本文主要是介绍Linux 下实现RTP实时打包发送H.264视频文件,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
在实现H264实时RTP打包和发送之前,我们需要先熟悉H264的编码原理及语法结构,然后是熟悉RTP协议以及RTP协议传输H264数据的相关准则。下面是与此相关的几篇博客。
H264语法结构及编码原理
RTP Payload H264
Linux 下实现RTP实时打包发送H.264码流
下面是rtp.c的代码
- /*=============================================================================
- * FileName: rtp.c
- * Desc: rtp payload h.264 data
- * Author: licaibiao
- * LastChange: 2017-04-07
- * =============================================================================*/
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <memory.h>
- #include <sys/types.h>
- #include <sys/socket.h>
- #include <arpa/inet.h>
- #include <netinet/in.h>
- #include <netdb.h>
- #include <unistd.h>
- #include "rtp.h"
- //#define DEBUG_LOG
- typedef struct
- {
- int startcodeprefix_len; //! 4 for parameter sets and first slice in picture, 3 for everything else (suggested)
- unsigned len; //! Length of the NAL unit (Excluding the start code, which does not belong to the NALU)
- unsigned max_size; //! Nal Unit Buffer size
- int forbidden_bit; //! should be always FALSE
- int nal_reference_idc; //! NALU_PRIORITY_xxxx
- int nal_unit_type; //! NALU_TYPE_xxxx
- charchar *buf; //! contains the first byte followed by the EBSP
- unsigned short lost_packets; //! true, if packet loss is detected
- } NALU_t;
- FILEFILE *bits = NULL; //!< the bit stream file
- static int FindStartCode2 (unsigned charchar *Buf);//查找开始字符0x000001
- static int FindStartCode3 (unsigned charchar *Buf);//查找开始字符0x00000001
- static int info2=0;
- static int info3=0;
- RTP_FIXED_HEADER *rtp_hdr;
- NALU_HEADER *nalu_hdr;
- FU_INDICATOR *fu_ind;
- FU_HEADER *fu_hdr;
- NALU_t *AllocNALU(int buffersize)
- {
- NALU_t *n;
- if ((n = (NALU_t*)calloc (1, sizeof (NALU_t))) == NULL)
- {
- printf("AllocNALU: n");
- exit(0);
- }
- n->max_size = buffersize;
- if((n->buf = (char*)calloc (buffersize, sizeof (char))) == NULL)
- {
- free (n);
- printf ("AllocNALU: n->buf");
- exit(0);
- }
- return n;
- }
- void FreeNALU(NALU_t *n)
- {
- if (n)
- {
- if (n->buf)
- {
- free(n->buf);
- n->buf=NULL;
- }
- free (n);
- }
- }
- void OpenBitstreamFile (charchar *fn)
- {
- if (NULL == (bits = fopen(fn, "rb")))
- {
- printf("open file error\n");
- exit(0);
- }
- }
- //这个函数输入为一个NAL结构体,主要功能为得到一个完整的NALU并保存在NALU_t的buf中,获取他的长度,填充F,IDC,TYPE位。
- //并且返回两个开始字符之间间隔的字节数,即包含有前缀的NALU的长度
- //前缀之后的第一个字节为 NALU_HEADER
- int GetAnnexbNALU (NALU_t *nalu)
- {
- int pos = 0;
- int rewind;
- int StartCodeFound;
- unsigned charchar *Buf;
- if ((Buf = (unsigned char*)calloc (nalu->max_size , sizeof(char))) == NULL)
