/**
 * Preload & Cache System
 *
 * Prevents stuttering when seeking by pre-loading and caching:
 * - MIDI events in range
 * - Soundfont samples for instruments
 * - Lyrics in range
 * - Audio buffers
 */
export interface PreloadRange {
    startTime: number;
    endTime: number;
}
export interface CacheStats {
    midiEventsCached: number;
    instrumentsCached: number;
    lyricsCached: number;
    cacheHits: number;
    cacheMisses: number;
}
/**
 * MIDI Event Cache
 * Pre-cache MIDI events for smooth seeking
 */
export declare class MIDIEventCache {
    private cache;
    private stats;
    /**
     * Pre-cache MIDI events in time range
     */
    preloadRange(midiData: any, range: PreloadRange): void;
    /**
     * Get cached events for time
     */
    getEventsAt(time: number, lookAhead?: number): any[];
    /**
     * Find cache key containing time
     */
    private findCacheKey;
    /**
     * Clear cache
     */
    clear(): void;
    /**
     * Get cache stats
     */
    getStats(): CacheStats;
}
/**
 * Instrument Cache
 * Pre-warm soundfont instruments
 */
export declare class InstrumentCache {
    private warmedInstruments;
    private synthesizer;
    setSynthesizer(synth: any): void;
    /**
     * Pre-warm instruments used in MIDI
     */
    warmupInstruments(midiData: any): Promise<void>;
    /**
     * Check if instrument is warmed up
     */
    isWarmed(program: number): boolean;
    /**
     * Clear cache
     */
    clear(): void;
    /**
     * Get warmed instruments count
     */
    getWarmCount(): number;
}
/**
 * Lyric Cache
 * Pre-render lyrics for smooth display
 */
export declare class LyricCache {
    private cache;
    private preRenderRange;
    /**
     * Pre-render lyrics around time
     */
    preloadAround(lyrics: any[], currentTime: number, renderFn: (lyric: any) => string): void;
    /**
     * Get cached lyric
     */
    get(index: number): string | null;
    /**
     * Check if lyric is cached
     */
    has(index: number): boolean;
    /**
     * Set pre-render range
     */
    setPreRenderRange(seconds: number): void;
    /**
     * Clear cache
     */
    clear(): void;
    /**
     * Get cache size
     */
    size(): number;
}
/**
 * Seek Optimizer
 * Smooth seeking with pre-buffering
 */
export declare class SeekOptimizer {
    private midiCache;
    private instrumentCache;
    private lyricCache;
    private isPreloading;
    private preloadPromise;
    constructor();
    /**
     * Initialize with MIDI and synthesizer
     */
    initialize(midiData: any, synthesizer: any): Promise<void>;
    /**
     * Pre-load range before seeking
     */
    preloadRange(midiData: any, lyrics: any[], range: PreloadRange, lyricRenderFn: (lyric: any) => string): Promise<void>;
    private _doPreload;
    /**
     * Optimized seek with pre-buffering
     */
    seek(targetTime: number, midiData: any, lyrics: any[], lyricRenderFn: (lyric: any) => string, seekFn: (time: number) => void): Promise<void>;
    /**
     * Get MIDI cache
     */
    getMIDICache(): MIDIEventCache;
    /**
     * Get instrument cache
     */
    getInstrumentCache(): InstrumentCache;
    /**
     * Get lyric cache
     */
    getLyricCache(): LyricCache;
    /**
     * Get cache stats
     */
    getStats(): CacheStats;
    /**
     * Clear all caches
     */
    clear(): void;
}
/**
 * Progressive Preloader
 * Progressively preload entire song in background
 */
export declare class ProgressivePreloader {
    private optimizer;
    private chunkSize;
    private isPreloading;
    private currentChunk;
    constructor(optimizer: SeekOptimizer);
    /**
     * Start progressive preloading
     */
    startPreloading(midiData: any, lyrics: any[], duration: number, lyricRenderFn: (lyric: any) => string): Promise<void>;
    /**
     * Stop preloading
     */
    stop(): void;
    /**
     * Get preload progress (0-1)
     */
    getProgress(duration: number): number;
    /**
     * Set chunk size
     */
    setChunkSize(seconds: number): void;
}