模拟输入H.264流，输出封装格式文件

/**
*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;
}