模拟输入H.264流，输出封装格式文件

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/u013699869/article/details/49869835

/**
 *每次从H.264文件读取IO_BUFFER_SIZE字节的数据，
 *模拟输入H.264流，最终输出封装格式文件。
 */
#include "stdafx.h"

#define __STDC_CONSTANT_MACROS

extern "C"
{
#include "libavformat/avformat.h"
}

#define IO_BUFFER_SIZE 32768

int main(int argc, char* argv[])
{
	//const char *in_filename_v = argv[1]; //Input file URL
	//const char *out_filename = argv[2]; //Output file URL
	const char *in_filename_v = "media files/JINUSEAN_17s.h264"; //Input file URL
	const char *out_filename = "media files/JINUSEAN_17s.mkv"; //Output file URL
	
	AVOutputFormat *ofmt = NULL;
	AVFormatContext *ofmt_ctx = NULL;
	int ret;
	
	FILE *fp_open;
	fp_open = fopen(in_filename_v, "rb+");

	av_register_all();

	avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
	if (!ofmt_ctx) {
	printf("Could not create output context\n");
	ret = AVERROR_UNKNOWN;
	goto end;
	}
	ofmt = ofmt_ctx->oformat;
	AVCodec *codec = avcodec_find_encoder(AV_CODEC_ID_H264);
	if (!codec) {
		printf("Could not find encoder for '%s'\n",
			avcodec_get_name(AV_CODEC_ID_H264));
		goto end;
	}
	AVStream *out_stream = avformat_new_stream(ofmt_ctx, codec);
	if (!out_stream) {
		printf("Failed allocating output stream\n");
		ret = AVERROR_UNKNOWN;
		goto end;
	}
	out_stream->codec->codec_tag = 0;
	/* Some formats want stream headers to be separate. */
	if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
		out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;

	printf("==========Output Information==========\n");
	av_dump_format(ofmt_ctx, 0, out_filename, 1);
	printf("======================================\n");
	//Open output file
	if (!(ofmt->flags & AVFMT_NOFILE)) {
		if (avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE) < 0) {
			printf("Could not open output file '%s'", out_filename);
			goto end;
		}
	}

	//虽然不起作用，但必须设置AVCodecContext中的width和height，
	//否则，调avformat_write_header()时，报错：dimensions not set.
	ofmt_ctx->streams[0]->codec->width=1;
	ofmt_ctx->streams[0]->codec->height=1;
	
	//Write file header
	if (avformat_write_header(ofmt_ctx, NULL) < 0) {
		printf("Error occurred when opening output file\n");
		goto end;
	}

	out_stream->r_frame_rate.num = 30000;
	out_stream->r_frame_rate.den = 1001;
	//temp为临时缓冲区，存储上一次传入数据剩余的不完整帧和本次传入的数据。
	uint8_t *temp = (uint8_t *)malloc(4 * IO_BUFFER_SIZE);
	//上一次传入数据剩余的不完整帧的大小。
	int residue_len = 0;
	int frame_index = 0;
	for (int i = 0; i < 200; i++)
	{
		uint8_t *buf = (uint8_t *)malloc(IO_BUFFER_SIZE);
		fread(buf, 1, IO_BUFFER_SIZE, fp_open);
		memcpy(temp + residue_len, buf, IO_BUFFER_SIZE);
		int frame_header = 0;
		//之所以从j==1开始，是因为j==0必然是帧头，现在要找的是下一个帧头
		for (int j = 1; j <= residue_len + IO_BUFFER_SIZE - 5; j++)
		{
			if (temp[j] == 0x00 && temp[j + 1] == 0x00 && temp[j + 2] == 0x00 && temp[j + 3] == 0x01 && temp[j + 4] != 0x68)
			{
				AVPacket pkt;
				av_init_packet(&pkt);
				pkt.size = j - frame_header;
				pkt.data = (uint8_t *)malloc(j - frame_header);
				memcpy(pkt.data, temp+frame_header, j - frame_header);
				//认为带SPS信息的为关键帧。若不正确标记关键帧，则不能正常随机定位或快进快退。
				if (temp[frame_header + 4] == 0x67)
				{
					pkt.flags |= AV_PKT_FLAG_KEY;
				}
				AVRational time_base = out_stream->time_base;
				//Duration between 2 frames (μs)
				int64_t calc_duration = (double)AV_TIME_BASE / av_q2d(out_stream->r_frame_rate);
				//Parameters
				pkt.pts = (double)(frame_index*calc_duration) / (double)(av_q2d(time_base)*AV_TIME_BASE);
				pkt.dts = pkt.pts;
				pkt.duration = (double)calc_duration / (double)(av_q2d(time_base)*AV_TIME_BASE);
				frame_index++;
                printf("Write 1 Packet. size:%5d\tpts:%lld\n", pkt.size, pkt.pts);
				if (av_interleaved_write_frame(ofmt_ctx, &pkt) < 0)
				{
					printf("Error muxing packet\n");
					break;
				}
				av_free_packet(&pkt);
				frame_header = j;
			}
			else
			{
				continue;
			}
		}
		residue_len = residue_len + IO_BUFFER_SIZE - frame_header;
		//即使有重叠区域，也允许这样进行内存拷贝，要拷贝的尾部数据会覆盖temp+frame_header以后的重叠区域。
		memcpy(temp, temp + frame_header, residue_len);
		free(buf);

	}
	free(temp);

	//Write file trailer
	av_write_trailer(ofmt_ctx);

end:
	/* close output */
	if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
		avio_close(ofmt_ctx->pb);
	avformat_free_context(ofmt_ctx);
	fclose(fp_open);
	return 0;
}