本文深入解析了x265项目中的关键编解码函数，包括DCT变换、DST变换及其逆变换等核心算法的实现细节。通过对源代码的逐行解读，介绍了不同尺寸块的变换过程及量化、反量化步骤。
注：问号以及未注释部分 会在x265-1.9版本内更新
/*****************************************************************************
* Copyright (C) 2013 x265 project
*
* Authors: Mandar Gurav <mandar@multicorewareinc.com>
* Deepthi Devaki Akkoorath <deepthidevaki@multicorewareinc.com>
* Mahesh Pittala <mahesh@multicorewareinc.com>
* Rajesh Paulraj <rajesh@multicorewareinc.com>
* Min Chen <min.chen@multicorewareinc.com>
* Praveen Kumar Tiwari <praveen@multicorewareinc.com>
* Nabajit Deka <nabajit@multicorewareinc.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111, USA.
*
* This program is also available under a commercial proprietary license.
* For more information, contact us at license @ x265.com.
*****************************************************************************/
#include "common.h"
#include "primitives.h"
#include "contexts.h" // costCoeffNxN_c
#include "threading.h" // CLZ
using namespace X265_NS;
#if _MSC_VER
#pragma warning(disable: 4127) // conditional expression is constant, typical for templated functions
#endif
// Fast DST Algorithm. Full matrix multiplication for DST and Fast DST algorithm
// give identical results
/** 函数功能 ：对残差块进行4x4DST变换并对其转置
* \参数 block ：残差数据
* \参数 coeff ：存储行变换后的数据
* \参数 shift ：行变换移位个数
* \返回 ：null
**/
static void fastForwardDst(const int16_t* block, int16_t* coeff, int shift) // input block, output coeff
{
//功能：行变换 X*DST'
int c[4];
int rnd_factor = 1 << (shift - 1);
for (int i = 0; i < 4; i++)
{
// Intermediate Variables
c[0] = block[4 * i + 0] + block[4 * i + 3];
c[1] = block[4 * i + 1] + block[4 * i + 3];
c[2] = block[4 * i + 0] - block[4 * i + 1];
c[3] = 74 * block[4 * i + 2];
coeff[i] = (int16_t)((29 * c[0] + 55 * c[1] + c[3] + rnd_factor) >> shift);
coeff[4 + i] = (int16_t)((74 * (block[4 * i + 0] + block[4 * i + 1] - block[4 * i + 3]) + rnd_factor) >> shift);
coeff[8 + i] = (int16_t)((29 * c[2] + 55 * c[0] - c[3] + rnd_factor) >> shift);
coeff[12 + i] = (int16_t)((55 * c[2] - 29 * c[1] + c[3] + rnd_factor) >> shift);
}
}
static void inversedst(const int16_t* tmp, int16_t* block, int shift) // input tmp, output block
{
int i, c[4];
int rnd_factor = 1 << (shift - 1);
for (i = 0; i < 4; i++)
{
// Intermediate Variables
c[0] = tmp[i] + tmp[8 + i];
c[1] = tmp[8 + i] + tmp[12 + i];
c[2] = tmp[i] - tmp[12 + i];
c[3] = 74 * tmp[4 + i];
block[4 * i + 0] = (int16_t)x265_clip3(-32768, 32767, (29 * c[0] + 55 * c[1] + c[3] + rnd_factor) >> shift);
block[4 * i + 1] = (int16_t)x265_clip3(-32768, 32767, (55 * c[2] - 29 * c[1] + c[3] + rnd_factor) >> shift);
block[4 * i + 2] = (int16_t)x265_clip3(-32768, 32767, (74 * (tmp[i] - tmp[8 + i] + tmp[12 + i]) + rnd_factor) >> shift);
block[4 * i + 3] = (int16_t)x265_clip3(-32768, 32767, (55 * c[0] + 29 * c[2] - c[3] + rnd_factor) >> shift);
}
}
/** 函数功能 ：对残差块进行16x16DCT变换并对其转置
* \参数 block ：残差数据
* \参数 coeff ：存储行变换后的数据
* \参数 shift ：行变换移位个数
* \返回 ：null
**/
static void partialButterfly16(const int16_t* src, int16_t* dst, int shift, int line)
{
//功能：行变换 X*DCT’
int j, k;
int E[8], O[8];
int EE[4], EO[4];
int EEE[2], EEO[2];
int add = 1 << (shift - 1);
for (j = 0; j < line; j++)
{
/* E and O */
for (k = 0; k < 8; k++)
{
E[k] = src[k] + src[15 - k];
O[k] = src[k] - src[15 - k];
}
/* EE and EO */
for (k = 0; k < 4; k++)
{
EE[k] = E[k] + E[7 - k];
EO[k] = E[k] - E[7 - k];
}
/* EEE and EEO */
EEE[0] = EE[0] + EE[3];
EEO[0] = EE[0] - EE[3];
EEE[1] = EE[1] + EE[2];
EEO[1] = EE[1] - EE[2];
dst[0] = (int16_t)((g_t16[0][0] * EEE[0] + g_t16[0][1] * EEE[1] + add) >> shift);
dst[8 * line] = (int16_t)((g_t16[8][0] * EEE[0] + g_t16[8][1] * EEE[1] + add) >> shift);
dst[4 * line] = (int16_t)((g_t16[4][0] * EEO[0] + g_t16[4][1] * EEO[1] + add) >> shift);
dst[12 * line] = (int16_t)((g_t16[12][0] * EEO[0] + g_t16[12][1] * EEO[1] + add) >> shift);
for (k = 2; k < 16; k += 4)
{
dst[k * line] = (int16_t)((g_t16[k][0] * EO[0] + g_t16[k][1] * EO[1] + g_t16[k][2] * EO[2] +
g_t16[k][3] * EO[3] + add) >> shift);
}
for (k = 1; k < 16; k += 2)
{
dst[k * line] = (int16_t)((g_t16[k][0] * O[0] + g_t16[k][1] * O[1] + g_t16[k][2] * O[2] + g_t16[k][3] * O[3] +
g_t16[k][4] * O[4] + g_t16[k][5] * O[5] + g_t16[k][6] * O[6] + g_t16[k][7] * O[7] +
add) >> shift);
}
src += 16;
dst++;
}
}
/** 函数功能 ：对残差块进行32x32DCT变换并对其转置
* \参数 block ：残差数据
* \参数 coeff ：存储行变换后的数据
* \参数 shift ：行变换移位个数
* \返回 ：null
**/
static void partialButterfly32(const int16_t* src, int16_t* dst, int shift, int line)
{
//功能：行变换 X*DCT’
int j, k;
int E[16], O[16];
int EE[8], EO[8];
int EEE[4], EEO[4];
int EEEE[2], EEEO[2];
int add = 1 << (shift - 1);
for (j = 0; j < line; j++)
{
/* E and O*/
for (k = 0; k < 16; k++)
{
E[k] = src[k] + src[31 - k];
O[k] = src[k] - src[31 - k];
}
/* EE and EO */
for (k = 0; k < 8; k++)
{
EE[k] = E[k] + E[15 - k];
EO[k] = E[k] - E[15 - k];
}
/* EEE and EEO */
for (k = 0; k < 4; k++)
{
EEE[k] = EE[k] + EE[7 - k];
EEO[k] = EE[k] - EE[7 - k];
}
/* EEEE and EEEO */
EEEE[0] = EEE[0] + EEE[3];
EEEO[0] = EEE[0] - EEE[3];
EEEE[1] = EEE[1] + EEE[2];
EEEO[1] = EEE[1] - EEE[2];
