/** @packageDocumentation Audio properties for the Ogg Opus format, parsed from the OpusHead identification header (packet 0). */
import { AudioProperties } from "../../audioProperties.js";
import { ReadStyle } from "../../toolkit/types.js";
import type { OggFile } from "../oggFile.js";
/**
 * Audio properties for Ogg Opus files, parsed from the OpusHead identification
 * header (packet 0).
 *
 * OpusHead layout:
 *   "OpusHead"(8) + version(1) + channels(1) + preSkip(2 LE) +
 *   inputSampleRate(4 LE) + outputGain(2 LE signed) +
 *   channelMappingFamily(1)
 */
export declare class OpusProperties extends AudioProperties {
    /** Stream duration in milliseconds, computed from first and last granule positions. */
    private _lengthInMs;
    /** Average bitrate in kilobits per second, computed from stream length and duration. */
    private _bitrate;
    /** Number of audio channels as declared in the OpusHead header. */
    private _channels;
    /** Opus encoder version byte from the OpusHead header. */
    private _opusVersion;
    /** Original input sample rate before Opus encoding, in Hz. */
    private _inputSampleRate;
    /** Output gain in signed Q7.8 fixed-point format (divide by 256.0 to get dB). */
    private _outputGain;
    /**
     * Constructs an OpusProperties instance with the given read style.
     * @param readStyle - Level of detail for property parsing.
     */
    constructor(readStyle?: ReadStyle);
    /**
     * Asynchronously parse and return audio properties from the given Ogg Opus file.
     * @param file - The {@link OggFile} to read properties from.
     * @param readStyle - Level of detail for property parsing.
     * @returns A populated {@link OpusProperties} instance.
     */
    static create(file: OggFile, readStyle?: ReadStyle): Promise<OpusProperties>;
    /** Stream duration in milliseconds, computed from first and last granule positions. */
    get lengthInMilliseconds(): number;
    /** Average bitrate in kilobits per second, computed from stream length and duration. */
    get bitrate(): number;
    /** Opus always decodes at 48000 Hz regardless of the original input sample rate. */
    get sampleRate(): number;
    /** Number of audio channels as declared in the OpusHead header. */
    get channels(): number;
    /** Opus encoder version byte from the OpusHead header (major version in bits 4–7). */
    get opusVersion(): number;
    /** Original sample rate of the input audio before Opus encoding, in Hz. */
    get inputSampleRate(): number;
    /**
     * Output gain in signed Q7.8 fixed-point format.
     * Divide by 256.0 to convert to dB.
     */
    get outputGain(): number;
    /**
     * Reads and populates audio properties from the OpusHead identification header (packet 0).
     * @param file - The {@link OggFile} to read from.
     */
    private read;
}
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