本文详细解析了x265编码器中的率控机制，包括两遍编码模式下的统计文件利用、单遍编码模式下的平均比特率控制策略、基于下采样SATD的量化参数调整算法等内容。
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: Sumalatha Polureddy <sumalatha@multicorewareinc.com>
* Aarthi Priya Thirumalai <aarthi@multicorewareinc.com>
* Xun Xu, PPLive Corporation <xunxu@pptv.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 "param.h"
#include "frame.h"
#include "framedata.h"
#include "picyuv.h"
#include "encoder.h"
#include "slicetype.h"
#include "ratecontrol.h"
#include "sei.h"
#define BR_SHIFT 6
#define CPB_SHIFT 4
using namespace X265_NS;
/* Amortize the partial cost of I frames over the next N frames */
const int RateControl::s_slidingWindowFrames = 20;//滑动窗口大小
const char *RateControl::s_defaultStatFileName = "x265_2pass.log";
namespace {
#define CMP_OPT_FIRST_PASS(opt, param_val)\
{\
bErr = 0;\
p = strstr(opts, opt "=");\
char* q = strstr(opts, "no-"opt);\
if (p && sscanf(p, opt "=%d" , &i) && param_val != i)\
bErr = 1;\
else if (!param_val && !q && !p)\
bErr = 1;\
else if (param_val && (q || !strstr(opts, opt)))\
bErr = 1;\
if (bErr)\
{\
x265_log(m_param, X265_LOG_ERROR, "different " opt " setting than first pass (%d vs %d)\n", param_val, i);\
return false;\
}\
}
inline int calcScale(uint32_t x)
{
static uint8_t lut[16] = {4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0};
int y, z = (((x & 0xffff) - 1) >> 27) & 16;
x >>= z;
z += y = (((x & 0xff) - 1) >> 28) & 8;
x >>= y;
z += y = (((x & 0xf) - 1) >> 29) & 4;
x >>= y;
return z + lut[x&0xf];
}
inline int calcLength(uint32_t x)
{
static uint8_t lut[16] = {4, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0};
int y, z = (((x >> 16) - 1) >> 27) & 16;
x >>= z ^ 16;
z += y = ((x - 0x100) >> 28) & 8;
x >>= y ^ 8;
z += y = ((x - 0x10) >> 29) & 4;
x >>= y ^ 4;
return z + lut[x];
}
inline void reduceFraction(int* n, int* d)
{
int a = *n;
int b = *d;
int c;
if (!a || !b)
return;
c = a % b;
while (c)
{
a = b;
b = c;
c = a % b;
}
*n /= b;
*d /= b;
}
inline char *strcatFilename(const char *input, const char *suffix)
{
char *output = X265_MALLOC(char, strlen(input) + strlen(suffix) + 1);
if (!output)
{
x265_log(NULL, X265_LOG_ERROR, "unable to allocate memory for filename\n");
return NULL;
}
strcpy(output, input);
strcat(output, suffix);
return output;
}
inline double qScale2bits(RateControlEntry *rce, double qScale)
{
if (qScale < 0.1)
qScale = 0.1;
return (rce->coeffBits + .1) * pow(rce->qScale / qScale, 1.1)
+ rce->mvBits * pow(X265_MAX(rce->qScale, 1) / X265_MAX(qScale, 1), 0.5)
+ rce->miscBits;
}
inline void copyRceData(RateControlEntry* rce, RateControlEntry* rce2Pass)
{
rce->coeffBits = rce2Pass->coeffBits;
rce->mvBits = rce2Pass->mvBits;
rce->miscBits = rce2Pass->miscBits;
rce->iCuCount = rce2Pass->iCuCount;
rce->pCuCount = rce2Pass->pCuCount;
rce->skipCuCount = rce2Pass->skipCuCount;
rce->keptAsRef = rce2Pass->keptAsRef;
rce->qScale = rce2Pass->qScale;
rce->newQScale = rce2Pass->newQScale;
rce->expectedBits = rce2Pass->expectedBits;
rce->expectedVbv = rce2Pass->expectedVbv;
rce->blurredComplexity = rce2Pass->blurredComplexity;
rce->sliceType = rce2Pass->sliceType;
}
} // end anonymous namespace
/* Returns the zone for the current frame */
/** 函数功能 ： 获取当前帧所在的zone
/* 调用范围 ： 只在rateControlStart(只在CQP模式应用)、getDiffLimitedQScale和RateControl::getQScale函数中被调用
* \返回 ： 返回当前帧所在的zone * */
x265_zone* RateControl::getZone()
{
for (int i = m_param->rc.zoneCount - 1; i >= 0; i--)
{
x265_zone *z = &m_param->rc.zones[i];
if (m_framesDone + 1 >= z->startFrame && m_framesDone < z->endFrame)//如果当前帧在此范围内
return z;
}
return NULL;
}
RateControl::RateControl(x265_param& p)
{
m_param = &p; //获取当前配置参数
int lowresCuWidth = ((m_param->sourceWidth / 2) + X265_LOWRES_CU_SIZE - 1) >> X265_LOWRES_CU_BITS; //1/2下采样帧中一行有多少8x8块
int lowresCuHeight = ((m_param->sourceHeight / 2) + X265_LOWRES_CU_SIZE - 1) >> X265_LOWRES_CU_BITS;//1/2下采样帧中一列有多少8x8块
m_ncu = lowresCuWidth * lowresCuHeight;//1/2下采样帧中的8x8块个数
if (m_param->rc.cuTree) //如果应用cutree 设置强度系数为1 否则从配置参数中获取
m_qCompress = 1;
else
m_qCompress = m_param->rc.qCompress;//获取配置参数中的强度系数
// validate for param->rc, maybe it is need to add a function like x265_parameters_valiate()
m_residualFrames = 0;
m_partialResidualFrames = 0;
m_residualCost = 0;
m_partialResidualCost = 0;
m_rateFactorMaxIncrement = 0;
m_rateFactorMaxDecrement = 0;
m_fps = (double)m_param->fpsNum / m_param->fpsDenom;
m_startEndOrder.set(0); //初始化为0
m_bTerminated = false;
m_finalFrameCount = 0;
m_numEntries = 0;
m_isSceneTransition = false;
m_lastPredictorReset = 0;
if (m_param->rc.rateControlMode == X265_RC_CRF)
{
m_param->rc.qp = (int)m_param->rc.rfConstant;
m_param->rc.bitrate = 0;
double baseCplx = m_ncu * (m_param->bframes ? 120 : 80);//120*m_ncu
double mbtree_offset = m_param->rc.cuTree ? (1.0 - m_param->rc.qCompress) * 13.5 : 0;
m_rateFactorConstant = pow(baseCplx, 1 - m_qCompress) /
x265_qp2qScale(m_param->rc.rfConstant + mbtree_offset);//一般分辨率越大 此值越大 一般在0.0x之间
if (m_param->rc.rfConstantMax)//如果配置CRF 的最大量化值
{
m_rateFactorMaxIncrement = m_param->rc.rfConstantMax - m_param->rc.rfConstant;//求最大与配置之间的差值
if (m_rateFactorMaxIncrement <= 0)
{
x265_log(m_param, X265_LOG_WARNING, "CRF max must be greater than CRF\n");
m_rateFactorMaxIncrement = 0;
}
}
if (m_param->rc.rfConstantMin)//如果当前是CRF模式 并且 有配置最小crf值
m_rateFactorMaxDecrement = m_param->rc.rfConstant - m_param->rc.rfConstantMin;//求最小与配置之间的差值
}
m_isAbr = m_param->rc.rateControlMode != X265_RC_CQP && !m_param->rc.bStatRead;//是否应用ABR 当前不是CQP并且不是多pass 读的时候
m_2pass = m_param->rc.rateControlMode == X265_RC_ABR && m_param->rc.bStatRead;//判断当前是否是2pass
m_bitrate = m_param->rc.bitrate * 1000;//获取当前配置的目标码率
m_frameDuration = (double)m_param->fpsDenom / m_param->fpsNum; //当前播放一帧占用的时间（单位秒）
m_qp = m_param->rc.qp;//获取配置的固定QP
m_lastRceq = 1; /* handles the cmplxrsum when the previous frame cost is zero */
m_shortTermCplxSum = 0;
m_shortTermCplxCount = 0;
m_lastNonBPictType = I_SLICE;
m_isAbrReset = false;
m_lastAbrResetPoc = -1;
m_statFileOut = NULL;
m_cutreeStatFileOut = m_cutreeStatFileIn = NULL;
m_rce2Pass = NULL;
m_lastBsliceSatdCost = 0;
// vbv initialization
m_param->rc.vbvBufferSize = x265_clip3(0, 2000000, m_param->rc.vbvBufferSize);
m_param->rc.vbvMaxBitrate = x265_clip3(0, 2000000, m_param->rc.vbvMaxBitrate);
m_param->rc.vbvBufferInit = x265_clip3(0.0, 2000000.0, m_param->rc.vbvBufferInit);
m_singleFrameVbv = 0;
m_rateTolerance = 1.0;
if (m_param->rc.vbvBufferSize)
{
if (m_param->rc.rateControlMode == X265_RC_CQP)
{
x265_log(m_param, X265_LOG_WARNING, "VBV is incompatible with constant QP, ignored.\n");
m_param->rc.vbvBufferSize = 0;
m_param->rc.vbvMaxBitrate = 0;
}
else if (m_param->rc.vbvMaxBitrate == 0)
{
if (m_param->rc.rateControlMode == X265_RC_ABR)
{
x265_log(m_param, X265_LOG_WARNING, "VBV maxrate unspecified, assuming CBR\n");
m_param->rc.vbvMaxBitrate = m_param->rc.bitrate;
}
else
{
x265_log(m_param, X265_LOG_WARNING, "VBV bufsize set but maxrate unspecified, ignored\n");
m_param->rc.vbvBufferSize = 0;
}
}
else if (m_param->rc.vbvMaxBitrate < m_param->rc.bitrate &&
m_param->rc.rateControlMode == X265_RC_ABR)
{
x265_log(m_param, X265_LOG_WARNING, "max bitrate less than average bitrate, assuming CBR\n");
m_param->rc.bitrate = m_param->rc.vbvMaxBitrate;
}
}
else if (m_param->rc.vbvMaxBitrate)
{
x265_log(m_param, X265_LOG_WARNING, "VBV maxrate specified, but no bufsize, ignored\n");
m_param->rc.vbvMaxBitrate = 0;
}
m_isVbv = m_param->rc.vbvMaxBitrate > 0 && m_param->rc.vbvBufferSize > 0;//判断是否应用VBV
if (m_param->bEmitHRDSEI && !m_isVbv)
{
x265_log(m_param, X265_LOG_WARNING, "NAL HRD parameters require VBV parameters, ignored\n");
m_param->bEmitHRDSEI = 0;
}
m_isCbr = m_param->rc.rateControlMode == X265_RC_ABR && m_isVbv && !m_2pass && m_param->rc.vbvMaxBitrate <= m_param->rc.bitrate;//CBR模式 如果最大码率设定小于目标码率
if (m_param->rc.bStrictCbr && !m_isCbr)
{
x265_log(m_param, X265_LOG_WARNING, "strict CBR set without CBR mode, ignored\n");
m_param->rc.bStrictCbr = 0;
}
if(m_param->rc.bStrictCbr)//如果严格控制目标码率 降低因子
m_rateTolerance = 0.7;
m_bframeBits = 0;
m_leadingNoBSatd = 0;
m_ipOffset = 6.0 * X265_LOG2(m_param->rc.ipFactor);//用途：I帧与P帧的qp参数关系 P = Iqp + m_ipOffset 默认 2.9125608156077503
m_pbOffset = 6.0 * X265_LOG2(m_param->rc.pbFactor);//用途：P帧与B帧的qp参数关系 B = Pqp + m_pbOffset 默认 2.2710694220159415
/* Adjust the first frame in order to stabilize the quality level compared to the rest */
#define ABR_INIT_QP_MIN (24) //ABR默认的最小QP
#define ABR_INIT_QP_MAX (40)
#define ABR_SCENECUT_INIT_QP_MIN (12)//场景切换的最小QP 12
#define CRF_INIT_QP (int)m_param->rc.rfConstant //CRF模式下的默认QP
for (int i = 0; i < 3; i++)
m_lastQScaleFor[i] = x265_qp2qScale(m_param->rc.rateControlMode == X265_RC_CRF ? CRF_INIT_QP : ABR_INIT_QP_MIN);//初始化Qsclae
if (m_param->rc.rateControlMode == X265_RC_CQP)//固定QP模式
{
if (m_qp && !m_param->bLossless)//如果m_qp不为0 并且不是无损压缩模式
{
m_qpConstant[P_SLICE] = m_qp;//P帧获取QP
m_qpConstant[I_SLICE] = x265_clip3(QP_MIN, QP_MAX_MAX, (int)(m_qp - m_ipOffset + 0.5));//I帧获取QP
m_qpConstant[B_SLICE] = x265_clip3(QP_MIN, QP_MAX_MAX, (int)(m_qp + m_pbOffset + 0.5));//B帧获取QP
}
else
{
m_qpConstant[P_SLICE] = m_qpConstant[I_SLICE] = m_qpConstant[B_SLICE] = m_qp;//无损模式获取相同的QP值 4
}
}
/* qpstep - value set as encoder specific */
m_lstep = pow(2, m_param->rc.qpStep / 6.0);//初始化m_lstep
for (int i = 0; i < 2; i++)
m_cuTreeStats.qpBuffer[i] = NULL;
}
/** 函数功能 ： ？？？分析加权信息(每个list的第一帧分析加权与否，其它不加权)
/* 调用范围 ： 只在Encoder::create()和RateControl::checkAndResetABR函数中被调用
* \参数 rce ： ？？？当前编码帧
* \参数 isFrameDone ： 当前帧是否编码完毕 rateEstimateQscale为false rateControlEnd为true
* \返回 ： ？？null * */
bool RateControl::init(const SPS& sps)
{
if (m_isVbv)
{
/* We don't support changing the ABR bitrate right now,
* so if the stream starts as CBR, keep it CBR. */
if (m_param->rc.vbvBufferSize < (int)(m_param->rc.vbvMaxBitrate / m_fps))
{
m_param->rc.vbvBufferSize = (int)(m_param->rc.vbvMaxBitrate / m_fps);
x265_log(m_param, X265_LOG_WARNING, "VBV buffer size cannot be smaller than one frame, using %d kbit\n",
m_param->rc.vbvBufferSize);
}
int vbvBufferSize = m_param->rc.vbvBufferSize * 1000;
int vbvMaxBitrate = m_param->rc.vbvMaxBitrate * 1000;//一秒钟占用的最大bits
if (m_param->bEmitHRDSEI)
{
const HRDInfo* hrd = &sps.vuiParameters.hrdParameters;
vbvBufferSize = hrd->cpbSizeValue << (hrd->cpbSizeScale + CPB_SHIFT);
vbvMaxBitrate = hrd->bitRateValue << (hrd->bitRateScale + BR_SHIFT);
}
m_bufferRate = vbvMaxBitrate / m_fps;//平均每帧最大的bits占用数目
m_vbvMaxRate = vbvMaxBitrate;//一秒钟占用的最大bits
m_bufferSize = vbvBufferSize;//获取一秒的bits buffer大小
m_singleFrameVbv = m_bufferRate * 1.1 > m_bufferSize;//如果平均每帧最大的bits占用数目*1.1 大于一秒的bits buffer大小
if (m_param->rc.vbvBufferInit > 1.)
