import { Talk } from '../types/voice';
import { VoiceEngine } from './VoiceEngine';
export type UnrealSpeechCodec = 'libmp3lame' | 'pcm_mulaw' | 'pcm_s16le';
/**
 * Unreal Speech voice synthesis engine.
 */
export declare class UnrealSpeechEngine implements VoiceEngine {
    private apiEndpoint;
    private bitrate;
    private speed;
    private pitch;
    private codec;
    private temperature?;
    /**
     * Set Unreal Speech /stream API endpoint URL.
     */
    setApiEndpoint(apiUrl: string): void;
    /**
     * Set audio bitrate such as 192k or 320k.
     */
    setBitrate(bitrate?: string): void;
    /**
     * Set speaking speed (-1.0 - 1.0).
     */
    setSpeed(speed?: number): void;
    /**
     * Set pitch (0.5 - 1.5).
     */
    setPitch(pitch?: number): void;
    /**
     * Set output codec.
     */
    setCodec(codec?: UnrealSpeechCodec): void;
    /**
     * Set generation temperature (0.1 - 0.8).
     */
    setTemperature(temperature?: number): void;
    fetchAudio(input: Talk, speaker: string, apiKey?: string): Promise<ArrayBuffer>;
    getTestMessage(textVoiceText?: string): string;
    private isSupportedCodec;
}