使用ffmpeg将h264视频文件转Mp4格式保存

其实具体的代码ffmpeg的官方demo做的功能已经很完善了，自己也就修修补补，下面直接上代码

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <tchar.h>

//这里是个坑，不加extern "C"，死活编译不过
extern "C"
{
	#include "libavformat/avformat.h"
};


using namespace std;



 
int _tmain(int argc, _TCHAR* argv[])
{
	AVOutputFormat *ofmt = NULL;
	//创建输入AVFormatContext对象和输出AVFormatContext对象
	AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
	AVPacket pkt;
	const char *in_filename;
	int ret, i;
	int stream_index = 0;
	int *stream_mapping = NULL;
	int stream_mapping_size = 0;

	in_filename  = “C:\\test.h264”;

	//产生对应的录像文件名
	SYSTEMTIME systime;
	GetLocalTime(&systime);
	char cTime[128];
	sprintf(cTime,"%4d/%02d/%02d %02d:%02d:%02d.%03d\n",
		systime.wYear,systime.wMonth,systime.wDay,systime.wHour,
		systime.wMinute, systime.wSecond,systime.wMilliseconds);
	char out_filename[128];
	sprintf_s(out_filename,128,"%s.mp4",cTime);

	//打开视频文件
	if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
		//LogMessage::DebugLogInfo("ReCode", "打开视频流失败");
		return -1;
	}
	//获取视频文件信息
	if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
		//LogMessage::DebugLogInfo("ReCode", "获取视频流信息失败");
		return -1;
	}

	//打印信息
	//av_dump_format(ifmt_ctx, 0, in_filename, 0);

	//输出文件分配空间
	avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
	if (!ofmt_ctx) {
		//LogMessage::DebugLogInfo("ReCode", "输出文件分配空间分配失败");
		return -1;
	}

	stream_mapping_size = ifmt_ctx->nb_streams;
	stream_mapping = (int *)av_mallocz_array(stream_mapping_size, sizeof(*stream_mapping));
	if (!stream_mapping) {

		//LogMessage::DebugLogInfo("ReCode", "获取mapping失败");
		return -1;
	}

	ofmt = ofmt_ctx->oformat;

	for (i = 0; i < ifmt_ctx->nb_streams; i++) {
		AVStream *out_stream;
		AVStream *in_stream = ifmt_ctx->streams[i];
		AVCodecParameters *in_codecpar = in_stream->codecpar;

		if (in_codecpar->codec_type != AVMEDIA_TYPE_AUDIO &&
			in_codecpar->codec_type != AVMEDIA_TYPE_VIDEO &&
			in_codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE) {
				stream_mapping[i] = -1;
				continue;
		}

		stream_mapping[i] = stream_index++;

		out_stream = avformat_new_stream(ofmt_ctx, NULL);
		if (!out_stream) {
			//fprintf(stderr, "Failed allocating output stream\n");
			//LogMessage::DebugLogInfo("ReCode", "分配流对象失败");
			return -1;
		}

		ret = avcodec_parameters_copy(out_stream->codecpar, in_codecpar);
		if (ret < 0) {
			//LogMessage::DebugLogInfo("ReCode", "拷贝视频code失败");
			return -1;
		}
		out_stream->codecpar->codec_tag = 0;
	}

	//打开文件
	if (!(ofmt->flags & AVFMT_NOFILE)) {
		ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
		if (ret < 0) {
			//LogMessage::DebugLogInfo("ReCode", "打开输出文件失败");
			return -1;
		}
	}
	//开始写入文件头
	ret = avformat_write_header(ofmt_ctx, NULL);
	if (ret < 0) {
		//LogMessage::DebugLogInfo("ReCode", "写入文件头失败");
		return -1;
	}
	int m_frame_index = 0;
	//开始读取视频流，并获取pkt信息
	while (1) {
		AVStream *in_stream, *out_stream;

		ret = av_read_frame(ifmt_ctx, &pkt);
		if (ret < 0)
			break;

		in_stream  = ifmt_ctx->streams[pkt.stream_index];
		if (pkt.stream_index >= stream_mapping_size ||
			stream_mapping[pkt.stream_index] < 0) {
				av_packet_unref(&pkt);
				continue;
		}

		pkt.stream_index = stream_mapping[pkt.stream_index];
		out_stream = ofmt_ctx->streams[pkt.stream_index];

		//从摄像头直接保存的h264文件，重新编码时得自己加时间戳，不然转换出来的是没有时间的
		if(pkt.pts==AV_NOPTS_VALUE){
			//Write PTS
			AVRational time_base1=in_stream->time_base;
			//Duration between 2 frames (us)
			int64_t calc_duration=(double)AV_TIME_BASE/av_q2d(in_stream->r_frame_rate);
			//Parameters
			pkt.pts=(double)(m_frame_index*calc_duration)/(double)(av_q2d(time_base1)*AV_TIME_BASE);
			pkt.dts=pkt.pts;
			pkt.duration=(double)calc_duration/(double)(av_q2d(time_base1)*AV_TIME_BASE);
		}

		/* copy packet */
		pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
		pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
		pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);
		pkt.pos = -1;

		ret = av_interleaved_write_frame(ofmt_ctx, &pkt);
		if (ret < 0) {
			break;
		}
		av_packet_unref(&pkt);
		m_frame_index++;
	}

	av_write_trailer(ofmt_ctx);

	avformat_close_input(&ifmt_ctx);

	// close output 
	if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
		avio_closep(&ofmt_ctx->pb);
	avformat_free_context(ofmt_ctx);

	av_freep(&stream_mapping);
	return 0;
}