/src/libavif/ext/aom/av1/common/mv.h

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/*
 * Copyright (c) 2016, Alliance for Open Media. All rights reserved.
 *
 * This source code is subject to the terms of the BSD 2 Clause License and
 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
 * was not distributed with this source code in the LICENSE file, you can
 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
 * Media Patent License 1.0 was not distributed with this source code in the
 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
 */

#ifndef AOM_AV1_COMMON_MV_H_
#define AOM_AV1_COMMON_MV_H_

#include <stdlib.h>

#include "av1/common/common.h"
#include "av1/common/common_data.h"
#include "aom_dsp/aom_filter.h"
#include "aom_dsp/flow_estimation/flow_estimation.h"

#ifdef __cplusplus
extern "C" {
#endif

#define INVALID_MV 0x80008000
#define INVALID_MV_ROW_COL -32768
#define GET_MV_RAWPEL(x) (((x) + 3 + ((x) >= 0)) >> 3)
#define GET_MV_SUBPEL(x) ((x)*8)

#define MARK_MV_INVALID(mv)                \
  do {                                     \
    ((int_mv *)(mv))->as_int = INVALID_MV; \
  } while (0)
#define CHECK_MV_EQUAL(x, y) (((x).row == (y).row) && ((x).col == (y).col))

// The motion vector in units of full pixel
typedef struct fullpel_mv {
  int16_t row;
  int16_t col;
} FULLPEL_MV;

// The motion vector in units of 1/8-pel
typedef struct mv {
  int16_t row;
  int16_t col;
} MV;

static const MV kZeroMv = { 0, 0 };
static const FULLPEL_MV kZeroFullMv = { 0, 0 };

typedef union int_mv {
  uint32_t as_int;
  MV as_mv;
  FULLPEL_MV as_fullmv;
} int_mv; /* facilitates faster equality tests and copies */

typedef struct mv32 {
  int32_t row;
  int32_t col;
} MV32;

// The mv limit for fullpel mvs
typedef struct {
  int col_min;
  int col_max;
  int row_min;
  int row_max;
} FullMvLimits;

// The mv limit for subpel mvs
typedef struct {
  int col_min;
  int col_max;
  int row_min;
  int row_max;
} SubpelMvLimits;

static inline FULLPEL_MV get_fullmv_from_mv(const MV *subpel_mv) {
  const FULLPEL_MV full_mv = { (int16_t)GET_MV_RAWPEL(subpel_mv->row),
                               (int16_t)GET_MV_RAWPEL(subpel_mv->col) };
  return full_mv;
}

static inline MV get_mv_from_fullmv(const FULLPEL_MV *full_mv) {
  const MV subpel_mv = { (int16_t)GET_MV_SUBPEL(full_mv->row),
                         (int16_t)GET_MV_SUBPEL(full_mv->col) };
  return subpel_mv;
}

static inline void convert_fullmv_to_mv(int_mv *mv) {
  mv->as_mv = get_mv_from_fullmv(&mv->as_fullmv);
}

// Bits of precision used for the model
#define WARPEDMODEL_PREC_BITS 16

#define WARPEDMODEL_TRANS_CLAMP (128 << WARPEDMODEL_PREC_BITS)
#define WARPEDMODEL_NONDIAGAFFINE_CLAMP (1 << (WARPEDMODEL_PREC_BITS - 3))

// Bits of subpel precision for warped interpolation
#define WARPEDPIXEL_PREC_BITS 6
#define WARPEDPIXEL_PREC_SHIFTS (1 << WARPEDPIXEL_PREC_BITS)

#define WARP_PARAM_REDUCE_BITS 6

#define WARPEDDIFF_PREC_BITS (WARPEDMODEL_PREC_BITS - WARPEDPIXEL_PREC_BITS)

typedef struct {
  int global_warp_allowed;
  int local_warp_allowed;
} WarpTypesAllowed;

// The order of values in the wmmat matrix below is best described
// by the affine transformation:
//      [x'     (m2 m3 m0   [x
//  z .  y'  =   m4 m5 m1 *  y
//       1]       0  0 1)    1]
typedef struct {
  int32_t wmmat[MAX_PARAMDIM];
  int16_t alpha, beta, gamma, delta;
  TransformationType wmtype;
  int8_t invalid;
} WarpedMotionParams;

