这是用RTP（RFC3350）按RFC2550封装MPEG ES流数据的发送程序。学习RTP的路真的辛苦。在网上收集的有关RTP的程序都是那种只负责RTP数据包发送的库，如jrtplib等，他们的DEMO 程序都只是用来发发字符串，编编聊天程序，无论是国内还是国外，都没有结合真正的应用的DEMO。其实我的目的很简单，就是写发个视频流服务器，不用复杂，只用把基本原理弄懂，因为这样你才能有的放矢。与网上和RTP相关的库没有应用不一让，当你尝试以流媒体服务器、linux来baidu或 google时，你搜出来完非就那么几类：
1.FFSERVER
FFMPEG2的DEMO,说它有名只是因为这类程序太少了。FFMPEG2是很好用，我现在还在用，但这个DEMO就有很多“炒作”的嫌疑了。好像在做着FFMPEG2库的演示而不是真的视频流服务器。后来想想，这不正是作者想要的吗，但这不是我想要的。编解码部分我会很偏向FFMPEG这个“大杂会 ”，其它部分我会选择其它的“强者”
2.Darwin、Helix
两个都是非常有名软件，也只能称之为软件了，因为就算Darwin有源码，这种代码规模，也不适合用于嵌入式。说回软件本身，真的很有名。它们都是很真真拿来商业化运行的软件，但我是研发人员，不是视频流服务商，对不起，Apple，对不起，Microsoft。
3.LIVE555
如果说上面两个和我都相关性为零（当然了，也是困扰了N周以后痛苦得出的结论），那LIVE555真的给了我一条出路，它是一个代码规模非常合适，又非常强大的媒体解决方案（称之为方案是因为它功能非常的丰富）。有长一段时间，我想去弄懂它的源码，不过和网上的很多人一样，最后软下来了，毕竟，去把这么多东西揉在一起，框架会弄得很复杂，因为我们要把这些完全不同的东西不断一层一层的抽像，最后抽像成一样（哲学呀）。它结构复杂是我中断分析它原来的其中一个原因，但不是主要原因。它结构的复杂程度也没胡像很多人网上说的那样严重，如果你是一个C++的热忱爱好者，你反而会迷上这段代码，当然了，对C的爱好都来说，当然是一种折磨了。暂时把我自己归类在C++爱好者范畴吧，呵呵，我很欣赏这段原码。主要原因是我不希望被某一个库绑死。LIVE555是有编解码能力，但我更希望它只做服务器的工作。
因此，最终后回来的老路上来，没有帮助，就得自己帮自己，从最基础的RFC看起。经过了N天（周）的英文，终于领会了如果在RTP承载MPEG数据包。在这个过程中很得到了一些LIVE555的帮助（通过对Ethereal捕捉的LIVE555数据包进行分析）。先把程序弄上来，原理性的以后有空再写，程序只有一个.cpp文件，在vs.net 2003下编译通过，播放的视频文件在http://www.cnitblog.com/Files/tinnal/ES流解释程序.rar 内，播放的客户端采用VLC，其下载地址为http://www.videolan.org/ 。选择打开网络串流，然后选择“UDP/RTP”端口，输入程序的输出端口1000，然后才运行程序，你将在VLC内看到测试的广播视频，IP不一样的话自己改改就行。其它所谓的原理性的，也就是看RFC 3350、RFC2550以及iso13818－2的一些重点地方。
// MPEG2RTP.h
#include < stdio.h >
#include < stdlib.h >
#include < conio.h >
#include < string .h >
#include < winsock2.h >
#include < winsock2.h >
// #include "mem.h"
// <! Start code or other signal
#define PACK_STARTCODE (unsigned int)0x000001ba
#define SYSTEM_HEADER_STARTCODE (unsigned int)0x000001bb
#define PICTURE_START_CODE (unsigned int)0x00000100
#define GROUP_START_CODE (unsigned int)0x000000B8
#define ISO_11172_ENDCODE (unsigned int)0x000001b9
#define SEQUENCE_HEADER_CODE (unsigned int)0x000001b3
#define PACKET_BUFFER_END (unsigned int)0x00000000
#define MAX_RTP_PKT_LENGTH 1440
#define HEADER_LENGTH 16
#define DEST_IP "192.168.0.98"
#define DEST_PORT 1000
#define MPA 14 /*MPEG PAYLOAD TYPE */
#define MPV 32
typedef struct
{
/* byte 0 */
unsigned char csrc_len: 4 ; /* expect 0 */
unsigned char extension: 1 ; /* expect 1, see RTP_OP below */
unsigned char padding: 1 ; /* expect 0 */
unsigned char version: 2 ; /* expect 2 */
/* byte 1 */
unsigned char payload: 7 ; /* RTP_PAYLOAD_RTSP */
unsigned char marker: 1 ; /* expect 1 */
/* bytes 2, 3 */
unsigned short seq_no;
/* bytes 4-7 */
unsigned long timestamp;
/* bytes 8-11 */
unsigned long ssrc; /* stream number is used here. */
} RTP_FIXED_HEADER;
typedef struct {
// byte 0
unsigned char TR_high2: 2 ; /* Temporal Reference high 2 bits */
unsigned char T: 1 ; /* video specific head extension flag */