m_param->rc.vbvBufferInit = x265_clip3(0.0, 1.0, m_param->rc.vbvBufferInit / m_param->rc.vbvBufferSize);
m_param->rc.vbvBufferInit = x265_clip3(0.0, 1.0, X265_MAX(m_param->rc.vbvBufferInit, m_bufferRate / m_bufferSize));
m_bufferFillFinal = m_bufferSize * m_param->rc.vbvBufferInit;//？？？
}
m_totalBits = 0;
m_encodedBits = 0;
m_framesDone = 0;
m_residualCost = 0;
m_partialResidualCost = 0;
m_amortizeFraction = 0.85;
m_amortizeFrames = 75;
if (m_param->totalFrames && m_param->totalFrames <= 2 * m_fps && m_param->rc.bStrictCbr) /* Strict CBR segment encode *///编码帧数过少并且严格按照目标码率
{
m_amortizeFraction = 0.85;
m_amortizeFrames = m_param->totalFrames / 2;//重置为一半帧数
}
for (int i = 0; i < s_slidingWindowFrames; i++)
{
m_satdCostWindow[i] = 0;
m_encodedBitsWindow[i] = 0;
}
m_sliderPos = 0;
m_isPatternPresent = false;
m_numBframesInPattern = 0;
/* 720p videos seem to be a good cutoff for cplxrSum */
double tuneCplxFactor = (m_param->rc.cuTree && m_ncu > 3600) ? 2.5 : 1;//720p以上参数为2.5 以下为1.0
/* estimated ratio that produces a reasonable QP for the first I-frame */
m_cplxrSum = .01 * pow(7.0e5, m_qCompress) * pow(m_ncu, 0.5) * tuneCplxFactor;//初始化用于估计第一帧I帧的QP参数
m_wantedBitsWindow = m_bitrate * m_frameDuration;//初始化当前第一帧需要的bit数目
m_accumPNorm = .01;
m_accumPQp = (m_param->rc.rateControlMode == X265_RC_CRF ? CRF_INIT_QP : ABR_INIT_QP_MIN) * m_accumPNorm;//初始化为0.01*24
/* Frame Predictors used in vbv */
initFramePredictors();
if (!m_statFileOut && (m_param->rc.bStatWrite || m_param->rc.bStatRead))
{
/* If the user hasn't defined the stat filename, use the default value */
const char *fileName = m_param->rc.statFileName;
if (!fileName)
fileName = s_defaultStatFileName;
/* Load stat file and init 2pass algo */
if (m_param->rc.bStatRead)
{
m_expectedBitsSum = 0;
char *p, *statsIn, *statsBuf;
/* read 1st pass stats */
statsIn = statsBuf = x265_slurp_file(fileName);
if (!statsBuf)
return false;
if (m_param->rc.cuTree)
{
char *tmpFile = strcatFilename(fileName, ".cutree");
if (!tmpFile)
return false;
m_cutreeStatFileIn = fopen(tmpFile, "rb");
X265_FREE(tmpFile);
if (!m_cutreeStatFileIn)
{
x265_log(m_param, X265_LOG_ERROR, "can't open stats file %s\n", tmpFile);
return false;
}
}
/* check whether 1st pass options were compatible with current options */
if (strncmp(statsBuf, "#options:", 9))
{
x265_log(m_param, X265_LOG_ERROR,"options list in stats file not valid\n");
return false;
}
{
int i, j;
uint32_t k , l;
bool bErr = false;
char *opts = statsBuf;
statsIn = strchr(statsBuf, '\n');
if (!statsIn)
{
x265_log(m_param, X265_LOG_ERROR, "Malformed stats file\n");
return false;
}
*statsIn = '\0';
statsIn++;
if (sscanf(opts, "#options: %dx%d", &i, &j) != 2)
{
x265_log(m_param, X265_LOG_ERROR, "Resolution specified in stats file not valid\n");
return false;
}
if ((p = strstr(opts, " fps=")) == 0 || sscanf(p, " fps=%u/%u", &k, &l) != 2)
{
x265_log(m_param, X265_LOG_ERROR, "fps specified in stats file not valid\n");
return false;
}
if (k != m_param->fpsNum || l != m_param->fpsDenom)
{
x265_log(m_param, X265_LOG_ERROR, "fps mismatch with 1st pass (%u/%u vs %u/%u)\n",
m_param->fpsNum, m_param->fpsDenom, k, l);
return false;
}
CMP_OPT_FIRST_PASS("bitdepth", m_param->internalBitDepth);
CMP_OPT_FIRST_PASS("weightp", m_param->bEnableWeightedPred);
CMP_OPT_FIRST_PASS("bframes", m_param->bframes);
CMP_OPT_FIRST_PASS("b-pyramid", m_param->bBPyramid);
CMP_OPT_FIRST_PASS("open-gop", m_param->bOpenGOP);
CMP_OPT_FIRST_PASS("keyint", m_param->keyframeMax);
CMP_OPT_FIRST_PASS("scenecut", m_param->scenecutThreshold);
if ((p = strstr(opts, "b-adapt=")) != 0 && sscanf(p, "b-adapt=%d", &i) && i >= X265_B_ADAPT_NONE && i <= X265_B_ADAPT_TRELLIS)
{
m_param->bFrameAdaptive = i;
}
else if (m_param->bframes)
{
x265_log(m_param, X265_LOG_ERROR, "b-adapt method specified in stats file not valid\n");
return false;
}
if ((p = strstr(opts, "rc-lookahead=")) != 0 && sscanf(p, "rc-lookahead=%d", &i))
m_param->lookaheadDepth = i;
}
/* find number of pics */
p = statsIn;
int numEntries;
for (numEntries = -1; p; numEntries++)
p = strchr(p + 1, ';');
if (!numEntries)
{
x265_log(m_param, X265_LOG_ERROR, "empty stats file\n");
return false;
}
m_numEntries = numEntries;
if (m_param->totalFrames < m_numEntries && m_param->totalFrames > 0)
{
x265_log(m_param, X265_LOG_WARNING, "2nd pass has fewer frames than 1st pass (%d vs %d)\n",
m_param->totalFrames, m_numEntries);
}
if (m_param->totalFrames > m_numEntries)
{
x265_log(m_param, X265_LOG_ERROR, "2nd pass has more frames than 1st pass (%d vs %d)\n",
m_param->totalFrames, m_numEntries);
return false;
}
m_rce2Pass = X265_MALLOC(RateControlEntry, m_numEntries);
if (!m_rce2Pass)
{
x265_log(m_param, X265_LOG_ERROR, "Rce Entries for 2 pass cannot be allocated\n");
return false;
}
/* init all to skipped p frames */
for (int i = 0; i < m_numEntries; i++)
{
RateControlEntry *rce = &m_rce2Pass[i];
rce->sliceType = P_SLICE;
rce->qScale = rce->newQScale = x265_qp2qScale(20);
rce->miscBits = m_ncu + 10;
rce->newQp = 0;
}
/* read stats */
p = statsIn;
double totalQpAq = 0;
for (int i = 0; i < m_numEntries; i++)
{
RateControlEntry *rce;
int frameNumber;
char picType;
int e;
char *next;
double qpRc, qpAq;
next = strstr(p, ";");
if (next)
*next++ = 0;
e = sscanf(p, " in:%d ", &frameNumber);
if (frameNumber < 0 || frameNumber >= m_numEntries)
{
x265_log(m_param, X265_LOG_ERROR, "bad frame number (%d) at stats line %d\n", frameNumber, i);
return false;
}
rce = &m_rce2Pass[frameNumber];
e += sscanf(p, " in:%*d out:%*d type:%c q:%lf q-aq:%lf tex:%d mv:%d misc:%d icu:%lf pcu:%lf scu:%lf",
&picType, &qpRc, &qpAq, &rce->coeffBits,
&rce->mvBits, &rce->miscBits, &rce->iCuCount, &rce->pCuCount,
&rce->skipCuCount);
rce->keptAsRef = true;
if (picType == 'b' || picType == 'p')
rce->keptAsRef = false;
if (picType == 'I' || picType == 'i')
rce->sliceType = I_SLICE;
else if (picType == 'P' || picType == 'p')
rce->sliceType = P_SLICE;
else if (picType == 'B' || picType == 'b')
rce->sliceType = B_SLICE;
else
e = -1;
if (e < 10)
{
x265_log(m_param, X265_LOG_ERROR, "statistics are damaged at line %d, parser out=%d\n", i, e);
return false;
}
rce->qScale = x265_qp2qScale(qpRc);
totalQpAq += qpAq;
p = next;
}
X265_FREE(statsBuf);
if (m_param->rc.rateControlMode == X265_RC_ABR)
{
if (!initPass2())
return false;
} /* else we're using constant quant, so no need to run the bitrate allocation */
}
/* Open output file */
/* If input and output files are the same, output to a temp file
* and move it to the real name only when it's complete */
if (m_param->rc.bStatWrite)
{
char *p, *statFileTmpname;
statFileTmpname = strcatFilename(fileName, ".temp");
if (!statFileTmpname)
return false;
m_statFileOut = fopen(statFileTmpname, "wb");
X265_FREE(statFileTmpname);
if (!m_statFileOut)
{
x265_log(m_param, X265_LOG_ERROR, "can't open stats file %s\n", statFileTmpname);
return false;
}
p = x265_param2string(m_param);
if (p)
fprintf(m_statFileOut, "#options: %s\n", p);
X265_FREE(p);
if (m_param->rc.cuTree && !m_param->rc.bStatRead)
{
statFileTmpname = strcatFilename(fileName, ".cutree.temp");
if (!statFileTmpname)
return false;
m_cutreeStatFileOut = fopen(statFileTmpname, "wb");
X265_FREE(statFileTmpname);
if (!m_cutreeStatFileOut)
{
x265_log(m_param, X265_LOG_ERROR, "can't open mbtree stats file %s\n", statFileTmpname);
return false;
}
}
}
if (m_param->rc.cuTree)
{
m_cuTreeStats.qpBuffer[0] = X265_MALLOC(uint16_t, m_ncu * sizeof(uint16_t));
if (m_param->bBPyramid && m_param->rc.bStatRead)
m_cuTreeStats.qpBuffer[1] = X265_MALLOC(uint16_t, m_ncu * sizeof(uint16_t));
m_cuTreeStats.qpBufPos = -1;
}
}
return true;
}
void RateControl::initHRD(SPS& sps)
{
int vbvBufferSize = m_param->rc.vbvBufferSize * 1000;
int vbvMaxBitrate = m_param->rc.vbvMaxBitrate * 1000;
// Init HRD
HRDInfo* hrd = &sps.vuiParameters.hrdParameters;
hrd->cbrFlag = m_isCbr;
// normalize HRD size and rate to the value / scale notation
hrd->bitRateScale = x265_clip3(0, 15, calcScale(vbvMaxBitrate) - BR_SHIFT);
hrd->bitRateValue = (vbvMaxBitrate >> (hrd->bitRateScale + BR_SHIFT));
hrd->cpbSizeScale = x265_clip3(0, 15, calcScale(vbvBufferSize) - CPB_SHIFT);
hrd->cpbSizeValue = (vbvBufferSize >> (hrd->cpbSizeScale + CPB_SHIFT));
int bitRateUnscale = hrd->bitRateValue << (hrd->bitRateScale + BR_SHIFT);
int cpbSizeUnscale = hrd->cpbSizeValue << (hrd->cpbSizeScale + CPB_SHIFT);
// arbitrary
#define MAX_DURATION 0.5
TimingInfo *time = &sps.vuiParameters.timingInfo;
int maxCpbOutputDelay = (int)(X265_MIN(m_param->keyframeMax * MAX_DURATION * time->timeScale / time->numUnitsInTick, INT_MAX));
int maxDpbOutputDelay = (int)(sps.maxDecPicBuffering * MAX_DURATION * time->timeScale / time->numUnitsInTick);
int maxDelay = (int)(90000.0 * cpbSizeUnscale / bitRateUnscale + 0.5);
hrd->initialCpbRemovalDelayLength = 2 + x265_clip3(4, 22, 32 - calcLength(maxDelay));
hrd->cpbRemovalDelayLength = x265_clip3(4, 31, 32 - calcLength(maxCpbOutputDelay));
hrd->dpbOutputDelayLength = x265_clip3(4, 31, 32 - calcLength(maxDpbOutputDelay));
#undef MAX_DURATION
}
bool RateControl::initPass2()
{
uint64_t allConstBits = 0;
uint64_t allAvailableBits = uint64_t(m_param->rc.bitrate * 1000. * m_numEntries * m_frameDuration);
double rateFactor, stepMult;
double qBlur = m_param->rc.qblur;
double cplxBlur = m_param->rc.complexityBlur;
const int filterSize = (int)(qBlur * 4) | 1;
double expectedBits;
double *qScale, *blurredQscale;
double baseCplx = m_ncu * (m_param->bframes ? 120 : 80);
double clippedDuration = CLIP_DURATION(m_frameDuration) / BASE_FRAME_DURATION;
/* find total/average complexity & const_bits */
for (int i = 0; i < m_numEntries; i++)
allConstBits += m_rce2Pass[i].miscBits;
if (allAvailableBits < allConstBits)
{
x265_log(m_param, X265_LOG_ERROR, "requested bitrate is too low. estimated minimum is %d kbps\n",
(int)(allConstBits * m_fps / m_numEntries * 1000.));
return false;
}
/* Blur complexities, to reduce local fluctuation of QP.
* We don't blur the QPs directly, because then one very simple frame
* could drag down the QP of a nearby complex frame and give it more
* bits than intended. */
for (int i = 0; i < m_numEntries; i++)
{
double weightSum = 0;
double cplxSum = 0;
double weight = 1.0;
double gaussianWeight;
/* weighted average of cplx of future frames */
for (int j = 1; j < cplxBlur * 2 && j < m_numEntries - i; j++)
{
RateControlEntry *rcj = &m_rce2Pass[i + j];
weight *= 1 - pow(rcj->iCuCount / m_ncu, 2);
if (weight < 0.0001)
break;
gaussianWeight = weight * exp(-j * j / 200.0);
weightSum += gaussianWeight;
cplxSum += gaussianWeight * (qScale2bits(rcj, 1) - rcj->miscBits) / clippedDuration;
}
/* weighted average of cplx of past frames */
weight = 1.0;
for (int j = 0; j <= cplxBlur * 2 && j <= i; j++)
{
RateControlEntry *rcj = &m_rce2Pass[i - j];
gaussianWeight = weight * exp(-j * j / 200.0);
weightSum += gaussianWeight;
cplxSum += gaussianWeight * (qScale2bits(rcj, 1) - rcj->miscBits) / clippedDuration;
weight *= 1 - pow(rcj->iCuCount / m_ncu, 2);
if (weight < .0001)
break;
}
m_rce2Pass[i].blurredComplexity = cplxSum / weightSum;
}
CHECKED_MALLOC(qScale, double, m_numEntries);
if (filterSize > 1)
{
CHECKED_MALLOC(blurredQscale, double, m_numEntries);
}
else
blurredQscale = qScale;
/* Search for a factor which, when multiplied by the RCEQ values from
* each frame, adds up to the desired total size.
* There is no exact closed-form solution because of VBV constraints and
* because qscale2bits is not invertible, but we can start with the simple
* approximation of scaling the 1st pass by the ratio of bitrates.
* The search range is probably overkill, but speed doesn't matter here. */
expectedBits = 1;
for (int i = 0; i < m_numEntries; i++)
{
RateControlEntry* rce = &m_rce2Pass[i];
double q = getQScale(rce, 1.0);
expectedBits += qScale2bits(rce, q);
m_lastQScaleFor[rce->sliceType] = q;
}
stepMult = allAvailableBits / expectedBits;
rateFactor = 0;
for (double step = 1E4 * stepMult; step > 1E-7 * stepMult; step *= 0.5)
{
expectedBits = 0;
rateFactor += step;
m_lastNonBPictType = -1;
m_lastAccumPNorm = 1;
m_accumPNorm = 0;
m_lastQScaleFor[0] = m_lastQScaleFor[1] =
m_lastQScaleFor[2] = pow(baseCplx, 1 - m_qCompress) / rateFactor;
/* find qscale */
for (int i = 0; i < m_numEntries; i++)
{
RateControlEntry *rce = &m_rce2Pass[i];
qScale[i] = getQScale(rce, rateFactor);
m_lastQScaleFor[rce->sliceType] = qScale[i];
}
/* fixed I/B qscale relative to P */
for (int i = m_numEntries - 1; i >= 0; i--)
{
qScale[i] = getDiffLimitedQScale(&m_rce2Pass[i], qScale[i]);
X265_CHECK(qScale[i] >= 0, "qScale became negative\n");
}
/* smooth curve */
if (filterSize > 1)
{
X265_CHECK(filterSize % 2 == 1, "filterSize not an odd number\n");
for (int i = 0; i < m_numEntries; i++)
{
double q = 0.0, sum = 0.0;
for (int j = 0; j < filterSize; j++)
{
int idx = i + j - filterSize / 2;
double d = idx - i;
double coeff = qBlur == 0 ? 1.0 : exp(-d * d / (qBlur * qBlur));
if (idx < 0 || idx >= m_numEntries)
continue;
if (m_rce2Pass[i].sliceType != m_rce2Pass[idx].sliceType)
continue;
q += qScale[idx] * coeff;
sum += coeff;
}
blurredQscale[i] = q / sum;
}
}
/* find expected bits */
for (int i = 0; i < m_numEntries; i++)
{
RateControlEntry *rce = &m_rce2Pass[i];
rce->newQScale = clipQscale(NULL, rce, blurredQscale[i]); // check if needed
X265_CHECK(rce->newQScale >= 0, "new Qscale is negative\n");
expectedBits += qScale2bits(rce, rce->newQScale);
}
if (expectedBits > allAvailableBits)
rateFactor -= step;
}
X265_FREE(qScale);
if (filterSize > 1)
X265_FREE(blurredQscale);
if (m_isVbv)
if (!vbv2Pass(allAvailableBits))
return false;
expectedBits = countExpectedBits();
if (fabs(expectedBits / allAvailableBits - 1.0) > 0.01)
{
double avgq = 0;
for (int i = 0; i < m_numEntries; i++)
avgq += m_rce2Pass[i].newQScale;
avgq = x265_qScale2qp(avgq / m_numEntries);
if (expectedBits > allAvailableBits || !m_isVbv)
x265_log(m_param, X265_LOG_WARNING, "Error: 2pass curve failed to converge\n");
x265_log(m_param, X265_LOG_WARNING, "target: %.2f kbit/s, expected: %.2f kbit/s, avg QP: %.4f\n",
(double)m_param->rc.bitrate,
expectedBits * m_fps / (m_numEntries * 1000.),
avgq);
if (expectedBits < allAvailableBits && avgq < QP_MIN + 2)
{
x265_log(m_param, X265_LOG_WARNING, "try reducing target bitrate\n");
}
else if (expectedBits > allAvailableBits && avgq > QP_MAX_SPEC - 2)
{
x265_log(m_param, X265_LOG_WARNING, "try increasing target bitrate\n");
}
else if (!(m_2pass && m_isVbv))
x265_log(m_param, X265_LOG_WARNING, "internal error\n");
}
return true;
fail:
x265_log(m_param, X265_LOG_WARNING, "two-pass ABR initialization failed\n");
return false;
}
bool RateControl::vbv2Pass(uint64_t allAvailableBits)
{
/* for each interval of bufferFull .. underflow, uniformly increase the qp of all
* frames in the interval until either buffer is full at some intermediate frame or the
* last frame in the interval no longer underflows. Recompute intervals and repeat.
