基于RTP的H264视频数据打包解包类
2023-09-27 14:29:31 时间
from:http://blog.csdn.net/dengzikun/article/details/5807694
最近考虑使用RTP替换原有的高清视频传输协议，遂上网查找有关H264视频RTP打包、解包的文档和代码。功夫不负有心人，找到不少有价值的文档和代码。参考这些资料，写了H264 RTP打包类、解包类，实现了单个NAL单元包和FU_A分片单元包。对于丢包处理，采用简单的策略：丢弃随后的所有数据包，直到收到关键帧。测试效果还不错，代码贴上来，若能为同道中人借鉴一二，足矣。两个类的使用说明如下(省略了错误处理过程)：
DWORD H264SSRC ;
CH264_RTP_PACK pack ( H264SSRC ) ;
BYTE *pVideoData ;
DWORD Size, ts ;
bool IsEndOfFrame ;
WORD wLen ;
pack.Set ( pVideoData, Size, ts, IsEndOfFrame ) ;
BYTE *pPacket ;
while ( pPacket = pack.Get ( wLen ) )
{
// rtp packet process
// ...
}
HRESULT hr ;
CH264_RTP_UNPACK unpack ( hr ) ;
BYTE *pRtpData ;
WORD inSize;
int outSize ;
BYTE *pFrame = unpack.Parse_RTP_Packet ( pRtpData, inSize, outSize ) ;
if ( pFrame != NULL )
{
// frame process
// ...
}
////////////////////////////////////////////////////////////////////////////////////////// // class CH264_RTP_PACK start class CH264_RTP_PACK #define RTP_VERSION 2 typedef struct NAL_msg_s { bool eoFrame ; unsigned char type; // NAL type unsigned char *start; // pointer to first location in the send buffer unsigned char *end; // pointer to last location in send buffer unsigned long size ; } NAL_MSG_t; typedef struct { //LITTLE_ENDIAN unsigned short cc:4; /* CSRC count */ unsigned short x:1; /* header extension flag */ unsigned short p:1; /* padding flag */ unsigned short v:2; /* packet type */ unsigned short pt:7; /* payload type */ unsigned short m:1; /* marker bit */ unsigned short seq; /* sequence number */ unsigned long ts; /* timestamp */ unsigned long ssrc; /* synchronization source */ } rtp_hdr_t; typedef struct tagRTP_INFO { NAL_MSG_t nal; // NAL information rtp_hdr_t rtp_hdr; // RTP header is assembled here int hdr_len; // length of RTP header unsigned char *pRTP; // pointer to where RTP packet has beem assembled unsigned char *start; // pointer to start of payload unsigned char *end; // pointer to end of payload unsigned int s_bit; // bit in the FU header unsigned int e_bit; // bit in the FU header bool FU_flag; // fragmented NAL Unit flag } RTP_INFO; public: CH264_RTP_PACK(unsigned long H264SSRC, unsigned char H264PAYLOADTYPE=96, unsigned short MAXRTPPACKSIZE=1472 ) { m_MAXRTPPACKSIZE = MAXRTPPACKSIZE ; if ( m_MAXRTPPACKSIZE 10000 ) { m_MAXRTPPACKSIZE = 10000 ; } if ( m_MAXRTPPACKSIZE 50 ) { m_MAXRTPPACKSIZE = 50 ; } memset ( m_RTP_Info, 0, sizeof(m_RTP_Info) ) ; m_RTP_Info.rtp_hdr.pt = H264PAYLOADTYPE ; m_RTP_Info.rtp_hdr.ssrc = H264SSRC ; m_RTP_Info.rtp_hdr.v = RTP_VERSION ; m_RTP_Info.rtp_hdr.seq = 0 ; } ~CH264_RTP_PACK(void) { } //传入Set的数据必须是一个完整的NAL,起始码为0x00000001。 //起始码之前至少预留10个字节，以避免内存COPY操作。 //打包完成后，原缓冲区内的数据被破坏。 