- printf ("GetAnnexbNALU: Could not allocate Buf memory\n");
- printf("nalu->max_size=%d\n",(int)nalu->max_size);
- memset(Buf,0,nalu->max_size);
- nalu->startcodeprefix_len = 3;//初始化码流序列的开始字符为3个字节
- if (3 != fread (Buf, 1, 3, bits))//从码流中读3个字节
- {
- free(Buf);
- return 0;
- }
- info2 = FindStartCode2 (Buf);//判断是否为0x000001
- if(info2 != 1)
- {
- //如果不是,再读一个字节
- if(1 != fread(Buf+3, 1, 1, bits))//读一个字节
- {
- free(Buf);
- return 0;
- }
- info3 = FindStartCode3 (Buf);//判断是否为0x00000001
- if (info3 != 1)//如果不是,返回-1
- {
- free(Buf);
- return -1;
- }
- else
- {
- //如果是0x00000001,得到开始前缀为4个字节
- pos = 4;
- nalu->startcodeprefix_len = 4;
- }
- }
- else
- {
- //如果是0x000001,得到开始前缀为3个字节
- nalu->startcodeprefix_len = 3;
- pos = 3;
- }
- //查找下一个开始字符的标志位
- StartCodeFound = 0;
- info2 = 0;
- info3 = 0;
- while (!StartCodeFound)
- {
- if (feof (bits))//判断是否到了文件尾
- {
- nalu->len = (pos-1) - nalu->startcodeprefix_len;
- printf("nalu->len1=%d\n",nalu->len );
- memcpy (nalu->buf, &Buf[nalu->startcodeprefix_len], nalu->len); //拷贝一个完整NALU,不拷贝起始前缀0x000001或0x00000001
- nalu->forbidden_bit = nalu->buf[0] & 0x80; // 1 bit
- nalu->nal_reference_idc = nalu->buf[0] & 0x60; // 2 bit
- nalu->nal_unit_type = nalu->buf[0] & 0x1f; // 5 bit
- free(Buf);
- return pos - 1;
- }
- Buf[pos++] = fgetc (bits);//读一个字节到BUF中
- info3 = FindStartCode3(&Buf[pos-4]);//判断是否为0x00000001
- if(info3 != 1)
- {
- info2 = FindStartCode2(&Buf[pos-3]);//判断是否为0x000001
- }
- StartCodeFound = (info2 == 1 || info3 == 1);
- }
- // Here, we have found another start code (and read length of startcode bytes more than we should
- // have. Hence, go back in the file
- rewind = (info3 == 1) ? -4 : -3;
- if (0 != fseek (bits, rewind, SEEK_CUR))//把文件指针指向前一个NALU的末尾
- {
- free(Buf);
- printf("GetAnnexbNALU: Cannot fseek in the bit stream file");
- }
- // Here the Start code, the complete NALU, and the next start code is in the Buf.
- // The size of Buf is pos, pos+rewind are the number of bytes excluding the next
- // start code, and (pos+rewind)-startcodeprefix_len is the size of the NALU excluding the start code
- nalu->len = (pos+rewind) - nalu->startcodeprefix_len;
- printf("nalu->len2=%d\n",nalu->len );
- memcpy (nalu->buf, &Buf[nalu->startcodeprefix_len], nalu->len);//拷贝一个完整NALU,不拷贝起始前缀0x000001或0x00000001
- nalu->forbidden_bit = nalu->buf[0] & 0x80; // 1 bit
- nalu->nal_reference_idc = nalu->buf[0] & 0x60; // 2 bit
- nalu->nal_unit_type = nalu->buf[0] & 0x1f; // 5 bit
- free(Buf);
- return (pos+rewind);//返回两个开始字符之间间隔的字节数,即包含有前缀的NALU的长度
- }
- //输出NALU长度和TYPE
- void dump(NALU_t *n)
- {
- if (!n)return;
- //printf("a new nal:");