* Then do the converse to put bits back into overflow areas until target size is met */
double *fills;
double expectedBits = 0;
double adjustment;
double prevBits = 0;
int t0, t1;
int iterations = 0 , adjMin, adjMax;
CHECKED_MALLOC(fills, double, m_numEntries + 1);
fills++;
/* adjust overall stream size */
do
{
iterations++;
prevBits = expectedBits;
if (expectedBits)
{ /* not first iteration */
adjustment = X265_MAX(X265_MIN(expectedBits / allAvailableBits, 0.999), 0.9);
fills[-1] = m_bufferSize * m_param->rc.vbvBufferInit;
t0 = 0;
/* fix overflows */
adjMin = 1;
while (adjMin && findUnderflow(fills, &t0, &t1, 1))
{
adjMin = fixUnderflow(t0, t1, adjustment, MIN_QPSCALE, MAX_MAX_QPSCALE);
t0 = t1;
}
}
fills[-1] = m_bufferSize * (1. - m_param->rc.vbvBufferInit);
t0 = 0;
/* fix underflows -- should be done after overflow, as we'd better undersize target than underflowing VBV */
adjMax = 1;
while (adjMax && findUnderflow(fills, &t0, &t1, 0))
adjMax = fixUnderflow(t0, t1, 1.001, MIN_QPSCALE, MAX_MAX_QPSCALE );
expectedBits = countExpectedBits();
}
while ((expectedBits < .995 * allAvailableBits) && ((int64_t)(expectedBits+.5) > (int64_t)(prevBits+.5)));
if (!adjMax)
x265_log(m_param, X265_LOG_WARNING, "vbv-maxrate issue, qpmax or vbv-maxrate too low\n");
/* store expected vbv filling values for tracking when encoding */
for (int i = 0; i < m_numEntries; i++)
m_rce2Pass[i].expectedVbv = m_bufferSize - fills[i];
X265_FREE(fills - 1);
return true;
fail:
x265_log(m_param, X265_LOG_ERROR, "malloc failure in two-pass VBV init\n");
return false;
}
/* In 2pass, force the same frame types as in the 1st pass */
int RateControl::rateControlSliceType(int frameNum)
{
if (m_param->rc.bStatRead)
{
if (frameNum >= m_numEntries)
{
/* We could try to initialize everything required for ABR and
* adaptive B-frames, but that would be complicated.
* So just calculate the average QP used so far. */
m_param->rc.qp = (m_accumPQp < 1) ? ABR_INIT_QP_MAX : (int)(m_accumPQp + 0.5);
m_qpConstant[P_SLICE] = x265_clip3(QP_MIN, QP_MAX_MAX, m_param->rc.qp);
m_qpConstant[I_SLICE] = x265_clip3(QP_MIN, QP_MAX_MAX, (int)(m_param->rc.qp - m_ipOffset + 0.5));
m_qpConstant[B_SLICE] = x265_clip3(QP_MIN, QP_MAX_MAX, (int)(m_param->rc.qp + m_pbOffset + 0.5));
x265_log(m_param, X265_LOG_ERROR, "2nd pass has more frames than 1st pass (%d)\n", m_numEntries);
x265_log(m_param, X265_LOG_ERROR, "continuing anyway, at constant QP=%d\n", m_param->rc.qp);
if (m_param->bFrameAdaptive)
x265_log(m_param, X265_LOG_ERROR, "disabling adaptive B-frames\n");
m_isAbr = 0;
m_2pass = 0;
m_param->rc.rateControlMode = X265_RC_CQP;
m_param->rc.bStatRead = 0;
m_param->bFrameAdaptive = 0;
m_param->scenecutThreshold = 0;
m_param->rc.cuTree = 0;
if (m_param->bframes > 1)
m_param->bframes = 1;
return X265_TYPE_AUTO;
}
int frameType = m_rce2Pass[frameNum].sliceType == I_SLICE ? (frameNum > 0 && m_param->bOpenGOP ? X265_TYPE_I : X265_TYPE_IDR)
: m_rce2Pass[frameNum].sliceType == P_SLICE ? X265_TYPE_P
: (m_rce2Pass[frameNum].sliceType == B_SLICE && m_rce2Pass[frameNum].keptAsRef? X265_TYPE_BREF : X265_TYPE_B);
return frameType;
}
else
return X265_TYPE_AUTO;
}
/** 函数功能 ： 初始化Predictor
/* 调用范围 ： 只在RateControl::init和RateControl::rateControlStart函数中被调用
* \返回 ： null * */
void RateControl::initFramePredictors()
{
//在初始化和场景切换帧处重置
/* Frame Predictors used in vbv */
for (int i = 0; i < 4; i++)
{
m_pred[i].coeff = 1.0;
m_pred[i].count = 1.0;
m_pred[i].decay = 0.5;
m_pred[i].offset = 0.0;
}
m_pred[0].coeff = m_pred[3].coeff = 0.75;
if (m_param->rc.qCompress >= 0.8) // when tuned for grain
{
m_pred[1].coeff = 0.75;
m_pred[0].coeff = m_pred[3].coeff = 0.50;
}
}
/** 函数功能 ： 计算估计当前帧应用的量化参数
/* 调用范围 ： 只在FrameEncoder::compressFrame()函数中被调用
* \参数 curFrame ： 当前编码帧
* \参数 rce ： 当前帧的RC编码参数类
* \参数 enc ： 上层encodr类
* \返回 ： 返回当前帧估计的量化参数 * */
int RateControl::rateControlStart(Frame* curFrame, RateControlEntry* rce, Encoder* enc)
{
//功能：
// 1.循环等待触发
// 2.初始化RC帧类型等基本信息
// 3.如果是2pass：？？？
// 4.根据场景切换帧信息选择是否初始化Predictor
// 5.如果应用VBV：更新bitsbuffer 根据当前level规定设置当前帧最大占用的bits
// 6.如果应用ABR,CRF或者当前为2pass：估计当前帧的m_qp值
// 否则 如果是CQP模式 获取当前帧的QP值 （加上相应的offset）
// 7.更新数据 并返回当前帧估计的量化参数
int orderValue = m_startEndOrder.get();//获取当前RC线程控制参量
int startOrdinal = rce->encodeOrder * 2;//触发参量值
while (orderValue < startOrdinal && !m_bTerminated)//循环等待
orderValue = m_startEndOrder.waitForChange(orderValue);//等待参量数据改变
if (!curFrame) //无帧信息情况 一般不进入
{
// faked rateControlStart calls when the encoder is flushing
m_startEndOrder.incr();
return 0;
}
FrameData& curEncData = *curFrame->m_encData;//获取当前帧的编码信息
m_curSlice = curEncData.m_slice;//获取当前帧的slice
m_sliceType = m_curSlice->m_sliceType;//获取当前的slice类型
rce->sliceType = m_sliceType;//获取当前的slice类型
if (!m_2pass)//如果是1pass
rce->keptAsRef = IS_REFERENCED(curFrame);//判断当前是否可作参考帧
m_predType = getPredictorType(curFrame->m_lowres.sliceType, m_sliceType);//获取predictor应用的标号 0：不可参考b帧 1： P帧 2：I帧 3：可参考B帧
rce->poc = m_curSlice->m_poc;//获取当前poc
if (m_param->rc.bStatRead)//？？？？
{
X265_CHECK(rce->poc >= 0 && rce->poc < m_numEntries, "bad encode ordinal\n");
copyRceData(rce, &m_rce2Pass[rce->poc]);
}
rce->isActive = true;//RC启动
bool isRefFrameScenecut = m_sliceType!= I_SLICE && m_curSlice->m_refPicList[0][0]->m_lowres.bScenecut == 1; //如果其前向第一个参考帧为场景切换帧
//设x为场景切换帧
//IBBBPBBBxBBBPBBBP 对应m_isSceneTransition值
//00000000111111110
if (curFrame->m_lowres.bScenecut) //如果当前帧为场景切换帧
{
m_isSceneTransition = true;//场景切换帧置为ture
m_lastPredictorReset = rce->encodeOrder;//记录Predictor重置的编码位置（编码顺序） rce->encodeOrder
initFramePredictors();//初始化Predictor
}
else if (m_sliceType != B_SLICE && !isRefFrameScenecut)//当前是P帧或者不是场景切换帧的I帧 并且 前向参考不是场景切换帧
m_isSceneTransition = false;//置为false
if (rce->encodeOrder < m_lastPredictorReset + m_param->frameNumThreads)//如果遇到场景切换帧 或者首帧 将当前的的count置为0 有几个framethread 进入初始化几次
{
rce->rowPreds[0][0].count = 0;
}
rce->bLastMiniGopBFrame = curFrame->m_lowres.bLastMiniGopBFrame;//标记当前帧是否为当前GOP的最后一个B帧
rce->bufferRate = m_bufferRate;//平均每帧最大的bits占用数目
rce->rowCplxrSum = 0.0;//初始化
rce->rowTotalBits = 0;//初始化
//功能：更新bitsbuffer 根据当前level规定设置当前帧最大占用的bits
// 1.根据情况初始化Predictor （场景切换帧后）
// 2.更新bitsbuffer
// 3.根据当前level下最小压缩比设置当前帧相应的frameSizeMaximum（当前帧占用的最大bits）
if (m_isVbv)//如果应用VBV
{
//初始化Predictor
if (rce->rowPreds[0][0].count == 0)
{
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 2; j++)
{
rce->rowPreds[i][j].coeff = 0.25;
rce->rowPreds[i][j].count = 1.0;
rce->rowPreds[i][j].decay = 0.5;
rce->rowPreds[i][j].offset = 0.0;
}
}
}
rce->rowPred[0] = &rce->rowPreds[m_sliceType][0];//指向当前帧类型位置 便于计算
rce->rowPred[1] = &rce->rowPreds[m_sliceType][1];//指向当前帧类型位置 便于计算
m_predictedBits = m_totalBits;//获取当前已经编码帧总的bits
updateVbvPlan(enc);//VBV中更新根据当前帧并行情况更新当前RCbuffer
rce->bufferFill = m_bufferFill;//获取更新后的值
int mincr = enc->m_vps.ptl.minCrForLevel;//当前的最小压缩比 CR 表示 CompressionRatio
//根据当前level下最小压缩比设置当前帧相应的frameSizeMaximum（当前帧占用的最大bits）
/* Profiles above Main10 don't require maxAU size check, so just set the maximum to a large value. */
if (enc->m_vps.ptl.profileIdc > Profile::MAIN10 || enc->m_vps.ptl.levelIdc == Level::NONE)//如果是MAINSTILLPICTURE、MAINREXT档次或者没有等级定位
rce->frameSizeMaximum = 1e9; //设为一个大值
else
{
/* The spec has a special case for the first frame. */
if (rce->encodeOrder == 0)//第一帧
{
/* 1.5 * (Max( PicSizeInSamplesY, fR * MaxLumaSr) + MaxLumaSr * (AuCpbRemovalTime[ 0 ] -AuNominalRemovalTime[ 0 ])) ? MinCr */
double fr = 1. / 300;//压缩因子 用于估计bits
int picSizeInSamplesY = m_param->sourceWidth * m_param->sourceHeight;//当前帧的像素个数
rce->frameSizeMaximum = 8 * 1.5 * X265_MAX(picSizeInSamplesY, fr * enc->m_vps.ptl.maxLumaSrForLevel) / mincr;//8表示一般一个像素占用8比特 1.5表示 4:2:0 格式 1.5帧（含有两个色度）
}
else
{
/* 1.5 * MaxLumaSr * (AuCpbRemovalTime[ n ] - AuCpbRemovalTime[ n - 1 ]) / MinCr */
rce->frameSizeMaximum = 8 * 1.5 * enc->m_vps.ptl.maxLumaSrForLevel * m_frameDuration / mincr;//当前level下当前帧占用的最大bits
}
}
}
//功能：估计当前帧的m_qp值
// 1.如果应用ABR或者VBV 获取framecost 记录连续b帧cost相同数目，并在后一个非B帧中设置为同一模式(个数大于配置的B帧个数时)
// 2.预估当前帧的m_qp
if (m_isAbr || m_2pass) // ABR,CRF
{
if (m_isAbr || m_isVbv)
{
m_currentSatd = curFrame->m_lowres.satdCost >> (X265_DEPTH - 8); //获取当前的framecost 如果需要参考帧，取参考帧列表中各自第一帧当做参考帧的framecost
/* Update rce for use in rate control VBV later */
rce->lastSatd = m_currentSatd;//更新当前最新的SATD值
X265_CHECK(rce->lastSatd, "satdcost cannot be zero\n");
/* Detect a pattern for B frames with same SATDcost to identify a series of static frames
* and the P frame at the end of the series marks a possible case for ABR reset logic */
if (m_param->bframes) //如果有B帧 功能：记录连续b帧cost相同数目，并在后一个非B帧中设置为同一模式(个数大于配置的B帧个数时)
{
if (m_sliceType != B_SLICE && m_numBframesInPattern > m_param->bframes)//如果当前是（I帧或者P帧） 并且相同cost的个数大于配置的B帧个数
{
m_isPatternPresent = true;//置为同一模式
}
else if (m_sliceType == B_SLICE && !IS_REFERENCED(curFrame))//如果当前是B帧并且不是B参考帧
{
if (m_currentSatd != m_lastBsliceSatdCost && !rce->bLastMiniGopBFrame)//如果当前B帧的cost不等于上一个B帧（编码顺序）的cost 并且不是当前帧是否为当前GOP的最后一个B帧
{
m_isPatternPresent = false;//开始一个新的模式 置为false
m_lastBsliceSatdCost = m_currentSatd;//记录最新B帧的framecost
m_numBframesInPattern = 0;//相同cost的个数置为0
}
else if (m_currentSatd == m_lastBsliceSatdCost)//如果当期B帧cost等于最近一个B帧的cost
m_numBframesInPattern++;//累加相同cost的个数
}
}
}
/* For a scenecut that occurs within the mini-gop, enable scene transition
* switch until the next mini-gop to ensure a min qp for all the frames within
* the scene-transition mini-gop */
double q = x265_qScale2qp(rateEstimateQscale(curFrame, rce));//预估当前帧的qscale并将预估qscale转换成qp参数 ？？？
q = x265_clip3((double)QP_MIN, (double)QP_MAX_MAX, q);//clip操作防止越界
m_qp = int(q + 0.5);//四舍五入转换成整数qp参数
rce->qpaRc = curEncData.m_avgQpRc = curEncData.m_avgQpAq = q;//获取预估qp参数值（未四舍五入）
/* copy value of lastRceq into thread local rce struct *to be used in RateControlEnd() */
rce->qRceq = m_lastRceq;//获取数据对应未加权的qscale
accumPQpUpdate();//累加m_accumPQp*0.95+m_qp和m_accumPNorm*0.95+1
}
else // CQP 固定QP模式
{
if (m_sliceType == B_SLICE && IS_REFERENCED(curFrame))//如果是B参考帧
m_qp = (m_qpConstant[B_SLICE] + m_qpConstant[P_SLICE]) / 2; //QP取B帧和P帧的一半
else
m_qp = m_qpConstant[m_sliceType];//获取相应帧对应的QP
curEncData.m_avgQpAq = curEncData.m_avgQpRc = m_qp;//获取当前帧的QP值
