王纲文件分隔

#ifndef PCH_H
#define PCH_H
extern "C"
{
    #include "libavutil/opt.h"
    #include "libavutil/channel_layout.h"
    #include "libavutil/common.h"
    #include "libavutil/imgutils.h"
    #include "libavutil/mathematics.h"
    #include "libavutil/samplefmt.h"
    #include "libavutil/time.h"
    #include "libavutil/fifo.h"
    #include "libavcodec/avcodec.h"
    #include "libavformat/avformat.h"
    #include "libavformat/avio.h"
    //#include "libavfilter/avfiltergraph.h"
    #include "libavfilter/avfilter.h"
    #include "libavfilter/buffersink.h"
    #include "libavfilter/buffersrc.h"
    #include "libswscale/swscale.h"
    #include "libswresample/swresample.h"
}
#endif

// CGFileCut.cpp : 定义控制台应用程序的入口点。
//
/* Copyright [c] 2017-2027 By Gang.Wang Allrights Reserved 
   This file give a simple example of how to cut video file.
   Any questions, you can join QQ group for help, QQ
   Group number:127903734.
*/
//#include "stdafx.h"
#include <string>
#include <memory>
#include <thread>
#include <iostream>
using namespace std;
#include "pch.h"

AVFormatContext *inputContext = nullptr;
AVFormatContext * outputContext;
int64_t lastReadPacktTime ;

static int interrupt_cb(void *ctx)
{
    int  timeout  = 3;
    if(av_gettime() - lastReadPacktTime > timeout *1000 *1000)
    {
        return -1;
    }
    return 0;
}

int OpenInput(string inputUrl)
{
    inputContext = avformat_alloc_context();    
    lastReadPacktTime = av_gettime();
    inputContext->interrupt_callback.callback = interrupt_cb;
    int ret = avformat_open_input(&inputContext, inputUrl.c_str(), nullptr,nullptr);
    if(ret < 0)
    {
        av_log(NULL, AV_LOG_ERROR, "Input file open input failed\n");
        return  ret;
    }
    ret = avformat_find_stream_info(inputContext,nullptr);
    if(ret < 0)
    {
        av_log(NULL, AV_LOG_ERROR, "Find input file stream inform failed\n");
    }
    else
    {
        av_log(NULL, AV_LOG_FATAL, "Open input file  %s success\n",inputUrl.c_str());
    }
    return ret;
}


shared_ptr<AVPacket> ReadPacketFromSource()
{
    shared_ptr<AVPacket> packet(static_cast<AVPacket*>(av_malloc(sizeof(AVPacket))), [&](AVPacket *p) { av_packet_free(&p); av_freep(&p);});
    av_init_packet(packet.get());
    lastReadPacktTime = av_gettime();
    int ret = av_read_frame(inputContext, packet.get());
    if(ret >= 0)
    {
        return packet;
    }
    else
    {
        return nullptr;
    }
}

int OpenOutput(string outUrl)
{

    int ret  = avformat_alloc_output_context2(&outputContext, nullptr, "flv", outUrl.c_str());
    if(ret < 0)
    {
        av_log(NULL, AV_LOG_ERROR, "open output context failed\n");
        goto Error;
    }

    ret = avio_open2(&outputContext->pb, outUrl.c_str(), AVIO_FLAG_WRITE,nullptr, nullptr);    
    if(ret < 0)
    {
        av_log(NULL, AV_LOG_ERROR, "open avio failed");
        goto Error;
    }

    for(int i = 0; i < inputContext->nb_streams; i++)
    {
        AVStream * stream = avformat_new_stream(outputContext, inputContext->streams[i]->codec->codec);                
        ret = avcodec_copy_context(stream->codec, inputContext->streams[i]->codec);    
        if(ret < 0)
        {
            av_log(NULL, AV_LOG_ERROR, "copy coddec context failed");
            goto Error;
        }
    }

    ret = avformat_write_header(outputContext, nullptr);
    if(ret < 0)
    {
        av_log(NULL, AV_LOG_ERROR, "format write header failed");
        goto Error;
    }

    av_log(NULL, AV_LOG_FATAL, " Open output file success %s\n",outUrl.c_str());            
    return ret ;
Error:
    if(outputContext)
    {
        for(int i = 0; i < outputContext->nb_streams; i++)
        {
            avcodec_close(outputContext->streams[i]->codec);
        }
        avformat_close_input(&outputContext);
    }
    return ret ;
}

void Init()
{
    av_register_all();
    avfilter_register_all();
    avformat_network_init();
    av_log_set_level(AV_LOG_ERROR);
}

void CloseInput()
{
    if(inputContext != nullptr)
    {
        avformat_close_input(&inputContext);
    }
}

void CloseOutput()
{
    if(outputContext != nullptr)
    {
        for(int i = 0 ; i < outputContext->nb_streams; i++)
        {
            AVCodecContext *codecContext = outputContext->streams[i]->codec;
            avcodec_close(codecContext);
        }
        avformat_close_input(&outputContext);
    }
}

int WritePacket(shared_ptr<AVPacket> packet)
{
    auto inputStream = inputContext->streams[packet->stream_index];
    auto outputStream = outputContext->streams[packet->stream_index];                
    return av_interleaved_write_frame(outputContext, packet.get());
}

int main(int argc, char* argv[])
{
    //第20S开始，去掉8S
    int startPacketNum = 500;
     int  discardtPacketNum = 200;
     int packetCount = 0;
     int64_t lastPacketPts  = AV_NOPTS_VALUE;
     int64_t lastPts  = AV_NOPTS_VALUE;
    Init();
    int ret = OpenInput("D:\\test.flv");
    if(ret >= 0)
    {
        ret = OpenOutput("D:\\out1.flv"); 
    }
    if(ret <0) goto Error;
     while(true)
     {
        auto packet = ReadPacketFromSource();
        if(packet)
        {
            packetCount++;
            if(packetCount <= 500 || packetCount >= 700)
            {
                if(packetCount >= 700)
                {
                    if(packet->pts - lastPacketPts > 120)
                    {
                        lastPts = lastPacketPts ;
                    }
                    else
                    {
                        auto diff = packet->pts - lastPacketPts;
                        lastPts += diff; 
                    }
                }
                lastPacketPts = packet->pts;
                if(lastPts != AV_NOPTS_VALUE)
                {
                    packet->pts = packet->dts = lastPts;
                }
                ret = WritePacket(packet);
            }
        }
        else
        {
            break;
        }
     }
     cout <<"Cut File End "<<endl;
    Error:
    CloseInput();
    CloseOutput();
    while(true)
    {
        this_thread::sleep_for(chrono::seconds(100));
    }
    return 0;
}