unsigned char MBZ: 5 ; /* unused */
// byte1
unsigned char TR_low8: 8 ; /* Temporal Reference low 8 bits */
// byte3
unsigned char P: 3 ; /* picture type; 1=I,2=P,3=B,4=D */
unsigned char E: 1 ; /* set if last byte of payload is slice end code */
unsigned char B: 1 ; /* set if start of payload is slice start code */
unsigned char S: 1 ; /* sequence header present flag */
unsigned char N: 1 ; /* N bit; used in MPEG 2 */
unsigned char AN: 1 ; /* Active N bit */
// byte4
unsigned char FFC: 3 ; /* forward_f_code */
unsigned char FFV: 1 ; /* full_pel_forward_vector */
unsigned char BFC: 3 ; /* backward_f_code */
unsigned char FBV: 1 ; /* full_pel_backward_vector */
} MPEG_VID_SPECIFIC_HDR; /* 4 BYTES */
enum reading_status {
SLICE_AGAIN,
SLICE_BREAK,
UNKNOWN,
SLICE,
SEQUENCE_HEADER,
GROUP_START,
PICTURE
} ;
void validate_file();
float frame_rate( int buffer_index);
unsigned int read_picture_type( int buffer_index);
unsigned int read_FBV( int buffer_index);
unsigned int read_BFC( int buffer_index);
unsigned int read_FFV( int buffer_index);
unsigned int read_FFC( int buffer_index);
unsigned int extract_temporal_reference( int buffer_index);
unsigned int find_next_start_code(unsigned int * buffer_index);
void reset_buffer_index( void );
BOOL InitWinsock();
#include < stdio.h > #include < stdlib.h > #include < conio.h > #include < string .h > #include < winsock2.h > #include < winsock2.h > // #include "mem.h"// <! Start code or other signal #define PACK_STARTCODE (unsigned int)0x000001ba #define SYSTEM_HEADER_STARTCODE (unsigned int)0x000001bb #define PICTURE_START_CODE (unsigned int)0x00000100 #define GROUP_START_CODE (unsigned int)0x000000B8 #define ISO_11172_ENDCODE (unsigned int)0x000001b9 #define SEQUENCE_HEADER_CODE (unsigned int)0x000001b3 #define PACKET_BUFFER_END (unsigned int)0x00000000 #define MAX_RTP_PKT_LENGTH 1440 #define HEADER_LENGTH 16 #define DEST_IP "192.168.0.98" #define DEST_PORT 1000 #define MPA 14 /*MPEG PAYLOAD TYPE */ #define MPV 32 typedef struct {
/* byte 0 */ 
unsigned char csrc_len: 4 ; /* expect 0 */ unsigned char extension: 1 ; /* expect 1, see RTP_OP below */ unsigned char padding: 1 ; /* expect 0 */ unsigned char version: 2 ; /* expect 2 */ /* byte 1 */ unsigned char payload: 7 ; /* RTP_PAYLOAD_RTSP */ unsigned char marker: 1 ; /* expect 1 */ /* bytes 2, 3 */ unsigned short seq_no; /* bytes 4-7 */ unsigned long timestamp; /* bytes 8-11 */ unsigned long ssrc; /* stream number is used here. */ } RTP_FIXED_HEADER; typedef struct { // byte 0 unsigned char TR_high2: 2 ; /* Temporal Reference high 2 bits */ unsigned char T: 1 ; /* video specific head extension flag */ unsigned char MBZ: 5 ; /* unused */ // byte1 unsigned char TR_low8: 8 ; /* Temporal Reference low 8 bits */ // byte3 unsigned char P: 3 ; /* picture type; 1=I,2=P,3=B,4=D */ unsigned char E: 1 ; /* set if last byte of payload is slice end code */ unsigned char B: 1 ; /* set if start of payload is slice start code */ unsigned char S: 1 ; /* sequence header present flag */ unsigned char N: 1 ; /* N bit; used in MPEG 2 */ unsigned char AN: 1 ; /* Active N bit */ // byte4 unsigned char FFC: 3 ; /* forward_f_code */ unsigned char FFV: 1 ; /* full_pel_forward_vector */ unsigned char BFC: 3 ; /* backward_f_code */ unsigned char FBV: 1 ; /* full_pel_backward_vector */ } MPEG_VID_SPECIFIC_HDR; /* 4 BYTES */ enum reading_status { SLICE_AGAIN, SLICE_BREAK, UNKNOWN, SLICE, SEQUENCE_HEADER, GROUP_START, PICTURE } ;void validate_file();float frame_rate( int buffer_index); unsigned int read_picture_type( int buffer_index); unsigned int read_FBV( int buffer_index); unsigned int read_BFC( int buffer_index); unsigned int read_FFV( int buffer_index); unsigned int read_FFC( int buffer_index); unsigned int extract_temporal_reference( int buffer_index); unsigned int find_next_start_code(unsigned int * buffer_index);void reset_buffer_index( void ); BOOL InitWinsock();
//MPEG2RTP.cpp// 这个程序主要用于RTP封装MPEG2数据的学习和测试，不作任何其它用途
// 软件在VS.net 2003中编译通过，但在linux下作小量修改也应编译通过。// 通过VLC测试，VLC能正确接收和解码由本程序发送的TEST.MPV编码流。// // 作者：冯富秋 Tinnal// 邮箱：tinnal@163.com #include " MPEG2RTP.h " #pragma comment(lib, " Ws2_32 " ) unsigned char buf[MAX_RTP_PKT_LENGTH + 4 ]; // input buffer enum reading_status state = SEQUENCE_HEADER; unsigned int g_index_in_packet_buffer = HEADER_LENGTH;static unsigned long g_time_stamp = 0 ;static unsigned long g_time_stamp_current = 0 ;static float g_frame_rate = 0 ;static unsigned int g_delay_time = 0 ;static unsigned int g_timetramp_increment = 0 ; FILE * mpfd; SOCKET socket1; RTP_FIXED_HEADER * rtp_hdr; MPEG_VID_SPECIFIC_HDR * mpeg_hdr;#if 0 void Send_RTP_Packet(unsigned char * buf, int bytes){ int i = 0 ; int count = 0 ; printf( " /nPacket length %d/n " ,bytes); printf( " RTP Header: [M]:%s [sequence number]:0x%lx [timestamp]:0x%lx/n " , rtp_hdr -> marker == 1 ? " TRUE " : " FALSE " , rtp_hdr -> seq_no, rtp_hdr -> timestamp); printf( " [TR]:%d [AN]:%d [N]:%d [Sequence Header]:%s / /n [Begin Slice]: % s [End Slice]: % s / /n [Pictute Type]: % d / /n [FBV]: % d [BFC]: % d [FFV]: % d [FFC]: % d/n " , (mpeg_hdr -> TR_high2 << 8 | mpeg_hdr -> TR_low8), mpeg_hdr -> AN, mpeg_hdr -> N, mpeg_hdr -> S == 1 ? " TRUE " : " FALSE " , mpeg_hdr -> B == 1 ? " TRUE " : " FALSE " , mpeg_hdr -> E == 1 ? " TRUE " : " FALSE " , mpeg_hdr -> P, mpeg_hdr -> FBV, mpeg_hdr -> BFC, mpeg_hdr -> FFV, mpeg_hdr -> FFC); while (bytes -- ) { printf( " %02x " ,buf[count ++ ]); if ( ++ i == 16 ) { i = 0 ; printf( " /n " );