- printf(" len: %d ", n->len);
- printf("nal_unit_type: %x\n", n->nal_unit_type);
- }
- int main(int argc, char* argv[])
- {
- //FILE *stream;
- //stream=fopen("Test.264", "wb");
- NALU_t *n;
- SOCKET socket1;
- char *nalu_payload;
- char sendbuf[1500];
- int len ;
- int bytes = 0;
- float framerate = 25;
- unsigned short seq_num = 0;
- unsigned int timestamp_increase = 0;
- unsigned int ts_current = 0;
- struct sockaddr_in server;
- len = sizeof(server);
- OpenBitstreamFile("./h264/test.h264");
- timestamp_increase = (unsigned int)(90000.0 / framerate); //+0.5);
- server.sin_family = AF_INET;
- server.sin_port = htons(DEST_PORT);
- server.sin_addr.s_addr = inet_addr(DEST_IP);
- socket1 = socket(AF_INET, SOCK_DGRAM, 0);
- n = AllocNALU(8000000);//为结构体nalu_t及其成员buf分配空间。返回值为指向nalu_t存储空间的指针
- while(!feof(bits))
- {
- GetAnnexbNALU(n);//每执行一次,文件的指针指向本次找到的NALU的末尾,下一个位置即为下个NALU的起始码0x000001
- dump(n);//输出NALU长度和TYPE
- //(1)一个NALU就是一个RTP包的情况: RTP_FIXED_HEADER(12字节) + NALU_HEADER(1字节) + EBPS
- //(2)一个NALU分成多个RTP包的情况: RTP_FIXED_HEADER (12字节) + FU_INDICATOR (1字节)+ FU_HEADER(1字节) + EBPS(1400字节)
- memset(sendbuf, 0, 1500);//清空sendbuf;此时会将上次的时间戳清空,因此需要ts_current来保存上次的时间戳值
- //rtp固定包头,为12字节,该句将sendbuf[0]的地址赋给rtp_hdr,以后对rtp_hdr的写入操作将直接写入sendbuf。
- rtp_hdr =(RTP_FIXED_HEADER*)&sendbuf[0];
- //设置RTP HEADER,
- rtp_hdr->csrc_len = 0;
- //rtp_hdr->extension=0;
- //rtp_hdr->padding=0;
- rtp_hdr->payload = H264; //负载类型号,
- rtp_hdr->version = 2; //版本号,此版本固定为2
- rtp_hdr->marker = 0; //标志位,由具体协议规定其值。
- rtp_hdr->ssrc = htonl(10); //随机指定为10,并且在本RTP会话中全局唯一 bytes 8-11
- // 当一个NALU小于1400字节的时候,采用一个单RTP包发送
- if(n->len<=1400)
- {
- //设置rtp M 位;
- rtp_hdr->marker = 1;
- rtp_hdr->seq_no = htons(seq_num ++); //序列号,每发送一个RTP包增1 bytes 2, 3
- //设置NALU HEADER,并将这个HEADER填入sendbuf[12]
- nalu_hdr = (NALU_HEADER*)&sendbuf[12]; //将sendbuf[12]的地址赋给nalu_hdr,之后对nalu_hdr的写入就将写入sendbuf中;
- nalu_hdr->F = n->forbidden_bit >> 7;
- nalu_hdr->NRI = n->nal_reference_idc >> 5;//有效数据在n->nal_reference_idc的第6,7位,需要右移5位才能将其值赋给nalu_hdr->NRI。
- nalu_hdr->TYPE = n->nal_unit_type;
- nalu_payload = &sendbuf[13];//同理将sendbuf[13]赋给nalu_payload
- memcpy(nalu_payload, n->buf + 1, n->len - 1);//去掉nalu头的nalu剩余内容写入sendbuf[13]开始的字符串。
- ts_current = ts_current + timestamp_increase;
- printf("ts_current=%d\n",ts_current);
- rtp_hdr->timestamp = htonl(ts_current);
- printf("ts_current1=%x\n",rtp_hdr->timestamp);
- bytes = n->len + 12+1; //获得sendbuf的长度,为nalu的长度(包含NALU头但除去起始前缀)加上rtp_header的固定长度12字节
- #ifdef DEBUG_LOG
- {
- int ii = 0;
- printf("-----------------------------------\n");
- for(ii=0; ii<22; ii++)
- {
