aom/aom_dsp/blend.h

/*
 * 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_DSP_BLEND_H_
#define AOM_DSP_BLEND_H_

#include "aom_ports/mem.h"

// Various blending functions and macros.
// See also the aom_blend_* functions in aom_dsp_rtcd.h

// Alpha blending with alpha values from the range [0, 64], where 64
// means use the first input and 0 means use the second input.

#define AOM_BLEND_A64_ROUND_BITS 6
#define AOM_BLEND_A64_MAX_ALPHA (1 << AOM_BLEND_A64_ROUND_BITS)  // 64

#define AOM_BLEND_A64(a, v0, v1)                                          \
  ROUND_POWER_OF_TWO((a) * (v0) + (AOM_BLEND_A64_MAX_ALPHA - (a)) * (v1), \
                     AOM_BLEND_A64_ROUND_BITS)

// Alpha blending with alpha values from the range [0, 256], where 256
// means use the first input and 0 means use the second input.
#define AOM_BLEND_A256_ROUND_BITS 8
#define AOM_BLEND_A256_MAX_ALPHA (1 << AOM_BLEND_A256_ROUND_BITS)  // 256

#define AOM_BLEND_A256(a, v0, v1)                                          \
  ROUND_POWER_OF_TWO((a) * (v0) + (AOM_BLEND_A256_MAX_ALPHA - (a)) * (v1), \
                     AOM_BLEND_A256_ROUND_BITS)

// Blending by averaging.
#define AOM_BLEND_AVG(v0, v1) ROUND_POWER_OF_TWO((v0) + (v1), 1)

#endif  // AOM_DSP_BLEND_H_