x265_zone* zone = getZone();//获取当前帧所在的zone
if (zone)
{
if (zone->bForceQp)//如果是QP模式
m_qp += zone->qp - m_qpConstant[P_SLICE];
else
m_qp -= (int)(6.0 * X265_LOG2(zone->bitrateFactor));//因子模式
}
}
if (m_sliceType != B_SLICE)//当前不是B帧
{
m_lastNonBPictType = m_sliceType;//更新最新的非B帧类型
m_leadingNoBSatd = m_currentSatd;//更新最新的非B帧的SATD值
}
rce->leadingNoBSatd = m_leadingNoBSatd;//暂无任何作用 获取当前RC的最新非B帧的SATD值
if (curFrame->m_forceqp)//如果应用QPfile
{
m_qp = (int32_t)(curFrame->m_forceqp + 0.5) - 1;//获取当前QP值
m_qp = x265_clip3(QP_MIN, QP_MAX_MAX, m_qp);//防止越界
rce->qpaRc = curEncData.m_avgQpRc = curEncData.m_avgQpAq = m_qp;//获取当前最新QP
if (m_isAbr || m_2pass)//如果应用ABR或者当前为2pass
{
rce->qpNoVbv = rce->qpaRc;//获取没有经过修正的量化参数
m_lastQScaleFor[m_sliceType] = x265_qp2qScale(rce->qpaRc);//qp转换为qpscale 存储最新的qscale值
if (rce->poc == 0)
m_lastQScaleFor[P_SLICE] = m_lastQScaleFor[m_sliceType] * fabs(m_param->rc.ipFactor);//第一帧加权
rce->frameSizePlanned = predictSize(&m_pred[m_predType], m_qp, (double)m_currentSatd);//获取预测的bits
}
}
m_framesDone++;//计数
return m_qp;//返回当前帧估计的量化参数
}
/** 函数功能 ： 累加m_accumPQp*0.95+m_qp和m_accumPNorm*0.95+1
/* 调用范围 ： 只在rateControlStart函数中被调用
* \返回 ： null * */
void RateControl::accumPQpUpdate()
{
m_accumPQp *= .95;
m_accumPNorm *= .95;
m_accumPNorm += 1;
if (m_sliceType == I_SLICE)
m_accumPQp += m_qp + m_ipOffset;
else
m_accumPQp += m_qp;
}
/** 函数功能 ： 获取predictor应用的标号 0：不可参考b帧 1： P帧 2：I帧 3：可参考B帧
/* 调用范围 ： 只在rateControlStart和RateControl::clipQscale函数中被调用
* \参数 lowresSliceType ： 在rateControlStart中：当前帧的帧类型(如X265_TYPE_IDR等) 在RateControl::clipQscale中：？？？
* \参数 sliceType ： 在rateControlStart中：当前帧的slice类型(如B_SLICE,P_SLICE,I_SLICE等)在RateControl::clipQscale中：？？？
* \返回 ： 返回predictor应用的标号 0：不可参考b帧 1： P帧 2：I帧 3：可参考B帧* */
int RateControl::getPredictorType(int lowresSliceType, int sliceType)
{
/* Use a different predictor for B Ref and B frames for vbv frame size predictions */
if (lowresSliceType == X265_TYPE_BREF)
return 3;
return sliceType;
}
double RateControl::getDiffLimitedQScale(RateControlEntry *rce, double q)
{
// force I/B quants as a function of P quants
const double lastPqScale = m_lastQScaleFor[P_SLICE];
const double lastNonBqScale = m_lastQScaleFor[m_lastNonBPictType];
if (rce->sliceType == I_SLICE)
{
double iq = q;
double pq = x265_qp2qScale(m_accumPQp / m_accumPNorm);
double ipFactor = fabs(m_param->rc.ipFactor);
/* don't apply ipFactor if the following frame is also I */
if (m_accumPNorm <= 0)
q = iq;
else if (m_param->rc.ipFactor < 0)
q = iq / ipFactor;
else if (m_accumPNorm >= 1)
q = pq / ipFactor;
else
q = m_accumPNorm * pq / ipFactor + (1 - m_accumPNorm) * iq;
}
else if (rce->sliceType == B_SLICE)
{
if (m_param->rc.pbFactor > 0)
q = lastNonBqScale;
if (!rce->keptAsRef)
q *= fabs(m_param->rc.pbFactor);
}
else if (rce->sliceType == P_SLICE
&& m_lastNonBPictType == P_SLICE
&& rce->coeffBits == 0)
{
q = lastPqScale;
}
/* last qscale / qdiff stuff */
if (m_lastNonBPictType == rce->sliceType &&
(rce->sliceType != I_SLICE || m_lastAccumPNorm < 1))
{
double maxQscale = m_lastQScaleFor[rce->sliceType] * m_lstep;
double minQscale = m_lastQScaleFor[rce->sliceType] / m_lstep;
q = x265_clip3(minQscale, maxQscale, q);
}
m_lastQScaleFor[rce->sliceType] = q;
if (rce->sliceType != B_SLICE)
m_lastNonBPictType = rce->sliceType;
if (rce->sliceType == I_SLICE)
{
m_lastAccumPNorm = m_accumPNorm;
m_accumPNorm = 0;
m_accumPQp = 0;
}
if (rce->sliceType == P_SLICE)
{
double mask = 1 - pow(rce->iCuCount / m_ncu, 2);
m_accumPQp = mask * (x265_qScale2qp(q) + m_accumPQp);
m_accumPNorm = mask * (1 + m_accumPNorm);
}
x265_zone* zone = getZone();
if (zone)
{
if (zone->bForceQp)
q = x265_qp2qScale(zone->qp);
else
q /= zone->bitrateFactor;
}
return q;
}
double RateControl::countExpectedBits()
{
double expectedBits = 0;
for( int i = 0; i < m_numEntries; i++ )
{
RateControlEntry *rce = &m_rce2Pass[i];
rce->expectedBits = (uint64_t)expectedBits;
expectedBits += qScale2bits(rce, rce->newQScale);
}
return expectedBits;
}
bool RateControl::findUnderflow(double *fills, int *t0, int *t1, int over)
{
/* find an interval ending on an overflow or underflow (depending on whether
* we're adding or removing bits), and starting on the earliest frame that
* can influence the buffer fill of that end frame. */
const double bufferMin = .1 * m_bufferSize;
const double bufferMax = .9 * m_bufferSize;
double fill = fills[*t0 - 1];
double parity = over ? 1. : -1.;
int start = -1, end = -1;
for (int i = *t0; i < m_numEntries; i++)
{
fill += (m_frameDuration * m_vbvMaxRate -
qScale2bits(&m_rce2Pass[i], m_rce2Pass[i].newQScale)) * parity;
fill = x265_clip3(0.0, m_bufferSize, fill);
fills[i] = fill;
if (fill <= bufferMin || i == 0)
{
if (end >= 0)
break;
start = i;
}
else if (fill >= bufferMax && start >= 0)
end = i;
}
*t0 = start;
*t1 = end;
return start >= 0 && end >= 0;
}
bool RateControl::fixUnderflow(int t0, int t1, double adjustment, double qscaleMin, double qscaleMax)
{
double qscaleOrig, qscaleNew;
bool adjusted = false;
if (t0 > 0)
t0++;
for (int i = t0; i <= t1; i++)
{
qscaleOrig = m_rce2Pass[i].newQScale;
qscaleOrig = x265_clip3(qscaleMin, qscaleMax, qscaleOrig);
qscaleNew = qscaleOrig * adjustment;
qscaleNew = x265_clip3(qscaleMin, qscaleMax, qscaleNew);
m_rce2Pass[i].newQScale = qscaleNew;
adjusted = adjusted || (qscaleNew != qscaleOrig);
}
return adjusted;
}
bool RateControl::cuTreeReadFor2Pass(Frame* frame)
{
uint8_t sliceTypeActual = (uint8_t)m_rce2Pass[frame->m_poc].sliceType;
if (m_rce2Pass[frame->m_poc].keptAsRef)
{
/* TODO: We don't need pre-lookahead to measure AQ offsets, but there is currently
* no way to signal this */
uint8_t type;
if (m_cuTreeStats.qpBufPos < 0)
{
do
{
m_cuTreeStats.qpBufPos++;
if (!fread(&type, 1, 1, m_cutreeStatFileIn))
goto fail;
if (fread(m_cuTreeStats.qpBuffer[m_cuTreeStats.qpBufPos], sizeof(uint16_t), m_ncu, m_cutreeStatFileIn) != (size_t)m_ncu)
goto fail;
if (type != sliceTypeActual && m_cuTreeStats.qpBufPos == 1)
{
x265_log(m_param, X265_LOG_ERROR, "CU-tree frametype %d doesn't match actual frametype %d.\n", type, sliceTypeActual);
return false;
}
}
while(type != sliceTypeActual);
}
for (int i = 0; i < m_ncu; i++)
{
int16_t qpFix8 = m_cuTreeStats.qpBuffer[m_cuTreeStats.qpBufPos][i];
frame->m_lowres.qpCuTreeOffset[i] = (double)(qpFix8) / 256.0;
frame->m_lowres.invQscaleFactor[i] = x265_exp2fix8(frame->m_lowres.qpCuTreeOffset[i]);
}
m_cuTreeStats.qpBufPos--;
}
return true;
fail:
x265_log(m_param, X265_LOG_ERROR, "Incomplete CU-tree stats file.\n");
return false;
}
/** 函数功能 ： 根据当前已编码bits数目修正预估的qscale值并计算overflow值（qScale *= overflow）
/* 调用范围 ： 只在rateEstimateQscale函数中被调用
* \参数 qScale ： qscale参数
* \返回 ： 返回修正后的qscale值 * */
double RateControl::tuneAbrQScaleFromFeedback(double qScale)
{
double abrBuffer = 2 * m_rateTolerance * m_bitrate;//最大使用的ABRbuffer大小
if (m_currentSatd)//如果当前帧的framecost不等于0
{
/* use framesDone instead of POC as poc count is not serial with bframes enabled */
double overflow = 1.0;//用于计算上溢 本次初始化无意义
double timeDone = (double)(m_framesDone - m_param->frameNumThreads + 1) * m_frameDuration;//当前RC里面帧的总时长 减去并行个数加上当前的一个
double wantedBits = timeDone * m_bitrate;//当前需要的总共bits数目 （RC里面的所有帧）
int64_t encodedBits = m_totalBits;//获取当前RC已编码占用的bits
if (m_param->totalFrames && m_param->totalFrames <= 2 * m_fps)//如果当前编码的总帧数不够2秒钟
{
abrBuffer = m_param->totalFrames * (m_bitrate / m_fps);//ABRbuffer修正为这些帧总共需要的空间
encodedBits = m_encodedBits;//获取时间编码bits (without ammortization)
}
if (wantedBits > 0 && encodedBits > 0 && (!m_partialResidualFrames ||
m_param->rc.bStrictCbr)) //已经有编码数据
{
abrBuffer *= X265_MAX(1, sqrt(timeDone));//修正当前buffer
overflow = x265_clip3(.5, 2.0, 1.0 + (encodedBits - wantedBits) / abrBuffer);//获取上溢值
qScale *= overflow;//修正当前qscale
}
}
return qScale;//返回修正后的qscale值
}
/** 函数功能 ： ？？？分析加权信息(每个list的第一帧分析加权与否，其它不加权)
/* 调用范围 ： 只在rateControlStart函数中被调用
* \参数 curFrame ： 当前编码帧
* \参数 rce ： ？？？当前编码帧
* \返回 ： ？？null * */
double RateControl::rateEstimateQscale(Frame* curFrame, RateControlEntry *rce)
{
//功能：？？？
// 1. 如果是2pass环节 无须计算（只需验证是否帧类型一致） 如果是1pass并且应用ABR：计算滑动窗口平均framecost和
// 2. 如果当前是B帧：根据向后参考帧获取预估qscale值，获取当前帧预估bits 返回预估当前帧的qscale值
// 3. 如果当前为I帧或者P帧：获取当前帧预估bits 返回预估当前帧的qscale值
double q;//用于存储当前帧估计的qscale值
if (m_2pass)//如果当前处在应用2pass
{
if (m_sliceType != rce->sliceType)//2pass中 如果帧类型不匹配报错
{
x265_log(m_param, X265_LOG_ERROR, "slice=%c but 2pass stats say %c\n",
g_sliceTypeToChar[m_sliceType], g_sliceTypeToChar[rce->sliceType]);
}
}
else
{
if (m_isAbr)//应用ABR 功能：计算滑动窗口平均framecost和
{
double slidingWindowCplxSum = 0;//用于计算滑动窗口平均framecost和
//计算方式：假设当前序列为 F0 F1 F2 F3 F4.....
//则： F0 = 0 F1 = F0*0.5 F2 = (F0*0.5 + F1)*0.5 F3 = ((F0*0.5 + F1)*0.5 + F2)*0.5 F4 = (((F0*0.5 + F1)*0.5 + F2)*0.5 + F3)*0.5
int start = m_sliderPos > s_slidingWindowFrames ? m_sliderPos : 0;//获取当前滑动窗口的下标 循环队列
for (int cnt = 0; cnt < s_slidingWindowFrames; cnt++, start++)//获取滑动窗口framecost和
{
int pos = start % s_slidingWindowFrames;//获取当前下标
slidingWindowCplxSum *= 0.5;
if (!m_satdCostWindow[pos])
break;
slidingWindowCplxSum += m_satdCostWindow[pos];//累加当前framecost
}
rce->movingAvgSum = slidingWindowCplxSum;//获取滑动窗口平均framecost和
m_satdCostWindow[m_sliderPos % s_slidingWindowFrames] = rce->lastSatd;//获取当前下标
m_sliderPos++;//用于标示下一帧的滑动窗口下标
}
}
if (m_sliceType == B_SLICE)//如果当前是B帧：根据向后参考帧获取预估qscale值，获取当前帧预估bits 返回预估当前帧的qscale值
{
/* B-frames don't have independent rate control, but rather get the
* average QP of the two adjacent P-frames + an offset */
Slice* prevRefSlice = m_curSlice->m_refPicList[0][0]->m_encData->m_slice;//获取前向帧slice
Slice* nextRefSlice = m_curSlice->m_refPicList[1][0]->m_encData->m_slice;//获取后向帧slice
double q0 = m_curSlice->m_refPicList[0][0]->m_encData->m_avgQpRc;//获取前向参考帧的平均QP
double q1 = m_curSlice->m_refPicList[1][0]->m_encData->m_avgQpRc;//获取后向参考帧的平均QP
bool i0 = prevRefSlice->m_sliceType == I_SLICE;//判断前向参考帧是否为I帧
bool i1 = nextRefSlice->m_sliceType == I_SLICE;//判断后向参考帧是否为I帧
int dt0 = abs(m_curSlice->m_poc - prevRefSlice->m_poc);//获取当前编码帧与前向参考帧的距离
int dt1 = abs(m_curSlice->m_poc - nextRefSlice->m_poc);//获取当前编码帧与后向参考帧的距离
// Skip taking a reference frame before the Scenecut if ABR has been reset.
