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Sherpa ONNX
Apache-2.0Sherpa ONNX is an offline speech processing engine replacing cloud voice APIs with local text-to-speech and recognition across mobile and edge hardware.
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Overview
Sherpa ONNX packages next-generation Kaldi speech technologies into a standalone C++ runtime driven by ONNX Runtime, handling text-to-speech, recognition, and voice analysis without network access. The engine compiles to self-contained binaries across x86, ARM, RISC-V, and embedded NPUs, exposing bindings for twelve programming languages. It gives developers an offline alternative to cloud speech services for mobile apps, edge devices, and backend services.
Why Sherpa ONNX instead of ElevenLabs
ElevenLabs delivers nuanced human emotion, instant voice cloning, and expressive pacing through cloud neural models. That fidelity requires an outbound network connection, introducing 200 to 800 milliseconds of latency, jitter, and ongoing per-character billing. Sherpa ONNX moves speech generation directly onto local hardware, executing compact architectures like Kokoro, Piper, and Matcha-TTS on the host CPU or edge accelerator. For voice assistants, IVR systems, and robotics, local execution eliminates network lag and functions without internet connectivity.
The operational trade-off centers on vocal fidelity versus deterministic control. ElevenLabs excels at studio narrations that small edge models cannot match. Sherpa ONNX trades dramatic expressiveness for speed, reaching real-time factors below 0.1 on standard x86 servers and mobile processors. Migrating from cloud APIs like ElevenLabs or Amazon Polly means deploying the runtime as a WebSocket daemon or embedding its C++ or Go libraries into application binaries. Teams forgo managed infrastructure and zero-shot emotion controls, but gain zero-latency streaming, total data privacy, and predictable operating costs.
What it does well
- Multi-platform hardware acceleration: runs on x86_64, ARM, and RISC-V, supporting Rockchip RKNN, Qualcomm QNN, and Ascend NPUs to offload inference from the host CPU.
- Broad programming language support: provides native bindings for C++, C, Python, Go, Rust, C#, Swift, Kotlin, Java, Dart, and JavaScript without extra wrapper layers.
- Self-contained mobile packaging: supplies pre-compiled Android AAR archives, iOS frameworks, and WebAssembly builds that run inside client apps without external runtimes.
- Unified audio processing toolchain: combines speech synthesis with streaming speech recognition, Silero voice activity detection, and speaker diarization in a single binary.
