/**
 * Quantise a 4×4 block's 16 raster-order coefficients using the same Q
 * lookup the decoder uses.
 *
 * @param raster — input coefficients in raster order; reconstructed
 *                 (level × Q) values are written back here so callers
 *                 can run the inverse transform from a buffer that
 *                 matches the decoder's expected residual.
 * @param zigzag — output 16 levels in zig-zag scan order (the order the
 *                 token-tree encoder will serialise).
 * @param dqDc, dqAc — Q values for DC (index 0) / AC (other 15)
 *                     coefficients.
 *
 * @returns true if any non-zero level was produced (the "non-zero" flag
 * the encoder uses to drive the EOB-only short-circuit and the
 * mb_no_skip_coef bit).
 */
export declare function quantizeBlock(raster: Int16Array, rasterOff: number, zigzag: Int16Array, zigzagOff: number, dqDc: number, dqAc: number): boolean;
/**
 * Quantise the Y2 (DC-of-each-Y-block) block. Same algorithm but the
 * first coefficient (DC of the Y2 block itself) is excluded from EOB
 * detection in libwebp's MB encoder — the encoder still serialises it
 * as a normal coefficient. We expose the same nonzero flag so callers
 * can pin the `mb_no_skip_coef` bit correctly.
 */
export declare function quantizeY2Block(raster: Int16Array, rasterOff: number, zigzag: Int16Array, zigzagOff: number, dqDc: number, dqAc: number): boolean;