flutter_gemma_speech 0.2.0

On-device speech (STT + TTS) for flutter_gemma via the LiteRT C API + dart:ffi. Opt-in Stt/TtsBackendProvider.

flutter_gemma_speech

On-device speech for flutter_gemma — STT and TTS today, a voice loop later — via the LiteRT C API + dart:ffi. Opt-in package: add it only if your app needs speech-to-text or text-to-speech.

This package depends on flutter_gemma_litertlm, which owns the shared libLiteRtLm native bundle and exposes the LiteRt interpreter FFI (LiteRtBindings) used here.

Status

• STT works end-to-end for moonshine-tiny (raw-PCM seq2seq) via LiteRtSttBackend; whisper/parakeet (log-mel) profiles are follow-ons.
• TTS works end-to-end for Matcha (litert-community/Matcha-TTS, 22050 Hz) via LiteRtTtsBackend — a 3-graph LiteRT pipeline (encoder → CFM decoder → HiFi-GAN vocoder) producing 16-bit PCM; kokoro/supertonic are follow-ons.

Both backends are pure factories (canHandle always true) — the model is selected per-install via SttModelType / TtsModelType, not the backend.

Usage

import 'package:flutter_gemma/flutter_gemma.dart';
import 'package:flutter_gemma_speech/flutter_gemma_speech.dart';

await FlutterGemma.initialize(
  sttBackends: [LiteRtSttBackend()],
  ttsBackends: [LiteRtTtsBackend()],
);

// Text-to-speech (Matcha): install the bundle once, then synthesize.
await FlutterGemma.installTts()
    .fromNetwork('https://huggingface.co/litert-community/Matcha-TTS/resolve/main/')
    .ofType(TtsModelType.matcha)
    .install();

final synth = await FlutterGemma.getActiveTts();
final pcm = await synth.synthesize('Hello world.'); // Uint8List, 16-bit PCM
print(synth.sampleRate); // 22050
await synth.close();

Platforms

Platform	STT	TTS
Android / iOS	✅ FFI	✅ FFI
macOS / Linux / Windows	✅ FFI	✅ FFI
Web	🚧 stub UnsupportedError	🚧 stub UnsupportedError

No hook/build.dart of its own — the native library is bundled by flutter_gemma_litertlm's Native Assets hook and shared transitively.