import type { Talk } from '../types/voice';
import type { VoiceEngine } from './VoiceEngine';
export type GeminiTtsModel = 'gemini-3.1-flash-tts-preview' | 'gemini-2.5-flash-preview-tts' | 'gemini-2.5-pro-preview-tts' | (string & {});
/**
 * Gemini TTS voice synthesis engine.
 * Uses the Gemini API with API key authentication.
 */
export declare class GeminiTtsEngine implements VoiceEngine {
    private baseUrl;
    private model;
    private languageCode;
    private prompt?;
    private createWavFromPcm;
    /**
     * Set custom Gemini TTS API endpoint
     */
    setApiEndpoint(apiUrl: string): void;
    /**
     * Set Gemini TTS model
     */
    setModel(model: GeminiTtsModel): void;
    /**
     * Set synthesis language code
     */
    setLanguageCode(languageCode: string): void;
    /**
     * Set optional synthesis prompt
     */
    setPrompt(prompt?: string): void;
    fetchAudio(input: Talk, speaker: string, apiKey?: string): Promise<ArrayBuffer>;
    getTestMessage(textVoiceText?: string): string;
}