公司网站域名是什么意思,盘锦做网站电话,微信小程序怎么做活动,海南省建设网站的公司阅读了librtmp的源码#xff0c;简单记录下。
首先补充下AMF格式基本知识
1 AMF格式 AMF是Action Message Format(动作消息格式)的简写#xff0c;它是一种二进制的数据格式。它的设计是为了把actionscript里面的数据(包括Object, Array, Boolean, Number等)序列化成二进制…阅读了librtmp的源码简单记录下。
首先补充下AMF格式基本知识
1 AMF格式 AMF是Action Message Format(动作消息格式)的简写它是一种二进制的数据格式。它的设计是为了把actionscript里面的数据(包括Object, Array, Boolean, Number等)序列化成二进制数据然后把这段数据随意发送给其他接收方程序比如发给远程的服务器在远程服务器那边可以把这段数据给还原出来以此达到一个数据传输的作用。
1.1 AMFObject AMF分成两种 1. AMF0基本的数据转换规则 2. AMF3是AMF0的扩展
AMF0数据类型
// AMF0数据类型
typedef enum
{AMF_NUMBER 0, // 数字(double)AMF_BOOLEAN, // 布尔AMF_STRING, // 字符串AMF_OBJECT, // 对象AMF_MOVIECLIP, // 保留,未使用AMF_NULL, // nullAMF_UNDEFINED, // 未定义AMF_REFERENCE, // 引用AMF_ECMA_ARRAY, // 数组AMF_OBJECT_END, // 对象结束AMF_STRICT_ARRAY, // 严格的数组AMF_DATE, // 日期AMF_LONG_STRING, // 长字符串AMF_UNSUPPORTED, // 未支持AMF_RECORDSET, // 保留,未使用AMF_XML_DOC, // xml文档AMF_TYPED_OBJECT, // 有类型的对象AMF_AVMPLUS, // 需要扩展到AMF3AMF_INVALID 0xff // 无效的
}AMFDataType;
AMF3数据类型
// AMF3数据类型
typedef enum
{AMF3_UNDEFINED 0, // 未定义AMF3_NULL, // nullAMF3_FALSE, // falseAMF3_TRUE, // trueAMF3_INTEGER, // 数字intAMF3_DOUBLE, // doubleAMF3_STRING, // 字符串AMF3_XML_DOC, // xml文档AMF3_DATE, // 日期AMF3_ARRAY, // 数组AMF3_OBJECT, // 对象AMF3_XML, // xmlAMF3_BYTE_ARRAY // 字节数组
} AMF3DataType;
AMF定义了自己的字符串类型 // AMF自定义的字符串typedef struct AVal{char *av_val;int av_len;} AVal;// AVal的快速初始化
#define AVC(str) {str,sizeof(str)-1}
// 比较AVal字符串
#define AVMATCH(a1,a2) ((a1)-av_len (a2)-av_len !memcmp((a1)-av_val,(a2)-av_val,(a1)-av_len))
AMFObject表示AMF对象o_num 代表 o_props的个数 一个对象内部可以包含N个对象属性
// AMF对象, 就是由一系列的属性构成的
typedef struct AMFObject
{int o_num; // 属性数目;struct AMFObjectProperty *o_props; // 属性数组;
} AMFObject;
AMFObjectProperty表示AMF对象属性即key-value键值对。p_name表示keyp_type表示value的类型p_vu表示value的数值。
// AMF对象的属性;
typedef struct AMFObjectProperty
{AVal p_name; // 属性名称;AMFDataType p_type; // 属性类型;union{double p_number;AVal p_aval;AMFObject p_object;} p_vu; // 属性数值;int16_t p_UTCoffset; // UTC偏移;
} AMFObjectProperty;
p_vu设置为联合体的目的
当p_type为number时, m_vu取值double类型 p_number;
当p_type为string时, m_vu取值AVal类型 p_aval;
当p_type为object时, m_vu取值AMFObject类型 p_object。
1.2 编码格式
浮点数 0x00 8字节浮点数
Bool型 0x01 1字节Bool值
短字符串 0x02 2字节长度 字符串 长字符串 0x02 4字节长度 字符串
对象 0x03 属性1名称长度 属性1名称 1字节属性1类型 n字节属性1值 属性2名称长度 属性2名称 1字节属性2类型 n字节属性2值 3字节结尾标志
2 librtmp源码分析
2.1 RTMP_ParseURL
解析URL得到协议名称(protocol)主机名称(host)应用程序名称(app)
2.2 HandShake握手
handshake.h文件里面的HandShake有些代码是处理rtmp加密版协议考虑普通的rtmp协议分析rtmp.c文件里的HandShake
static int
HandShake(RTMP *r, int FP9HandShake)
{int i;uint32_t uptime, suptime;int bMatch;char type;char clientbuf[RTMP_SIG_SIZE 1], *clientsig clientbuf 1;char serversig[RTMP_SIG_SIZE];clientbuf[0] 0x03; /* not encrypted */uptime htonl(RTMP_GetTime());memcpy(clientsig, uptime, 4);memset(clientsig[4], 0, 4);#ifdef _DEBUGfor (i 8; i RTMP_SIG_SIZE; i)clientsig[i] 0xff;
