/**
 * Layer III scalefactor and Huffman decoding.
 *
 * This is where a granule's 576 frequency lines come from. Three regions, coded
 * differently because their statistics differ:
 *
 * 1. **big_values** — the low and mid frequencies, where real energy lives.
 *    Coded as (x, y) pairs from one of 32 Huffman tables, chosen per region.
 * 2. **count1** — the high-frequency tail, where almost everything has quantized
 *    to -1, 0, or +1. Coded as quadruples, since a general table would waste bits
 *    on values that never occur.
 * 3. **rzero** — everything above that is implicitly zero and costs nothing.
 *
 * The decoder does not know where count1 ends; it decodes until the granule's
 * declared `part2_3_length` bits are consumed. That is why {@link decodeHuffman}
 * takes a bit limit rather than a count.
 */
import { BitReader } from '../io/bits.js';
import type { GranuleInfo } from './sideinfo.js';
/** Decoded scalefactors for one granule and channel. */
export interface Scalefactors {
    /** Per scalefactor band, for long blocks. 22 entries. */
    long: Int32Array;
    /** Per band per window, for short blocks. `short[window][band]`, 13 bands. */
    short: Int32Array[];
}
/** Allocates a reusable scalefactor structure. */
export declare function createScalefactors(): Scalefactors;
/**
 * Decodes MPEG-1 scalefactors.
 *
 * `scfsi` lets granule 1 reuse granule 0's scalefactors for a band group rather
 * than retransmitting them — a meaningful saving, since scalefactors are sent
 * for every granule otherwise.
 */
export declare function decodeScalefactorsMpeg1(br: BitReader, granule: GranuleInfo, scfsi: number[], granuleIndex: number, previous: Scalefactors, out: Scalefactors): number;
/**
 * Decodes MPEG-2 / 2.5 scalefactors.
 *
 * A different scheme entirely: `scalefac_compress` is 9 bits and encodes both the
 * band partitioning and the bit widths, rather than indexing a small table.
 */
export declare function decodeScalefactorsMpeg2(br: BitReader, granule: GranuleInfo, isIntensityRight: boolean, out: Scalefactors): number;
export interface HuffmanResult {
    /** Quantized values, signed. Always 576 entries. */
    values: Int32Array;
    /** Index one past the last non-zero value. */
    nonZeroCount: number;
    /** Bits actually consumed. */
    bitsUsed: number;
}
/**
 * Decodes one granule's quantized frequency lines.
 *
 * @param br Positioned at the start of this granule's Huffman data.
 * @param maxBits `part2_3_length` minus the scalefactor bits already read.
 */
export declare function decodeHuffman(br: BitReader, granule: GranuleInfo, sampleRate: number, maxBits: number, out: Int32Array): HuffmanResult;
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