/** @packageDocumentation Audio properties implementation for MPEG (MP3) and ADTS (AAC) files, including VBR (Xing/VBRI) support. */
import { AudioProperties } from "../audioProperties.js";
import { ReadStyle } from "../toolkit/types.js";
import { MpegVersion, ChannelMode } from "./mpegHeader.js";
import type { MpegFile } from "./mpegFile.js";
/**
 * Audio properties for MPEG (MP3) and ADTS (AAC) streams.
 *
 * Reads frame headers to determine duration, bitrate, sample rate and
 * channel layout. Handles both CBR and VBR (Xing / VBRI) streams.
 */
export declare class MpegProperties extends AudioProperties {
    /** Duration of the audio stream in milliseconds. */
    private _lengthInMs;
    /** Average bitrate in kbps. */
    private _bitrate;
    /** Sample rate in Hz. */
    private _sampleRate;
    /** Number of audio channels. */
    private _channels;
    /** MPEG version of the first audio frame. */
    private _version;
    /** MPEG layer number (1, 2, or 3); 0 for ADTS. */
    private _layer;
    /** Whether CRC protection is enabled. */
    private _protectionEnabled;
    /** Whether the audio is flagged as copyrighted. */
    private _isCopyrighted;
    /** Whether the audio is flagged as an original recording. */
    private _isOriginal;
    /** Whether the stream is an ADTS (AAC) stream. */
    private _isADTS;
    /** Channel mode of the first audio frame. */
    private _channelMode;
    /**
     * Private constructor — use the static {@link MpegProperties.create} factory method.
     * @param readStyle - The read-style detail level passed to the base class.
     */
    private constructor();
    /**
     * Creates an `MpegProperties` instance by reading the audio stream from `file`.
     *
     * @param file - The MPEG file whose audio properties should be determined.
     * @param readStyle - The level of detail to use when scanning the stream (default: `ReadStyle.Average`).
     * @returns A fully populated `MpegProperties` instance.
     */
    static create(file: MpegFile, readStyle?: ReadStyle): Promise<MpegProperties>;
    /** Gets the duration of the audio stream in milliseconds. */
    get lengthInMilliseconds(): number;
    /** Gets the average audio bitrate in kbps. */
    get bitrate(): number;
    /** Gets the audio sample rate in Hz. */
    get sampleRate(): number;
    /** Gets the number of audio channels. */
    get channels(): number;
    /** Gets the MPEG version of the first audio frame. */
    get version(): MpegVersion;
    /** Gets the MPEG layer number (1, 2, or 3); 0 for ADTS streams. */
    get layer(): number;
    /** Gets whether CRC protection is enabled. */
    get protectionEnabled(): boolean;
    /** Gets whether the audio is flagged as copyrighted. */
    get isCopyrighted(): boolean;
    /** Gets whether the audio is flagged as an original recording. */
    get isOriginal(): boolean;
    /** Gets whether the stream is an ADTS (AAC) stream. */
    get isADTS(): boolean;
    /** Gets the channel mode of the first audio frame. */
    get channelMode(): ChannelMode;
    /**
     * Populates all property fields by scanning the audio frames in `file`.
     * Handles VBR (Xing/VBRI), ADTS, and CBR streams.
     *
     * @param file - The MPEG file to read audio data from.
     */
    private read;
    /**
     * Scans ADTS frames to compute an average bitrate, then derives the stream duration.
     *
     * @param file - The MPEG file being analysed.
     * @param firstOffset - Byte offset of the first ADTS frame.
     * @param firstHeader - The parsed header of the first ADTS frame.
     */
    private readADTS;
    /**
     * Calculates the stream duration from the byte extents between the first and
     * last valid frames using the already-computed bitrate.
     *
     * @param file - The MPEG file being analysed.
     * @param firstOffset - Byte offset of the first valid frame.
     * @param _firstHeader - The first frame header (reserved for future use).
     */
    private computeLength;
}
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