- printf("buf%d=%x ", ii, (unsigned char)sendbuf[ii]);
- }
- printf("\n");
- printf("------------------------------------\n");
- }
- #endif
- sendto(socket1, sendbuf, bytes, 0, (struct sockaddr *)&server, sizeof(server));
- usleep(40000);
- //fwrite(sendbuf,bytes, 1, stream);
- }
- else if(n->len>1400)
- {
- //得到该nalu需要用多少长度为1400字节的RTP包来发送
- int k = 0;
- int l = 0;
- int t = 0; //用于指示当前发送的是第几个分片RTP包
- k = n->len / 1400; //需要k个1400字节的RTP包
- l = n->len % 1400; //最后一个RTP包的需要装载的字节数
- ts_current = ts_current+timestamp_increase;
- printf("ts_current=%d\n",ts_current);
- rtp_hdr->timestamp = htonl(ts_current);
- while(t <= k)
- {
- rtp_hdr->seq_no = htons(seq_num++); //序列号,每发送一个RTP包增1
- if(!t) //发送一个需要分片的NALU的第一个分片,置FU HEADER的S位
- {
- //设置rtp M 位;
- rtp_hdr->marker = 0;
- //设置FU INDICATOR,并将这个HEADER填入sendbuf[12]
- fu_ind = (FU_INDICATOR*)&sendbuf[12]; //将sendbuf[12]的地址赋给fu_ind,之后对fu_ind的写入就将写入sendbuf中;
- fu_ind->F = n->forbidden_bit >> 7;
- fu_ind->NRI = n->nal_reference_idc >> 5;
- fu_ind->TYPE = 28;
- //设置FU HEADER,并将这个HEADER填入sendbuf[13]
- fu_hdr = (FU_HEADER*)&sendbuf[13];
- fu_hdr->E = 0;
- fu_hdr->R = 0;
- fu_hdr->S = 1;
- fu_hdr->TYPE = n->nal_unit_type;
- nalu_payload = &sendbuf[14]; //同理将sendbuf[14]赋给nalu_payload
- memcpy(nalu_payload, n->buf + 1, 1400);//去掉NALU头
- bytes = 1400 + 12 + 2; //获得sendbuf的长度,为nalu的长度(除去起始前缀和NALU头)加上rtp_header,fu_ind,fu_hdr的固定长度14字节
- #ifdef DEBUG_LOG
- {
- int ii=0;
- printf("-----------------------------------\n");
- for(ii=0;ii<22;ii++)
- {
- printf("buf%d=%x ",ii,(unsigned char)sendbuf[ii]);
- }
- printf("\n");
- printf("------------------------------------\n");
- }
- #endif
- sendto(socket1, sendbuf, bytes, 0, (struct sockaddr *)&server, sizeof(server));
- //fwrite(sendbuf,bytes, 1, stream);
- //usleep(20000);
- t++;
- }
- //发送一个需要分片的NALU的非第一个分片,清零FU HEADER的S位,如果该分片是该NALU的最后一个分片,置FU HEADER的E位
- else if(k == t)//发送的是最后一个分片,注意最后一个分片的长度可能超过1400字节(当l>1386时)。
- {
- //设置rtp M 位;当前传输的是最后一个分片时该位置1
- rtp_hdr->marker = 1;
- //设置FU INDICATOR,并将这个HEADER填入sendbuf[12]
- fu_ind = (FU_INDICATOR*)&sendbuf[12]; //将sendbuf[12]的地址赋给fu_ind,之后对fu_ind的写入就将写入sendbuf中;
- fu_ind->F = n->forbidden_bit >> 7;
- fu_ind->NRI = n->nal_reference_idc >> 5;
- fu_ind->TYPE = 28;
- //设置FU HEADER,并将这个HEADER填入sendbuf[13]
- fu_hdr = (FU_HEADER*)&sendbuf[13];
- fu_hdr->R = 0;
- fu_hdr->S = 0;
- fu_hdr->TYPE = n->nal_unit_type;
- fu_hdr->E = 1;
- nalu_payload = &sendbuf[14];//同理将sendbuf[14]的地址赋给nalu_payload
- if((n != NULL) && (n->buf != NULL) && (l > 1))
- {
- memcpy(nalu_payload, n->buf + t * 1400 + 1, l - 1);//将nalu最后剩余的l-1(去掉了一个字节的NALU头)字节内容写入sendbuf[14]开始的字符串。
