmake -B build
cmake --build build --config Release

Self-contained executables (no runtime DLL/.so dependencies) — build the core and ggml statically into each CLI with -DRS_STATIC_EXE=ON:

# Windows / MSVC
cmake -B build -G "Visual Studio 17 2022" -A x64 -DRS_STATIC_EXE=ON
cmake --build build --config Release --parallel
# Linux / macOS
cmake -B build -DRS_STATIC_EXE=ON -DCMAKE_BUILD_TYPE=Release
cmake --build build -j

Build artifacts are located in the build/ directory:

• rs-asr-offline — Offline ASR command-line tool
• rs-asr-vad-online — VAD-segmented quasi-streaming ASR command-line tool
• rs-asr-online — True chunked streaming ASR (X-ASR; mic or WAV, live partials)
• rs-tts-offline — Offline TTS command-line tool
• rs-server — OpenAI-compatible HTTP API + MCP server (ASR + TTS)
• rs-quantize — Model quantization tool

Core Commands

Offline ASR

./build/rs-asr-offline \
  -m /path/to/funasr-nano-fp16.gguf \
  -w /path/to/audio.wav \
  -t 4 \
  --gpu true

VAD-segmented ASR

./build/rs-asr-offline \
  -m /path/to/funasr-nano-fp16.gguf \
  -v /path/to/silero_vad_v6.gguf \
  -w /path/to/audio.wav \
  -t 4 \
  --vad-threshold 0.5 \
  --silence-ms 600

Hotword biasing (FunASR-Nano)

# Bias proper nouns / fix homophones (e.g. 郭总 → 虢总); use --hotword-file for a large list
./build/rs-asr-offline \
  -m /path/to/funasr-nano-fp16.gguf \
  -w /path/to/audio.wav \
  --hotwords "虢总,阿里巴巴"

See docs/funasr-nano.md for details.

Streaming ASR (X-ASR)

# WAV, real-time paced with live partials (or --fast to run as fast as possible)
./build/rs-asr-online -m /path/to/xasr-q4_k_m.gguf -w /path/to/audio.wav --chunk-len 32
# Microphone
./build/rs-asr-online -m /path/to/xasr-q4_k_m.gguf --mic --chunk-len 16

See docs/x-asr.md for the model, chunk-size / latency tradeoffs, and GGUF conversion.

Text to speech

./build/rs-tts-offline \
  -m /path/to/omnivoice-f16.gguf \
  -t "Hello, welcome to RapidSpeech!" \
  --instruct "male, young adult, moderate pitch" \
  --lang English \
  --n-steps 32 \
  -o output.wav

Quantization

./build/rs-quantize /path/to/input-f16.gguf /path/to/output-q4_k.gguf q4_k

Server (OpenAI API + MCP)

# Serve ASR + TTS over an OpenAI-compatible HTTP API and MCP
./build/rs-server --asr-model xasr.gguf --tts-model omnivoice.gguf --port 8080

curl http://127.0.0.1:8080/v1/audio/transcriptions -F file=@audio.wav -F model=rapidspeech-asr
curl http://127.0.0.1:8080/v1/audio/speech -H 'content-type: application/json' \
     -d '{"input":"hello","voice":"female"}' --output out.wav

Also runs as an MCP server (stdio for Claude Desktop, or POST /mcp) and exposes WebSocket streaming endpoints (streaming ASR with partial/final, VAD-segmented ASR, segmented + pure streaming TTS), plus a browser test console (--web-dir examples/server → http://host:port/webui.html). See examples/server/README.md.

Python

See Python examples for offline ASR, streaming ASR, offline TTS, streaming TTS, VAD, and voice cloning.

🤝 Contributing

If you are interested in the following areas, we welcome your PRs or participation in discussions:

• Adapting more models to the framework.
• Refining and optimizing the project architecture.
• Improving inference performance.

Acknowledgements

1. Fun-ASR
2. llama.cpp
3. ggml
4. cppjieba — Chinese word segmentation
5. WeText — text normalization (ITN/TN)
6. miniaudio — single-file audio I/O
7. X-ASR Streaming-focused automatic speech recognition models