x265-1.7版本-encoder/encoder.h注释

最新推荐文章于 2024-03-12 14:31:51 发布
原创最新推荐文章于 2024-03-12 14:31:51 发布 · 1.2w 阅读
0 ·
CC 4.0 BY-SA版权
x265代码注释专栏收录该内容
74 篇文章
订阅专栏
本文详细解析了x265编码器的源码结构，包括其内部类和函数的作用，以及如何实现高效的视频编码过程。重点介绍了熵编码、帧编码、动态图片缓冲区、预测算法和比特率控制等关键组件。
注：问号以及未注释部分会在x265-1.8版本内更新
/*****************************************************************************
 * Copyright (C) 2013 x265 project
 *
 * Authors: Steve Borho <steve@borho.org>
 *
 * 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.
 *****************************************************************************/

#ifndef X265_ENCODER_H
#define X265_ENCODER_H

#include "common.h"
#include "slice.h"
#include "scalinglist.h"
#include "x265.h"
#include "nal.h"

struct x265_encoder {};

namespace x265 {
// private namespace
extern const char g_sliceTypeToChar[3];

class Entropy;

struct EncStats
{
    double        m_psnrSumY;
    double        m_psnrSumU;
    double        m_psnrSumV;
    double        m_globalSsim;
    double        m_totalQp;
    uint64_t      m_accBits;
    uint32_t      m_numPics;

    EncStats()
    {
        m_psnrSumY = m_psnrSumU = m_psnrSumV = m_globalSsim = 0;
        m_accBits = 0;
        m_numPics = 0;
        m_totalQp = 0;
    }

    void addQP(double aveQp);

    void addPsnr(double psnrY, double psnrU, double psnrV);

    void addBits(uint64_t bits);

    void addSsim(double ssim);
};

class FrameEncoder;
class DPB;
class Lookahead;
class RateControl;
class ThreadPool;

class Encoder : public x265_encoder
{
public:

    int                m_pocLast;         // 当前已经读入的视频帧数（从0开始计数，初始化为-1）time index (POC)
    int                m_encodedFrameNum; // 计数当前编码的帧数 （从1开始计数）
    int                m_outputCount;

    int                m_bframeDelay;//延迟帧数：p->bframes ? (p->bBPyramid ? 2 : 1) : 0;  一般等于2
    int64_t            m_firstPts;  //第一帧，其值等于最先进入的pts号(一般等于0)
    int64_t            m_bframeDelayTime;//延迟的pts号个数 一般等于2
    int64_t            m_prevReorderedPts[2];//存储前两帧的PTS，用于计算DTS

    ThreadPool*        m_threadPool;
    FrameEncoder*      m_frameEncoder[X265_MAX_FRAME_THREADS];//存储frame并行的个数，用于帧级编码的多线程
    DPB*               m_dpb;

    Frame*             m_exportedPic;

    int                m_numPools;
    int                m_curEncoder;//记录当前是哪个FrmaeEncoder，每完成一个m_curEncoder = (m_curEncoder + 1) % m_param->frameNumThreads;

    /* cached PicYuv offset arrays, shared by all instances of
     * PicYuv created by this encoder */
    //当前只为指针，其存储空间在某一个frame的m_fencPic中，整个空间在编码器中只申请一次
    /*如：一幅图像416x240 总过有7x4个LCU 
    m_cuOffsetY[0] = 0 m_cuOffsetY[1] = 64 m_cuOffsetY[2]= 128 m_cuOffsetY[7] = 40960 = 640*64 (640是步长含有扩边值)
    m_cuOffsetC[0] = 0 m_cuOffsetC[1] = 32 m_cuOffsetC[2]= 64  m_cuOffsetC[7] = 13312 = 416*64 (416是步长含有扩边值)
    m_buOffsetY[0] = 0 m_buOffsetY[1] =  4 m_buOffsetY[2]= 2560 (按照4x4块计算 zigzag排序  2560 = 640*4)
    m_buOffsetC[0] = 0 m_buOffsetC[1] =  2 m_buOffsetY[2]= 832 (按照2x2块计算 zigzag排序   832  = 416*2)
    **/   
    intptr_t*          m_cuOffsetY; //申请空间为一帧LCU个数，按照行列对应亮度LCU的pixel地址
    intptr_t*          m_cuOffsetC; //申请空间为一帧LCU个数，按照行列对应色度LCU的pixel地址
    intptr_t*          m_buOffsetY; //申请空间为一个LCU的part个数（默认256个4x4），为当前亮度位置与LCU首地址的偏移地址 （按照zigzag4x4排序）
    intptr_t*          m_buOffsetC; //申请空间为一个LCU的part个数（默认256个4x4），为当前色度位置与LCU首地址的偏移地址 （按照zigzag2x2排序）

    /* Collect statistics globally */
    EncStats           m_analyzeAll;
    EncStats           m_analyzeI;
    EncStats           m_analyzeP;
    EncStats           m_analyzeB;
    FILE*              m_csvfpt;
    int64_t            m_encodeStartTime;

    // weighted prediction
    int                m_numLumaWPFrames;    // number of P frames with weighted luma reference
    int                m_numChromaWPFrames;  // number of P frames with weighted chroma reference
    int                m_numLumaWPBiFrames;  // number of B frames with weighted luma reference
    int                m_numChromaWPBiFrames; // number of B frames with weighted chroma reference
    FILE*              m_analysisFile;
    int                m_conformanceMode;
    VPS                m_vps;
    SPS                m_sps;
    PPS                m_pps;
    NALList            m_nalList;
    ScalingList        m_scalingList;      // quantization matrix information

    int                m_lastBPSEI;
    uint32_t           m_numDelayedPic;//当前列表中有多少帧未编码 每当读入一帧++，每当编码完毕一帧减--

    x265_param*        m_param;
    x265_param*        m_latestParam;
    RateControl*       m_rateControl;
    Lookahead*         m_lookahead;    //用于帧类型决策以及framecost计算
    Window             m_conformanceWindow;

    bool               m_bZeroLatency;     // x265_encoder_encode() returns NALs for the input picture, zero lag
    bool               m_aborted;          // 用于检错处理，出错（如内存申请失败等）置为true  初始化为false fatal error detected
    bool               m_reconfigured;      // reconfigure of encoder detected

    Encoder();
    ~Encoder() {}

    void create();
    void stopJobs();
    void destroy();

    int encode(const x265_picture* pic, x265_picture *pic_out);

    int reconfigureParam(x265_param* encParam, x265_param* param);

    void getStreamHeaders(NALList& list, Entropy& sbacCoder, Bitstream& bs);

    void fetchStats(x265_stats* stats, size_t statsSizeBytes);

    void writeLog(int argc, char **argv);

    void printSummary();

    char* statsString(EncStats&, char*);

    char* statsCSVString(EncStats& stat, char* buffer);

    void configure(x265_param *param);

    void updateVbvPlan(RateControl* rc);

    void allocAnalysis(x265_analysis_data* analysis);

    void freeAnalysis(x265_analysis_data* analysis);

    void readAnalysisFile(x265_analysis_data* analysis, int poc);

    void writeAnalysisFile(x265_analysis_data* pic);

    void finishFrameStats(Frame* pic, FrameEncoder *curEncoder, uint64_t bits);

protected:

    void initVPS(VPS *vps);
    void initSPS(SPS *sps);
    void initPPS(PPS *pps);
};
}

#endif // ifndef X265_ENCODER_H