#elsefor (i 8; i RTMP_SIG_SIZE; i)clientsig[i] (char)(rand() % 256);
#endifif (!WriteN(r, clientbuf, RTMP_SIG_SIZE 1))return FALSE;if (ReadN(r, type, 1) ! 1) /* 0x03 or 0x06 */return FALSE;RTMP_Log(RTMP_LOGDEBUG, %s: Type Answer : %02X, __FUNCTION__, type);if (type ! clientbuf[0])RTMP_Log(RTMP_LOGWARNING, %s: Type mismatch: client sent %d, server answered %d,__FUNCTION__, clientbuf[0], type);if (ReadN(r, serversig, RTMP_SIG_SIZE) ! RTMP_SIG_SIZE)return FALSE;/* decode server response */memcpy(suptime, serversig, 4);suptime ntohl(suptime);RTMP_Log(RTMP_LOGDEBUG, %s: Server Uptime : %d, __FUNCTION__, suptime);RTMP_Log(RTMP_LOGDEBUG, %s: FMS Version : %d.%d.%d.%d, __FUNCTION__,serversig[4], serversig[5], serversig[6], serversig[7]);/* 2nd part of handshake */if (!WriteN(r, serversig, RTMP_SIG_SIZE))return FALSE;if (ReadN(r, serversig, RTMP_SIG_SIZE) ! RTMP_SIG_SIZE)return FALSE;bMatch (memcmp(serversig, clientsig, RTMP_SIG_SIZE) 0);if (!bMatch){RTMP_Log(RTMP_LOGWARNING, %s, client signature does not match!, __FUNCTION__);}return TRUE;
}
1填充C00x3C1填充时间戳和随机数共1536byte
2发送C0 C1给服务器
3从服务器读取S0比对是否为0x3从服务器读取S1
4把S1作为C2发送给服务器
5从服务器读取S2比对C1和S2相同则握手成功
2.3 RTMP_Connect
建立NetConnection
主要调用了两个函数RTMP_Connect0和RTMP_Connect1
RTMP_Connect0
建立Socket连接
RTMP_Connect1
建立RTMP连接HandShake完成握手SendConnectPacket发送connect命令建立RTMP连接
SendConnectPacket
填充packet头
m_nChannel -- chunk Stream ID
m_headerType -- chunk header中的basic header中的fmt
m_packetType -- Message Type ID填充的0x14表示命令消息
m_nTimeStamp -- 时间戳
m_nInfoField2 -- chunk fmt为0时header的最后四个字节即Message Stream ID
m_hasAbsTimestamp -- 时间戳是绝对的还是相对的即chunk type为0时为绝对时间戳其他类型时为时间戳增量 packet.m_nChannel 0x03; /* control channel (invoke) */packet.m_headerType RTMP_PACKET_SIZE_LARGE;packet.m_packetType RTMP_PACKET_TYPE_INVOKE;packet.m_nTimeStamp 0;packet.m_nInfoField2 0;packet.m_hasAbsTimestamp 0;packet.m_body pbuf RTMP_MAX_HEADER_SIZE;
将av_x串化为x如av_connect串化为connect
#define SAVC(x) static const AVal av_##x AVC(#x)SAVC(app);
SAVC(connect);
SAVC(flashVer);
SAVC(swfUrl);
SAVC(pageUrl);
SAVC(tcUrl);
SAVC(fpad);
SAVC(capabilities);
SAVC(audioCodecs);
SAVC(videoCodecs);
SAVC(videoFunction);
SAVC(objectEncoding);
SAVC(secureToken);
SAVC(secureTokenResponse);
SAVC(type);
SAVC(nonprivate);
按照RTMP协议规范 7.2.1.1 发送connect命令
命令名connectAMF编码
enc AMF_EncodeString(enc, pend, av_connect);
Transaction ID AMF编码
enc AMF_EncodeNumber(enc, pend, r-m_numInvokes);
设置connect 命令中使用的名值对对象
对象格式起始0x3
*enc AMF_OBJECT;
属性app名字为r-Link.app
enc AMF_EncodeNamedString(enc, pend, av_app, r-Link.app);
属性flashver
enc AMF_EncodeNamedString(enc, pend, av_flashVer, r-Link.flashVer);
属性swfUrl
enc AMF_EncodeNamedString(enc, pend, av_swfUrl, r-Link.swfUrl);
