/**
 * Audio format conversion utilities
 * Provides conversion between different audio formats (WAV, MP3, OGG)
 */
/**
 * Supported audio formats for conversion
 */
export type AudioFormat = "wav" | "mp3" | "ogg";
/**
 * Audio conversion options
 */
export interface AudioConversionOptions {
    /** Target sample rate (default: preserve original) */
    sampleRate?: number;
    /** Target bit rate for compressed formats like MP3 (default: 128kbps) */
    bitRate?: number;
    /** Audio quality (0-9 for OGG, 0-320 for MP3) */
    quality?: number;
}
/**
 * Result of audio conversion
 */
export interface AudioConversionResult {
    /** Converted audio data */
    audioBytes: Uint8Array;
    /** Target format */
    format: AudioFormat;
    /** MIME type of the converted audio */
    mimeType: string;
}
/**
 * Check if audio conversion is available in the current environment
 *
 * Audio format conversion is currently only supported in Node.js environments
 * due to the need for external tools like ffmpeg or native Node.js modules.
 *
 * In browser environments:
 * - Engines return their native format without conversion
 * - WebSpeech API engines use browser's native audio capabilities
 * - Format requests are honored only when engines natively support them
 */
export declare function isAudioConversionAvailable(): boolean;
/**
 * Get MIME type for audio format
 */
export declare function getMimeTypeForFormat(format: AudioFormat): string;
/**
 * Extract WAV audio parameters from WAV file header
 */
export declare function extractWavParameters(wavBytes: Uint8Array): {
    sampleRate: number;
    channels: number;
    bitsPerSample: number;
    dataOffset: number;
    dataSize: number;
} | null;
/**
 * Convert audio between formats using available Node.js tools
 */
export declare function convertAudioFormat(inputBytes: Uint8Array, targetFormat: AudioFormat, options?: AudioConversionOptions): Promise<AudioConversionResult>;
/**
 * Check if ffmpeg is available
 */
export declare function isFFmpegAvailable(): Promise<boolean>;