/* clang-format off */
static const WarpedMotionParams default_warp_params = {
  { 0, 0, (1 << WARPEDMODEL_PREC_BITS), 0, 0, (1 << WARPEDMODEL_PREC_BITS) },
  0, 0, 0, 0,
  IDENTITY,
  0,
};
/* clang-format on */

// The following constants describe the various precisions
// of different parameters in the global motion experiment.
//
// Given the general homography:
//      [x'     (a  b  c   [x
//  z .  y'  =   d  e  f *  y
//       1]      g  h  i)    1]
//
// Constants using the name ALPHA here are related to parameters
// a, b, d, e. Constants using the name TRANS are related
// to parameters c and f.
//
// Anything ending in PREC_BITS is the number of bits of precision
// to maintain when converting from double to integer.
//
// The ABS parameters are used to create an upper and lower bound
// for each parameter. In other words, after a parameter is integerized
// it is clamped between -(1 << ABS_XXX_BITS) and (1 << ABS_XXX_BITS).
//
// XXX_PREC_DIFF and XXX_DECODE_FACTOR
// are computed once here to prevent repetitive
// computation on the decoder side. These are
// to allow the global motion parameters to be encoded in a lower
// precision than the warped model precision. This means that they
// need to be changed to warped precision when they are decoded.
//
// XX_MIN, XX_MAX are also computed to avoid repeated computation

#define SUBEXPFIN_K 3
#define GM_TRANS_PREC_BITS 6
#define GM_ABS_TRANS_BITS 12
#define GM_ABS_TRANS_ONLY_BITS (GM_ABS_TRANS_BITS - GM_TRANS_PREC_BITS + 3)
#define GM_TRANS_PREC_DIFF (WARPEDMODEL_PREC_BITS - GM_TRANS_PREC_BITS)
#define GM_TRANS_ONLY_PREC_DIFF (WARPEDMODEL_PREC_BITS - 3)
#define GM_TRANS_DECODE_FACTOR (1 << GM_TRANS_PREC_DIFF)
#define GM_TRANS_ONLY_DECODE_FACTOR (1 << GM_TRANS_ONLY_PREC_DIFF)

#define GM_ALPHA_PREC_BITS 15
#define GM_ABS_ALPHA_BITS 12
#define GM_ALPHA_PREC_DIFF (WARPEDMODEL_PREC_BITS - GM_ALPHA_PREC_BITS)
#define GM_ALPHA_DECODE_FACTOR (1 << GM_ALPHA_PREC_DIFF)

#define GM_TRANS_MAX (1 << GM_ABS_TRANS_BITS)
#define GM_ALPHA_MAX (1 << GM_ABS_ALPHA_BITS)

#define GM_TRANS_MIN -GM_TRANS_MAX
#define GM_ALPHA_MIN -GM_ALPHA_MAX

static inline int block_center_x(int mi_col, BLOCK_SIZE bs) {
  const int bw = block_size_wide[bs];
  return mi_col * MI_SIZE + bw / 2 - 1;
}

static inline int block_center_y(int mi_row, BLOCK_SIZE bs) {
  const int bh = block_size_high[bs];
  return mi_row * MI_SIZE + bh / 2 - 1;
}

static inline int convert_to_trans_prec(int allow_hp, int coor) {
  if (allow_hp)
    return ROUND_POWER_OF_TWO_SIGNED(coor, WARPEDMODEL_PREC_BITS - 3);
  else
    return ROUND_POWER_OF_TWO_SIGNED(coor, WARPEDMODEL_PREC_BITS - 2) * 2;
}
static inline void integer_mv_precision(MV *mv) {
  int mod = (mv->row % 8);
  if (mod != 0) {
    mv->row -= mod;
    if (abs(mod) > 4) {
      if (mod > 0) {
        mv->row += 8;
      } else {
        mv->row -= 8;
      }
    }
  }

  mod = (mv->col % 8);
  if (mod != 0) {
    mv->col -= mod;
    if (abs(mod) > 4) {
      if (mod > 0) {
        mv->col += 8;
      } else {
        mv->col -= 8;
      }
    }
  }
}
// Convert a global motion vector into a motion vector at the centre of the
// given block.
//
// The resulting motion vector will have three fractional bits of precision. If
// allow_hp is zero, the bottom bit will always be zero. If CONFIG_AMVR and
// is_integer is true, the bottom three bits will be zero (so the motion vector
// represents an integer)
static inline int_mv gm_get_motion_vector(const WarpedMotionParams *gm,
                                          int allow_hp, BLOCK_SIZE bsize,
                                          int mi_col, int mi_row,
                                          int is_integer) {
  int_mv res;

