import { Talk, VoiceActor } from '../types/voice';
import { VoiceEngine } from './VoiceEngine';
/**
 * None (no voice) engine
 * Implementation using Null Object pattern that performs no voice processing
 */
export declare class NoneEngine implements VoiceEngine {
    /**
     * Get voice data (performs no processing)
     * @param input script
     * @param speaker speaker ID
     * @param apiKey API key (not used)
     * @param voiceActor voice actor information (not used)
     * @returns empty ArrayBuffer
     */
    fetchAudio(input: Talk, speaker: string, apiKey?: string, voiceActor?: VoiceActor): Promise<ArrayBuffer>;
    /**
     * Get test message
     * @param textVoiceText custom text
     * @returns test message
     */
    getTestMessage(textVoiceText?: string): string;
    /**
     * Set custom API endpoint URL (performs no processing)
     * @param apiUrl custom API endpoint URL
     */
    setApiEndpoint?(apiUrl: string): void;
}