if (m_lastAbrResetPoc >= 0)//如果前面有非B帧 ABR进行重置
{
if (prevRefSlice->m_sliceType == P_SLICE && prevRefSlice->m_poc < m_lastAbrResetPoc)//如果前向帧为P帧 并且 前向帧在重置位置之前
{
i0 = i1; //获取后向帧是否为I帧
dt0 = dt1;//获取后向帧距离
q0 = q1;//获取后向帧QP
}
}
if (prevRefSlice->m_sliceType == B_SLICE && IS_REFERENCED(m_curSlice->m_refPicList[0][0]))//如果前向参考帧为B帧 并且 前向参考帧为可参考B帧
q0 -= m_pbOffset / 2; //修正前向参考帧的平均QP
if (nextRefSlice->m_sliceType == B_SLICE && IS_REFERENCED(m_curSlice->m_refPicList[1][0]))//如果后向参考帧为B帧 并且 后向参考帧为可参考B帧
q1 -= m_pbOffset / 2;//修正前向参考帧的平均QP
if (i0 && i1)//如果前向和后向参考帧都为I帧
q = (q0 + q1) / 2 + m_ipOffset;//获取当前预估QP值：其平均值
else if (i0)//如果前向参考帧为I帧
q = q1;//获取后向帧的平均QP值
else if (i1)//如果后向参考帧为I帧
q = q0;//获取前向参考帧的平均QP值
else
q = (q0 * dt1 + q1 * dt0) / (dt0 + dt1);//获取按距离加权的平均QP值
if (IS_REFERENCED(curFrame))//如果当前帧为可参考帧
q += m_pbOffset / 2;//QP增加一半PBoffset
else
q += m_pbOffset;//QP增加PBoffset
/* Set a min qp at scenechanges and transitions */
if (m_isSceneTransition)//如果当前帧是场景切换帧
{
q = X265_MAX(ABR_SCENECUT_INIT_QP_MIN, q);//取最大QP
double minScenecutQscale =x265_qp2qScale(ABR_SCENECUT_INIT_QP_MIN); //获取最小Qscale值
m_lastQScaleFor[P_SLICE] = X265_MAX(minScenecutQscale, m_lastQScaleFor[P_SLICE]);//更新P帧最新qscale值
}
double qScale = x265_qp2qScale(q);//获取当前预估的qscale值
rce->qpNoVbv = q;//获取未经VBV修正的qp参数
double lmin = 0, lmax = 0;//暂存最大 和最小qscale值
if (m_isVbv)//如果应用VBV
{
lmin = m_lastQScaleFor[P_SLICE] / m_lstep;//获取最小qscale
lmax = m_lastQScaleFor[P_SLICE] * m_lstep;//获取最大qscale
if (m_isCbr)//如果为CBR
{
qScale = tuneAbrQScaleFromFeedback(qScale);//根据当前已编码bits数目修正预估的qscale值并计算overflow值（qScale *= overflow）
if (!m_isAbrReset)//如果当前没有被重置ABR
qScale = x265_clip3(lmin, lmax, qScale);//clip 当前的qscale值
q = x265_qScale2qp(qScale);//获取qp量化参数
}
if (!m_2pass)//如果不是2pass
{
qScale = clipQscale(curFrame, rce, qScale);//根据下采样SATD信息修正qscale值
/* clip qp to permissible range after vbv-lookahead estimation to avoid possible
* mispredictions by initial frame size predictors */
if (m_pred[m_predType].count == 1)//如果当前帧类型值update过一次predictor
qScale = x265_clip3(lmin, lmax, qScale);//clip操作 防止越界
m_lastQScaleFor[m_sliceType] = qScale;//获取最新的qscale值
rce->frameSizePlanned = predictSize(&m_pred[m_predType], qScale, (double)m_currentSatd);//预测当前帧需要的bits
}
else
rce->frameSizePlanned = qScale2bits(rce, qScale);//根据1pass 数据 获取2pass当前计划占用的bits
/* Limit planned size by MinCR */
rce->frameSizePlanned = X265_MIN(rce->frameSizePlanned, rce->frameSizeMaximum);////预估bits与当前level下当前帧占用的最大bit去最小值
rce->frameSizeEstimated = rce->frameSizePlanned;//获取预估bits
}
rce->newQScale = qScale;//获取当前的预估qscale
return qScale;//返回预估的qscale
}
else //如果当前为I帧或者P帧
{
//功能：获取当前帧预估bits 返回预估当前帧的qscale值
// 1. 如果当前是2pass：？？？
// 否则如果当前不是2pass：预估当前帧的qscale值 并 根据下采样SATD信息修正qscale值（仅限VBV模式）
// 2. 获取当前帧预估bits 返回预估当前帧的qscale值
double abrBuffer = 2 * m_rateTolerance * m_bitrate;//获取当前可用buffer
if (m_2pass)//？？？？
{
int64_t diff;
if (!m_isVbv)
{
m_predictedBits = m_totalBits;
if (rce->encodeOrder < m_param->frameNumThreads)
m_predictedBits += (int64_t)(rce->encodeOrder * m_bitrate / m_fps);
else
m_predictedBits += (int64_t)(m_param->frameNumThreads * m_bitrate / m_fps);
}
/* Adjust ABR buffer based on distance to the end of the video. */
if (m_numEntries > rce->encodeOrder)
{
uint64_t finalBits = m_rce2Pass[m_numEntries - 1].expectedBits;
double videoPos = (double)rce->expectedBits / finalBits;
double scaleFactor = sqrt((1 - videoPos) * m_numEntries);
abrBuffer *= 0.5 * X265_MAX(scaleFactor, 0.5);
}
diff = m_predictedBits - (int64_t)rce->expectedBits;
q = rce->newQScale;
q /= x265_clip3(0.5, 2.0, (double)(abrBuffer - diff) / abrBuffer);
if (m_expectedBitsSum > 0)
{
/* Adjust quant based on the difference between
* achieved and expected bitrate so far */
double curTime = (double)rce->encodeOrder / m_numEntries;
double w = x265_clip3(0.0, 1.0, curTime * 100);
q *= pow((double)m_totalBits / m_expectedBitsSum, w);
}
rce->qpNoVbv = x265_qScale2qp(q);
if (m_isVbv)
{
/* Do not overflow vbv */
double expectedSize = qScale2bits(rce, q);
double expectedVbv = m_bufferFill + m_bufferRate - expectedSize;
double expectedFullness = rce->expectedVbv / m_bufferSize;
double qmax = q * (2 - expectedFullness);
double sizeConstraint = 1 + expectedFullness;
qmax = X265_MAX(qmax, rce->newQScale);
if (expectedFullness < .05)
qmax = MAX_MAX_QPSCALE;
qmax = X265_MIN(qmax, MAX_MAX_QPSCALE);
while (((expectedVbv < rce->expectedVbv/sizeConstraint) && (q < qmax)) ||
((expectedVbv < 0) && (q < MAX_MAX_QPSCALE)))
{
q *= 1.05;
expectedSize = qScale2bits(rce, q);
expectedVbv = m_bufferFill + m_bufferRate - expectedSize;
}
}
q = x265_clip3(MIN_QPSCALE, MAX_MAX_QPSCALE, q);
}
else //不是2pass
{
/* 1pass ABR */
/* Calculate the quantizer which would have produced the desired
* average bitrate if it had been applied to all frames so far.
* Then modulate that quant based on the current frame's complexity
* relative to the average complexity so far (using the 2pass RCEQ).
* Then bias the quant up or down if total size so far was far from
* the target.
* Result: Depending on the value of rate_tolerance, there is a
* tradeoff between quality and bitrate precision. But at large
* tolerances, the bit distribution approaches that of 2pass. */
//功能：预估当前帧的qscale值 并 根据下采样SATD信息修正qscale值（仅限VBV模式）
// 1.预估RC计算复杂度 初始化
// 2.获取预估qscale
// 3.如果应用VBV：根据下采样SATD信息修正qscale值 否则 只是简单的clip操作
double overflow = 1;//用于调整当前估计的qscale *= overflow
double lqmin = MIN_QPSCALE, lqmax = MAX_MAX_QPSCALE; //用于标记最大和最小qsclae 防止越界（后面会对其根据实际情况更新） 分别为 0.21249999999999999 615.46574234477100
/*m_shortTermCplxSum 当前非B帧及以前所有非B帧 framecost * (fps/25)的平均和
计算方式： 设当前序列 I0BBBP1BBBP2BBBP3
则当前m_shortTermCplxSum = （（（I0*fps/25)*0.5 + P1*fps/25）*0.5 + P2*fps/25）*0.5 + P3
m_shortTermCplxCount 当前帧以前非B帧个数 + 1
I0 = 1
P1 = I0*0.5 + 1 = 1.5
P2 = P1*0.5 + 1 = 1.75
P3 = P2*0.5 + 1 = 1.875
**/
m_shortTermCplxSum *= 0.5;//加权求和
m_shortTermCplxCount *= 0.5;//加权求和
m_shortTermCplxSum += m_currentSatd / (CLIP_DURATION(m_frameDuration) / BASE_FRAME_DURATION);//计算当前的加权framecost fps越大，其权重越大
m_shortTermCplxCount++; //累加
/* coeffBits to be used in 2-pass */
rce->coeffBits = (int)m_currentSatd;//获取当前帧的framecost值
rce->blurredComplexity = m_shortTermCplxSum / m_shortTermCplxCount; //预估当前的计算复杂度 （当前非B帧及以前所有非B帧 framecost * (fps/25)的平均和） / (当前帧以前非B帧个数 + 1 )
rce->mvBits = 0;//初始化
rce->sliceType = m_sliceType;//无须重新赋值 冗余代码
//功能：获取预估qscale
if (m_param->rc.rateControlMode == X265_RC_CRF)//如果当前为CRF模式
{
q = getQScale(rce, m_rateFactorConstant);//获取预测qscale
}
else
{
if (!m_param->rc.bStatRead)//如果不是2pass读
checkAndResetABR(rce, false);//检测是否下溢（前面占用bits过少 防止当前非B帧占用bits过多）用于下溢检测并重置ABR
double initialQScale = getQScale(rce, m_wantedBitsWindow / m_cplxrSum);//获取预测的qscale如果有对应zone信息对qcale进行修正
q = tuneAbrQScaleFromFeedback(initialQScale);//根据当前已编码bits数目修正预估的qscale值
overflow = q / initialQScale;//获取tuneAbrQScaleFromFeedback计算的上溢值
}
if (m_sliceType == I_SLICE && m_param->keyframeMax > 1
&& m_lastNonBPictType != I_SLICE && !m_isAbrReset)//如果当前为I帧 并且IDR间隔大于1 并且 前一个非B帧不为I帧 并且没有重置
{
if (!m_param->rc.bStrictCbr)//如果不是严格按照目标码率
q = x265_qp2qScale(m_accumPQp / m_accumPNorm);//直接获取平均qscale
q /= fabs(m_param->rc.ipFactor);//获取I帧的qscale
}
else if (m_framesDone > 0)//如果RC中帧数大于0
{
if (m_param->rc.rateControlMode != X265_RC_CRF)//当前不为CRF模式
{
lqmin = m_lastQScaleFor[m_sliceType] / m_lstep;//更新最小qscale
lqmax = m_lastQScaleFor[m_sliceType] * m_lstep;//更新最大qscale
if (!m_partialResidualFrames)//如果当前没有均摊帧数
{
if (overflow > 1.1 && m_framesDone > 3)
lqmax *= m_lstep;//更新最大qscale
else if (overflow < 0.9)
lqmin /= m_lstep;//更新最小qscale
}
q = x265_clip3(lqmin, lqmax, q);//clip当前qscale 防止越界
}
}
else if (m_qCompress != 1 && m_param->rc.rateControlMode == X265_RC_CRF)//CRF模式
{
q = x265_qp2qScale(CRF_INIT_QP) / fabs(m_param->rc.ipFactor);//获取CFR模式下的qscale
}
else if (m_framesDone == 0 && !m_isVbv && m_param->rc.rateControlMode == X265_RC_ABR)//ABR 并且非VBV模式下 第一帧更新最大qscale
{
/* for ABR alone, clip the first I frame qp */
lqmax = x265_qp2qScale(ABR_INIT_QP_MAX) * m_lstep;//更新最大qscale （根据初始最大qp）
q = X265_MIN(lqmax, q);//防止越界
}
q = x265_clip3(MIN_QPSCALE, MAX_MAX_QPSCALE, q);//clip操作防止越界
/* Set a min qp at scenechanges and transitions */
if (m_isSceneTransition)//如果当前是场景切换帧
{
double minScenecutQscale =x265_qp2qScale(ABR_SCENECUT_INIT_QP_MIN); //场景切换应用的最小QP 12 对应的qscale
q = X265_MAX(minScenecutQscale, q);//取最大的qscale
m_lastQScaleFor[P_SLICE] = X265_MAX(minScenecutQscale, m_lastQScaleFor[P_SLICE]);//更新P帧qscale
}
rce->qpNoVbv = x265_qScale2qp(q);//获取vbv修正前的量化参数
q = clipQscale(curFrame, rce, q);//如果应用VBV：根据下采样SATD信息修正qscale值 否则 只是简单的clip操作
/* clip qp to permissible range after vbv-lookahead estimation to avoid possible
* mispredictions by initial frame size predictors, after each scenecut */
bool isFrameAfterScenecut = m_sliceType!= I_SLICE && m_curSlice->m_refPicList[0][0]->m_lowres.bScenecut;// 当前帧紧挨帧场景切换帧（编码顺序）如果当前帧不是I帧 并且 其前向参考的第一帧为场景切换帧
if (!m_2pass && m_isVbv && isFrameAfterScenecut)//如果当前为1pass 并且应用VBV 并且在场景切换帧后面
q = x265_clip3(lqmin, lqmax, q);//clip操作
}
m_lastQScaleFor[m_sliceType] = q;//获取当分B帧的最新qscale
if ((m_curSlice->m_poc == 0 || m_lastQScaleFor[P_SLICE] < q) && !(m_2pass && !m_isVbv))//（如果是第一帧或者P初始化qscale过小 ）
m_lastQScaleFor[P_SLICE] = q * fabs(m_param->rc.ipFactor);//修正P帧的最新qscale
if (m_2pass && m_isVbv)//如果当前是2pass 并且应用VBV
rce->frameSizePlanned = qScale2bits(rce, q);//？？？
else
rce->frameSizePlanned = predictSize(&m_pred[m_predType], q, (double)m_currentSatd);//获取当前帧预估的bits
/* Always use up the whole VBV in this case. */
if (m_singleFrameVbv)//如果单帧占用bits过大
rce->frameSizePlanned = m_bufferRate;//直接将其置为：平均每帧最大的bits占用数目
/* Limit planned size by MinCR */
if (m_isVbv)//如果应用VBV
rce->frameSizePlanned = X265_MIN(rce->frameSizePlanned, rce->frameSizeMaximum);//预估bits与当前level下当前帧占用的最大bit去最小值
rce->frameSizeEstimated = rce->frameSizePlanned;//获取预估bits
rce->newQScale = q;//获取当前的预估qscale
return q;//返回预估的qscale
}
}
/** 函数功能 ： 当前帧编码一半时即时更新数据，便于后续帧快速估计 更新m_startEndOrder计数
/* 调用范围 ： 只在processRowEncoder函数中被调用
* \参数 rce ： 当前帧RC相关数据
* \返回 ： null * */
void RateControl::rateControlUpdateStats(RateControlEntry* rce)
{
if (!m_param->rc.bStatWrite && !m_param->rc.bStatRead)//没有应用多pass结构 既不是读模式 也不是写模式
{
if (rce->sliceType == I_SLICE)//如果当前为I帧
{
/* previous I still had a residual; roll it into the new loan */
if (m_partialResidualFrames)//如果已经更新过数据
rce->rowTotalBits += m_partialResidualCost * m_partialResidualFrames;//当前bits加上剩余bits
if ((m_param->totalFrames != 0) && (m_amortizeFrames > (m_param->totalFrames - m_framesDone)))//编码剩余帧数不够分摊帧数
{
m_amortizeFrames = 0;//置为0
m_amortizeFraction = 0;//置为0
}
else
{
double depreciateRate = 1.1;//因子
m_amortizeFrames = (int)(m_amortizeFrames / depreciateRate);//更新分摊帧数
m_amortizeFraction /= depreciateRate;//更新分摊分数
m_amortizeFrames = X265_MAX(m_amortizeFrames, MIN_AMORTIZE_FRAME);//不能小于默认最小值
m_amortizeFraction = X265_MAX(m_amortizeFraction, MIN_AMORTIZE_FRACTION);//不能小于默认最小值
}
rce->amortizeFrames = m_amortizeFrames;//获取分摊帧数
rce->amortizeFraction = m_amortizeFraction;//获取分摊因子
m_partialResidualFrames = X265_MIN((int)rce->amortizeFrames, m_param->keyframeMax);//获取当前分摊帧数
m_partialResidualCost = (int)((rce->rowTotalBits * rce->amortizeFraction) / m_partialResidualFrames);//获取当前I帧的剩余cost
rce->rowTotalBits -= m_partialResidualCost * m_partialResidualFrames;//减去更新后的bits
}
else if (m_partialResidualFrames)//非I帧
{
rce->rowTotalBits += m_partialResidualCost;//修正增加当前I帧的剩余cost
m_partialResidualFrames--;//减减
}
}
if (rce->sliceType != B_SLICE)//非B帧
rce->rowCplxrSum = rce->rowTotalBits * x265_qp2qScale(rce->qpaRc) / rce->qRceq;//获取cost值
else
rce->rowCplxrSum = rce->rowTotalBits * x265_qp2qScale(rce->qpaRc) / (rce->qRceq * fabs(m_param->rc.pbFactor));//获取cost值
m_cplxrSum += rce->rowCplxrSum;//获取预测cost
m_totalBits += rce->rowTotalBits;//累加RC中占有的bits
/* do not allow the next frame to enter rateControlStart() until this
* frame has updated its mid-frame statistics */
//只有在此运行之后，下一个rateControlStart()才继续运行
if (m_param->rc.rateControlMode == X265_RC_ABR || m_isVbv)//如果应用ABR或者VBV
{
m_startEndOrder.incr();//更新计数
if (rce->encodeOrder < m_param->frameNumThreads - 1)//刚启动时多更新一次
m_startEndOrder.incr(); // faked rateControlEnd calls for negative frames
}
}
/** 函数功能 ： 检测是否下溢（前面占用bits过少 防止当前非B帧占用bits过多）rateEstimateQscale中用于下溢检测并重置ABR rateControlEnd用于关闭前面重置的标志位
/* 调用范围 ： 只在rateEstimateQscale和RateControl::rateControlEnd函数中被调用
* \参数 rce ： 当前编码帧的RC参数
* \参数 isFrameDone ： 当前帧是否编码完毕 rateEstimateQscale为false rateControlEnd为true
* \返回 ： null * */
void RateControl::checkAndResetABR(RateControlEntry* rce, bool isFrameDone)
{
//在rateEstimateQscale中只在非B帧中进入
//在rateControlEnd中：所有帧类型都可以进入
//一般都符合规则 在此不会改变什么
double abrBuffer = 2 * m_rateTolerance * m_bitrate;//ARR最多用的buffer大小
// Check if current Slice is a scene cut that follows low detailed/blank frames
if (rce->lastSatd > 4 * rce->movingAvgSum)//如果当前帧的framecost 大于4倍的滑动窗口平均framecost和
{
if (!m_isAbrReset && rce->movingAvgSum > 0
&& (m_isPatternPresent || !m_param->bframes)) //如果m_isAbrReset为false并且滑动窗口平均cost大于0 并且 序列无B帧或连续大于bframes个数b帧cost相同 （(m_isPatternPresent || !m_param->bframes)）这条很难达到一般不进入
{
int pos = X265_MAX(m_sliderPos - m_param->frameNumThreads, 0);//排除并行中的frame
int64_t shrtTermWantedBits = (int64_t) (X265_MIN(pos, s_slidingWindowFrames) * m_bitrate * m_frameDuration);//当前窗口内应该拥有的bits
int64_t shrtTermTotalBitsSum = 0; //统计当前窗口占用的实际bits
// Reset ABR if prev frames are blank to prevent further sudden overflows/ high bit rate spikes.
