12、FFMPEG学习笔记记录之视频格编码

基本思想:记录学习夏曹俊ffmpeg基本函数使用,window11+clion_mingw+ffmpeg库，基本函数使用和yuv编码h264

cmakelists.txt

cmake_minimum_required(VERSION 3.16)
project(untitled1)
find_package(OpenCV REQUIRED)
set(CMAKE_CXX_STANDARD 14)


add_executable(untitled1 main.cpp)
target_link_libraries(untitled1
        ${OpenCV_LIBS}
        -lavformat -lavcodec -lswscale -lavutil -lz
        )

mian.cpp

#include <iostream>
#include <vector>
#include <opencv2/highgui.hpp>
#include <opencv2/video.hpp>
#include <opencv2/opencv.hpp>

extern "C"
{
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavutil/imgutils.h>
#include <libswscale/swscale.h>
#include <libavutil/avutil.h>
}
#include "fstream"
using namespace std;
using namespace cv;

int main() {

    string filename="1920_1080_generate_min.h264";
    ofstream ofs;
    ofs.open(filename,ios::binary);

  //寻找编码器
    auto codec=avcodec_find_encoder(AV_CODEC_ID_H264);
    if(!codec){
        cerr<<"find avcodec fail "<<endl;
        return -1;
    }
    //　编码上下文
    auto c=avcodec_alloc_context3(codec);
    if(!c){
        cerr<<"find avcodetext fail"<<endl;
        return -1;
    }

    //设定上下文参数
    c->width=1920;
    c->height=1080;
    c->time_base={1,25};
    c->pix_fmt=AV_PIX_FMT_YUV420P; //指定原数据像素格式，于编码相关
    c->thread_count=16;
    //打开编码上下文
    int ret=avcodec_open2(c,codec,NULL);
     if(ret){
         char buf[1024]={0};
         av_strerror(ret,buf,sizeof(buf)-1);
         cerr<<buf<<endl;
         return -1;
     }
    auto frame=av_frame_alloc();
    frame->width=c->width;
    frame->height=c->height;
    frame->format=c->pix_fmt;
    ret=av_frame_get_buffer(frame,0);
    if(ret){
        char buf[1024]={0};
        av_strerror(ret,buf,sizeof(buf)-1);
        cerr<<buf<<endl;
        return -1;
    }

    auto packet=av_packet_alloc();

    for(int i=0;i<250;i++){
        //生成yvv数据
        for(int y=0;y<c->height;y++){
            for(int x=0;x<c->width;x++){
                frame->data[0][y*frame->linesize[0]+x]=x+y+i*3;
            }
        }

        for(int y=0;y<c->height/2;y++){
            for(int x=0;x<c->width/2;x++){
                frame->data[1][y*frame->linesize[1]+x]=128+y+i*2;
                frame->data[2][y*frame->linesize[2]+x]=64+x+i*5;
            }
        }
        frame->pts=i;
        //10秒视频 发送未压缩帧到线程中
        ret= avcodec_send_frame(c,frame);
        if(ret){
            char buf[1024]={0};
            av_strerror(ret,buf,sizeof(buf)-1);
            cerr<<buf<<endl;
            return -1;
        }

        while(ret>=0){//一个frame可以返回多个packet
           ret= avcodec_receive_packet(c,packet);
           if(ret==AVERROR(EAGAIN)||ret==AVERROR_EOF){
               break;
           }
            if(ret){
                char buf[1024]={0};
                av_strerror(ret,buf,sizeof(buf)-1);
                cerr<<buf<<endl;
                return -1;
            }

            ofs.write((char*)packet->data,packet->size);
            av_packet_unref(packet);
        }


    }

ofs.close();
   av_packet_free(&packet);
    av_frame_free(&frame);

    avcodec_free_context(&c);

     //编码
    return 0;
}