属性tcUrl
enc AMF_EncodeNamedString(enc, pend, av_tcUrl, r-Link.tcUrl);
属性fpad
enc AMF_EncodeNamedBoolean(enc, pend, av_fpad, FALSE);
属性capabilities
enc AMF_EncodeNamedNumber(enc, pend, av_capabilities, 15.0);
属性audioCodecs
enc AMF_EncodeNamedNumber(enc, pend, av_audioCodecs, r-m_fAudioCodecs);
属性videoCodecs
enc AMF_EncodeNamedNumber(enc, pend, av_videoCodecs, r-m_fVideoCodecs);
属性videoFunction
enc AMF_EncodeNamedNumber(enc, pend, av_videoFunction, 1.0);
属性pageUrl
enc AMF_EncodeNamedString(enc, pend, av_pageUrl, r-Link.pageUrl);
属性objectEncoding
enc AMF_EncodeNamedNumber(enc, pend, av_objectEncoding, r-m_fEncoding);
对象格式结束0x00 0x00 0x09
*enc 0; *enc 0; *enc AMF_OBJECT_END;
wireshark抓包示意 2.4 RTMP_ConnectStream
在NetConnection基础上建立一个NetStream
主要调用了两个函数RTMP_ReadPacket和RTMP_ClientPacket
RTMP_ReadPacket
从socket接收消息块chunk解析chunk存放在RTMPPacket。此处是块chunk而不是消息message因为消息在网络传输会分割成块。一个消息可能封装多个块当所有块读取完再处理消息。
按照RTMP协议规范 5.3.1解析chunk int
RTMP_ReadPacket(RTMP *r, RTMPPacket *packet)
{uint8_t hbuf[RTMP_MAX_HEADER_SIZE] { 0 };char *header (char *)hbuf;int nSize, hSize, nToRead, nChunk;int didAlloc FALSE;int extendedTimestamp;RTMP_Log(RTMP_LOGDEBUG2, %s: fd%d, __FUNCTION__, r-m_sb.sb_socket);if (ReadN(r, (char *)hbuf, 1) 0){RTMP_Log(RTMP_LOGERROR, %s, failed to read RTMP packet header, __FUNCTION__);return FALSE;}packet-m_headerType (hbuf[0] 0xc0) 6; // fmt(2bit)packet-m_nChannel (hbuf[0] 0x3f); // 块流ID(2-63)header;if (packet-m_nChannel 0) // 块流ID第一个字节为0,表示块流ID占2个字节,表示ID的范围是64-319(第二个字节 64){if (ReadN(r, (char *)hbuf[1], 1) ! 1){RTMP_Log(RTMP_LOGERROR, %s, failed to read RTMP packet header 2nd byte,__FUNCTION__);return FALSE;}packet-m_nChannel hbuf[1];packet-m_nChannel 64;header;}else if (packet-m_nChannel 1) // 块流ID第一个字节为1,表示块流ID占3个字节,表示ID范围是64-65599(第三个字节*256 第二个字节 64){int tmp;if (ReadN(r, (char *)hbuf[1], 2) ! 2){RTMP_Log(RTMP_LOGERROR, %s, failed to read RTMP packet header 3nd byte,__FUNCTION__);return FALSE;}tmp (hbuf[2] 8) hbuf[1];packet-m_nChannel tmp 64;RTMP_Log(RTMP_LOGDEBUG, %s, m_nChannel: %0x, __FUNCTION__, packet-m_nChannel);header 2;}nSize packetSize[packet-m_headerType]; //ChunkMsgHeader 4种类型,大小分别11/7/3/0,数组值多加了1if (packet-m_nChannel r-m_channelsAllocatedIn){int n packet-m_nChannel 10;int *timestamp realloc(r-m_channelTimestamp, sizeof(int) * n);RTMPPacket **packets realloc(r-m_vecChannelsIn, sizeof(RTMPPacket*) * n);if (!timestamp)free(r-m_channelTimestamp);if (!packets)free(r-m_vecChannelsIn);r-m_channelTimestamp timestamp;r-m_vecChannelsIn packets;if (!timestamp || !packets) {r-m_channelsAllocatedIn 0;return FALSE;}memset(r-m_channelTimestamp r-m_channelsAllocatedIn, 0, sizeof(int) * (n - r-m_channelsAllocatedIn));memset(r-m_vecChannelsIn r-m_channelsAllocatedIn, 0, sizeof(RTMPPacket*) * (n - r-m_channelsAllocatedIn));r-m_channelsAllocatedIn n;}if (nSize RTMP_LARGE_HEADER_SIZE) /* if we get a full header the timestamp is absolute */packet-m_hasAbsTimestamp TRUE; // 11字节完整ChunkMsgHeader的TimeStamp是绝对时间戳else if (nSize RTMP_LARGE_HEADER_SIZE){ /* using values from the last message of this channel */if (r-m_vecChannelsIn[packet-m_nChannel])memcpy(packet, r-m_vecChannelsIn[packet-m_nChannel],sizeof(RTMPPacket));}nSize--; // 真实的ChunkMsgHeader的大小,此处减1是因为前面获取包类型的时候多加了1if (nSize 0 ReadN(r, header, nSize) ! nSize){RTMP_Log(RTMP_LOGERROR, %s, failed to read RTMP packet header. type: %x,__FUNCTION__, (unsigned int)hbuf[0]);return FALSE;}hSize nSize (header - (char *)hbuf); // 目前已经读取的字节数 basic header chunk msg headerif (nSize 3) // chunk msg header为11/7/3字节,fmt类型值为0/1/2{packet-m_nTimeStamp AMF_DecodeInt24(header); // 首部前3个字节为timestamp/*RTMP_Log(RTMP_LOGDEBUG, %s, reading RTMP packet chunk on channel %x, headersz %i, timestamp %i, abs timestamp %i, __FUNCTION__, packet.m_nChannel, nSize, packet.m_nTimeStamp, packet.m_hasAbsTimestamp); */if (nSize 6) // chunk msg header为11或7字节,fmt类型值为0或1{packet-m_nBodySize AMF_DecodeInt24(header 3); // msg lengthpacket-m_nBytesRead 0;if (nSize 6){packet-m_packetType header[6]; // msg type idif (nSize 11)packet-m_nInfoField2 DecodeInt32LE(header 7); // msg stream id,小端字节序}}}extendedTimestamp packet-m_nTimeStamp 0xffffff; //timestamp为0xffffff,则需要extend timestamp,占4字节if (extendedTimestamp){if (ReadN(r, header nSize, 4) ! 4){RTMP_Log(RTMP_LOGERROR, %s, failed to read extended timestamp,__FUNCTION__);return FALSE;}packet-m_nTimeStamp AMF_DecodeInt32(header nSize);hSize 4;}RTMP_LogHexString(RTMP_LOGDEBUG2, (uint8_t *)hbuf, hSize);if (packet-m_nBodySize 0 packet-m_body NULL){if (!RTMPPacket_Alloc(packet, packet-m_nBodySize)){RTMP_Log(RTMP_LOGDEBUG, %s, failed to allocate packet, __FUNCTION__);return FALSE;}didAlloc TRUE;packet-m_headerType (hbuf[0] 0xc0) 6;}nToRead packet-m_nBodySize - packet-m_nBytesRead;nChunk r-m_inChunkSize;if (nToRead nChunk)nChunk nToRead;/* Does the caller want the raw chunk? */if (packet-m_chunk){packet-m_chunk-c_headerSize hSize; // 块头大小memcpy(packet-m_chunk-c_header, hbuf, hSize); // 填充块头数据packet-m_chunk-c_chunk packet-m_body packet-m_nBytesRead; // 块消息数据缓冲区packet-m_chunk-c_chunkSize nChunk; // 块大小}// 读取一个块大小的数据存入块消息数据缓冲区if (ReadN(r, packet-m_body packet-m_nBytesRead, nChunk) ! nChunk){RTMP_Log(RTMP_LOGERROR, %s, failed to read RTMP packet body. len: %u,__FUNCTION__, packet-m_nBodySize);return FALSE;}RTMP_LogHexString(RTMP_LOGDEBUG2, (uint8_t *)packet-m_body packet-m_nBytesRead, nChunk);packet-m_nBytesRead nChunk;/* keep the packet as ref for other packets on this channel */if (!r-m_vecChannelsIn[packet-m_nChannel])r-m_vecChannelsIn[packet-m_nChannel] malloc(sizeof(RTMPPacket));memcpy(r-m_vecChannelsIn[packet-m_nChannel], packet, sizeof(RTMPPacket));if (extendedTimestamp){r-m_vecChannelsIn[packet-m_nChannel]-m_nTimeStamp 0xffffff;}if (RTMPPacket_IsReady(packet)) // 读取完毕{/* make packets timestamp absolute */if (!packet-m_hasAbsTimestamp)packet-m_nTimeStamp r-m_channelTimestamp[packet-m_nChannel]; /* timestamps seem to be always relative!! */r-m_channelTimestamp[packet-m_nChannel] packet-m_nTimeStamp;/* reset the data from the stored packet. we keep the header since we may use it later if a new packet for this channel *//* arrives and requests to re-use some info (small packet header) */r-m_vecChannelsIn[packet-m_nChannel]-m_body NULL;r-m_vecChannelsIn[packet-m_nChannel]-m_nBytesRead 0;r-m_vecChannelsIn[packet-m_nChannel]-m_hasAbsTimestamp FALSE; /* can only be false if we reuse header */}else{packet-m_body NULL; /* so it wont be erased on free */}return TRUE;
}RTMP_ClientPacket
根据接收到的消息Message类型的不同做出不同的响应 int
RTMP_ClientPacket(RTMP *r, RTMPPacket *packet)
{int bHasMediaPacket 0;switch (packet-m_packetType){case RTMP_PACKET_TYPE_CHUNK_SIZE: // msg type 0x1 设置块大小/* chunk size */HandleChangeChunkSize(r, packet);break;case RTMP_PACKET_TYPE_BYTES_READ_REPORT: // msg type 0x3 确认/* bytes read report */RTMP_Log(RTMP_LOGDEBUG, %s, received: bytes read report, __FUNCTION__);break;case RTMP_PACKET_TYPE_CONTROL: // msg type 0x4 用户控制/* ctrl */HandleCtrl(r, packet);break;case RTMP_PACKET_TYPE_SERVER_BW: // msg type 0x5 确认窗口大小/* server bw */HandleServerBW(r, packet);break;case RTMP_PACKET_TYPE_CLIENT_BW: // msg type 0x6 设置对端带宽/* client bw */HandleClientBW(r, packet);break;case RTMP_PACKET_TYPE_AUDIO: // msy type 0x8 音频/* audio data *//*RTMP_Log(RTMP_LOGDEBUG, %s, received: audio %lu bytes, __FUNCTION__, packet.m_nBodySize); */HandleAudio(r, packet);bHasMediaPacket 1;if (!r-m_mediaChannel)r-m_mediaChannel packet-m_nChannel;if (!r-m_pausing)r-m_mediaStamp packet-m_nTimeStamp;break;case RTMP_PACKET_TYPE_VIDEO: // msg type 0x9 视频/* video data *//*RTMP_Log(RTMP_LOGDEBUG, %s, received: video %lu bytes, __FUNCTION__, packet.m_nBodySize); */HandleVideo(r, packet);bHasMediaPacket 1;if (!r-m_mediaChannel)r-m_mediaChannel packet-m_nChannel;if (!r-m_pausing)r-m_mediaStamp packet-m_nTimeStamp;break;case RTMP_PACKET_TYPE_FLEX_STREAM_SEND: // msg type 0xf AMF3编码 数据消息/* flex stream send */RTMP_Log(RTMP_LOGDEBUG,%s, flex stream send, size %u bytes, not supported, ignoring,__FUNCTION__, packet-m_nBodySize);break;case RTMP_PACKET_TYPE_FLEX_SHARED_OBJECT: // msg type 0x10 AMF3编码 共享对象消息/* flex shared object */RTMP_Log(RTMP_LOGDEBUG,%s, flex shared object, size %u bytes, not supported, ignoring,__FUNCTION__, packet-m_nBodySize);break;case RTMP_PACKET_TYPE_FLEX_MESSAGE: // msg type 0x11 AMF3编码 命令消息/* flex message */{RTMP_Log(RTMP_LOGDEBUG,%s, flex message, size %u bytes, not fully supported,__FUNCTION__, packet-m_nBodySize);/*RTMP_LogHex(packet.m_body, packet.m_nBodySize); *//* some DEBUG code */