- bytes = l - 1 + 12 + 2; //获得sendbuf的长度,为剩余nalu的长度l-1加上rtp_header,FU_INDICATOR,FU_HEADER三个包头共14字节
- #ifdef DEBUG_LOG
- {
- int ii=0;
- printf("-----------------------------------\n");
- for(ii=0;ii<22;ii++)
- {
- printf("buf%d=%x ",ii,(unsigned char)sendbuf[ii]);
- }
- printf("\n");
- printf("------------------------------------\n");
- }
- #endif
- sendto(socket1, sendbuf, bytes, 0, (struct sockaddr *)&server, sizeof(server));
- }
- else
- {
- printf("n->buf == NULL !\n");
- }
- //fwrite(sendbuf,bytes, 1, stream);
- //usleep(20000);
- t++;
- }
- else if(t < k && 0 != t)
- {
- //设置rtp M 位;
- rtp_hdr->marker = 0;
- //设置FU INDICATOR,并将这个HEADER填入sendbuf[12]
- fu_ind = (FU_INDICATOR*)&sendbuf[12]; //将sendbuf[12]的地址赋给fu_ind,之后对fu_ind的写入就将写入sendbuf中;
- fu_ind->F = n->forbidden_bit>>7;
- fu_ind->NRI = n->nal_reference_idc>>5;
- fu_ind->TYPE = 28;
- //设置FU HEADER,并将这个HEADER填入sendbuf[13]
- fu_hdr = (FU_HEADER*)&sendbuf[13];
- //fu_hdr->E=0;
- fu_hdr->R = 0;
- fu_hdr->S = 0;
- fu_hdr->E = 0;
- fu_hdr->TYPE = n->nal_unit_type;
- nalu_payload = &sendbuf[14]; //同理将sendbuf[14]的地址赋给nalu_payload
- memcpy(nalu_payload, n->buf + t * 1400 + 1, 1400);//去掉起始前缀的nalu剩余内容写入sendbuf[14]开始的字符串。
- bytes = 1400 + 12 + 2; //获得sendbuf的长度,为nalu的长度(除去原NALU头)加上rtp_header,fu_ind,fu_hdr的固定长度14字节
- #ifdef DEBUG_LOG
- {
- int ii = 0;
- printf("-----------------------------------\n");
- for(ii=0;ii<22;ii++)
- {
- printf("buf%d=%x ",ii,(unsigned char)sendbuf[ii]);
- }
- printf("\n");
- printf("------------------------------------\n");
- }
- #endif
- sendto(socket1, sendbuf, bytes, 0, (struct sockaddr *)&server, sizeof(server));
- //fwrite(sendbuf, bytes, 1, stream);
- //usleep(20000);
- t++;
- }
- }
- usleep(40000);
- }
- }
- FreeNALU(n);
- fclose(bits);
- bits = NULL;
- //fclose(stream);
- return 0;
- }
- static int FindStartCode2 (unsigned charchar *Buf)
- {
- if(Buf[0]!=0 || Buf[1]!=0 || Buf[2] !=1) return 0; //判断是否为0x000001,如果是返回1
- else return 1;
- }
- static int FindStartCode3 (unsigned charchar *Buf)
- {
- if(Buf[0]!=0 || Buf[1]!=0 || Buf[2] !=0 || Buf[3] !=1) return 0;//判断是否为0x00000001,如果是返回1
- else return 1;
- }
上面的代码是实现h.264数据的实时打包和发送,接收和显示端,我们可以使用VLC或是Mplayer播放器来实现。完整的工程目录为:
- rtp_h264
- ├── h264
- │ └── test.h264
- ├── Makefile
- ├── rtp.c
- ├── rtp.h
- └── sdp
- ├── mplayer.sdp
- └── vlc.sdp
编译工程,在运行工程之前,先将sdp 文件拖到播放器中,然后运行程序就可以直接看到视频画面。
这里需要注意几点
(1)使用VLC播放器会出现有点卡顿,且播放时间显示异常,但是用MPlayer播放器不会存在这些问题
(2)程序中的usleep() 延时是必须的,如果发送太快,播放器会处理不过来
(3)H.264 的SPS和PPS数据是h.264文件的开始两帧,需要客户端先运行才能获取到。
完整的工程(包括sdp文件)可以在这里下载:Linux 下RTP实时打包发送H.264码流
这篇关于Linux 下实现RTP实时打包发送H.264视频文件的文章就介绍到这儿,希望我们推荐的文章对编程师们有所帮助!