av1/encoder/txb_rdopt.h

/*
 * Copyright (c) 2021, 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_ENCODER_TXB_RDOPT_H_
#define AOM_AV1_ENCODER_TXB_RDOPT_H_

#include "av1/common/blockd.h"
#include "av1/common/txb_common.h"
#include "av1/encoder/encoder.h"

#ifdef __cplusplus
extern "C" {
#endif

/*!\brief Adjust the magnitude of quantized coefficients to achieve better
 * rate-distortion (RD) trade-off.
 *
 * \ingroup coefficient_coding
 *
 * This function goes through each coefficient and greedily choose to lower
 * the coefficient magnitude by 1 or not based on the RD score.
 *
 * The coefficients are processing in reversed scan order.
 *
 * Note that, the end of block position (eob) may change if the original last
 * coefficient is lowered to zero.
 *
 * \param[in]    cpi            Top-level encoder structure
 * \param[in]    x              Pointer to structure holding the data for the
                                current encoding macroblock
 * \param[in]    plane          The index of the current plane
 * \param[in]    block          The index of the current transform block in the
 * \param[in]    tx_size        The transform size
 * \param[in]    tx_type        The transform type
 * \param[in]    txb_ctx        Context info for entropy coding transform block
 * skip flag (tx_skip) and the sign of DC coefficient (dc_sign).
 * \param[out]   rate_cost      The entropy cost of coding the transform block
 * after adjustment of coefficients.
 * \param[in]    sharpness      When sharpness > 0, the function will be less
 * aggressive towards lowering the magnitude of coefficients.
 * In this way, the transform block will contain more high-frequency
 * coefficients and therefore will preserve the sharpness of the reconstructed
 * block.
 */
int av1_optimize_txb(const struct AV1_COMP *cpi, MACROBLOCK *x, int plane,
                     int block, TX_SIZE tx_size, TX_TYPE tx_type,
                     const TXB_CTX *const txb_ctx, int *rate_cost,
                     int sharpness);

/*!\brief Compute the entropy cost of coding coefficients in a transform block.
 *
 * \ingroup coefficient_coding
 *
 * \param[in]    x                    Pointer to structure holding the data for
 the current encoding macroblock.
 * \param[in]    plane                The index of the current plane.
 * \param[in]    block                The index of the current transform block
 in the
 * macroblock. It's defined by number of 4x4 units that have been coded before
 * the currernt transform block.
 * \param[in]    tx_size              The transform size.
 * \param[in]    tx_type              The transform type.
 * \param[in]    txb_ctx              Context info for entropy coding transform
 block
 * skip flag (tx_skip) and the sign of DC coefficient (dc_sign).
 * \param[in]    reduced_tx_set_used  Whether the transform type is chosen from
 * a reduced set.
 */
int av1_cost_coeffs_txb(const MACROBLOCK *x, const int plane, const int block,
                        const TX_SIZE tx_size, const TX_TYPE tx_type,
                        const TXB_CTX *const txb_ctx, int reduced_tx_set_used);

/*!\brief Estimate the entropy cost of coding a transform block using Laplacian
 * distribution.
 *
 * \ingroup coefficient_coding
 *
 * This function compute the entropy costs of the end of block position (eob)
 * and the transform type (tx_type) precisely.
 *
 * Then using \ref av1_cost_coeffs_txb_estimate to estimate the entropy costs
 * of coefficients in the transform block.
 *
 * In the end, the function returns the sum of entropy costs of end of block
 * position (eob), transform type (tx_type) and coefficients.
 *
 * Compared to \ref av1_cost_coeffs_txb, this function is much faster but less
 * accurate.
 *
 * \param[in]    x              Pointer to structure holding the data for the
                                current encoding macroblock
 * \param[in]    plane          The index of the current plane
 * \param[in]    block          The index of the current transform block in the
 * macroblock. It's defined by number of 4x4 units that have been coded before
 * the currernt transform block
 * \param[in]    tx_size        The transform size
 * \param[in]    tx_type        The transform type
 * \param[in]    txb_ctx        Context info for entropy coding transform block
 * skip flag (tx_skip) and the sign of DC coefficient (dc_sign).
 * \param[in]    reduced_tx_set_used  Whether the transform type is chosen from
 * a reduced set.
 * \param[in]    adjust_eob     Whether to adjust the end of block position
 (eob)
 * or not.
 * \return       int            Estimated entropy cost of coding the transform
 block.
 */
int av1_cost_coeffs_txb_laplacian(const MACROBLOCK *x, const int plane,
                                  const int block, const TX_SIZE tx_size,
                                  const TX_TYPE tx_type,
                                  const TXB_CTX *const txb_ctx,
                                  const int reduced_tx_set_used,
                                  const int adjust_eob);

/*!\brief Estimate the entropy cost of transform coefficients using Laplacian
 * distribution.
 *
 * \ingroup coefficient_coding
 *
 * This function assumes each transform coefficient is of its own Laplacian
 * distribution and the coefficient is the only observation of the Laplacian
 * distribution.
 *
 * Based on that, each coefficient's coding cost can be estimated by computing
 * the entropy of the corresponding Laplacian distribution.
 *
 * This function then return the sum of the estimated entropy cost for all
 * coefficients in the transform block.
 *
 * Note that the entropy cost of end of block (eob) and transform type (tx_type)
 * are not included.
 *
 * \param[in]    x              Pointer to structure holding the data for the
                                current encoding macroblock
 * \param[in]    plane          The index of the current plane
 * \param[in]    block          The index of the current transform block in the
 * macroblock. It's defined by number of 4x4 units that have been coded before
 * the currernt transform block
 * \param[in]    tx_size        The transform size
 * \param[in]    tx_type        The transform type
 * \return       int            Estimated entropy cost of coefficients in the
 * transform block.
 */
int av1_cost_coeffs_txb_estimate(const MACROBLOCK *x, const int plane,
                                 const int block, const TX_SIZE tx_size,
                                 const TX_TYPE tx_type);

#ifdef __cplusplus
}
#endif

#endif  // AOM_AV1_ENCODER_TXB_RDOPT_H_