分别从封装格式为mp4、flv、ts文件中提取出AVC(h264)并写入文件

/*****************************************************************//*** \file   WriteAVC.cpp* \brief  提取视频中的视频流，写入为AVC(h264)文件* * \author 13648* \date   April 2024*********************************************************************/
#define _CRT_SECURE_NO_WARNINGS
#include "myLog.h"
#include <iostream>extern "C"
{
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavcodec/bsf.h>
}#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avcodec.lib")/*** 由于h264有两种格式，一种mp4格式（不带startcode，sps，pps信息）一种annexb格式（带startcode，sps、pps信息）* 但是大多数的编解码器只支持annexb格式pkt数据，* 因此在处理mp4或者flv格式的文件时需要使用h264_mp4toannexb比特流过滤器处理*/
int main()
{AVFormatContext* ifmt_ctx = NULL;const std::string in_filename = "./MediaFile/input_5s.flv";		// input_5s.flv input_5s.tsint nRet = avformat_open_input(&ifmt_ctx, in_filename.c_str(), NULL, NULL);if (nRet != 0){LOG_WARNING("avformat_open_input error\n");return -1;}nRet = avformat_find_stream_info(ifmt_ctx, NULL);if (nRet < 0){LOG_WARNING("avformat_find_stream_info faild\n");avformat_close_input(&ifmt_ctx);return -2;}int video_idx = av_find_best_stream(ifmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);if (video_idx < 0){LOG_WARNING("avformat_find_stream_info faild\n");avformat_close_input(&ifmt_ctx);return -3;}const std::string out_filename = "./MediaFile/input_5s.h264";FILE* out_fp = fopen(out_filename.c_str(), "wb");if (!out_fp){LOG_WARNING("open out_filename faild\n");avformat_close_input(&ifmt_ctx);return -4;}// 获取比特流过滤器const AVBitStreamFilter* bsfilter = av_bsf_get_by_name("h264_mp4toannexb");AVBSFContext* bsf_ctx = NULL;// 初始化比特流过滤器av_bsf_alloc(bsfilter, &bsf_ctx);// 给过滤器上下文添加解码器属性avcodec_parameters_copy(bsf_ctx->par_in, ifmt_ctx->streams[video_idx]->codecpar);av_bsf_init(bsf_ctx);AVPacket* pkt = av_packet_alloc();pkt->data = NULL;pkt->size = 0;while (true){nRet = av_read_frame(ifmt_ctx, pkt);if (nRet < 0){LOG_WARNING("av_read_frame file finish\n");break;}if (nRet == 0 && pkt->stream_index == video_idx){
#if 1if (av_bsf_send_packet(bsf_ctx, pkt) != 0)	// 发送包到比特流过滤器添加startcode、sps、pps信息{av_packet_unref(pkt);continue;}av_packet_unref(pkt);				// 清除，下面使用这个pkt接收bsf处理后的包while (av_bsf_receive_packet(bsf_ctx, pkt) == 0)	// 添加sps pps后可能不止一个包{size_t writeLen = fwrite(pkt->data, 1, pkt->size, out_fp);if (writeLen != pkt->size){LOG_WARNING("write pkt error\n");}fflush(out_fp);av_packet_unref(pkt);}
#else// 如果是ts流(自带sps pps信息,可以直接写入)size_t writeLen = fwrite(pkt->data, 1, pkt->size, out_fp);if (writeLen != pkt->size){LOG_WARNING("fwrite pkt error\n");}av_packet_unref(pkt);
#endif}else if(nRet == 0) {av_packet_unref(pkt);}}if (pkt){av_packet_free(&pkt);}if (out_fp){fclose(out_fp);}if (bsf_ctx){av_bsf_free(&bsf_ctx);}if (ifmt_ctx){avformat_close_input(&ifmt_ctx);}return 0;
}