bool Set ( unsigned char *NAL_Buf, unsigned long NAL_Size, unsigned long Time_Stamp, bool End_Of_Frame ) { unsigned long startcode = StartCode(NAL_Buf) ; if ( startcode != 0x01000000 ) { return false ; } int type = NAL_Buf[4] 0x1f ; if ( type 1 || type 12 ) { return false ; } m_RTP_Info.nal.start = NAL_Buf ; m_RTP_Info.nal.size = NAL_Size ; m_RTP_Info.nal.eoFrame = End_Of_Frame ; m_RTP_Info.nal.type = m_RTP_Info.nal.start[4] ; m_RTP_Info.nal.end = m_RTP_Info.nal.start + m_RTP_Info.nal.size ; m_RTP_Info.rtp_hdr.ts = Time_Stamp ; m_RTP_Info.nal.start += 4 ; // skip the syncword if ( (m_RTP_Info.nal.size + 7) m_MAXRTPPACKSIZE ) { m_RTP_Info.FU_flag = true ; m_RTP_Info.s_bit = 1 ; m_RTP_Info.e_bit = 0 ; m_RTP_Info.nal.start += 1 ; // skip NAL header } else { m_RTP_Info.FU_flag = false ; m_RTP_Info.s_bit = m_RTP_Info.e_bit = 0 ; } m_RTP_Info.start = m_RTP_Info.end = m_RTP_Info.nal.start ; m_bBeginNAL = true ; return true ; } //循环调用Get获取RTP包，直到返回值为NULL unsigned char* Get ( unsigned short *pPacketSize ) { if ( m_RTP_Info.end == m_RTP_Info.nal.end ) { *pPacketSize = 0 ; return NULL ; } if ( m_bBeginNAL ) { m_bBeginNAL = false ; } else { m_RTP_Info.start = m_RTP_Info.end; // continue with the next RTP-FU packet } int bytesLeft = m_RTP_Info.nal.end - m_RTP_Info.start ; int maxSize = m_MAXRTPPACKSIZE - 12 ; // sizeof(basic rtp header) == 12 bytes if ( m_RTP_Info.FU_flag ) maxSize -= 2 ; if ( bytesLeft maxSize ) { m_RTP_Info.end = m_RTP_Info.start + maxSize ; // limit RTP packetsize to 1472 bytes } else { m_RTP_Info.end = m_RTP_Info.start + bytesLeft ; } if ( m_RTP_Info.FU_flag ) { // multiple packet NAL slice if ( m_RTP_Info.end == m_RTP_Info.nal.end ) { m_RTP_Info.e_bit = 1 ; } } m_RTP_Info.rtp_hdr.m = m_RTP_Info.nal.eoFrame ? 1 : 0 ; // should be set at EofFrame if ( m_RTP_Info.FU_flag !m_RTP_Info.e_bit ) { m_RTP_Info.rtp_hdr.m = 0 ; } m_RTP_Info.rtp_hdr.seq++ ; unsigned char *cp = m_RTP_Info.start ; cp -= ( m_RTP_Info.FU_flag ? 14 : 12 ) ; m_RTP_Info.pRTP = cp ; unsigned char *cp2 = (unsigned char *) m_RTP_Info.rtp_hdr ; cp[0] = cp2[0] ; cp[1] = cp2[1] ; cp[2] = ( m_RTP_Info.rtp_hdr.seq 8 ) 0xff ; cp[3] = m_RTP_Info.rtp_hdr.seq 0xff ; cp[4] = ( m_RTP_Info.rtp_hdr.ts 24 ) 0xff ; cp[5] = ( m_RTP_Info.rtp_hdr.ts 16 ) 0xff ; cp[6] = ( m_RTP_Info.rtp_hdr.ts 8 ) 0xff ; cp[7] = m_RTP_Info.rtp_hdr.ts 0xff ; cp[8] = ( m_RTP_Info.rtp_hdr.ssrc 24 ) 0xff ; cp[9] = ( m_RTP_Info.rtp_hdr.ssrc 16 ) 0xff ; cp[10] = ( m_RTP_Info.rtp_hdr.ssrc 8 ) 0xff ; cp[11] = m_RTP_Info.rtp_hdr.ssrc 0xff ; m_RTP_Info.hdr_len = 12 ; /*! * /n The FU indicator octet has the following format: * /n * /n +---------------+ * /n MSB |0|1|2|3|4|5|6|7| LSB * /n +-+-+-+-+-+-+-+-+ * /n |F|NRI| Type | * /n +---------------+ * /n * /n The FU header has the following format: * /n * /n +---------------+ * /n |0|1|2|3|4|5|6|7| * /n +-+-+-+-+-+-+-+-+ * /n |S|E|R| Type | * /n +---------------+ */ if ( m_RTP_Info.FU_flag ) { // FU indicator F|NRI|Type cp[12] = ( m_RTP_Info.nal.type 0xe0 ) | 28 ; //Type is 28 for FU_A //FU header S|E|R|Type cp[13] = ( m_RTP_Info.s_bit 7 ) | ( m_RTP_Info.e_bit 6 ) | ( m_RTP_Info.nal.type 0x1f ) ; //R = 0, must be ignored by receiver m_RTP_Info.s_bit = m_RTP_Info.e_bit= 0 ; m_RTP_Info.hdr_len = 14 ; } m_RTP_Info.start = cp[m_RTP_Info.hdr_len] ; // new start of payload *pPacketSize = m_RTP_Info.hdr_len + ( m_RTP_Info.end - m_RTP_Info.start ) ; return m_RTP_Info.pRTP ; } private: unsigned int StartCode( unsigned char *cp ) { unsigned int d32 ; d32 = cp[3] ; d32 = 8 ; d32 |= cp[2] ; d32 = 8 ; d32 |= cp[1] ; d32 = 8 ; d32 |= cp[0] ; return d32 ; } private: RTP_INFO m_RTP_Info ; bool m_bBeginNAL ; unsigned short m_MAXRTPPACKSIZE ; // class CH264_RTP_PACK end ////////////////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////////////////// // class CH264_RTP_UNPACK start class CH264_RTP_UNPACK #define RTP_VERSION 2 #define BUF_SIZE (1024 * 500) typedef struct { //LITTLE_ENDIAN unsigned short cc:4; /* CSRC count */ unsigned short x:1; /* header extension flag */ unsigned short p:1; /* padding flag */ unsigned short v:2; /* packet type */ unsigned short pt:7; /* payload type */ unsigned short m:1; /* marker bit */ unsigned short seq; /* sequence number */ unsigned long ts; /* timestamp */ unsigned long ssrc; /* synchronization source */ } rtp_hdr_t; public: CH264_RTP_UNPACK ( HRESULT hr, unsigned char H264PAYLOADTYPE = 96 ) : m_bSPSFound(false) , m_bWaitKeyFrame(true) , m_bPrevFrameEnd(false) , m_bAssemblingFrame(false) , m_wSeq(1234) , m_ssrc(0) { m_pBuf = new BYTE[BUF_SIZE] ; if ( m_pBuf == NULL ) { hr = E_OUTOFMEMORY ; return ; } m_H264PAYLOADTYPE = H264PAYLOADTYPE ; m_pEnd = m_pBuf + BUF_SIZE ; m_pStart = m_pBuf ; m_dwSize = 0 ; hr = S_OK ; } ~CH264_RTP_UNPACK(void) { delete [] m_pBuf ; } //pBuf为H264 RTP视频数据包，nSize为RTP视频数据包字节长度，outSize为输出视频数据帧字节长度。 //返回值为指向视频数据帧的指针。输入数据可能被破坏。 BYTE* Parse_RTP_Packet ( BYTE *pBuf, unsigned short nSize, int *outSize ) { if ( nSize = 12 ) { return NULL ; } BYTE *cp = (BYTE*) m_RTP_Header ; cp[0] = pBuf[0] ; cp[1] = pBuf[1] ; m_RTP_Header.seq = pBuf[2] ; m_RTP_Header.seq = 8 ; m_RTP_Header.seq |= pBuf[3] ; m_RTP_Header.ts = pBuf[4] ; m_RTP_Header.ts = 8 ; m_RTP_Header.ts |= pBuf[5] ; m_RTP_Header.ts = 8 ; m_RTP_Header.ts |= pBuf[6] ; m_RTP_Header.ts = 8 ; m_RTP_Header.ts |= pBuf[7] ; m_RTP_Header.ssrc = pBuf[8] ; m_RTP_Header.ssrc = 8 ; m_RTP_Header.ssrc |= pBuf[9] ; m_RTP_Header.ssrc = 8 ; m_RTP_Header.ssrc |= pBuf[10] ; m_RTP_Header.ssrc = 8 ; m_RTP_Header.ssrc |= pBuf[11] ; BYTE *pPayload = pBuf + 12 ; DWORD PayloadSize = nSize - 12 ; // Check the RTP version number (it should be 2): if ( m_RTP_Header.v != RTP_VERSION ) { return NULL ; } /* // Skip over any