/**
 * TTS Stream Bridge — generates TTS audio server-side and pipes PCM data
 * into FFmpeg's audio track for RTMP streaming.
 *
 * Uses pipe:3 (a 4th stdio fd) as the audio input to FFmpeg. Writes PCM
 * silence when idle and decoded TTS audio when speaking. This avoids FIFO
 * complexity and works cross-platform.
 *
 * @module services/tts-stream-bridge
 */
import type { Writable } from "node:stream";
import type { TtsConfig, TtsProvider } from "../config/types.messages";
/** Resolved TTS configuration for a speak() call. */
export interface ResolvedTtsConfig {
    provider: TtsProvider;
    elevenlabs?: {
        apiKey: string;
        voiceId: string;
        modelId: string;
        voiceSettings?: Record<string, unknown>;
    };
    openai?: {
        apiKey: string;
        model: string;
        voice: string;
    };
    edge?: {
        voice: string;
    };
}
/** Public interface for the TTS stream bridge. */
export interface ITtsStreamBridge {
    attach(stream: Writable): void;
    detach(): void;
    isAttached(): boolean;
    isSpeaking(): boolean;
    speak(text: string, config: ResolvedTtsConfig): Promise<boolean>;
}
declare class TtsStreamBridge implements ITtsStreamBridge {
    private writeStream;
    private tickTimer;
    private pcmQueue;
    private _speaking;
    private silenceChunk;
    constructor();
    /** Attach the bridge to an FFmpeg stdio pipe (pipe:3). */
    attach(stream: Writable): void;
    /** Detach from FFmpeg — stops tick loop and clears queue. */
    detach(): void;
    /** Whether the bridge is currently attached to an FFmpeg process. */
    isAttached(): boolean;
    /** Whether TTS audio is currently being played. */
    isSpeaking(): boolean;
    /**
     * Generate TTS for the given text and queue PCM audio for playback.
     * Non-blocking — queues audio and returns immediately after generation.
     */
    speak(text: string, config: ResolvedTtsConfig): Promise<boolean>;
    /** Called every CHUNK_MS — writes next PCM chunk (TTS or silence) to FFmpeg. */
    private tick;
    private generateTts;
    private generateElevenlabs;
    private generateOpenai;
    private generateEdge;
    /** Decode MP3 audio to raw s16le PCM using an FFmpeg subprocess. */
    private decodeMp3ToPcm;
}
/**
 * Resolve TTS configuration from milady config, finding the best available
 * provider with valid API keys.
 */
export declare function resolveTtsConfig(ttsConfig: TtsConfig | undefined): ResolvedTtsConfig | null;
/**
 * Get a summary of available TTS providers and their status.
 */
export declare function getTtsProviderStatus(ttsConfig: TtsConfig | undefined): {
    configuredProvider: string | null;
    hasApiKey: boolean;
    resolvedProvider: string | null;
};
export declare const ttsStreamBridge: TtsStreamBridge;
export {};
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