#if 0RTMP_LIB_AMFObject obj;int nRes obj.Decode(packet.m_body1, packet.m_nBodySize-1);if(nRes 0) {RTMP_Log(RTMP_LOGERROR, %s, error decoding AMF3 packet, __FUNCTION__);/*return; */}obj.Dump();
#endifif (HandleInvoke(r, packet-m_body 1, packet-m_nBodySize - 1) 1)bHasMediaPacket 2;break;}case RTMP_PACKET_TYPE_INFO: // msg type 0x12 AMF0编码数据消息/* metadata (notify) */RTMP_Log(RTMP_LOGDEBUG, %s, received: notify %u bytes, __FUNCTION__,packet-m_nBodySize);if (HandleMetadata(r, packet-m_body, packet-m_nBodySize))bHasMediaPacket 1;break;case RTMP_PACKET_TYPE_SHARED_OBJECT: // msg type 0x13 AMF0编码共享对象消息RTMP_Log(RTMP_LOGDEBUG, %s, shared object, not supported, ignoring,__FUNCTION__);break;case RTMP_PACKET_TYPE_INVOKE: // msg type 0x14 AMF0编码命令消息/* invoke */RTMP_Log(RTMP_LOGDEBUG, %s, received: invoke %u bytes, __FUNCTION__,packet-m_nBodySize);/*RTMP_LogHex(packet.m_body, packet.m_nBodySize); */if (HandleInvoke(r, packet-m_body, packet-m_nBodySize) 1)bHasMediaPacket 2;break;case RTMP_PACKET_TYPE_FLASH_VIDEO: // msg type 0x16 统计消息{/* go through FLV packets and handle metadata packets */unsigned int pos 0;uint32_t nTimeStamp packet-m_nTimeStamp;while (pos 11 packet-m_nBodySize){uint32_t dataSize AMF_DecodeInt24(packet-m_body pos 1); /* size without header (11) and prevTagSize (4) */if (pos 11 dataSize 4 packet-m_nBodySize){RTMP_Log(RTMP_LOGWARNING, Stream corrupt?!);break;}if (packet-m_body[pos] 0x12){HandleMetadata(r, packet-m_body pos 11, dataSize);}else if (packet-m_body[pos] 8 || packet-m_body[pos] 9){nTimeStamp AMF_DecodeInt24(packet-m_body pos 4);nTimeStamp | (packet-m_body[pos 7] 24);}pos (11 dataSize 4);}if (!r-m_pausing)r-m_mediaStamp nTimeStamp;/* FLV tag(s) *//*RTMP_Log(RTMP_LOGDEBUG, %s, received: FLV tag(s) %lu bytes, __FUNCTION__, packet.m_nBodySize); */bHasMediaPacket 1;break;}default:RTMP_Log(RTMP_LOGDEBUG, %s, unknown packet type received: 0x%02x, __FUNCTION__,packet-m_packetType);
#ifdef _DEBUGRTMP_LogHex(RTMP_LOGDEBUG, packet-m_body, packet-m_nBodySize);
#endif}return bHasMediaPacket;
}主要关注msg type 0x14 的消息AMF0编码的命令消息。这在RTMP连接中是非常常见的比如说各种控制命令播放暂停停止等。消息处理函数HandleInvoke
HandleInvoke
主要分析createStream流程
RTMP_Connect建立网络连接后服务器返回_result给客户端
如果是connect的回应调用RTMP_SendCreateStream发送createStream给服务器服务器返回_result给客户端 if (AVMATCH(methodInvoked, av_connect)){...RTMP_SendCreateStream(r);...}
如果是createStream的回应使能推流调用SendPublish发送publish反之调用SendPlaylist获取播放列表和SendPlay 发送play开始播放流媒体数据 else if (AVMATCH(methodInvoked, av_createStream)){r-m_stream_id (int)AMFProp_GetNumber(AMF_GetProp(obj, NULL, 3));if (r-Link.protocol RTMP_FEATURE_WRITE){SendPublish(r);}else{if (r-Link.lFlags RTMP_LF_PLST)SendPlaylist(r);SendPlay(r);RTMP_SendCtrl(r, 3, r-m_stream_id, r-m_nBufferMS);}}