dst[0] = (int16_t)((g_t32[0][0] * EEEE[0] + g_t32[0][1] * EEEE[1] + add) >> shift);
dst[16 * line] = (int16_t)((g_t32[16][0] * EEEE[0] + g_t32[16][1] * EEEE[1] + add) >> shift);
dst[8 * line] = (int16_t)((g_t32[8][0] * EEEO[0] + g_t32[8][1] * EEEO[1] + add) >> shift);
dst[24 * line] = (int16_t)((g_t32[24][0] * EEEO[0] + g_t32[24][1] * EEEO[1] + add) >> shift);
for (k = 4; k < 32; k += 8)
{
dst[k * line] = (int16_t)((g_t32[k][0] * EEO[0] + g_t32[k][1] * EEO[1] + g_t32[k][2] * EEO[2] +
g_t32[k][3] * EEO[3] + add) >> shift);
}
for (k = 2; k < 32; k += 4)
{
dst[k * line] = (int16_t)((g_t32[k][0] * EO[0] + g_t32[k][1] * EO[1] + g_t32[k][2] * EO[2] +
g_t32[k][3] * EO[3] + g_t32[k][4] * EO[4] + g_t32[k][5] * EO[5] +
g_t32[k][6] * EO[6] + g_t32[k][7] * EO[7] + add) >> shift);
}
for (k = 1; k < 32; k += 2)
{
dst[k * line] = (int16_t)((g_t32[k][0] * O[0] + g_t32[k][1] * O[1] + g_t32[k][2] * O[2] + g_t32[k][3] * O[3] +
g_t32[k][4] * O[4] + g_t32[k][5] * O[5] + g_t32[k][6] * O[6] + g_t32[k][7] * O[7] +
g_t32[k][8] * O[8] + g_t32[k][9] * O[9] + g_t32[k][10] * O[10] + g_t32[k][11] *
O[11] + g_t32[k][12] * O[12] + g_t32[k][13] * O[13] + g_t32[k][14] * O[14] +
g_t32[k][15] * O[15] + add) >> shift);
}
src += 32;
dst++;
}
}
/** 函数功能 ：对残差块进行8x8DCT变换并对其转置
* \参数 block ：残差数据
* \参数 coeff ：存储行变换后的数据
* \参数 shift ：行变换移位个数
* \返回 ：null
**/
static void partialButterfly8(const int16_t* src, int16_t* dst, int shift, int line)
{
//功能：X*DCT'
int j, k;
int E[4], O[4];
int EE[2], EO[2];
int add = 1 << (shift - 1);
for (j = 0; j < line; j++)
{
/* E and O*/
for (k = 0; k < 4; k++)
{
E[k] = src[k] + src[7 - k];
O[k] = src[k] - src[7 - k];
}
/* EE and EO */
EE[0] = E[0] + E[3];
EO[0] = E[0] - E[3];
EE[1] = E[1] + E[2];
EO[1] = E[1] - E[2];
dst[0] = (int16_t)((g_t8[0][0] * EE[0] + g_t8[0][1] * EE[1] + add) >> shift);
dst[4 * line] = (int16_t)((g_t8[4][0] * EE[0] + g_t8[4][1] * EE[1] + add) >> shift);
dst[2 * line] = (int16_t)((g_t8[2][0] * EO[0] + g_t8[2][1] * EO[1] + add) >> shift);
dst[6 * line] = (int16_t)((g_t8[6][0] * EO[0] + g_t8[6][1] * EO[1] + add) >> shift);
dst[line] = (int16_t)((g_t8[1][0] * O[0] + g_t8[1][1] * O[1] + g_t8[1][2] * O[2] + g_t8[1][3] * O[3] + add) >> shift);
dst[3 * line] = (int16_t)((g_t8[3][0] * O[0] + g_t8[3][1] * O[1] + g_t8[3][2] * O[2] + g_t8[3][3] * O[3] + add) >> shift);
dst[5 * line] = (int16_t)((g_t8[5][0] * O[0] + g_t8[5][1] * O[1] + g_t8[5][2] * O[2] + g_t8[5][3] * O[3] + add) >> shift);
dst[7 * line] = (int16_t)((g_t8[7][0] * O[0] + g_t8[7][1] * O[1] + g_t8[7][2] * O[2] + g_t8[7][3] * O[3] + add) >> shift);
src += 8;
dst++;
}
}
static void partialButterflyInverse4(const int16_t* src, int16_t* dst, int shift, int line)
{
int j;
int E[2], O[2];
int add = 1 << (shift - 1);
for (j = 0; j < line; j++)
{
/* Utilizing symmetry properties to the maximum to minimize the number of multiplications */
O[0] = g_t4[1][0] * src[line] + g_t4[3][0] * src[3 * line];
O[1] = g_t4[1][1] * src[line] + g_t4[3][1] * src[3 * line];
E[0] = g_t4[0][0] * src[0] + g_t4[2][0] * src[2 * line];
E[1] = g_t4[0][1] * src[0] + g_t4[2][1] * src[2 * line];
/* Combining even and odd terms at each hierarchy levels to calculate the final spatial domain vector */
dst[0] = (int16_t)(x265_clip3(-32768, 32767, (E[0] + O[0] + add) >> shift));
dst[1] = (int16_t)(x265_clip3(-32768, 32767, (E[1] + O[1] + add) >> shift));
dst[2] = (int16_t)(x265_clip3(-32768, 32767, (E[1] - O[1] + add) >> shift));
dst[3] = (int16_t)(x265_clip3(-32768, 32767, (E[0] - O[0] + add) >> shift));
src++;
dst += 4;
}
}
static void partialButterflyInverse8(const int16_t* src, int16_t* dst, int shift, int line)
{
int j, k;
int E[4], O[4];
int EE[2], EO[2];
int add = 1 << (shift - 1);
for (j = 0; j < line; j++)
{
/* Utilizing symmetry properties to the maximum to minimize the number of multiplications */
for (k = 0; k < 4; k++)
{
O[k] = g_t8[1][k] * src[line] + g_t8[3][k] * src[3 * line] + g_t8[5][k] * src[5 * line] + g_t8[7][k] * src[7 * line];
}
EO[0] = g_t8[2][0] * src[2 * line] + g_t8[6][0] * src[6 * line];
EO[1] = g_t8[2][1] * src[2 * line] + g_t8[6][1] * src[6 * line];
EE[0] = g_t8[0][0] * src[0] + g_t8[4][0] * src[4 * line];
EE[1] = g_t8[0][1] * src[0] + g_t8[4][1] * src[4 * line];
/* Combining even and odd terms at each hierarchy levels to calculate the final spatial domain vector */
E[0] = EE[0] + EO[0];
E[3] = EE[0] - EO[0];
E[1] = EE[1] + EO[1];
E[2] = EE[1] - EO[1];
for (k = 0; k < 4; k++)
{
dst[k] = (int16_t)x265_clip3(-32768, 32767, (E[k] + O[k] + add) >> shift);
dst[k + 4] = (int16_t)x265_clip3(-32768, 32767, (E[3 - k] - O[3 - k] + add) >> shift);
}
src++;
dst += 8;
}
}
static void partialButterflyInverse16(const int16_t* src, int16_t* dst, int shift, int line)
{
int j, k;
int E[8], O[8];
int EE[4], EO[4];
int EEE[2], EEO[2];
int add = 1 << (shift - 1);
for (j = 0; j < line; j++)
{
/* Utilizing symmetry properties to the maximum to minimize the number of multiplications */
for (k = 0; k < 8; k++)
{
O[k] = g_t16[1][k] * src[line] + g_t16[3][k] * src[3 * line] + g_t16[5][k] * src[5 * line] + g_t16[7][k] * src[7 * line] +
