voice_core #

Cancellable, provider-neutral voice conversation and turn orchestration.

Session state (preparing, active, stopping, failed) is independent from turn state (listening, thinking, speaking, interrupted). Generation IDs reject stale events after cancellation, while serialized sentence synthesis preserves output order.

import 'package:voice_core/voice_core.dart';

final segmenter = IncrementalSentenceSegmenter();
final sentences = segmenter.add('Hello. How are you?');

Duplex #

The default flow is half-duplex with VAD-driven barge-in. Capture can stay active while STT is gated during playback.

VoiceDuplexConfig opts into full duplex, where recognition stays live through playback so the user can speak over the assistant without losing the start of the utterance. It requires an echo-cancelled microphone: with the mic open during playback and nothing removing the speaker bleed, the recognizer hears the assistant. voice_flutter's VoiceFullDuplexSetup builds that composition and hands back the resolved config.

final controller = VoiceConversationController(
  input: input,
  backend: backend,
  synthesizer: tts,
  output: output,
  duplex: VoiceDuplexConfig.fullDuplex(),
);

What barge-in means in each mode:

Full duplex requested without echo cancellation resolves to half duplex, and duplex.isDegraded says so. That is deliberate: the degraded mode must never be worse than the no-AEC baseline. VoiceEchoCancellationFallback.acceptEchoRisk runs full duplex anyway, and is never a default. Every snapshot carries the mode actually in effect as duplexMode.

voice_core has no Flutter dependency and no dependency on audio_aec; it is told whether the microphone is clean rather than cleaning it. Use voice_flutter for ready-made graph input/output bridges and widgets.