for (int i = 0; i < s_slidingWindowFrames ; i++)
shrtTermTotalBitsSum += m_encodedBitsWindow[i];//统计当前窗口占用的实际bits
double underflow = (shrtTermTotalBitsSum - shrtTermWantedBits) / abrBuffer;//前面由于B帧占用的bits过少，防止下溢，造成当前编码的非B帧占用的bits过大
const double epsilon = 0.0001f;//阈值
if (underflow < epsilon && !isFrameDone)//小于阈值并且在rateEstimateQscale函数进入的
{
init(*m_curSlice->m_sps);//重新初始化RC
m_shortTermCplxSum = rce->lastSatd / (CLIP_DURATION(m_frameDuration) / BASE_FRAME_DURATION);//从开始统计非B帧cost 前面的丢弃
m_shortTermCplxCount = 1;//重新计数
m_isAbrReset = true;//标记ABR重置
m_lastAbrResetPoc = rce->poc;//记录最后的重置poc位置
}
}
else if (m_isAbrReset && isFrameDone)//rateControlEnd进入 用于清除已经set的flag
{
// Clear flag to reset ABR and continue as usual.
m_isAbrReset = false;
}
}
}
void RateControl::hrdFullness(SEIBufferingPeriod *seiBP)
{
const VUI* vui = &m_curSlice->m_sps->vuiParameters;
const HRDInfo* hrd = &vui->hrdParameters;
int num = 90000;
int denom = hrd->bitRateValue << (hrd->bitRateScale + BR_SHIFT);
reduceFraction(&num, &denom);
int64_t cpbState = (int64_t)m_bufferFillFinal;
int64_t cpbSize = (int64_t)hrd->cpbSizeValue << (hrd->cpbSizeScale + CPB_SHIFT);
if (cpbState < 0 || cpbState > cpbSize)
{
x265_log(m_param, X265_LOG_WARNING, "CPB %s: %.0lf bits in a %.0lf-bit buffer\n",
cpbState < 0 ? "underflow" : "overflow", (float)cpbState/denom, (float)cpbSize/denom);
}
seiBP->m_initialCpbRemovalDelay = (uint32_t)(num * cpbState + denom) / denom;
seiBP->m_initialCpbRemovalDelayOffset = (uint32_t)(num * cpbSize + denom) / denom - seiBP->m_initialCpbRemovalDelay;
}
/** 函数功能 ： VBV中更新根据当前帧并行情况更新当前RCbuffer
/* 调用范围 ： 只在RateControl::rateControlStart函数中被调用
* \参数 enc ： 上层encodr类
* \返回 ： null * */
void RateControl::updateVbvPlan(Encoder* enc)
{
m_bufferFill = m_bufferFillFinal;//获取当前码率控制中一秒钟占用的最大的buffer
enc->updateVbvPlan(this);//VBV中更新根据当前帧并行情况更新当前RCbuffer
}
/** 函数功能 ： 根据当前帧类型的predictor qscale参数 以及对应下采样的SATD值 预估当前块/帧 占用的bits
/* 调用范围 ： 只在rateControlStart、rateEstimateQscale、clipQscale、predictRowsSizeSum函数中被调用
* \参数 p ： rateControlStart：m_pred[m_predType]预测器(forceqp时应)、rateEstimateQscale：m_pred[m_predType]、clipQscale：m_pred[m_predType]预测器、predictRowsSizeSum：rowPred[0]、rowPred[1]
* \参数 q ： rateControlStart：当前量化参数(forceqp时应)、rateEstimateQscale：qscale参数、clipQscale：qscale参数、predictRowsSizeSum：当前的qscale值
* \参数 var ： rateControlStart：当前帧的framecost(forceqp时应)、rateEstimateQscale：当前帧的framecost、clipQscale：当前帧的framecost、predictRowsSizeSum：当前行未编码CTU的SATD和
* \返回 ： 返回预测bits * */
double RateControl::predictSize(Predictor *p, double q, double var)
{
return (p->coeff * var + p->offset) / (q * p->count);//预测当前帧的bits
}
/** 函数功能 ： 如果应用VBV：根据下采样SATD信息修正qscale值 否则 只是简单的clip操作
/* 调用范围 ： 只在initPass2()、rateEstimateQscale函数中被调用
* \参数 curFrame ： 当前编码帧
* \参数 rce ： 当前编码帧的相关码率控制信息
* \参数 q ： qscale参数
* \返回 ： 返回修正后的qscale * */
double RateControl::clipQscale(Frame* curFrame, RateControlEntry* rce, double q)
{
// B-frames are not directly subject to VBV,
// since they are controlled by referenced P-frames' QPs.
double q0 = q;//存储函数进来时的qscale值
if (m_isVbv && m_currentSatd > 0 && curFrame)//framecost不为0
{
//功能：根据下采样SATD信息修正qscale值
// 1. 如果应用lookachead 或者 应用cuTree 或者应用scencecut 或者 应用自适应B帧决策
// : 根据下采样SATD值预测未来的bits占用数目 从而修正当前的qscale
// 否则：根据当前bits 修正当前的qscale
// 2. 根据当前bits以及level定义值 修正qscale
if (m_param->lookaheadDepth || m_param->rc.cuTree ||
m_param->scenecutThreshold ||
(m_param->bFrameAdaptive && m_param->bframes))//应用lookachead 或者 应用cuTree 或者应用scencecut 或则 应用自适应B帧决策
{
/* Lookahead VBV: If lookahead is done, raise the quantizer as necessary
* such that no frames in the lookahead overflow and such that the buffer
* is in a reasonable state by the end of the lookahead. */
int loopTerminate = 0;
/* Avoid an infinite loop. */
//功能：根据下采样SATD值预测未来的bits占用数目 从而修正当前的qscale
for (int iterations = 0; iterations < 1000 && loopTerminate != 3; iterations++)
{
double frameQ[3];//用于存储IPB帧的加权qscale
double curBits;//存储当前预测未来某帧占用的bits
curBits = predictSize(&m_pred[m_predType], q, (double)m_currentSatd);//预测当前占用的bits
double bufferFillCur = m_bufferFill - curBits;//当前剩余的bitsbuffer
double targetFill;//存储目标填充
double totalDuration = m_frameDuration; //当前播放一帧占用的时间（单位秒）
frameQ[P_SLICE] = m_sliceType == I_SLICE ? q * m_param->rc.ipFactor : (m_sliceType == B_SLICE ? q / m_param->rc.pbFactor : q);//如果当前是I帧 P帧qscale直接获取（q * m_param->rc.ipFactor）P帧直接获取q B帧 q / m_param->rc.pbFactor
frameQ[B_SLICE] = frameQ[P_SLICE] * m_param->rc.pbFactor;//B帧 = P帧* m_param->rc.pbFactor
frameQ[I_SLICE] = frameQ[P_SLICE] / m_param->rc.ipFactor;//I帧 = P帧 / m_param->rc.ipFactor
/* Loop over the planned future frames. */
for (int j = 0; bufferFillCur >= 0; j++)//循环遍历未来帧占用的bits 直到遍历一秒钟 或者 buffer剩余为0
{
int type = curFrame->m_lowres.plannedType[j];
if (type == X265_TYPE_AUTO || totalDuration >= 1.0)//累加一秒帧数 直接退出
break;
totalDuration += m_frameDuration;//累加帧时间
double wantedFrameSize = m_vbvMaxRate * m_frameDuration;//占用的最大bits
if (bufferFillCur + wantedFrameSize <= m_bufferSize)//如果没有溢出
bufferFillCur += wantedFrameSize;//累加bits
int64_t satd = curFrame->m_lowres.plannedSatd[j] >> (X265_DEPTH - 8);//获取下采样cost值
type = IS_X265_TYPE_I(type) ? I_SLICE : IS_X265_TYPE_B(type) ? B_SLICE : P_SLICE;//获取slice类型
int predType = getPredictorType(curFrame->m_lowres.plannedType[j], type);//获取predictor标号
curBits = predictSize(&m_pred[predType], frameQ[type], (double)satd);//预测当前bits
bufferFillCur -= curBits;//剩余bitsbuffer 减去当前预测bits
}
/* Try to get the buffer at least 50% filled, but don't set an impossible goal. */
double finalDur = 1;//存储遍历未来帧的秒数（一般是0.x秒）
if (m_param->rc.bStrictCbr)//如果严格按照目标码率控制
{
finalDur = x265_clip3(0.4, 1.0, totalDuration);//获取遍历未来帧的秒数（一般是0.x秒）
}
targetFill = X265_MIN(m_bufferFill + totalDuration * m_vbvMaxRate * 0.5 , m_bufferSize * (1 - 0.5 * finalDur));//获取目标填充bitsbuffer 不能超过一半buffer
if (bufferFillCur < targetFill)//遍历剩余buffer 小于目标填充buffer 占用bits过大
{
q *= 1.01;//提高qscale
loopTerminate |= 1;//或一
continue;
}
/* Try to get the buffer not more than 80% filled, but don't set an impossible goal. */
targetFill = x265_clip3(m_bufferSize * (1 - 0.2 * finalDur), m_bufferSize, m_bufferFill - totalDuration * m_vbvMaxRate * 0.5);
if (m_isCbr && bufferFillCur > targetFill && !m_isSceneTransition)//CBR模式 并且剩余buffer过大
{
q /= 1.01;//降低qscale
loopTerminate |= 2;//或2
continue;
}
break;
}
q = X265_MAX(q0 / 2, q);//不能修正超过一半
}
else//一般不进入：
{
/* Fallback to old purely-reactive algorithm: no lookahead. */
if ((m_sliceType == P_SLICE || m_sliceType == B_SLICE ||
(m_sliceType == I_SLICE && m_lastNonBPictType == I_SLICE)) &&
m_bufferFill / m_bufferSize < 0.5)//占用bits过少
{
q /= x265_clip3(0.5, 1.0, 2.0 * m_bufferFill / m_bufferSize);//调大qscale 因为除以的是一个小数
}
// Now a hard threshold to make sure the frame fits in VBV.
// This one is mostly for I-frames.
double bits = predictSize(&m_pred[m_predType], q, (double)m_currentSatd);//预测当前占用的bits
// For small VBVs, allow the frame to use up the entire VBV.
double maxFillFactor;
maxFillFactor = m_bufferSize >= 5 * m_bufferRate ? 2 : 1;//最大因子
// For single-frame VBVs, request that the frame use up the entire VBV.
double minFillFactor = m_singleFrameVbv ? 1 : 2;//最小一字
for (int iterations = 0; iterations < 10; iterations++)
{
double qf = 1.0;
if (bits > m_bufferFill / maxFillFactor)
qf = x265_clip3(0.2, 1.0, m_bufferFill / (maxFillFactor * bits));
q /= qf;
bits *= qf;
if (bits < m_bufferRate / minFillFactor)
q *= bits * minFillFactor / m_bufferRate;
bits = predictSize(&m_pred[m_predType], q, (double)m_currentSatd);
}
q = X265_MAX(q0, q);//不能超过原来的qscale
}
/* Apply MinCR restrictions */
double pbits = predictSize(&m_pred[m_predType], q, (double)m_currentSatd);//预测当前帧占用的bist
if (pbits > rce->frameSizeMaximum)//如果bits大于当前level定义值
q *= pbits / rce->frameSizeMaximum;//调大qscale
/* To detect frames that are more complex in SATD costs compared to prev window, yet
* lookahead vbv reduces its qscale by half its value. Be on safer side and avoid drastic
* qscale reductions for frames high in complexity */
bool mispredCheck = rce->movingAvgSum && m_currentSatd >= rce->movingAvgSum && q <= q0 / 2;
if (!m_isCbr || (m_isAbr && mispredCheck))
q = X265_MAX(q0, q);
if (m_rateFactorMaxIncrement)//最大与配置之间的差值:m_param->rc.rfConstantMax - m_param->rc.rfConstant
{
double qpNoVbv = x265_qScale2qp(q0);//未经vbv修正的mv
double qmax = X265_MIN(MAX_MAX_QPSCALE,x265_qp2qScale(qpNoVbv + m_rateFactorMaxIncrement));//最大qscale
return x265_clip3(MIN_QPSCALE, qmax, q);//clip 防止越界
}
}
if (m_2pass)//如果当前为2pass 根据最大qscale值和最小qscale 修正当前qscale
{
double min = log(MIN_QPSCALE);
double max = log(MAX_MAX_QPSCALE);
q = (log(q) - min) / (max - min) - 0.5;
q = 1.0 / (1.0 + exp(-4 * q));
q = q*(max - min) + min;
return exp(q);
}
return x265_clip3(MIN_QPSCALE, MAX_MAX_QPSCALE, q);//返回修正后的qscale
}
/** 函数功能 ： 计算当前帧已经编码bits加上未编码预测bits
/* 调用范围 ： 只在rowDiagonalVbvRateControl函数中被调用
* \参数 curFrame ： 当前编码帧
* \参数 rce ： 当前帧的码率控制数据
* \参数 qpVbv ： 当前更新后的QP参数
* \参数 encodedBitsSoFar ： 用于回存当前帧已经编码的bits
* \返回 ： 返回当前帧已经编码bits加上未编码预测bits * */
double RateControl::predictRowsSizeSum(Frame* curFrame, RateControlEntry* rce, double qpVbv, int32_t& encodedBitsSoFar)
{
uint32_t rowSatdCostSoFar = 0, totalSatdBits = 0;//分别用于存储：当前已经编码完毕的CTU对应的SATD和、未编码预测bits
encodedBitsSoFar = 0;//初始为0 累加当前已经编码完毕的bits
double qScale = x265_qp2qScale(qpVbv);//量化参数转换为qscale
FrameData& curEncData = *curFrame->m_encData;//获取当前帧的编码数据
int picType = curEncData.m_slice->m_sliceType;//获取slice类型：B_SLICE,P_SLICE,I_SLICE
Frame* refFrame = curEncData.m_slice->m_refPicList[0][0];//获取前向参考帧
uint32_t maxRows = curEncData.m_slice->m_sps->numCuInHeight;//CTU列数
uint32_t maxCols = curEncData.m_slice->m_sps->numCuInWidth;//CTU行数
for (uint32_t row = 0; row < maxRows; row++)//遍历所有CTU行
{
encodedBitsSoFar += curEncData.m_rowStat[row].encodedBits;//累加当前已经编码完毕的bits
rowSatdCostSoFar = curEncData.m_rowStat[row].diagSatd;//累加当前已经编码完毕的CTU对应的SATD
uint32_t satdCostForPendingCus = curEncData.m_rowStat[row].satdForVbv - rowSatdCostSoFar;//当前CTU行还未编码的SATD和
satdCostForPendingCus >>= X265_DEPTH - 8;//根据像素位宽修正
if (satdCostForPendingCus > 0)//还有未编码的CTU
{
double pred_s = predictSize(rce->rowPred[0], qScale, satdCostForPendingCus);//预估当前行未编码CTU占用的bits
uint32_t refRowSatdCost = 0, refRowBits = 0, intraCostForPendingCus = 0;//refRowSatdCost 用于累加当前行未编码CTU参考帧对应位置的下采样cost, refRowBits 累加当前行未编码CTU参考帧对应位置的bits, intraCostForPendingCus 当前行intraSATD值 减去 当前CTU行已编码CTU的对应下采样计算的intraSATD值
double refQScale = 0;//用于存储参考帧的refscale
if (picType != I_SLICE)//如果当前不是I帧
{
FrameData& refEncData = *refFrame->m_encData;//获取参考帧的编码数据
uint32_t endCuAddr = maxCols * (row + 1);//当前行最后一个CTU