g_t16[9][k] * src[9 * line] + g_t16[11][k] * src[11 * line] + g_t16[13][k] * src[13 * line] + g_t16[15][k] * src[15 * line];
}
for (k = 0; k < 4; k++)
{
EO[k] = g_t16[2][k] * src[2 * line] + g_t16[6][k] * src[6 * line] + g_t16[10][k] * src[10 * line] + g_t16[14][k] * src[14 * line];
}
EEO[0] = g_t16[4][0] * src[4 * line] + g_t16[12][0] * src[12 * line];
EEE[0] = g_t16[0][0] * src[0] + g_t16[8][0] * src[8 * line];
EEO[1] = g_t16[4][1] * src[4 * line] + g_t16[12][1] * src[12 * line];
EEE[1] = g_t16[0][1] * src[0] + g_t16[8][1] * src[8 * line];
/* Combining even and odd terms at each hierarchy levels to calculate the final spatial domain vector */
for (k = 0; k < 2; k++)
{
EE[k] = EEE[k] + EEO[k];
EE[k + 2] = EEE[1 - k] - EEO[1 - k];
}
for (k = 0; k < 4; k++)
{
E[k] = EE[k] + EO[k];
E[k + 4] = EE[3 - k] - EO[3 - k];
}
for (k = 0; k < 8; k++)
{
dst[k] = (int16_t)x265_clip3(-32768, 32767, (E[k] + O[k] + add) >> shift);
dst[k + 8] = (int16_t)x265_clip3(-32768, 32767, (E[7 - k] - O[7 - k] + add) >> shift);
}
src++;
dst += 16;
}
}
static void partialButterflyInverse32(const int16_t* src, int16_t* dst, int shift, int line)
{
int j, k;
int E[16], O[16];
int EE[8], EO[8];
int EEE[4], EEO[4];
int EEEE[2], EEEO[2];
int add = 1 << (shift - 1);
for (j = 0; j < line; j++)
{
/* Utilizing symmetry properties to the maximum to minimize the number of multiplications */
for (k = 0; k < 16; k++)
{
O[k] = g_t32[1][k] * src[line] + g_t32[3][k] * src[3 * line] + g_t32[5][k] * src[5 * line] + g_t32[7][k] * src[7 * line] +
g_t32[9][k] * src[9 * line] + g_t32[11][k] * src[11 * line] + g_t32[13][k] * src[13 * line] + g_t32[15][k] * src[15 * line] +
g_t32[17][k] * src[17 * line] + g_t32[19][k] * src[19 * line] + g_t32[21][k] * src[21 * line] + g_t32[23][k] * src[23 * line] +
g_t32[25][k] * src[25 * line] + g_t32[27][k] * src[27 * line] + g_t32[29][k] * src[29 * line] + g_t32[31][k] * src[31 * line];
}
for (k = 0; k < 8; k++)
{
EO[k] = g_t32[2][k] * src[2 * line] + g_t32[6][k] * src[6 * line] + g_t32[10][k] * src[10 * line] + g_t32[14][k] * src[14 * line] +
g_t32[18][k] * src[18 * line] + g_t32[22][k] * src[22 * line] + g_t32[26][k] * src[26 * line] + g_t32[30][k] * src[30 * line];
}
for (k = 0; k < 4; k++)
{
EEO[k] = g_t32[4][k] * src[4 * line] + g_t32[12][k] * src[12 * line] + g_t32[20][k] * src[20 * line] + g_t32[28][k] * src[28 * line];
}
EEEO[0] = g_t32[8][0] * src[8 * line] + g_t32[24][0] * src[24 * line];
EEEO[1] = g_t32[8][1] * src[8 * line] + g_t32[24][1] * src[24 * line];
EEEE[0] = g_t32[0][0] * src[0] + g_t32[16][0] * src[16 * line];
EEEE[1] = g_t32[0][1] * src[0] + g_t32[16][1] * src[16 * line];
/* Combining even and odd terms at each hierarchy levels to calculate the final spatial domain vector */
EEE[0] = EEEE[0] + EEEO[0];
EEE[3] = EEEE[0] - EEEO[0];
EEE[1] = EEEE[1] + EEEO[1];
EEE[2] = EEEE[1] - EEEO[1];
for (k = 0; k < 4; k++)
{
EE[k] = EEE[k] + EEO[k];
EE[k + 4] = EEE[3 - k] - EEO[3 - k];
}
for (k = 0; k < 8; k++)
{
E[k] = EE[k] + EO[k];
E[k + 8] = EE[7 - k] - EO[7 - k];
}
for (k = 0; k < 16; k++)
{
dst[k] = (int16_t)x265_clip3(-32768, 32767, (E[k] + O[k] + add) >> shift);
dst[k + 16] = (int16_t)x265_clip3(-32768, 32767, (E[15 - k] - O[15 - k] + add) >> shift);
}
src++;
dst += 32;
}
}
/** 函数功能 ：对残差块进行DCT变换并对其转置
* \参数 block ：残差数据
* \参数 coeff ：存储行变换后的数据
* \参数 shift ：行变换移位个数
* \返回 ：null
**/
static void partialButterfly4(const int16_t* src, int16_t* dst, int shift, int line)
{
//功能： X*DCT'
int j;
int E[2], O[2];
int add = 1 << (shift - 1);
for (j = 0; j < line; j++)
{
/* E and O */
E[0] = src[0] + src[3];
O[0] = src[0] - src[3];
E[1] = src[1] + src[2];
O[1] = src[1] - src[2];
dst[0] = (int16_t)((g_t4[0][0] * E[0] + g_t4[0][1] * E[1] + add) >> shift);
dst[2 * line] = (int16_t)((g_t4[2][0] * E[0] + g_t4[2][1] * E[1] + add) >> shift);
dst[line] = (int16_t)((g_t4[1][0] * O[0] + g_t4[1][1] * O[1] + add) >> shift);
dst[3 * line] = (int16_t)((g_t4[3][0] * O[0] + g_t4[3][1] * O[1] + add) >> shift);
src += 4;
dst++;
}
}
/** 函数功能 ：对残差系数作4x4DST变换
* \参数 src ：残差数据
* \参数 dst ：DST变换后存储地址（空间大小为4x4）
* \参数 srcStride ：残差块步长
* \返回 ：null
**/
static void dst4_c(const int16_t* src, int16_t* dst, intptr_t srcStride)
{
const int shift_1st = 1 + X265_DEPTH - 8;//行变换移位个数：1
const int shift_2nd = 8;//列变换移位个数:8
ALIGN_VAR_32(int16_t, coef[4 * 4]);//4x4空间用于存储行变换后的数据
ALIGN_VAR_32(int16_t, block[4 * 4]);//4x4空间用于存储残差块数据
for (int i = 0; i < 4; i++)
{
memcpy(&block[i * 4], &src[i * srcStride], 4 * sizeof(int16_t));//将残差块数据存储到block中
}
/*
测试样例：
当前残差 block
-46 -39 -42 -42
-43 -39 -29 -27
-32 -31 -31 -28
-22 -20 -21 -17
**/
fastForwardDst(block, coef, shift_1st);//对残差块进行变换并对其转置
/*
行变换后并移位后的数据
-5057 -3903 -3639 -2360
-1591 -2035 -1295 -925
-967 -910 -517 -324
-572 -226 -319 -295
DST =
29 55 74 84
74 74 0 -74
84 -29 -74 55
55 -84 74 -29
X*DST' (X为前面的残差,DST'为DST的转置)
=X* 29 55 74 84
74 74 0 -74
84 -29 -74 55
55 -84 74 -29
=
-10115 -3182 -1935 -1144
-7806 -4070 -1820 -452
-7279 -2590 -1035 -638
-4720 -1850 -649 -591
对其移1位（四舍五入）
-5057 -1591 -967 -572
-3903 -2035 -910 -226