} } printf( " /n " ); } #else Send_RTP_Packet(unsigned char * buf, int bytes){ return send( socket1, ( char * ) buf, bytes, 0 ); } #endif void main( int argc, char * argv[]){ unsigned int next_start_code; unsigned int next_start_code_index; unsigned int sent_bytes; unsigned short seq_num = 0 ; unsigned short stream_num = 10 ; struct sockaddr_in server; int len = sizeof (server);#if 0 mpfd = fopen( " E://tinnal//live555//vc_proj//es//Debug//test.mpv " , " rb " ); #else if (argc < 2 ) { printf( " /nUSAGE: %s mpegfile/nExiting../n/n " ,argv[ 0 ]); exit( 0 ); } mpfd = fopen(argv[ 1 ], " rb " );#endif if (mpfd == NULL ) { printf( " /nERROR: could not open input file %s/n/n " ,argv[ 1 ]); exit( 0 ); } rtp_hdr = (RTP_FIXED_HEADER * ) & buf[ 0 ]; mpeg_hdr = (MPEG_VID_SPECIFIC_HDR * ) & buf[ 12 ]; memset(( void * )rtp_hdr, 0 , 12 ); // zero-out the rtp fixed hdr memset(( void * )mpeg_hdr, 0 , 4 ); // zero-out the video specific hdr memset(( void * )buf, 0 ,MAX_RTP_PKT_LENGTH + 4 ); InitWinsock(); server.sin_family = AF_INET; server.sin_port = htons(DEST_PORT); // server的监听端口 server.sin_addr.s_addr = inet_addr(DEST_IP); // server的地址 socket1 = socket(AF_INET,SOCK_DGRAM, 0 ); connect(socket1, ( const sockaddr * ) & server, len) ; // read the first packet from the mpeg file // always read 4 extra bytes in (in case there's a startcode there) // but dont send more than MAX_RTP_PKT_LENGTH in one packet fread( & (buf[HEADER_LENGTH]), MAX_RTP_PKT_LENGTH - HEADER_LENGTH + 4 , 1 ,mpfd); validate_file(); do { /* initialization of the two RTP headers */ rtp_hdr -> seq_no = htons(seq_num ++ ); rtp_hdr -> payload = MPV; rtp_hdr -> version = 2 ; rtp_hdr -> marker = 0 ; rtp_hdr -> ssrc = htonl(stream_num); mpeg_hdr -> S = mpeg_hdr -> E = mpeg_hdr -> B = 0 ; do { next_start_code = find_next_start_code( & next_start_code_index); if ((next_start_code > 0x100 ) && (next_start_code < 0x1b0 ) ) { // <! We reach the first slice start code in current packet buffer. // <! Set the B flag of the mpeg special header if (state == SEQUENCE_HEADER || state == GROUP_START || state == PICTURE || state == UNKNOWN) { state = SLICE; mpeg_hdr -> B = 1 ; } // <! We reach slice start code in current packet again. // <! Set the E flag of the mpeg special header, // <! and update the sent_bytes to the last slice data end. else if (state == SLICE || state == SLICE_AGAIN) { state = SLICE_AGAIN; sent_bytes = next_start_code_index; mpeg_hdr -> E = 1 ; } // <! We reach slice start code(the previous slice end) // <! for a broken slice. set the E flag. // <! According to RFC2550, we shouldn't put another slice data to this packet, // <! instead of sent it out. else if (state == SLICE_BREAK) { state = UNKNOWN; sent_bytes = next_start_code_index; mpeg_hdr -> E = 1 ; goto Sent_Packet; } } switch (next_start_code) { case SEQUENCE_HEADER_CODE: // <! SEQUENCE_HEADER_CODE after SLICE_START_CODE // <! we must sent the packet now, so that, the SEQUENCE_HEADER_CODE // <! will appear at the start of the next packet if (state == SLICE || state == SLICE_AGAIN) { state = SEQUENCE_HEADER; sent_bytes = next_start_code_index; // <! Accord to RFC 2550, // <! at the end of a frame we should set RTP marker bit to 1. rtp_hdr -> marker = 1 ; goto Sent_Packet; } state = SEQUENCE_HEADER; g_frame_rate = frame_rate(next_start_code_index); g_delay_time = (unsigned int )( 1000.0 / g_frame_rate + 0.5 ); // ms g_timetramp_increment = (unsigned int )( 90000.0 / g_frame_rate + 0.5 ); // 90K Hz mpeg_hdr -> S = 1 ; break ; case GROUP_START_CODE: // <! GROUP_START_CODE after SLICE_START_CODE // <! we must sent the packet now, so that, the GROUP_START_CODE // <! will appear at the start of the next packet if (state == SLICE || state == SLICE_AGAIN) { state = GROUP_START; sent_bytes = next_start_code_index; // <! Accord to RFC 2550, // <! at the end of a frame we should set RTP marker bit to 1. rtp_hdr -> marker = 1 ; goto Sent_Packet; } state = GROUP_START; case PICTURE_START_CODE: // <! PICTURE_START_CODE after PICTURE_START_CODE // <! we must sent the packet now, so that, the PICTURE_START_CODE // <! will appear at the start of the next packet if (state == SLICE || state == SLICE_AGAIN) { state = PICTURE; sent_bytes = next_start_code_index; // <! Accord to RFC 2550, // <! at the end of a frame we should set RTP marker bit to 1. rtp_hdr -> marker = 1 ; goto Sent_Packet; } state = PICTURE; mpeg_hdr -> TR_high2 = (extract_temporal_reference(next_start_code_index) & 0x300 ) >> 8 ; mpeg_hdr -> TR_low8 = extract_temporal_reference(next_start_code_index) & 0xff ; mpeg_hdr -> P = read_picture_type(next_start_code_index); // now read the motion vectors information if ( (mpeg_hdr -> P == 2 ) || (mpeg_hdr -> P == 3 )) { // if B- or P-type picture, need forward mv mpeg_hdr -> FFV = read_FFV(next_start_code_index); mpeg_hdr -> FFC = read_FFC(next_start_code_index); } if ( mpeg_hdr -> P == 3 ) { // if B-type pictue, need backward mv mpeg_hdr -> FBV = read_FBV(next_start_code_index); mpeg_hdr -> BFC = read_BFC(next_start_code_index); } // <! Time stamp only increate per frame. // <! But I or P frame. if ( mpeg_hdr -> P == 1 || mpeg_hdr -> P == 2 ) { g_time_stamp += g_timetramp_increment; g_time_stamp_current = g_time_stamp; } else { g_time_stamp += g_timetramp_increment; } break ; case PACKET_BUFFER_END: // <! There is one more slice in the packet buffer // <! Anyway, we only sent the integrated slice if (state == SLICE_AGAIN) { state = UNKNOWN; goto Sent_Packet; } // <! There is one Slice in the packet buffer. // <! But the