/** Convert opaque RGBA pixels to the encoder's full-range BT.709 4:2:0 planes. */
export declare function rgbaToYuv420(data: Uint8Array, width: number, height: number, options?: { alphaEncodedSeparately?: boolean }): Yuv420;
/**
 * The alpha plane as an AV1 picture: alpha in luma, neutral chroma.
 *
 * AVIF carries alpha as a second image item whose luma plane IS the alpha
 * (MIAF auxiliary image, `urn:mpeg:mpegB:cicp:systems:auxiliary:alpha`).
 * Decoders read only that plane, so writing it through the same 4:2:0 path
 * as the colour image, with chroma pinned to 128, keeps one encoder for both.
 * Edge replication matches `rgbaToYuv420` so the planes line up block for
 * block.
 */
export declare function alphaToYuv420(data: Uint8Array, width: number, height: number): Yuv420;
/** Encode one adaptive-CDF tile using 4x4 DC-predicted DCT blocks. */
export declare function encodeIntraTile(source: Yuv420, baseQIdx: number): Uint8Array;
declare interface Yuv420 {
  y: Uint8Array
  u: Uint8Array
  v: Uint8Array
  yStride: number
  uvStride: number
  miCols: number
  miRows: number
}
declare class EncoderContext {
  mode: Uint8Array;
  skip: Uint8Array;
  partition: Uint8Array;
  lcoef: Uint8Array;
  ccoef: [Uint8Array, Uint8Array];
  constructor(n4: number);
  reset(): void;
}
declare class IntraTileEncoder {
  constructor(source: Yuv420, baseQIdx: number);
  encode(): Uint8Array;
}