CSRC identifiers in the header: if ( m_RTP_Header.cc ) { long cc = m_RTP_Header.cc * 4 ; if ( Size cc ) { return NULL ; } Size -= cc ; p += cc ; } // Check for ( ignore) any RTP header extension if ( m_RTP_Header.x ) { if ( Size 4 ) { return NULL ; } Size -= 4 ; p += 2 ; long l = p[0] ; l = 8 ; l |= p[1] ; p += 2 ; l *= 4 ; if ( Size l ) ; { return NULL ; } Size -= l ; p += l ; } // Discard any padding bytes: if ( m_RTP_Header.p ) { if ( Size == 0 ) { return NULL ; } long Padding = p[Size-1] ; if ( Size Padding ) { return NULL ; } Size -= Padding ; }*/ // Check the Payload Type. if ( m_RTP_Header.pt != m_H264PAYLOADTYPE ) { return NULL ; } int PayloadType = pPayload[0] 0x1f ; int NALType = PayloadType ; if ( NALType == 28 ) // FU_A { if ( PayloadSize 2 ) { return NULL ; } NALType = pPayload[1] 0x1f ; } if ( m_ssrc != m_RTP_Header.ssrc ) { m_ssrc = m_RTP_Header.ssrc ; SetLostPacket () ; } if ( NALType == 0x07 ) // SPS { m_bSPSFound = true ; } if ( !m_bSPSFound ) { return NULL ; } if ( NALType == 0x07 || NALType == 0x08 ) // SPS PPS { m_wSeq = m_RTP_Header.seq ; m_bPrevFrameEnd = true ; pPayload -= 4 ; *((DWORD*)(pPayload)) = 0x01000000 ; *outSize = PayloadSize + 4 ; return pPayload ; } if ( m_bWaitKeyFrame ) { if ( m_RTP_Header.m ) // frame end { m_bPrevFrameEnd = true ; if ( !m_bAssemblingFrame ) { m_wSeq = m_RTP_Header.seq ; return NULL ; } } if ( !m_bPrevFrameEnd ) { m_wSeq = m_RTP_Header.seq ; return NULL ; } else { if ( NALType != 0x05 ) // KEY FRAME { m_wSeq = m_RTP_Header.seq ; m_bPrevFrameEnd = false ; return NULL ; } } } /////////////////////////////////////////////////////////////// if ( m_RTP_Header.seq != (WORD)( m_wSeq + 1 ) ) // lost packet { m_wSeq = m_RTP_Header.seq ; SetLostPacket () ; return NULL ; } else { // 码流正常 m_wSeq = m_RTP_Header.seq ; m_bAssemblingFrame = true ; if ( PayloadType != 28 ) // whole NAL { *((DWORD*)(m_pStart)) = 0x01000000 ; m_pStart += 4 ; m_dwSize += 4 ; } else // FU_A { if ( pPayload[1] 0x80 ) // FU_A start { *((DWORD*)(m_pStart)) = 0x01000000 ; m_pStart += 4 ; m_dwSize += 4 ; pPayload[1] = ( pPayload[0] 0xE0 ) | NALType ; pPayload += 1 ; PayloadSize -= 1 ; } else { pPayload += 2 ; PayloadSize -= 2 ; } } if ( m_pStart + PayloadSize m_pEnd ) { CopyMemory ( m_pStart, pPayload, PayloadSize ) ; m_dwSize += PayloadSize ; m_pStart += PayloadSize ; } else // memory overflow { SetLostPacket () ; return NULL ; } if ( m_RTP_Header.m ) // frame end { *outSize = m_dwSize ; m_pStart = m_pBuf ; m_dwSize = 0 ; if ( NALType == 0x05 ) // KEY FRAME { m_bWaitKeyFrame = false ; } return m_pBuf ; } else { return NULL ; } } } void SetLostPacket() { m_bSPSFound = false ; m_bWaitKeyFrame = true ; m_bPrevFrameEnd = false ; m_bAssemblingFrame = false ; m_pStart = m_pBuf ; m_dwSize = 0 ; } private: rtp_hdr_t m_RTP_Header ; BYTE *m_pBuf ; bool m_bSPSFound ; bool m_bWaitKeyFrame ; bool m_bAssemblingFrame ; bool m_bPrevFrameEnd ; BYTE *m_pStart ; BYTE *m_pEnd ; DWORD m_dwSize ; WORD m_wSeq ; BYTE m_H264PAYLOADTYPE ; DWORD m_ssrc ; // class CH264_RTP_UNPACK end //////////////////////////////////////////////////////////////////////////////////////////