Slice is to big, so we break the slice. if (state == SLICE) { state = SLICE_BREAK; sent_bytes = next_start_code_index; goto Sent_Packet; } // <! There if a broke slice, but in current packet buffer // <! we could not find the end of the slice. // <! Let it in the broke state. if (state == SLICE_BREAK ) { state = SLICE_BREAK; sent_bytes = next_start_code_index; goto Sent_Packet; } break ; } } while (next_start_code != PACKET_BUFFER_END); Sent_Packet: rtp_hdr -> timestamp = htonl(g_time_stamp_current); Send_RTP_Packet(buf, sent_bytes); // copy the tail data to the head of the packet buffer memmove( & buf[HEADER_LENGTH], & buf[sent_bytes], MAX_RTP_PKT_LENGTH - sent_bytes); // reset the buffer index to zero reset_buffer_index(); // reading data into buffer again fread( & (buf[(MAX_RTP_PKT_LENGTH - sent_bytes) + HEADER_LENGTH]), sent_bytes - HEADER_LENGTH , 1 ,mpfd); // sleep g_delay_time msec for sending next picture data if (rtp_hdr -> marker == 1 ) Sleep( g_delay_time ); } while ( ! feof(mpfd)); closesocket(socket1); fclose(mpfd); printf( " stream end./n " ); } // ================================================================== unsigned int find_next_start_code(unsigned int * next_start_code_index) // NOTE: all start codes ARE byte-aligned { unsigned int byte0 = 0 ,byte1 = 0 ,byte2 = 0 ,byte3 = 0 ,startcode = 0 ; // while not startcode and have not exceeded max packet length while (g_index_in_packet_buffer < MAX_RTP_PKT_LENGTH) { if (buf[g_index_in_packet_buffer + 0 ] == 0 && buf[g_index_in_packet_buffer + 1 ] == 0 && buf[g_index_in_packet_buffer + 2 ] == 1 ) { // printf("FOUND startcode %d/n",indx); byte0 = ( int )buf[g_index_in_packet_buffer + 0 ]; byte1 = ( int )buf[g_index_in_packet_buffer + 1 ]; byte2 = ( int )buf[g_index_in_packet_buffer + 2 ]; byte3 = ( int )buf[g_index_in_packet_buffer + 3 ]; startcode = (byte0 << 24 ) + (byte1 << 16 ) + (byte2 << 8 ) + byte3; * next_start_code_index = g_index_in_packet_buffer; g_index_in_packet_buffer = g_index_in_packet_buffer + 4 ; return (startcode); } else g_index_in_packet_buffer ++ ; } // <! reach the end of the packet buffer if (g_index_in_packet_buffer >= (MAX_RTP_PKT_LENGTH)) { * next_start_code_index = g_index_in_packet_buffer - 1 ; g_index_in_packet_buffer = HEADER_LENGTH; return PACKET_BUFFER_END; } printf( " Error reading buffer../n " ); exit( - 1 ); return - 1 ; } void reset_buffer_index( void ){ g_index_in_packet_buffer = HEADER_LENGTH; } // ======================================================== float frame_rate( int buffer_index){ unsigned char frame_rate_code; frame_rate_code = (unsigned char )buf[buffer_index + 7 ] & 0xf ; switch (frame_rate_code) { case 0x1 : return 23.976 ; case 0x2 : return 24.0 ; case 0x3 : return 25.0 ; case 0x4 : return 29.97 ; case 0x5 : return 30.0 ; case 0x6 : return 50.0 ; case 0x7 : return 59.94 ; case 0x8 : return 60.0 ; default : return 0 ; } } // ======================================================== unsigned int extract_temporal_reference( int buffer_index) // 10 bits { unsigned int low2bits = 0 ,TR = 0 ; // TR = temporal reference; TR = (unsigned int ) (buf[buffer_index + 4 ]); TR <<= 2 ; low2bits = (unsigned int ) (buf[buffer_index + 5 ]); TR |= (low2bits >> 6 ); return (TR); } // ======================================================== unsigned int read_picture_type( int buffer_index){ unsigned int pictype = 0 ; pictype = (unsigned int ) buf[buffer_index + 5 ]; pictype = (pictype >> 3 ) & ( 0x7 ); return (pictype); } // ======================================================= unsigned int read_FFV( int buffer_index) // 1 bit { return ( ( int ) ((buf[buffer_index + 7 ] & ( 0x4 )) >> 2 )); } // ======================================================= unsigned int read_FFC( int buffer_index) // 3 bits { unsigned int FFC = 0 ,lowbit = 0 ; FFC = ( int ) (buf[buffer_index + 7 ] & ( 0x3 )); FFC <<= 1 ; lowbit = ( int ) ((buf[buffer_index + 8 ]) & ( 0x80 )); FFC = FFC | (lowbit >> 7 ); return (FFC); } // ======================================================= unsigned int read_FBV( int buffer_index) // 1 bit { return ( ( int ) ((buf[buffer_index + 8 ] & ( 0x40 )) >> 6 ) ); } // ======================================================= unsigned int read_BFC( int buffer_index) // 3 bits { return ( ( int ) ( (buf[buffer_index + 8 ] & ( 0x38 ) ) >> 3 ) ); } void validate_file(){ /* to validate the file, ensure the existance of a startcode */ int j = 0 ,valid = 0 ; while ((j ++< MAX_RTP_PKT_LENGTH) && ( ! valid)) { if ( ! (( int )buf[j + 0 ] + ( int )buf[j + 1 ]) && ((( int )buf[j + 2 ]) == 1 )) valid = 1 ; } if ( ! valid) { printf( " /nERROR: start code not found. / /nInput file must be a valid MPEG I file./n " ); exit( 0 ); } } BOOL InitWinsock(){ int Error; WORD VersionRequested; WSADATA WsaData; VersionRequested = MAKEWORD( 2 , 2 ); Error = WSAStartup(VersionRequested, & WsaData); // 启动WinSock2 if (Error != 0 ) { return FALSE; } else { if (LOBYTE(WsaData.wVersion) != 2 || HIBYTE(WsaData.wHighVersion) != 2 ) { WSACleanup(); return FALSE; } } return TRUE; }
完成这个测试程序后，我有了很大的信心，又重复看了RFC3550几编，其实，如果你真看了程序，你发现我只发送了RTP，并没有发送RTCP数据包，因此，我们是不能同步多个RTP流的。我没去编码下去，因为我觉得已经够了。这里强调，没用说的RTP没有了RTCP就不行！接下来的工作，就是把这个程序的下层发包函数去掉，采用RTP库JRTPLIB，我觉得这才应该是JRTPLIB的DEMO！如果有人问，就这样的一个程序就能完成任务了，要 JRTPLIB干嘛，其实，我不写RTCP相关代码的原因为多个：
1.RTCP里头有很多关于RTCP发送简隔的时间计算，RTP信息的统计，这种操作不是难，而是烦，我不想去写
2.RTCP和RTP一开始出来的时候并不是因为视频的点播等应用的，而是视频会议。RTCP有管理与会者的层面含义，这一功能在很多场合并不会用到。
3.我想简单，没有写多个流间的同步，如一个影片的视频和音频流。这些其实是RTCP来完成的。
我懒得去写，因为这些功作RTP的各个库类都做得很好。我觉得用库的最大优点就在这吧。