uint32_t startCuAddr = curEncData.m_rowStat[row].numEncodedCUs;//当前CTU行最后一个编码完毕的CTU位置
if (startCuAddr)//如果当前行编码完毕一个以上CTU
{
for (uint32_t cuAddr = startCuAddr + 1 ; cuAddr < endCuAddr; cuAddr++)//遍历当前帧所有未编码的CTU
{
refRowSatdCost += refEncData.m_cuStat[cuAddr].vbvCost;//累加参考帧对应位置的CTU cost 8x8下采样
refRowBits += refEncData.m_cuStat[cuAddr].totalBits; //累加参考帧对应位置的CTU占用的bits
}
}
else//如果当前行刚编码完毕第一个CTU
{
refRowBits = refEncData.m_rowStat[row].encodedBits;//直接获取参考帧对应行的bits
refRowSatdCost = refEncData.m_rowStat[row].satdForVbv;//直接获取参考帧对应行的下采样SATD值
}
refRowSatdCost >>= X265_DEPTH - 8;//根据位宽修正
refQScale = refEncData.m_rowStat[row].diagQpScale;//获取参考帧对应的diagQP scale值
}
if (picType == I_SLICE || qScale >= refQScale)//如果当前为I帧或者 当前scale大于参考帧的scale
{
if (picType == P_SLICE
&& refFrame
&& refFrame->m_encData->m_slice->m_sliceType == picType
&& refQScale > 0
&& refRowSatdCost > 0)//如果当前帧为P帧 并且 参考帧的帧类型也是P帧 并且 参考帧qscale大于0
{
if (abs((int32_t)(refRowSatdCost - satdCostForPendingCus)) < (int32_t)satdCostForPendingCus / 2)//参考帧未编码cost 与当前帧未编码cost 差距比较小
{
double predTotal = refRowBits * satdCostForPendingCus / refRowSatdCost * refQScale / qScale;//根据参考帧的bits 预测当前未编码块的bits
totalSatdBits += (int32_t)((pred_s + predTotal) * 0.5);//累加当前行未编码CTU占用的bits 并加上预测bits
continue;
}
}
totalSatdBits += (int32_t)pred_s;//累加当前行未编码CTU占用的bits
}
else if (picType == P_SLICE)//如果是P帧
{
intraCostForPendingCus = curEncData.m_rowStat[row].intraSatdForVbv - curEncData.m_rowStat[row].diagIntraSatd;//当前行intraSATD值 减去 当前CTU行已编码CTU的对应下采样计算的intraSATD值
intraCostForPendingCus >>= X265_DEPTH - 8;//根据像素位宽修正
/* Our QP is lower than the reference! */
double pred_intra = predictSize(rce->rowPred[1], qScale, intraCostForPendingCus);//预测当前块的bits
/* Sum: better to overestimate than underestimate by using only one of the two predictors. */
totalSatdBits += (int32_t)(pred_intra + pred_s);//累加当前行未编码CTU占用的bit 以及intra估计的bits
}
else//如果是B帧
totalSatdBits += (int32_t)pred_s;//累加当前行未编码CTU占用的bits
}
}
return totalSatdBits + encodedBitsSoFar;//返回当前帧已经编码bits加上未编码预测bits
}
/** 函数功能 ： 更新predictor、根据当前编码情况估计当前帧占用的bits、计算最优qp参数值、判断是否需要重新编码
/* 调用范围 ： 只在processRowEncoder函数中被调用(只在对角线CTU进入)
* \参数 curFrame ： 当前编码帧
* \参数 row ： 当前CTU行号
* \参数 rce ： 当前帧的码率控制数据
* \参数 qpVbv ： 当前CTU对应的baseQp量化参数（更新qp存入此）
* \返回 ： 0:正常编码 -1：qp跳到过大 需要重新编码 * */
int RateControl::rowDiagonalVbvRateControl(Frame* curFrame, uint32_t row, RateControlEntry* rce, double& qpVbv)
{
//功能：更新predictor、根据当前编码情况估计当前帧占用的bits、计算最优qp参数值、判断是否需要重新编码
// 1.根据当前bits 更新predictor
// 2.设置最大最小QP 以及剩余bits
// 3.如果当前CTU行不是最后一个CTU行：根据当前编码情况估计当前帧占用的bits 计算最优qp参数值
// 否则，是最后一个CTU行 ：根据当前编码情况估计当前帧占用的bits
FrameData& curEncData = *curFrame->m_encData;//获取当前帧数据
double qScaleVbv = x265_qp2qScale(qpVbv);//将量化参数转换为qscale值
uint64_t rowSatdCost = curEncData.m_rowStat[row].diagSatd;//获取当前CTU行已编码CTU的对应下采样计算的SATD值
double encodedBits = curEncData.m_rowStat[row].encodedBits;//获取当前CTU行已经编码CTU占用的bits累加值
if (row == 1)//如果当前是第二个CTU行（从0计数所有当前是第二个CTU行）
{
rowSatdCost += curEncData.m_rowStat[0].diagSatd;//累加 第一行已编码的CTU对应下采样的SATD和
encodedBits += curEncData.m_rowStat[0].encodedBits;//累加 第一CTU行已经编码CTU占用的bits累加值
}
rowSatdCost >>= X265_DEPTH - 8;//修正当前row的SATDcost
updatePredictor(rce->rowPred[0], qScaleVbv, (double)rowSatdCost, encodedBits);//求predictor中系数的CplxSum和
if (curEncData.m_slice->m_sliceType == P_SLICE)//如果当前为P帧
{
Frame* refFrame = curEncData.m_slice->m_refPicList[0][0];//获取前向参考帧
if (qpVbv < refFrame->m_encData->m_rowStat[row].diagQp)//如果当前QP参数比参考帧QP参数小
{
uint64_t intraRowSatdCost = curEncData.m_rowStat[row].diagIntraSatd;//获取当前CTU行已编码CTU的对应下采样计算的intraSATD值
if (row == 1)//如果是第二个CTU行
intraRowSatdCost += curEncData.m_rowStat[0].diagIntraSatd;//累加第一行的intraSATD值
intraRowSatdCost >>= X265_DEPTH - 8;//修正
updatePredictor(rce->rowPred[1], qScaleVbv, (double)intraRowSatdCost, encodedBits);//求predictor中系数的CplxSum和
}
}
int canReencodeRow = 1;//表示是否可以重新编码当前行 （默认是）
/* tweak quality based on difference from predicted size */
double prevRowQp = qpVbv;//当前CTU对应的baseQp量化参数
double qpAbsoluteMax = QP_MAX_MAX;//RC控制下的最大QP 69
double qpAbsoluteMin = QP_MIN;//最小QP 0
if (m_rateFactorMaxIncrement)//如果当前是CRF模式 并且 有配置最大crf值
qpAbsoluteMax = X265_MIN(qpAbsoluteMax, rce->qpNoVbv + m_rateFactorMaxIncrement);//更新最大QP
if (m_rateFactorMaxDecrement)//如果当前是CRF模式 并且 有配置最大crf值
qpAbsoluteMin = X265_MAX(qpAbsoluteMin, rce->qpNoVbv - m_rateFactorMaxDecrement);//更新最小QP
double qpMax = X265_MIN(prevRowQp + m_param->rc.qpStep, qpAbsoluteMax);//当前最大浮动到的QP最大值
double qpMin = X265_MAX(prevRowQp - m_param->rc.qpStep, qpAbsoluteMin);//当前最大浮动到的QP最小值
double stepSize = 0.5;//QP参数缩减的步长
double bufferLeftPlanned = rce->bufferFill - rce->frameSizePlanned;//当前buffer除去当前帧预测bits还剩下的buffer大小
const SPS& sps = *curEncData.m_slice->m_sps;//获取当前的SPS
double maxFrameError = X265_MAX(0.05, 1.0 / sps.numCuInHeight);//错误因子 CTU行总数的倒数
if (row < sps.numCuInHeight - 1)//不是最后一个CTU行
{
/* More threads means we have to be more cautious in letting ratecontrol use up extra bits. */
double rcTol = bufferLeftPlanned / m_param->frameNumThreads * m_rateTolerance;//在此存储buffer剩余的空间 考虑到并行操作：除以当前的frame并行个数
int32_t encodedBitsSoFar = 0;//存储目前当前帧已经编码完毕的CTU占用bits
double accFrameBits = predictRowsSizeSum(curFrame, rce, qpVbv, encodedBitsSoFar);//计算当前帧已经编码bits加上未编码预测bits (理解为一帧预估bits)
/* * Don't increase the row QPs until a sufficent amount of the bits of
* the frame have been processed, in case a flat area at the top of the
* frame was measured inaccurately. */
if (encodedBitsSoFar < 0.05f * rce->frameSizePlanned)//如果当前已编码bits占用不够计划bits的5%
qpMax = qpAbsoluteMax = prevRowQp;//由于bits占用过少，后面可以适当增加质量 在此降低最大qP设定
if (rce->sliceType != I_SLICE || (m_param->rc.bStrictCbr && rce->poc > 0))//如果当前不是I帧 或者采用严格目标码率执行并且不是第一帧
rcTol *= 0.5;//降低剩余buffer 使当前帧占用更少的bits
if (!m_isCbr)//如果当前不是CBR模式
qpMin = X265_MAX(qpMin, rce->qpNoVbv);//最小QP 取当前QP
double totalBitsNeeded = m_wantedBitsWindow;//获取当前应该需要的bits
if (m_param->totalFrames)
totalBitsNeeded = (m_param->totalFrames * m_bitrate) / m_fps;//获取视频需要的总的bits数目
double abrOvershoot = (accFrameBits + m_totalBits - m_wantedBitsWindow) / totalBitsNeeded;//表示：当前帧超出的bits占总序列bits的比值 (预估当前帧bits + 当前已用bits - 当前应该需要的bits）/(整个视频序列需要的bits)
//当前bits占用过多 循环增加QP步长
while (qpVbv < qpMax //保证小于最大QP设定
&& (((accFrameBits > rce->frameSizePlanned + rcTol) || // 保证当前帧的预估bits 小于 计算bits加上剩余buffer大小
(rce->bufferFill - accFrameBits < bufferLeftPlanned * 0.5) || //保证只占用剩余buffer 的一半
(accFrameBits > rce->frameSizePlanned && qpVbv < rce->qpNoVbv))//当前估计bits大于实际占用bits
&& (!m_param->rc.bStrictCbr ? 1 : abrOvershoot > 0.1))) //占用bits过大
{
qpVbv += stepSize;//增加QP
accFrameBits = predictRowsSizeSum(curFrame, rce, qpVbv, encodedBitsSoFar);//计算当前帧已经编码bits加上未编码预测bits (理解为一帧预估bits)
abrOvershoot = (accFrameBits + m_totalBits - m_wantedBitsWindow) / totalBitsNeeded;//表示：当前帧超出的bits占总序列bits的比值 (预估当前帧bits + 当前已用bits - 当前应该需要的bits）/(整个视频序列需要的bits)
}
//当前bits占用过小 减小QP
while (qpVbv > qpMin //保证大于最小QP设定
&& (qpVbv > curEncData.m_rowStat[0].diagQp || m_singleFrameVbv) //当前QP过大
&& (((accFrameBits < rce->frameSizePlanned * 0.8f && qpVbv <= prevRowQp) //当前bits占用过小
|| accFrameBits < (rce->bufferFill - m_bufferSize + m_bufferRate) * 1.1)
&& (!m_param->rc.bStrictCbr ? 1 : abrOvershoot < 0)))
{
qpVbv -= stepSize;//减小QP
accFrameBits = predictRowsSizeSum(curFrame, rce, qpVbv, encodedBitsSoFar);//计算当前帧已经编码bits加上未编码预测bits (理解为一帧预估bits)
abrOvershoot = (accFrameBits + m_totalBits - m_wantedBitsWindow) / totalBitsNeeded;//表示：当前帧超出的bits占总序列bits的比值 (预估当前帧bits + 当前已用bits - 当前应该需要的bits）/(整个视频序列需要的bits)
}
if (m_param->rc.bStrictCbr && m_param->totalFrames)//如果使其更严格的按照目标码率进行编码
{
double timeDone = (double)(m_framesDone) / m_param->totalFrames;//当前已经进入过RC的帧数的比重
while (qpVbv < qpMax && (qpVbv < rce->qpNoVbv + (m_param->rc.qpStep * timeDone)) &&
(timeDone > 0.75 && abrOvershoot > 0))
{
qpVbv += stepSize;//增加QP
accFrameBits = predictRowsSizeSum(curFrame, rce, qpVbv, encodedBitsSoFar);//计算当前帧已经编码bits加上未编码预测bits (理解为一帧预估bits)
abrOvershoot = (accFrameBits + m_totalBits - m_wantedBitsWindow) / totalBitsNeeded;//表示：当前帧超出的bits占总序列bits的比值 (预估当前帧bits + 当前已用bits - 当前应该需要的bits）/(整个视频序列需要的bits)
}
if (qpVbv > curEncData.m_rowStat[0].diagQp &&
abrOvershoot < -0.1 && timeDone > 0.5 && accFrameBits < rce->frameSizePlanned - rcTol)
{
qpVbv -= stepSize;//减小QP
accFrameBits = predictRowsSizeSum(curFrame, rce, qpVbv, encodedBitsSoFar);//计算当前帧已经编码bits加上未编码预测bits (理解为一帧预估bits)
}
}
/* avoid VBV underflow or MinCr violation */
while ((qpVbv < qpAbsoluteMax)
&& ((rce->bufferFill - accFrameBits < m_bufferRate * maxFrameError) ||
(rce->frameSizeMaximum - accFrameBits < rce->frameSizeMaximum * maxFrameError)))//占用bits依然过大
{
qpVbv += stepSize;//增加QP
accFrameBits = predictRowsSizeSum(curFrame, rce, qpVbv, encodedBitsSoFar);//计算当前帧已经编码bits加上未编码预测bits (理解为一帧预估bits)
}
rce->frameSizeEstimated = accFrameBits;//获取当前帧估计的bits
/* If the current row was large enough to cause a large QP jump, try re-encoding it. */
if (qpVbv > qpMax && prevRowQp < qpMax && canReencodeRow)//如果当前QP超过设定QP值 QP波动过大
{
/* Bump QP to halfway in between... close enough. */
qpVbv = x265_clip3(prevRowQp + 1.0f, qpMax, (prevRowQp + qpVbv) * 0.5);//重设QP
return -1;//跳出 重新编码
}
if (m_param->rc.rfConstantMin)//CRF模式 有配置最小CRF值
{
if (qpVbv < qpMin && prevRowQp > qpMin && canReencodeRow)
{
qpVbv = x265_clip3(qpMin, prevRowQp, (prevRowQp + qpVbv) * 0.5);//重设QP
return -1;//跳出 重新编码
}
}
}
else
{
int32_t encodedBitsSoFar = 0;//存储目前当前帧已经编码完毕的CTU占用bits
rce->frameSizeEstimated = predictRowsSizeSum(curFrame, rce, qpVbv, encodedBitsSoFar);//计算当前帧已经编码bits加上未编码预测bits (理解为一帧预估bits)
/* Last-ditch attempt: if the last row of the frame underflowed the VBV,
* try again. */
if ((rce->frameSizeEstimated > (rce->bufferFill - m_bufferRate * maxFrameError) &&
qpVbv < qpMax && canReencodeRow)) //占用bits过大
{
qpVbv = qpMax;//重设qp
return -1;//跳出 重新编码
}
}
return 0;//正常
}
/* modify the bitrate curve from pass1 for one frame */
/** 函数功能 ： 在1pass中只在非B帧应用获取预测的qscale如果有对应zone信息对qcale进行修正、在2pass中对所有帧应用获取预测的qscale如果有对应zone信息对qcale进行修正
/* 调用范围 ： 只在initPass2()和rateEstimateQscale（只在非B帧应用）函数中被调用 注意：1pass中只在rateEstimateQscale函数中调用 2pass中只在initPass2()调用
* \参数 rce ： 码流控制数据 在initPass2()：m_rce2Pass 在rateEstimateQscale：当前编码帧的RC参数
* \参数 rateFactor ： 参数因子在initPass2()：1.0 rateFactor 在rateEstimateQscale：在非B帧中进入 CRF:m_rateFactorConstant ABR:m_wantedBitsWindow / m_cplxrSum （当前需要的总bits/（已编码bits*qscale/m_lastRceq））
* \返回 ： 返回qscale值 * */
double RateControl::getQScale(RateControlEntry *rce, double rateFactor)
{
double q;//用于存储qscale
if (m_param->rc.cuTree)//如果应用cutree
{
// Scale and units are obtained from rateNum and rateDenom for videos with fixed frame rates.