23楼 _beginthreadex 2014-11-07 16:31发表 [回复]
调用博主的代码成功实现了对RTP包的解析和帧重组，直接保存成文件可以用VLC播放。另，博主的解包类里面似乎没有对SEI进行处理，所以在转换某个摄像机的视频时，我得到的数据全都是SPS与PPS，后查看直接保存的二进制文件，发现因为SEI也是有序列号的，不加1的话，下一次比较定会出错。已手动修改。
Re: dengzikun 2014-07-16 11:32发表 [回复]
回复chen495810242：typedef struct {#ifdef _BIG_ENDIAN
unsigned short v:2; /* packet type */
unsigned short p:1; /* padding flag */
unsigned short x:1; /* header extension flag */
unsigned short cc:4; /* CSRC count */
unsigned short m:1; /* marker bit */
unsigned short pt:7; /* payload type */
#else
unsigned short cc:4; /* CSRC count */
unsigned short x:1; /* header extension flag */
unsigned short p:1; /* padding flag */
unsigned short v:2; /* packet type */
unsigned short pt:7; /* payload type */
unsigned short m:1; /* marker bit */
#endif
uint16_t seq; /* sequence number */
uint32_t ts; /* timestamp */
uint32_t ssrc; /* synchronization source */
} rtp_hdr_t;
19楼 chinapacs 2012-06-29 14:16发表 [回复]
非常感谢谢！！！基于时间戳这一块，困扰我大半个月。。目前圆满解决。我采用的方式跟你的类似，再次谢谢您。memcpy(dst, nal[0].p_payload, i_frame_size);
if (count 1) {
struct timeval now;
gettimeofday( now, NULL);
double val = (now.tv_sec - firstTime.tv_sec) +
(now.tv_usec - firstTime.tv_usec) / 1000000.0;
ts_current= ts_current + val * 90000.0 + 0.5;
firstTime = now;
}
else {
ts_current= 0;
gettimeofday( firstTime, NULL);
}
count ++;
Re: dengzikun 2012-06-29 09:12发表 [回复] [引用] [举报]
回复chinapacs：class RTP_Timestamp{
public:
RTP_Timestamp(DWORD unit)
: m_dwUnit(unit)
{
QueryPerformanceFrequency ( (LARGE_INTEGER*) m_Freq ) ;
}
~RTP_Timestamp(void)
{
}
DWORD GetTime ()
{
__int64 current ;
QueryPerformanceCounter ( (LARGE_INTEGER*) current ) ;
DWORD ts = current * m_dwUnit / m_Freq ;
return ts ;
}
private:
DWORD m_dwUnit ;
__int64 m_Freq ;
};
RTP_Timestamp TS ( 90000 ) ;
每一帧调用TS.GetTime()获取时间戳。
RTP 和 RTSP的区别 RTP(Real-time Transport Protocol)是用于Internet上针对多媒体数据流的一种传输协议。RTP被定义为在一对一或一对多的传输情况下工作。其目的是提供时间信息和实现流同步。
RTP协议之Header结构解析 实时传输协议 RTP，RTP 提供带有实时特性的端对端数据传输服务，传输的数据如：交互式的音频和视频。那些服务包括有效载荷类型定义，序列号，时间戳和传输监测控制。应用程序在 UDP 上运行 RTP 来使用它的多路技术和 checksum 服务。
NALU头由一个字节组成,它的语法如下: +---------------+ |0|1|2|3|4|5|6|7| +-+-+-+-+-+-+-+-+ |F|NRI| Type | +---------------+ F: 1个比特.
H264 NALU 使用PS封装 RTP发送 最近由于项目平台需求，要将H264 NALU封装为PS再用RTP发送，PS封装按照ISO DEC-13818-1标准。一个PS包包含PS Header, PES Header, PS system header, PS system map等。
RTP协议全解析（H264码流和PS流） 写在前面：RTP的解析，网上找了很多资料，但是都不全，所以我力图整理出一个比较全面的解析， 其中借鉴了很多文章，我都列在了文章最后，在此表示感谢。 互联网的发展离不开大家的无私奉献，我决定从我做起，希望大家支持。