-3639 -1295 -517 -319
-2360 -925 -324 -295
对其转置 为了重新复用fastForwardDst函数
-5057 -3903 -3639 -2360
-1591 -2035 -1295 -925
-967 -910 -517 -324
-572 -226 -319 -295
**/
fastForwardDst(coef, dst, shift_2nd);//对残差块进行变换并对其转置（因为已经将其转置 在这里实质上做的是列变换）
/*
coeff=
-5057 -3903 -3639 -2360
-1591 -2035 -1295 -925
-967 -910 -517 -324
-572 -226 -319 -295
（coeff*DST’）'=
-3238 -1295 -561 -302
-1908 -781 -449 -145
-672 -116 -134 -133
-590 56 -22 -108
最终结果 DST*X*DST’/512 右移9位(1+8)
**/
}
/** 函数功能 ：对残差系数作4x4DCT变换
* \参数 src ：残差数据
* \参数 dst ：DCT变换后存储地址（空间大小为4x4）
* \参数 srcStride ：残差块步长
* \返回 ：null
**/
static void dct4_c(const int16_t* src, int16_t* dst, intptr_t srcStride)
{
const int shift_1st = 1 + X265_DEPTH - 8;//行变换移位个数：1
const int shift_2nd = 8;//列变换移位个数:8
ALIGN_VAR_32(int16_t, coef[4 * 4]);//4x4空间用于存储行变换后的数据
ALIGN_VAR_32(int16_t, block[4 * 4]);//4x4空间用于存储残差块数据
for (int i = 0; i < 4; i++)
{
memcpy(&block[i * 4], &src[i * srcStride], 4 * sizeof(int16_t));//将残差块数据存储到block中
}
/*
测试样例：
当前残差 block
-14 -17 -18 -20
-20 -18 -18 -19
-23 -25 -26 -25
-15 -19 -20 -19
**/
partialButterfly4(block, coef, shift_1st, 4);//对残差块进行变换并对其转置（因为已经将其转置 在这里实质上做的是列变换）
/*
行变换后并移位后的数据
-2208 -2400 -3168 -2336
267 -41 101 184
32 -96 96 160
67 -18 -5 31
DCT =
64 64 64 64
83 36 -36 -83
64 -64 -64 64
36 -83 83 -36
X*DCT' (X为前面的残差,DCT'为DCT的转置)
=X* 64 64 64 64
83 36 -36 -83
64 -64 -64 64
36 -83 83 -36
=
-4416 534 64 133
-4800 -83 -192 -36
-6336 202 192 -11
-4672 368 320 61
对其移1位（四舍五入）
-2208 267 32 67
-2400 -41 -96 -18
-3168 101 96 -5
-2336 184 160 31
对其转置 为了重新复用partialButterfly4函数
-2208 -2400 -3168 -2336
267 -41 101 184
32 -96 96 160
67 -18 -5 31
**/
partialButterfly4(coef, dst, shift_2nd, 4);//对残差块进行变换并对其转置（因为已经将其转置 在这里实质上做的是列变换）
/*
coeff=
-2208 -2400 -3168 -2336
267 -41 101 184
32 -96 96 160
67 -18 -5 31
（coeff*DCT’）'=
-2528 128 48 19
150 7 -68 10
256 98 48 30
-231 58 44 9
最终结果 DCT*X*DCT’/512 右移9位(1+8)
**/
}
/** 函数功能 ：对残差系数作8x8DCT变换 DCT*X*DCT’/2048
* \参数 src ：残差数据
* \参数 dst ：DCT变换后存储地址（空间大小为8x8）
* \参数 srcStride ：残差块步长
* \返回 ：null
**/
static void dct8_c(const int16_t* src, int16_t* dst, intptr_t srcStride)
{
const int shift_1st = 2 + X265_DEPTH - 8;//行变换移位个数：2
const int shift_2nd = 9;//列变换移位个数:9
ALIGN_VAR_32(int16_t, coef[8 * 8]);//8x8空间用于存储行变换后的数据
ALIGN_VAR_32(int16_t, block[8 * 8]);//8x8空间用于存储残差块数据
for (int i = 0; i < 8; i++)
{
memcpy(&block[i * 8], &src[i * srcStride], 8 * sizeof(int16_t));//将残差块数据存储到block中
}
/*
DCT=
{ 64, 64, 64, 64, 64, 64, 64, 64},
{ 89, 75, 50, 18,-18,-50,-75,-89},
{ 83, 36,-36,-83,-83,-36, 36, 83},
{ 75,-18,-89,-50, 50, 89, 18,-75},
{ 64,-64,-64, 64, 64,-64,-64, 64},
{ 50,-89, 18, 75,-75,-18, 89,-50},
{ 36,-83, 83,-36,-36, 83,-83, 36},
{ 18,-50, 75,-89, 89,-75, 50,-18}
**/
partialButterfly8(block, coef, shift_1st, 8);//对残差块进行变换并对其转置（因为已经将其转置 在这里实质上做的是列变换）
partialButterfly8(coef, dst, shift_2nd, 8);//对残差块进行变换并对其转置（因为已经将其转置 在这里实质上做的是列变换）
}
/** 函数功能 ：对残差系数作16x16DCT变换 DCT*X*DCT’/8192
* \参数 src ：残差数据
* \参数 dst ：DCT变换后存储地址（空间大小为16x16）
* \参数 srcStride ：残差块步长
* \返回 ：null
**/
static void dct16_c(const int16_t* src, int16_t* dst, intptr_t srcStride)
{
const int shift_1st = 3 + X265_DEPTH - 8;//行变换移位个数：3
const int shift_2nd = 10;//列变换移位个数:10
ALIGN_VAR_32(int16_t, coef[16 * 16]);//16x16空间用于存储行变换后的数据
ALIGN_VAR_32(int16_t, block[16 * 16]);//16x16空间用于存储残差块数据
for (int i = 0; i < 16; i++)
{
memcpy(&block[i * 16], &src[i * srcStride], 16 * sizeof(int16_t));//将残差块数据存储到block中
}
/*
{ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64},
{ 90, 87, 80, 70, 57, 43, 25, 9, -9,-25,-43,-57,-70,-80,-87,-90},
{ 89, 75, 50, 18,-18,-50,-75,-89,-89,-75,-50,-18, 18, 50, 75, 89},
{ 87, 57, 9,-43,-80,-90,-70,-25, 25, 70, 90, 80, 43, -9,-57,-87},
{ 83, 36,-36,-83,-83,-36, 36, 83, 83, 36,-36,-83,-83,-36, 36, 83},
{ 80, 9,-70,-87,-25, 57, 90, 43,-43,-90,-57, 25, 87, 70, -9,-80},
{ 75,-18,-89,-50, 50, 89, 18,-75,-75, 18, 89, 50,-50,-89,-18, 75},
{ 70,-43,-87, 9, 90, 25,-80,-57, 57, 80,-25,-90, -9, 87, 43,-70},
{ 64,-64,-64, 64, 64,-64,-64, 64, 64,-64,-64, 64, 64,-64,-64, 64},
{ 57,-80,-25, 90, -9,-87, 43, 70,-70,-43, 87, 9,-90, 25, 80,-57},
{ 50,-89, 18, 75,-75,-18, 89,-50,-50, 89,-18,-75, 75, 18,-89, 50},
{ 43,-90, 57, 25,-87, 70, 9,-80, 80, -9,-70, 87,-25,-57, 90,-43},
{ 36,-83, 83,-36,-36, 83,-83, 36, 36,-83, 83,-36,-36, 83,-83, 36},
{ 25,-70, 90,-80, 43, 9,-57, 87,-87, 57, -9,-43, 80,-90, 70,-25},
{ 18,-50, 75,-89, 89,-75, 50,-18,-18, 50,-75, 89,-89, 75,-50, 18},
{ 9,-25, 43,-57, 70,-80, 87,-90, 90,-87, 80,-70, 57,-43, 25, -9}
**/
partialButterfly16(block, coef, shift_1st, 16);//对残差块进行变换并对其转置（因为已经将其转置 在这里实质上做的是列变换）
partialButterfly16(coef, dst, shift_2nd, 16);//对残差块进行变换并对其转置（因为已经将其转置 在这里实质上做的是列变换）
}
/** 函数功能 ：对残差系数作32x32DCT变换 DCT*X*DCT’/32768
* \参数 src ：残差数据
* \参数 dst ：DCT变换后存储地址（空间大小为32x32）
* \参数 srcStride ：残差块步长
* \返回 ：null
**/
static void dct32_c(const int16_t* src, int16_t* dst, intptr_t srcStride)
{
const int shift_1st = 4 + X265_DEPTH - 8;//行变换移位个数：4
const int shift_2nd = 11;//列变换移位个数:11
ALIGN_VAR_32(int16_t, coef[32 * 32]);//32x32空间用于存储行变换后的数据
ALIGN_VAR_32(int16_t, block[32 * 32]);//32x32空间用于存储残差块数据