double timescale = (double)m_param->fpsDenom / (2 * m_param->fpsNum);//播放一帧时间的一半
q = pow(BASE_FRAME_DURATION / CLIP_DURATION(2 * timescale), 1 - m_param->rc.qCompress);//值：(fps/25)^(1 - m_param->rc.qCompress)
}
else
q = pow(rce->blurredComplexity, 1 - m_param->rc.qCompress);// rce->blurredComplexity = （当前非B帧及以前所有非B帧 framecost * (fps/25)的平均和） / (当前帧以前非B帧个数 + 1 )
// avoid NaN's in the Rceq
if (rce->coeffBits + rce->mvBits == 0)//很少有此情况 一般不进入 在1pass中此处rce->mvBits = 0 前面已经初始化 2pass中会有具体数据
q = m_lastQScaleFor[rce->sliceType];//选取默认qscale
else
{
m_lastRceq = q;//获取未经过加权的qscale
q /= rateFactor;//加权qscale
}
x265_zone* zone = getZone();//获取zone信息
if (zone)//如果有zone信息
{
if (zone->bForceQp)//固定qp模式
q = x265_qp2qScale(zone->qp);//获取qp对应的scale
else
q /= zone->bitrateFactor;//将当前的scale加权
}
return q;//返回qscale
}
/** 函数功能 ： 求predictor中系数的CplxSum和
/* 调用范围 ： 只在rowDiagonalVbvRateControl和RateControl::updateVbv函数中被调用
* \参数 p ： 在rowDiagonalVbvRateControl：rowPred[0] 和 rowPred[1] 在RateControl::updateVbv：m_pred[predType]
* \参数 q ： 在rowDiagonalVbvRateControl：qscale值 在RateControl::updateVbv：rce->qpaRc
* \参数 var ： 在rowDiagonalVbvRateControl：当前row已编码CTU的对应下采样SATD值的累加和 在RateControl::updateVbv：当前帧的SATD值 framecost
* \参数 bits ： 在rowDiagonalVbvRateControl：当前row已编码CTU占用bits的累加和 在RateControl::updateVbv：当前帧编码占用的实际bits
* \返回 ： null * */
void RateControl::updatePredictor(Predictor *p, double q, double var, double bits)
{
if (var < 10) //小采样cost太小 无须更新
return;
const double range = 2;//用于clip的返回
double old_coeff = p->coeff / p->count;//获取先前predictor中coeff的平均值
double new_coeff = bits * q / var;//用当前编码的实际bits 估计原先占用的系数为多少
double new_coeff_clipped = x265_clip3(old_coeff / range, old_coeff * range, new_coeff);//clip操作，使当前coeff与 先前coeff不能差距过大
double new_offset = bits * q - new_coeff_clipped * var;//求最新offset new coeff与clip coeff之间的差距
if (new_offset >= 0)//new coeff比clip结果大
new_coeff = new_coeff_clipped;//更新为clip结果
else
new_offset = 0;//new coeff比clip结果小，直接取offset为0
p->count *= p->decay;//先前count 乘以0.5
p->coeff *= p->decay;//先前coeff 乘以0.5
p->offset *= p->decay;//先前offset 乘以0.5
p->count++;//更新当前count个数
p->coeff += new_coeff;//更新最新coeff和
p->offset += new_offset;//更新最新offset和
}
/** 函数功能 ： 更新帧predictor并且更新当前最新的VBVbuffer
/* 调用范围 ： 只在rateControlEnd函数中被调用
* \参数 bits ： 当前帧编码完毕占用的实际bits数目
* \参数 rce ： 当前帧码率控制数据
* \返回 ： null * */
void RateControl::updateVbv(int64_t bits, RateControlEntry* rce)
{
int predType = rce->sliceType;//获取当前的slice类型 B_SLICE,P_SLICE,I_SLICE
predType = rce->sliceType == B_SLICE && rce->keptAsRef ? 3 : predType;//获取标号 用于predictor
if (rce->lastSatd >= m_ncu && rce->encodeOrder >= m_lastPredictorReset)
updatePredictor(&m_pred[predType], x265_qp2qScale(rce->qpaRc), (double)rce->lastSatd, (double)bits);//？？？
if (!m_isVbv)//如果不应用VBV
return;
m_bufferFillFinal -= bits;//当前预设bufferbits 减去当前帧的bits
if (m_bufferFillFinal < 0)//如果当前预设buffer不够 输出警告信息
x265_log(m_param, X265_LOG_WARNING, "poc:%d, VBV underflow (%.0f bits)\n", rce->poc, m_bufferFillFinal);
m_bufferFillFinal = X265_MAX(m_bufferFillFinal, 0);//clip操作 防止为负数
m_bufferFillFinal += m_bufferRate;//加上新的一帧最大占用的bits
m_bufferFillFinal = X265_MIN(m_bufferFillFinal, m_bufferSize);//防止溢出 不能超过最大的bits数目
}
/* After encoding one frame, update rate control state */
/** 函数功能 ： ？？？计算估计当前帧应用的量化参数
/* 调用范围 ： 只在FrameEncoder::compressFrame()函数中被调用
* \参数 curFrame ： 当前编码帧
* \参数 bits ： 当前帧编码完毕占用的总bits数目
* \参数 rce ： 当前帧的RC编码参数类
* \返回 ： 只会返回0 表示正常结束 * */
int RateControl::rateControlEnd(Frame* curFrame, int64_t bits, RateControlEntry* rce)
{
//功能：？？？
// 1. 等待触发（使RC按顺序进入）
// 2. 统计QP信息
// 3. 更新bits相关数据结构
// 4. ？？？
int orderValue = m_startEndOrder.get();//获取RC线程控制数据
int endOrdinal = (rce->encodeOrder + m_param->frameNumThreads) * 2 - 1;//执行End触发条件
while (orderValue < endOrdinal && !m_bTerminated)//循环等待
{
/* no more frames are being encoded, so fake the start event if we would
* have blocked on it. Note that this does not enforce rateControlEnd()
* ordering during flush, but this has no impact on the outputs */
if (m_finalFrameCount && orderValue >= 2 * m_finalFrameCount)//在读取全部帧时的执行End触发条件
break;
orderValue = m_startEndOrder.waitForChange(orderValue);//一直等待数据改变
}
FrameData& curEncData = *curFrame->m_encData;//获取编码帧数据
int64_t actualBits = bits;//获取当前帧实际编码bits
Slice *slice = curEncData.m_slice;//获取当前slice
if (m_param->rc.aqMode || m_isVbv)//如若应用自适应量化 或者应用VBV
{
if (m_isVbv)//如果应用VBV
{
/* determine avg QP decided by VBV rate control */
for (uint32_t i = 0; i < slice->m_sps->numCuInHeight; i++)
curEncData.m_avgQpRc += curEncData.m_rowStat[i].sumQpRc; //累加当前帧所有CTU行的sumQpRc和
curEncData.m_avgQpRc /= slice->m_sps->numCUsInFrame;//获取平均值
rce->qpaRc = curEncData.m_avgQpRc;//获取平均QP
}
if (m_param->rc.aqMode)//如果应用自适应量化
{
/* determine actual avg encoded QP, after AQ/cutree adjustments */
for (uint32_t i = 0; i < slice->m_sps->numCuInHeight; i++)//遍历CTU行
curEncData.m_avgQpAq += curEncData.m_rowStat[i].sumQpAq;//累加所有CTU行 CU的mqp
curEncData.m_avgQpAq /= (slice->m_sps->numCUsInFrame * NUM_4x4_PARTITIONS);//求平均值
}
else
curEncData.m_avgQpAq = curEncData.m_avgQpRc;//获取VBVqp值
}
if (m_isAbr)//如果应用ABR
{
if (m_param->rc.rateControlMode == X265_RC_ABR && !m_param->rc.bStatRead)//如果应用ABR并且当前不是2pass读情况
checkAndResetABR(rce, true);//用于关闭前面重置的标志位
if (m_param->rc.rateControlMode == X265_RC_CRF)//如果应用CRF模式
{
if (int(curEncData.m_avgQpRc + 0.5) == slice->m_sliceQp)
curEncData.m_rateFactor = m_rateFactorConstant;//获取相应值
else
{
/* If vbv changed the frame QP recalculate the rate-factor */
double baseCplx = m_ncu * (m_param->bframes ? 120 : 80);
double mbtree_offset = m_param->rc.cuTree ? (1.0 - m_param->rc.qCompress) * 13.5 : 0;
curEncData.m_rateFactor = pow(baseCplx, 1 - m_qCompress) /
x265_qp2qScale(int(curEncData.m_avgQpRc + 0.5) + mbtree_offset);//重新计算
}
}
}
if (m_isAbr && !m_isAbrReset)//如果应用ABR 并且 没有重置过
{
/* amortize part of each I slice over the next several frames, up to
* keyint-max, to avoid over-compensating for the large I slice cost */
if (!m_param->rc.bStatWrite && !m_param->rc.bStatRead)//不使用多pass结构
{
if (rce->sliceType == I_SLICE)//如果当前为I帧
{
/* previous I still had a residual; roll it into the new loan */
if (m_residualFrames)//如果有剩余分摊帧数
bits += m_residualCost * m_residualFrames;//当前bits加上剩余均摊cost
m_residualFrames = X265_MIN((int)rce->amortizeFrames, m_param->keyframeMax);//确定当前分摊帧数
m_residualCost = (int)((bits * rce->amortizeFraction) / m_residualFrames);//剩余帧分摊bits占用的平均cost
bits -= m_residualCost * m_residualFrames;
}
else if (m_residualFrames)//非I帧 并且有剩余分摊帧数
{
bits += m_residualCost;//当前bits加上平均均摊cost
m_residualFrames--;//均摊帧数减一
}
}
if (rce->sliceType != B_SLICE)//如果是非B帧
{
/* The factor 1.5 is to tune up the actual bits, otherwise the cplxrSum is scaled too low
* to improve short term compensation for next frame. */
m_cplxrSum += (bits * x265_qp2qScale(rce->qpaRc) / rce->qRceq) - (rce->rowCplxrSum);//获取一帧的bits*qscale值
}
else
{
/* Depends on the fact that B-frame's QP is an offset from the following P-frame's.
* Not perfectly accurate with B-refs, but good enough. */
m_cplxrSum += (bits * x265_qp2qScale(rce->qpaRc) / (rce->qRceq * fabs(m_param->rc.pbFactor))) - (rce->rowCplxrSum);//获取一帧的bits*qscale值
}
m_wantedBitsWindow += m_frameDuration * m_bitrate;//累加当前需要的bits
m_totalBits += bits - rce->rowTotalBits;//累加当前RC占用的bits（扣除前面累加的rowcount行占用的bits）
m_encodedBits += actualBits;//累加实际占用bits
int pos = m_sliderPos - m_param->frameNumThreads;//获取滑动窗口下标
if (pos >= 0)
m_encodedBitsWindow[pos % s_slidingWindowFrames] = actualBits;//滑动窗口获取实际bits
}
if (m_2pass)//如果当前处在2pass ？？？？
{
m_expectedBitsSum += qScale2bits(rce, x265_qp2qScale(rce->newQp));
m_totalBits += bits - rce->rowTotalBits;
}
if (m_isVbv)//应用VBV
{
updateVbv(actualBits, rce);//更新帧predictor并且更新当前最新的VBVbuffer
if (m_param->bEmitHRDSEI)//？？？？
{
const VUI *vui = &curEncData.m_slice->m_sps->vuiParameters;
const HRDInfo *hrd = &vui->hrdParameters;
const TimingInfo *time = &vui->timingInfo;
if (!curFrame->m_poc)
{
// first access unit initializes the HRD
rce->hrdTiming->cpbInitialAT = 0;
rce->hrdTiming->cpbRemovalTime = m_nominalRemovalTime = (double)m_bufPeriodSEI.m_initialCpbRemovalDelay / 90000;
}
else
{
rce->hrdTiming->cpbRemovalTime = m_nominalRemovalTime + (double)rce->picTimingSEI->m_auCpbRemovalDelay * time->numUnitsInTick / time->timeScale;
double cpbEarliestAT = rce->hrdTiming->cpbRemovalTime - (double)m_bufPeriodSEI.m_initialCpbRemovalDelay / 90000;
if (!curFrame->m_lowres.bKeyframe)
cpbEarliestAT -= (double)m_bufPeriodSEI.m_initialCpbRemovalDelayOffset / 90000;
rce->hrdTiming->cpbInitialAT = hrd->cbrFlag ? m_prevCpbFinalAT : X265_MAX(m_prevCpbFinalAT, cpbEarliestAT);
}
uint32_t cpbsizeUnscale = hrd->cpbSizeValue << (hrd->cpbSizeScale + CPB_SHIFT);
rce->hrdTiming->cpbFinalAT = m_prevCpbFinalAT = rce->hrdTiming->cpbInitialAT + actualBits / cpbsizeUnscale;
rce->hrdTiming->dpbOutputTime = (double)rce->picTimingSEI->m_picDpbOutputDelay * time->numUnitsInTick / time->timeScale + rce->hrdTiming->cpbRemovalTime;
}
}
rce->isActive = false;//设置当前帧已经确定好QP值
// Allow rateControlStart of next frame only when rateControlEnd of previous frame is over
m_startEndOrder.incr();//控制RC 线程数据 加加
return 0;//返回0 表示正常结束
}
/* called to write out the rate control frame stats info in multipass encodes */
int RateControl::writeRateControlFrameStats(Frame* curFrame, RateControlEntry* rce)
{
FrameData& curEncData = *curFrame->m_encData;
char cType = rce->sliceType == I_SLICE ? (rce->poc > 0 && m_param->bOpenGOP ? 'i' : 'I')
: rce->sliceType == P_SLICE ? 'P'
: IS_REFERENCED(curFrame) ? 'B' : 'b';
if (fprintf(m_statFileOut,
"in:%d out:%d type:%c q:%.2f q-aq:%.2f tex:%d mv:%d misc:%d icu:%.2f pcu:%.2f scu:%.2f ;\n",
rce->poc, rce->encodeOrder,
cType, curEncData.m_avgQpRc, curEncData.m_avgQpAq,
curFrame->m_encData->m_frameStats.coeffBits,
curFrame->m_encData->m_frameStats.mvBits,
curFrame->m_encData->m_frameStats.miscBits,
curFrame->m_encData->m_frameStats.percent8x8Intra * m_ncu,
curFrame->m_encData->m_frameStats.percent8x8Inter * m_ncu,
curFrame->m_encData->m_frameStats.percent8x8Skip * m_ncu) < 0)
goto writeFailure;
/* Don't re-write the data in multi-pass mode. */
if (m_param->rc.cuTree && IS_REFERENCED(curFrame) && !m_param->rc.bStatRead)
{
uint8_t sliceType = (uint8_t)rce->sliceType;
for (int i = 0; i < m_ncu; i++)
m_cuTreeStats.qpBuffer[0][i] = (uint16_t)(curFrame->m_lowres.qpCuTreeOffset[i] * 256.0);
if (fwrite(&sliceType, 1, 1, m_cutreeStatFileOut) < 1)
goto writeFailure;
if (fwrite(m_cuTreeStats.qpBuffer[0], sizeof(uint16_t), m_ncu, m_cutreeStatFileOut) < (size_t)m_ncu)
goto writeFailure;
}
return 0;
writeFailure:
x265_log(m_param, X265_LOG_ERROR, "RatecontrolEnd: stats file write failure\n");
return 1;
}
#if defined(_MSC_VER)
#pragma warning(disable: 4996) // POSIX function names are just fine, thank you
#endif
/* called when the encoder is flushing, and thus the final frame count is
* unambiguously known */
void RateControl::setFinalFrameCount(int count)
{
m_finalFrameCount = count;
/* unblock waiting threads */
m_startEndOrder.poke();
}
/* called when the encoder is closing, and no more frames will be output.
* all blocked functions must finish so the frame encoder threads can be
* closed */
void RateControl::terminate()
{
m_bTerminated = true;
/* unblock waiting threads */
m_startEndOrder.poke();
}
void RateControl::destroy()
{
const char *fileName = m_param->rc.statFileName;
if (!fileName)
fileName = s_defaultStatFileName;
if (m_statFileOut)
{
fclose(m_statFileOut);
char *tmpFileName = strcatFilename(fileName, ".temp");
int bError = 1;
if (tmpFileName)
{
unlink(fileName);
bError = rename(tmpFileName, fileName);
}
if (bError)
{
x265_log(m_param, X265_LOG_ERROR, "failed to rename output stats file to \"%s\"\n",
fileName);
}
X265_FREE(tmpFileName);
}
if (m_cutreeStatFileOut)
{
fclose(m_cutreeStatFileOut);
char *tmpFileName = strcatFilename(fileName, ".cutree.temp");
char *newFileName = strcatFilename(fileName, ".cutree");
int bError = 1;
if (tmpFileName && newFileName)
{
unlink(newFileName);
bError = rename(tmpFileName, newFileName);
}
if (bError)
{
x265_log(m_param, X265_LOG_ERROR, "failed to rename cutree output stats file to \"%s\"\n",
newFileName);
}
X265_FREE(tmpFileName);
X265_FREE(newFileName);
}
if (m_cutreeStatFileIn)
fclose(m_cutreeStatFileIn);
X265_FREE(m_rce2Pass);
for (int i = 0; i < 2; i++)
X265_FREE(m_cuTreeStats.qpBuffer[i]);
X265_FREE(m_param->rc.zones);
}
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