  if (gm->wmtype == IDENTITY) {
    res.as_int = 0;
    return res;
  }

  const int32_t *mat = gm->wmmat;
  int x, y, tx, ty;

  if (gm->wmtype == TRANSLATION) {
    // All global motion vectors are stored with WARPEDMODEL_PREC_BITS (16)
    // bits of fractional precision. The offset for a translation is stored in
    // entries 0 and 1. For translations, all but the top three (two if
    // cm->features.allow_high_precision_mv is false) fractional bits are always
    // zero.
    //
    // After the right shifts, there are 3 fractional bits of precision. If
    // allow_hp is false, the bottom bit is always zero (so we don't need a
    // call to convert_to_trans_prec here)
    //
    // Note: There is an AV1 specification bug here:
    //
    // gm->wmmat[0] is supposed to be the horizontal translation, and so should
    // go into res.as_mv.col, and gm->wmmat[1] is supposed to be the vertical
    // translation and so should go into res.as_mv.row
    //
    // However, in the spec, these assignments are accidentally reversed, and so
    // we must keep this incorrect logic to match the spec.
    //
    // See also: https://crbug.com/aomedia/3328
    res.as_mv.row = gm->wmmat[0] >> GM_TRANS_ONLY_PREC_DIFF;
    res.as_mv.col = gm->wmmat[1] >> GM_TRANS_ONLY_PREC_DIFF;
    assert(IMPLIES(1 & (res.as_mv.row | res.as_mv.col), allow_hp));
    if (is_integer) {
      integer_mv_precision(&res.as_mv);
    }
    return res;
  }

  x = block_center_x(mi_col, bsize);
  y = block_center_y(mi_row, bsize);

  if (gm->wmtype == ROTZOOM) {
    assert(gm->wmmat[5] == gm->wmmat[2]);
    assert(gm->wmmat[4] == -gm->wmmat[3]);
  }

  const int xc =
      (mat[2] - (1 << WARPEDMODEL_PREC_BITS)) * x + mat[3] * y + mat[0];
  const int yc =
      mat[4] * x + (mat[5] - (1 << WARPEDMODEL_PREC_BITS)) * y + mat[1];
  tx = convert_to_trans_prec(allow_hp, xc);
  ty = convert_to_trans_prec(allow_hp, yc);

  res.as_mv.row = ty;
  res.as_mv.col = tx;

  if (is_integer) {
    integer_mv_precision(&res.as_mv);
  }
  return res;
}

static inline TransformationType get_wmtype(const WarpedMotionParams *gm) {
  if (gm->wmmat[5] == (1 << WARPEDMODEL_PREC_BITS) && !gm->wmmat[4] &&
      gm->wmmat[2] == (1 << WARPEDMODEL_PREC_BITS) && !gm->wmmat[3]) {
    return ((!gm->wmmat[1] && !gm->wmmat[0]) ? IDENTITY : TRANSLATION);
  }
  if (gm->wmmat[2] == gm->wmmat[5] && gm->wmmat[3] == -gm->wmmat[4])
    return ROTZOOM;
  else
    return AFFINE;
}

typedef struct candidate_mv {
  int_mv this_mv;
  int_mv comp_mv;
} CANDIDATE_MV;

static inline int is_zero_mv(const MV *mv) {
  return *((const uint32_t *)mv) == 0;
}

static inline int is_equal_mv(const MV *a, const MV *b) {
  return *((const uint32_t *)a) == *((const uint32_t *)b);
}

static inline void clamp_mv(MV *mv, const SubpelMvLimits *mv_limits) {
  mv->col = clamp(mv->col, mv_limits->col_min, mv_limits->col_max);
  mv->row = clamp(mv->row, mv_limits->row_min, mv_limits->row_max);
}

static inline void clamp_fullmv(FULLPEL_MV *mv, const FullMvLimits *mv_limits) {
  mv->col = clamp(mv->col, mv_limits->col_min, mv_limits->col_max);
  mv->row = clamp(mv->row, mv_limits->row_min, mv_limits->row_max);
}

#ifdef __cplusplus
}  // extern "C"
#endif

#endif  // AOM_AV1_COMMON_MV_H_

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Created: 2025-07-18 06:57