for (int i = 0; i < 32; i++)
{
memcpy(&block[i * 32], &src[i * srcStride], 32 * sizeof(int16_t));//将残差块数据存储到block中
}
/*
{ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64},
{ 90, 90, 88, 85, 82, 78, 73, 67, 61, 54, 46, 38, 31, 22, 13, 4, -4,-13,-22,-31,-38,-46,-54,-61,-67,-73,-78,-82,-85,-88,-90,-90},
{ 90, 87, 80, 70, 57, 43, 25, 9, -9,-25,-43,-57,-70,-80,-87,-90,-90,-87,-80,-70,-57,-43,-25, -9, 9, 25, 43, 57, 70, 80, 87, 90},
{ 90, 82, 67, 46, 22, -4,-31,-54,-73,-85,-90,-88,-78,-61,-38,-13, 13, 38, 61, 78, 88, 90, 85, 73, 54, 31, 4,-22,-46,-67,-82,-90},
{ 89, 75, 50, 18,-18,-50,-75,-89,-89,-75,-50,-18, 18, 50, 75, 89, 89, 75, 50, 18,-18,-50,-75,-89,-89,-75,-50,-18, 18, 50, 75, 89},
{ 88, 67, 31,-13,-54,-82,-90,-78,-46, -4, 38, 73, 90, 85, 61, 22,-22,-61,-85,-90,-73,-38, 4, 46, 78, 90, 82, 54, 13,-31,-67,-88},
{ 87, 57, 9,-43,-80,-90,-70,-25, 25, 70, 90, 80, 43, -9,-57,-87,-87,-57, -9, 43, 80, 90, 70, 25,-25,-70,-90,-80,-43, 9, 57, 87},
{ 85, 46,-13,-67,-90,-73,-22, 38, 82, 88, 54, -4,-61,-90,-78,-31, 31, 78, 90, 61, 4,-54,-88,-82,-38, 22, 73, 90, 67, 13,-46,-85},
{ 83, 36,-36,-83,-83,-36, 36, 83, 83, 36,-36,-83,-83,-36, 36, 83, 83, 36,-36,-83,-83,-36, 36, 83, 83, 36,-36,-83,-83,-36, 36, 83},
{ 82, 22,-54,-90,-61, 13, 78, 85, 31,-46,-90,-67, 4, 73, 88, 38,-38,-88,-73, -4, 67, 90, 46,-31,-85,-78,-13, 61, 90, 54,-22,-82},
{ 80, 9,-70,-87,-25, 57, 90, 43,-43,-90,-57, 25, 87, 70, -9,-80,-80, -9, 70, 87, 25,-57,-90,-43, 43, 90, 57,-25,-87,-70, 9, 80},
{ 78, -4,-82,-73, 13, 85, 67,-22,-88,-61, 31, 90, 54,-38,-90,-46, 46, 90, 38,-54,-90,-31, 61, 88, 22,-67,-85,-13, 73, 82, 4,-78},
{ 75,-18,-89,-50, 50, 89, 18,-75,-75, 18, 89, 50,-50,-89,-18, 75, 75,-18,-89,-50, 50, 89, 18,-75,-75, 18, 89, 50,-50,-89,-18, 75},
{ 73,-31,-90,-22, 78, 67,-38,-90,-13, 82, 61,-46,-88, -4, 85, 54,-54,-85, 4, 88, 46,-61,-82, 13, 90, 38,-67,-78, 22, 90, 31,-73},
{ 70,-43,-87, 9, 90, 25,-80,-57, 57, 80,-25,-90, -9, 87, 43,-70,-70, 43, 87, -9,-90,-25, 80, 57,-57,-80, 25, 90, 9,-87,-43, 70},
{ 67,-54,-78, 38, 85,-22,-90, 4, 90, 13,-88,-31, 82, 46,-73,-61, 61, 73,-46,-82, 31, 88,-13,-90, -4, 90, 22,-85,-38, 78, 54,-67},
{ 64,-64,-64, 64, 64,-64,-64, 64, 64,-64,-64, 64, 64,-64,-64, 64, 64,-64,-64, 64, 64,-64,-64, 64, 64,-64,-64, 64, 64,-64,-64, 64},
{ 61,-73,-46, 82, 31,-88,-13, 90, -4,-90, 22, 85,-38,-78, 54, 67,-67,-54, 78, 38,-85,-22, 90, 4,-90, 13, 88,-31,-82, 46, 73,-61},
{ 57,-80,-25, 90, -9,-87, 43, 70,-70,-43, 87, 9,-90, 25, 80,-57,-57, 80, 25,-90, 9, 87,-43,-70, 70, 43,-87, -9, 90,-25,-80, 57},
{ 54,-85, -4, 88,-46,-61, 82, 13,-90, 38, 67,-78,-22, 90,-31,-73, 73, 31,-90, 22, 78,-67,-38, 90,-13,-82, 61, 46,-88, 4, 85,-54},
{ 50,-89, 18, 75,-75,-18, 89,-50,-50, 89,-18,-75, 75, 18,-89, 50, 50,-89, 18, 75,-75,-18, 89,-50,-50, 89,-18,-75, 75, 18,-89, 50},
{ 46,-90, 38, 54,-90, 31, 61,-88, 22, 67,-85, 13, 73,-82, 4, 78,-78, -4, 82,-73,-13, 85,-67,-22, 88,-61,-31, 90,-54,-38, 90,-46},
{ 43,-90, 57, 25,-87, 70, 9,-80, 80, -9,-70, 87,-25,-57, 90,-43,-43, 90,-57,-25, 87,-70, -9, 80,-80, 9, 70,-87, 25, 57,-90, 43},
{ 38,-88, 73, -4,-67, 90,-46,-31, 85,-78, 13, 61,-90, 54, 22,-82, 82,-22,-54, 90,-61,-13, 78,-85, 31, 46,-90, 67, 4,-73, 88,-38},
{ 36,-83, 83,-36,-36, 83,-83, 36, 36,-83, 83,-36,-36, 83,-83, 36, 36,-83, 83,-36,-36, 83,-83, 36, 36,-83, 83,-36,-36, 83,-83, 36},
{ 31,-78, 90,-61, 4, 54,-88, 82,-38,-22, 73,-90, 67,-13,-46, 85,-85, 46, 13,-67, 90,-73, 22, 38,-82, 88,-54, -4, 61,-90, 78,-31},
{ 25,-70, 90,-80, 43, 9,-57, 87,-87, 57, -9,-43, 80,-90, 70,-25,-25, 70,-90, 80,-43, -9, 57,-87, 87,-57, 9, 43,-80, 90,-70, 25},
{ 22,-61, 85,-90, 73,-38, -4, 46,-78, 90,-82, 54,-13,-31, 67,-88, 88,-67, 31, 13,-54, 82,-90, 78,-46, 4, 38,-73, 90,-85, 61,-22},
{ 18,-50, 75,-89, 89,-75, 50,-18,-18, 50,-75, 89,-89, 75,-50, 18, 18,-50, 75,-89, 89,-75, 50,-18,-18, 50,-75, 89,-89, 75,-50, 18},
{ 13,-38, 61,-78, 88,-90, 85,-73, 54,-31, 4, 22,-46, 67,-82, 90,-90, 82,-67, 46,-22, -4, 31,-54, 73,-85, 90,-88, 78,-61, 38,-13},
{ 9,-25, 43,-57, 70,-80, 87,-90, 90,-87, 80,-70, 57,-43, 25, -9, -9, 25,-43, 57,-70, 80,-87, 90,-90, 87,-80, 70,-57, 43,-25, 9},
{ 4,-13, 22,-31, 38,-46, 54,-61, 67,-73, 78,-82, 85,-88, 90,-90, 90,-90, 88,-85, 82,-78, 73,-67, 61,-54, 46,-38, 31,-22, 13, -4}
**/
partialButterfly32(block, coef, shift_1st, 32);//对残差块进行变换并对其转置（因为已经将其转置 在这里实质上做的是列变换）
partialButterfly32(coef, dst, shift_2nd, 32);//对残差块进行变换并对其转置（因为已经将其转置 在这里实质上做的是列变换）
}
static void idst4_c(const int16_t* src, int16_t* dst, intptr_t dstStride)
{
const int shift_1st = 7;
const int shift_2nd = 12 - (X265_DEPTH - 8);
ALIGN_VAR_32(int16_t, coef[4 * 4]);
ALIGN_VAR_32(int16_t, block[4 * 4]);
inversedst(src, coef, shift_1st); // Forward DST BY FAST ALGORITHM, block input, coef output
inversedst(coef, block, shift_2nd); // Forward DST BY FAST ALGORITHM, coef input, coeff output
for (int i = 0; i < 4; i++)
{
memcpy(&dst[i * dstStride], &block[i * 4], 4 * sizeof(int16_t));
}
}
static void idct4_c(const int16_t* src, int16_t* dst, intptr_t dstStride)
{
const int shift_1st = 7;
const int shift_2nd = 12 - (X265_DEPTH - 8);
