/**
 * ElevenLabs Text-to-Speech Handler
 *
 * Implementation of TTS using ElevenLabs API.
 *
 * @module voice/providers/ElevenLabsTTS
 */
import type { TTSHandler, TTSOptions, TTSResult, TTSVoice } from "../../types/index.js";
/**
 * ElevenLabs Text-to-Speech Handler
 *
 * Supports high-quality multilingual TTS with voice cloning.
 *
 * @see https://elevenlabs.io/docs/api-reference
 */
export declare class ElevenLabsTTS implements TTSHandler {
    private readonly apiKey;
    private readonly baseUrl;
    private voicesCache;
    private static readonly CACHE_TTL_MS;
    /**
     * Maximum text length (5000 characters)
     */
    readonly maxTextLength = 5000;
    constructor(apiKey?: string);
    isConfigured(): boolean;
    getVoices(languageCode?: string): Promise<TTSVoice[]>;
    synthesize(text: string, options?: TTSOptions): Promise<TTSResult>;
    /**
     * Map gender string to standard type
     */
    private mapGender;
    /**
     * Map TTSAudioFormat to ElevenLabs output format
     */
    private mapFormat;
    /**
     * Get sample rate from format string
     */
    private getSampleRate;
    /**
     * Map the ElevenLabs `output_format` string back to a canonical
     * TTSAudioFormat. mapFormat() falls back to mp3_44100_128 for unsupported
     * inputs, so this is needed to keep TTSResult.format honest.
     *
     * NOTE: ElevenLabs `pcm_*` outputs are RAW 16-bit signed-LE PCM samples
     * with no RIFF/WAV header. We surface that as `pcm16` (which exists in the
     * `TTSAudioFormat` union exactly for this case) — labeling it as `wav`
     * would cause consumers writing the buffer to a `.wav` file or feeding it
     * to a WAV parser to produce unplayable output (CodeRabbit review).
     */
    private effectiveFormat;
}