---
license: apache-2.0
library_name: unity-sentis
tags:
  - unity
  - sentis
  - on-device
  - keyword-spotting
  - wake-word
---

# sentis-openwakeword

OpenWakeWord wake-word detection converted to **Unity Inference Engine (Sentis)** FP16.

## Files

```
melspectrogram_fp16.sentis      # shared mel front end
embedding_model_fp16.sentis     # shared 96-dim embedding model
WakeWord/                       # per-word classifier heads (alexa, jarvis, Ronaldo)
OpenWakeWord.cs                 # self-contained Unity Sentis inference
```

## ⚠️ Wake-word sample models

The bundled per-word heads (`alexa`, `jarvis`, `Ronaldo`) are OpenWakeWord **sample** models named
after third-party trademarks and a real person. They are included only to demonstrate the detector.
**Do not ship them in a product** — train or substitute a neutral custom wake word instead.

## Pipeline

Three stacked models, streaming at 16 kHz. It mirrors the reference openWakeWord pipeline:

1. **Mel** — feed the latest `1760` int16-scaled samples (`1280` new + `480` lookback) as `[1, samples]`;
   it emits 32-bin mel frames. Apply the reference transform `mel = spec / 10 + 2` and append to a mel ring buffer.
2. **Embedding** — take the latest `76` mel frames as `[1, 76, 32, 1]`; it emits one 96-d feature vector
   (append to a feature ring buffer).
3. **Wake word** — take the latest `N` feature frames as `[1, N, 96]`; reduce-max the output to a single
   score in `[0, 1]`. Fire when it crosses your threshold (≈0.5), with a debounce.

A complete self-contained implementation lives in [`OpenWakeWord.cs`](OpenWakeWord.cs) (chunking, mel +
feature ring buffers, the `FunctionalGraph` `ReduceMax` score head, warmup/debounce, and a `Detected`
event). Minimal usage:

```csharp
var detector = new OpenWakeWord(detectionThreshold: 0.5f);
detector.Load(modelRoot); // folder holding the two shared models + WakeWord/alexa_v0.1_fp16.sentis
detector.Detected += d => Debug.Log($"{d.Name} {d.Probability:0.00}");
// each frame: push 16 kHz mono samples, then drain
detector.PushSamples(micSamples, micSampleCount);
detector.Pump();          // call regularly (e.g. once per frame)
```

## License & attribution

Apache-2.0. Converted from [dscripka/openWakeWord](https://github.com/dscripka/openWakeWord)
(Apache-2.0).