ALIGN_VAR_32(int16_t, coef[4 * 4]);
ALIGN_VAR_32(int16_t, block[4 * 4]);
partialButterflyInverse4(src, coef, shift_1st, 4); // Forward DST BY FAST ALGORITHM, block input, coef output
partialButterflyInverse4(coef, block, shift_2nd, 4); // Forward DST BY FAST ALGORITHM, coef input, coeff output
for (int i = 0; i < 4; i++)
{
memcpy(&dst[i * dstStride], &block[i * 4], 4 * sizeof(int16_t));
}
}
static void idct8_c(const int16_t* src, int16_t* dst, intptr_t dstStride)
{
const int shift_1st = 7;
const int shift_2nd = 12 - (X265_DEPTH - 8);
ALIGN_VAR_32(int16_t, coef[8 * 8]);
ALIGN_VAR_32(int16_t, block[8 * 8]);
partialButterflyInverse8(src, coef, shift_1st, 8);
partialButterflyInverse8(coef, block, shift_2nd, 8);
for (int i = 0; i < 8; i++)
{
memcpy(&dst[i * dstStride], &block[i * 8], 8 * sizeof(int16_t));
}
}
static void idct16_c(const int16_t* src, int16_t* dst, intptr_t dstStride)
{
const int shift_1st = 7;
const int shift_2nd = 12 - (X265_DEPTH - 8);
ALIGN_VAR_32(int16_t, coef[16 * 16]);
ALIGN_VAR_32(int16_t, block[16 * 16]);
partialButterflyInverse16(src, coef, shift_1st, 16);
partialButterflyInverse16(coef, block, shift_2nd, 16);
for (int i = 0; i < 16; i++)
{
memcpy(&dst[i * dstStride], &block[i * 16], 16 * sizeof(int16_t));
}
}
static void idct32_c(const int16_t* src, int16_t* dst, intptr_t dstStride)
{
const int shift_1st = 7;
const int shift_2nd = 12 - (X265_DEPTH - 8);
ALIGN_VAR_32(int16_t, coef[32 * 32]);
ALIGN_VAR_32(int16_t, block[32 * 32]);
partialButterflyInverse32(src, coef, shift_1st, 32);
partialButterflyInverse32(coef, block, shift_2nd, 32);
for (int i = 0; i < 32; i++)
{
memcpy(&dst[i * dstStride], &block[i * 32], 32 * sizeof(int16_t));
}
}
static void dequant_normal_c(const int16_t* quantCoef, int16_t* coef, int num, int scale, int shift)
{
#if HIGH_BIT_DEPTH
X265_CHECK(scale < 32768 || ((scale & 3) == 0 && shift > (X265_DEPTH - 8)), "dequant invalid scale %d\n", scale);
#else
// NOTE: maximum of scale is (72 * 256)
X265_CHECK(scale < 32768, "dequant invalid scale %d\n", scale);
#endif
X265_CHECK(num <= 32 * 32, "dequant num %d too large\n", num);
X265_CHECK((num % 8) == 0, "dequant num %d not multiple of 8\n", num);
X265_CHECK(shift <= 10, "shift too large %d\n", shift);
X265_CHECK(((intptr_t)coef & 31) == 0, "dequant coef buffer not aligned\n");
int add, coeffQ;
add = 1 << (shift - 1);
for (int n = 0; n < num; n++)
{
coeffQ = (quantCoef[n] * scale + add) >> shift;
coef[n] = (int16_t)x265_clip3(-32768, 32767, coeffQ);
}
}
static void dequant_scaling_c(const int16_t* quantCoef, const int32_t* deQuantCoef, int16_t* coef, int num, int per, int shift)
{
X265_CHECK(num <= 32 * 32, "dequant num %d too large\n", num);
int add, coeffQ;
shift += 4;
if (shift > per)
{
add = 1 << (shift - per - 1);
for (int n = 0; n < num; n++)
{
coeffQ = ((quantCoef[n] * deQuantCoef[n]) + add) >> (shift - per);
coef[n] = (int16_t)x265_clip3(-32768, 32767, coeffQ);
}
}
else
{
for (int n = 0; n < num; n++)
{
coeffQ = x265_clip3(-32768, 32767, quantCoef[n] * deQuantCoef[n]);
coef[n] = (int16_t)x265_clip3(-32768, 32767, coeffQ << (per - shift));
}
}
}
/** 函数功能 ： 常规量化，C语言版本
* \参数 coef ： 变换后的系数矩阵
* \参数 quantCoeff ： 前向量化表
* \参数 deltaU ： 存储每一个位置量化误差的buffer
* \参数 qCoef ： 输出的量化后的系数矩阵
* \参数 qBits ： 量化中需要右移的位数
* \参数 add ： 为了补偿量化中右移操作，右移操作前需要加上的补偿加数
* \参数 numCoeff ： 当前变换块中变换系数的个数
* \返回值 numSig ： 返回量化后非零系数的个数
*/
static uint32_t quant_c(const int16_t* coef, const int32_t* quantCoeff, int32_t* deltaU, int16_t* qCoef, int qBits, int add, int numCoeff)
{
X265_CHECK(qBits >= 8, "qBits less than 8\n"); // 确保右移的位数大于8
X265_CHECK((numCoeff % 16) == 0, "numCoeff must be multiple of 16\n"); // 确保系数个数是16的整数倍
int qBits8 = qBits - 8; // 用于计算量化误差时右移的位数
uint32_t numSig = 0;
for (int blockpos = 0; blockpos < numCoeff; blockpos++)
{
int level = coef[blockpos]; // 得到一个变换后的系数
int sign = (level < 0 ? -1 : 1); // 判断符号
int tmplevel = abs(level) * quantCoeff[blockpos]; // 变换系数的绝对值 * 前向量化值
level = ((tmplevel + add) >> qBits); // 加上补偿加数后右移
deltaU[blockpos] = ((tmplevel - (level << qBits)) >> qBits8); // 计算量化误差
if (level) // 如果量化后的系数不为0，则非零系数个数加1
++numSig;
level *= sign; // 恢复符号位
qCoef[blockpos] = (int16_t)x265_clip3(-32768, 32767, level); // 进行clip操作，并存储在量化矩阵中。可以看出这里限定量化后的值是一个有符号16-bit的数(-2^15~2^15-1)
}
return numSig;//返回量化后非零系数的个数
}
/** 函数功能 ： ？常规量化（与quant_c相比只是不用存储量化误差），C语言版本
** 调用范围 ： 只在Quant::rdoQuant中被调用
* \参数 coef ： 变换后的系数矩阵
* \参数 quantCoeff ： 前向量化表
* \参数 qCoef ： 输出的量化后的系数矩阵
* \参数 qBits ： 量化中需要右移的位数
* \参数 add ： 为了补偿量化中右移操作，右移操作前需要加上的补偿加数
* \参数 numCoeff ： 当前变换块中变换系数的个数
* \返回值 numSig ： 返回量化后非零系数的个数
*/
static uint32_t nquant_c(const int16_t* coef, const int32_t* quantCoeff, int16_t* qCoef, int qBits, int add, int numCoeff)
{
X265_CHECK((numCoeff % 16) == 0, "number of quant coeff is not multiple of 4x4\n"); // TU中的系数个数numCoeff需要是16的整数倍
X265_CHECK((uint32_t)add < ((uint32_t)1 << qBits), "2 ^ qBits less than add\n"); // 加数需要小于右移的大小
X265_CHECK(((intptr_t)quantCoeff & 31) == 0, "quantCoeff buffer not aligned\n"); // 前向量化表在内存中是对齐的
uint32_t numSig = 0;
for (int blockpos = 0; blockpos < numCoeff; blockpos++)
{
int level = coef[blockpos]; // 得到一个变换后的系数
int sign = (level < 0 ? -1 : 1); // 判断符号
int tmplevel = abs(level) * quantCoeff[blockpos]; // 变换系数的绝对值 * 前向量化值
level = ((tmplevel + add) >> qBits); // 加上补偿加数后右移
if (level) // 如果量化后的系数不为0，则非零系数个数加1
++numSig;
level *= sign; // 恢复符号位
qCoef[blockpos] = (int16_t)x265_clip3(-32768, 32767, level); // 进行clip操作，并存储在量化矩阵中。可以看出这里限定量化后的值是一个有符号16-bit的数(-2^15~2^15-1)
}
return numSig;
}
template<int trSize>
int count_nonzero_c(const int16_t* quantCoeff)
{
X265_CHECK(((intptr_t)quantCoeff & 15) == 0, "quant buffer not aligned\n");
int count = 0;
int numCoeff = trSize * trSize;
for (int i = 0; i < numCoeff; i++)
{
count += quantCoeff[i] != 0;
}
return count;
}
/** 函数功能 ：拷贝残差块到变换系数块
* \参数 coeff ：输出的变换系数块
* \参数 residual ：输入的残差块
* \参数 resiStride ：残差数据的步长
* \返回 ：残差块中的非零系数的个数
**/
template<int trSize>
uint32_t copy_count(int16_t* coeff, const int16_t* residual, intptr_t resiStride)
{
uint32_t numSig = 0;
for (int k = 0; k < trSize; k++)
{
for (int j = 0; j < trSize; j++)
{
coeff[k * trSize + j] = residual[k * resiStride + j];
numSig += (residual[k * resiStride + j] != 0);
}
}
return numSig;//残差块中的非零系数的个数
}
/** 函数功能 ：AC系数去噪：(AC系数的绝对值 - offset）*符号
* \参数 dctCoef ：输出的变换系数块
* \参数 resSum ：用于当前帧每个TU块中对应位置的绝对值和
* \参数 offset ：去噪偏移值
* \参数 numCoeff ：当前TU块的系数个数（一个TU块的全部系数包含零系数）
* \返回 ：null
**/
static void denoiseDct_c(int16_t* dctCoef, uint32_t* resSum, const uint16_t* offset, int numCoeff)
{
for (int i = 0; i < numCoeff; i++)//遍历所有dct系数
{
int level = dctCoef[i];//获取DCT系数值
int sign = level >> 31;//获取符号位，整数为0，负数为-1
level = (level + sign) ^ sign;//获取绝对值
resSum[i] += level;//统计当前位置的系数绝对值和
level -= offset[i];//(AC系数的绝对值 - offset）
dctCoef[i] = (int16_t)(level < 0 ? 0 : (level ^ sign) - sign);//获取符号位
}
}
/** 函数功能 ：？ 统计每个CG中的非零系数的符号、非零系数的标记（是否是非零系数）、非零系数个数，以及最后一个非零系数的位置
* \参数 scan ：编码参数扫描顺序表
* \参数 coeff ：经过常规量化后的系数
* \参数 coeffSign ：每一个CG中非零系数的符号，低位存储CG前面的非零系数，高位存储CG后面的非零系数
* \参数 coeffFlag ：每一个CG中非零系数的标记（可以对应语法元素sig_coeff_flag），高位存储CG前面的非零标记，低位存储CG后面的非零标记
* \参数 coeffNum ：每一个CG中非零系数的个数
* \参数 numSig ：非零系数的个数
* \参数 scanCG4x4 ：CG的扫描顺序
* \参数 trSize ：TU尺寸
* \返回 int : TU中最后一个非零系数的位置
**/
static int scanPosLast_c(const uint16_t *scan, const coeff_t *coeff, uint16_t *coeffSign, uint16_t *coeffFlag, uint8_t *coeffNum, int numSig, const uint16_t* /*scanCG4x4*/, const int /*trSize*/)
{
memset(coeffNum, 0, MLS_GRP_NUM * sizeof(*coeffNum));
memset(coeffFlag, 0, MLS_GRP_NUM * sizeof(*coeffFlag));
memset(coeffSign, 0, MLS_GRP_NUM * sizeof(*coeffSign));
int scanPosLast = 0;
do // 从头到尾扫描每一个常规量化后的系数
{
const uint32_t cgIdx = (uint32_t)scanPosLast >> MLS_CG_SIZE; // 得到CG的下标index，由于一个CG是4x4，所以向右移4位，即可得到CG的下标
// 这样右移之后只能得到按照Z型（即先行后列）扫描顺序的CG下标，而不是当前扫描模式的CG下标，所以这里CG的相关信息是依据Z型扫描存储的，而系数还是按照扫描顺序遍历的
const uint32_t posLast = scan[scanPosLast++]; // 得到当前扫描模式下的扫描位置
const int curCoeff = coeff[posLast]; // 得到扫描位置上的系数值
const uint32_t isNZCoeff = (curCoeff != 0); // 判断是否该系数为0
// get L1 sig map
// NOTE: the new algorithm is complicated, so I keep reference code here
//uint32_t posy = posLast >> log2TrSize;
//uint32_t posx = posLast - (posy << log2TrSize);
//uint32_t blkIdx0 = ((posy >> MLS_CG_LOG2_SIZE) << codingParameters.log2TrSizeCG) + (posx >> MLS_CG_LOG2_SIZE);
//const uint32_t blkIdx = ((posLast >> (2 * MLS_CG_LOG2_SIZE)) & ~maskPosXY) + ((posLast >> MLS_CG_LOG2_SIZE) & maskPosXY);
//sigCoeffGroupFlag64 |= ((uint64_t)isNZCoeff << blkIdx);
numSig -= isNZCoeff; // 如果当前系数是非零系数，则从非零系数的个数中减一
// TODO: optimize by instruction BTS
coeffSign[cgIdx] += (uint16_t)(((uint32_t)curCoeff >> 31) << coeffNum[cgIdx]); // 得到当前系数的符号位（向右移31位只剩下符号位），并移位累加到每一个CG的coeffSign[cgIdx]中。
// 如果当前CG中第一个非零系数出现（coeffNum[cgIdx]=0），则它的符号位被存放在最低位；紧接着来了第二个非零系数（coeffNum[cgIdx]=1），则它的符号被存放在次低位，以此类推。
coeffFlag[cgIdx] = (coeffFlag[cgIdx] << 1) + (uint16_t)isNZCoeff;
coeffNum[cgIdx] += (uint8_t)isNZCoeff; // 对每一个CG累加其中的非零系数的个数
}
while (numSig > 0); // 知道遍历所有的非零系数，则结束循环
return scanPosLast - 1; // 得到最后一个非零系数的扫描位置
}
static uint32_t findPosFirstLast_c(const int16_t *dstCoeff, const intptr_t trSize, const uint16_t scanTbl[16])
{
int n;
for (n = SCAN_SET_SIZE - 1; n >= 0; --n)
{
const uint32_t idx = scanTbl[n];
const uint32_t idxY = idx / MLS_CG_SIZE;
const uint32_t idxX = idx % MLS_CG_SIZE;
if (dstCoeff[idxY * trSize + idxX])
break;
}
X265_CHECK(n >= -1, "non-zero coeff scan failuare!\n");
uint32_t lastNZPosInCG = (uint32_t)n;
for (n = 0; n < SCAN_SET_SIZE; n++)
{
const uint32_t idx = scanTbl[n];
const uint32_t idxY = idx / MLS_CG_SIZE;
const uint32_t idxX = idx % MLS_CG_SIZE;
if (dstCoeff[idxY * trSize + idxX])
break;
}
uint32_t firstNZPosInCG = (uint32_t)n;
// NOTE: when coeff block all ZERO, the lastNZPosInCG is undefined and firstNZPosInCG is 16
return ((lastNZPosInCG << 16) | firstNZPosInCG);
}
static uint32_t costCoeffNxN_c(const uint16_t *scan, const coeff_t *coeff, intptr_t trSize, uint16_t *absCoeff, const uint8_t *tabSigCtx, uint32_t scanFlagMask, uint8_t *baseCtx, int offset, int scanPosSigOff, int subPosBase)
{
ALIGN_VAR_32(uint16_t, tmpCoeff[SCAN_SET_SIZE]);
uint32_t numNonZero = (scanPosSigOff < (SCAN_SET_SIZE - 1) ? 1 : 0);
uint32_t sum = 0;
// correct offset to match assembly
absCoeff -= numNonZero;
for (int i = 0; i < MLS_CG_SIZE; i++)
{
tmpCoeff[i * MLS_CG_SIZE + 0] = (uint16_t)abs(coeff[i * trSize + 0]);
tmpCoeff[i * MLS_CG_SIZE + 1] = (uint16_t)abs(coeff[i * trSize + 1]);
tmpCoeff[i * MLS_CG_SIZE + 2] = (uint16_t)abs(coeff[i * trSize + 2]);
tmpCoeff[i * MLS_CG_SIZE + 3] = (uint16_t)abs(coeff[i * trSize + 3]);
}
do
{
uint32_t blkPos, sig, ctxSig;
blkPos = scan[scanPosSigOff];
const uint32_t posZeroMask = (subPosBase + scanPosSigOff) ? ~0 : 0;
sig = scanFlagMask & 1;
scanFlagMask >>= 1;
X265_CHECK((uint32_t)(tmpCoeff[blkPos] != 0) == sig, "sign bit mistake\n");
if ((scanPosSigOff != 0) || (subPosBase == 0) || numNonZero)
{
const uint32_t cnt = tabSigCtx[blkPos] + offset;
ctxSig = cnt & posZeroMask;
//X265_CHECK(ctxSig == Quant::getSigCtxInc(patternSigCtx, log2TrSize, trSize, codingParameters.scan[subPosBase + scanPosSigOff], bIsLuma, codingParameters.firstSignificanceMapContext), "sigCtx mistake!\n");;
//encodeBin(sig, baseCtx[ctxSig]);
const uint32_t mstate = baseCtx[ctxSig];
const uint32_t mps = mstate & 1;
const uint32_t stateBits = PFX(entropyStateBits)[mstate ^ sig];
uint32_t nextState = (stateBits >> 24) + mps;
if ((mstate ^ sig) == 1)
nextState = sig;
X265_CHECK(sbacNext(mstate, sig) == nextState, "nextState check failure\n");
X265_CHECK(sbacGetEntropyBits(mstate, sig) == (stateBits & 0xFFFFFF), "entropyBits check failure\n");
baseCtx[ctxSig] = (uint8_t)nextState;
sum += stateBits;
}
assert(numNonZero <= 15);
assert(blkPos <= 15);
absCoeff[numNonZero] = tmpCoeff[blkPos];
numNonZero += sig;
scanPosSigOff--;
}
while(scanPosSigOff >= 0);
return (sum & 0xFFFFFF);
}
static uint32_t costCoeffRemain_c(uint16_t *absCoeff, int numNonZero, int idx)
{
uint32_t goRiceParam = 0;
uint32_t sum = 0;
int baseLevel = 3;
do
{
if (idx >= C1FLAG_NUMBER)
baseLevel = 1;
// TODO: the IDX is not really idx, so this check inactive
//X265_CHECK(baseLevel == ((idx < C1FLAG_NUMBER) ? (2 + firstCoeff2) : 1), "baseLevel check failurr\n");
int codeNumber = absCoeff[idx] - baseLevel;
if (codeNumber >= 0)
{
//writeCoefRemainExGolomb(absCoeff[idx] - baseLevel, goRiceParam);
uint32_t length = 0;
codeNumber = ((uint32_t)codeNumber >> goRiceParam) - COEF_REMAIN_BIN_REDUCTION;
if (codeNumber >= 0)
{
{
unsigned long cidx;
CLZ(cidx, codeNumber + 1);
length = cidx;
}
X265_CHECK((codeNumber != 0) || (length == 0), "length check failure\n");
codeNumber = (length + length);
}
sum += (COEF_REMAIN_BIN_REDUCTION + 1 + goRiceParam + codeNumber);
if (absCoeff[idx] > (COEF_REMAIN_BIN_REDUCTION << goRiceParam))
goRiceParam = (goRiceParam + 1) - (goRiceParam >> 2);
X265_CHECK(goRiceParam <= 4, "goRiceParam check failure\n");
}
baseLevel = 2;
idx++;
}
while(idx < numNonZero);
return sum;
}
static uint32_t costC1C2Flag_c(uint16_t *absCoeff, intptr_t numC1Flag, uint8_t *baseCtxMod, intptr_t ctxOffset)
{
uint32_t sum = 0;
uint32_t c1 = 1;
uint32_t firstC2Idx = 8;
uint32_t firstC2Flag = 2;
uint32_t c1Next = 0xFFFFFFFE;
int idx = 0;
do
{
uint32_t symbol1 = absCoeff[idx] > 1;
uint32_t symbol2 = absCoeff[idx] > 2;
//encodeBin(symbol1, baseCtxMod[c1]);
{
const uint32_t mstate = baseCtxMod[c1];
baseCtxMod[c1] = sbacNext(mstate, symbol1);
sum += sbacGetEntropyBits(mstate, symbol1);
}
if (symbol1)
c1Next = 0;
if (symbol1 + firstC2Flag == 3)
firstC2Flag = symbol2;
if (symbol1 + firstC2Idx == 9)
firstC2Idx = idx;
c1 = (c1Next & 3);
c1Next >>= 2;
X265_CHECK(c1 <= 3, "c1 check failure\n");
idx++;
}
while(idx < numC1Flag);
if (!c1)
{
X265_CHECK((firstC2Flag <= 1), "firstC2FlagIdx check failure\n");
baseCtxMod += ctxOffset;
//encodeBin(firstC2Flag, baseCtxMod[0]);
{
const uint32_t mstate = baseCtxMod[0];
baseCtxMod[0] = sbacNext(mstate, firstC2Flag);
sum += sbacGetEntropyBits(mstate, firstC2Flag);
}
}
return (sum & 0x00FFFFFF) + (c1 << 26) + (firstC2Idx << 28);
}
namespace X265_NS {
// x265 private namespace
void setupDCTPrimitives_c(EncoderPrimitives& p)
{
p.dequant_scaling = dequant_scaling_c;
p.dequant_normal = dequant_normal_c;
p.quant = quant_c;
p.nquant = nquant_c;
p.dst4x4 = dst4_c;
p.cu[BLOCK_4x4].dct = dct4_c;
p.cu[BLOCK_8x8].dct = dct8_c;
p.cu[BLOCK_16x16].dct = dct16_c;
p.cu[BLOCK_32x32].dct = dct32_c;
p.idst4x4 = idst4_c;
p.cu[BLOCK_4x4].idct = idct4_c;
p.cu[BLOCK_8x8].idct = idct8_c;
p.cu[BLOCK_16x16].idct = idct16_c;
p.cu[BLOCK_32x32].idct = idct32_c;
p.denoiseDct = denoiseDct_c;
p.cu[BLOCK_4x4].count_nonzero = count_nonzero_c<4>;
p.cu[BLOCK_8x8].count_nonzero = count_nonzero_c<8>;
p.cu[BLOCK_16x16].count_nonzero = count_nonzero_c<16>;
p.cu[BLOCK_32x32].count_nonzero = count_nonzero_c<32>;
p.cu[BLOCK_4x4].copy_cnt = copy_count<4>;
p.cu[BLOCK_8x8].copy_cnt = copy_count<8>;
p.cu[BLOCK_16x16].copy_cnt = copy_count<16>;
p.cu[BLOCK_32x32].copy_cnt = copy_count<32>;
p.scanPosLast = scanPosLast_c;
p.findPosFirstLast = findPosFirstLast_c;
p.costCoeffNxN = costCoeffNxN_c;
p.costCoeffRemain = costCoeffRemain_c;
p.costC1C2Flag = costC1C2Flag_c;
}
}
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