以下是rtmpdump拉流的打印可以更加清晰的看出代码的执行流程 2.5 RTMP_Read
FLV层读取数据主要调用Read_1_Packet从网络上读取RTMPPacket数据这个数据是不包含FLV头的RTMP_Read函数里增加flv头flv headerPrevious Tag Size共13字节
static const char flvHeader[] { F, L, V, 0x01,0x00, /* 0x04 audio, 0x01 video */0x00, 0x00, 0x00, 0x09,0x00, 0x00, 0x00, 0x00
};
Read_1_Packet
主要调用RTMP_ReadPacket和RTMP_ClientPacket()前一个负责从网络读取数据后一个负责处理数据。RTMP_ReadPacket读取的RTMPPacket数据是FLV的裸数据 Tag DataRead_1_Packet函数里增加Tag Header /* audio (0x08), video (0x09) or metadata (0x12) packets :* construct 11 byte header then add rtmp packets data */if (packet.m_packetType RTMP_PACKET_TYPE_AUDIO|| packet.m_packetType RTMP_PACKET_TYPE_VIDEO|| packet.m_packetType RTMP_PACKET_TYPE_INFO){nTimeStamp r-m_read.nResumeTS packet.m_nTimeStamp;prevTagSize 11 nPacketLen;*ptr packet.m_packetType;ptr;ptr AMF_EncodeInt24(ptr, pend, nPacketLen);#if 0if(packet.m_packetType RTMP_PACKET_TYPE_VIDEO) {/* H264 fix: */if((packetBody[0] 0x0f) 7) { /* CodecId H264 */uint8_t packetType *(packetBody1);uint32_t ts AMF_DecodeInt24(packetBody2); /* composition time */int32_t cts (ts0xff800000)^0xff800000;RTMP_Log(RTMP_LOGDEBUG, cts : %d\n, cts);nTimeStamp - cts;/* get rid of the composition time */CRTMP::EncodeInt24(packetBody2, 0);}RTMP_Log(RTMP_LOGDEBUG, VIDEO: nTimeStamp: 0x%08X (%d)\n, nTimeStamp, nTimeStamp);}
#endifptr AMF_EncodeInt24(ptr, pend, nTimeStamp);*ptr (char)((nTimeStamp 0xFF000000) 24);ptr;/* stream id */ptr AMF_EncodeInt24(ptr, pend, 0);}
2.6 RTMP_Write
解析FLV header和Tag header调用RTMP_SendPacket 发送Tag Data到网络
RTMP_SendPacket
主要是将Tag Data封装成chunk 数据send出去。RTMP_ReadPacket的逆向处理不过多分析。
2.7 字段注释 /*表示一个 raw chunk原始chunkc_header,c_headerSize保存chunk header的数据和大小c_chunk,c_chunkSize:保存chunk data的数据和大小*/typedef struct RTMPChunk{int c_headerSize;int c_chunkSize;char *c_chunk;char c_header[RTMP_MAX_HEADER_SIZE];} RTMPChunk;/*表示一个Messagem_headerType :表示m_chunk的类型即chunk header中的basic header中的fmtm_packetType :表示Message Type IDm_hasAbsTimestamp :表示时间戳是绝对的还是相对的即chunk type为0时为绝对时间戳其他类型时为时间戳增量m_nChannel :表示chunk Stream IDm_nTimeStamp :时间戳m_nInfoField2 :chunk fmt为0时header的最后四个字节即Message Stream IDm_nBodySize :Message的body的尺寸m_nBytesRead :已经读取到的body的字节数m_chunk :如果不为NULL表示用户想要获取chunk那么在读取Message时会填充这个字段m_body :Message的body*/typedef struct RTMPPacket{uint8_t m_headerType;uint8_t m_packetType;uint8_t m_hasAbsTimestamp; /* timestamp absolute or relative? */int m_nChannel;uint32_t m_nTimeStamp; /* timestamp */int32_t m_nInfoField2; /* last 4 bytes in a long header */uint32_t m_nBodySize;uint32_t m_nBytesRead;RTMPChunk *m_chunk;char *m_body;} RTMPPacket;/*RTMPSockBuf:RTMP的传输层的套接字及其缓存表示一个TCP套接字连接以及其读取缓存sb_socket :Socket套接字sb_size :buffer中未处理的字节数量即缓冲数据的大小sb_start :指向buffer中需要处理的字节即指向缓冲数据sb_buf :数据读取缓冲区sb_timedout :套接字是否中断sb_ssl :SSL相关数据*/typedef struct RTMPSockBuf{int sb_socket;int sb_size; /* number of unprocessed bytes in buffer */char *sb_start; /* pointer into sb_pBuffer of next byte to process */char sb_buf[RTMP_BUFFER_CACHE_SIZE]; /* data read from socket */int sb_timedout;void *sb_ssl;} RTMPSockBuf;/*RTMP的连接参数,即要建立RTMP连接所需的参数集注意:这是由客户端的用户提供的这个结构体里的字段的含义和rtmpdump中的选项联系紧密,可以查看rtmpdump中选项的含义来帮助我们理解它们*/typedef struct RTMP_LNK{AVal hostname; //要连接的服务器的主机名AVal sockshost; //代理主机名称AVal playpath0; /* parsed from URL */AVal playpath; /* passed in explicitly */AVal tcUrl; //要连接的目标流的URL,默认值为:rtmp[e]://host[:port]/app/playpath,由解析出的各个字段值拼接而成AVal swfUrl; //媒体的SWF播放器的URL,默认不设置任何值AVal pageUrl; //嵌入网页的媒体的URL,默认不设置任何值AVal app; //要连接的服务器上的appAVal auth;AVal flashVer; //用于运行SWF播放器的Flash插件的版本,默认为“LUX 10,0,32,18AVal subscribepath; //要访问的流的名称AVal usherToken;AVal token; //SecureToken Response中要使用的key,当服务器需要一个SecureToken验证时使用AVal pubUser;AVal pubPasswd;AMFObject extras;int edepth;int seekTime;int stopTime;#define RTMP_LF_AUTH 0x0001 /* using auth param */
#define RTMP_LF_LIVE 0x0002 /* stream is live */
#define RTMP_LF_SWFV 0x0004 /* do SWF verification */
#define RTMP_LF_PLST 0x0008 /* send playlist before play */
#define RTMP_LF_BUFX 0x0010 /* toggle stream on BufferEmpty msg */
#define RTMP_LF_FTCU 0x0020 /* free tcUrl on close */
#define RTMP_LF_FAPU 0x0040 /* free app on close */int lFlags;int swfAge;int protocol; //服务器的rtmp协议类型int timeout; /* connection timeout in seconds */int pFlags; /* unused, but kept to avoid breaking ABI */unsigned short socksport; //代理主机的端口unsigned short port; //服务器的端口#ifdef CRYPTO
#define RTMP_SWF_HASHLEN 32void *dh; /* for encryption */void *rc4keyIn;void *rc4keyOut;uint32_t SWFSize;uint8_t SWFHash[RTMP_SWF_HASHLEN];char SWFVerificationResponse[RTMP_SWF_HASHLEN10];
#endif} RTMP_LNK;//RTMP业务层,即建立rtmp流之后对rtmp流做必要操作所需的参数//必要操作如:seek操作,resume操作/* state for read() wrapper */typedef struct RTMP_READ{char *buf; //指向读取缓冲区char *bufpos; //指向未处理数据的指针unsigned int buflen; //未处理数据的大小uint32_t timestamp; //RTMP流的当前时间戳uint8_t dataType; //RTMP流的数据类型,即是否包含音频数据和视频数据 0x04为音频 0x01为视频,使用的是flv的表示法uint8_t flags; //解析flag,包含以下几个值
#define RTMP_READ_HEADER 0x01 //表示是否在当前rtmp流的开头中插入flv header,默认不会设置这个状态,置位表示已添加flv header
#define RTMP_READ_RESUME 0x02 //表示是否要进行resume
#define RTMP_READ_NO_IGNORE 0x04
#define RTMP_READ_GOTKF 0x08 //表示是否完成了resume
#define RTMP_READ_GOTFLVK 0x10
#define RTMP_READ_SEEKING 0x20 //表示是否要执行seek操作int8_t status; //读取的当前状态,表示当前的流的分析结果,为以下四个取值,为0表示正常
#define RTMP_READ_COMPLETE -3
#define RTMP_READ_ERROR -2
#define RTMP_READ_EOF -1
#define RTMP_READ_IGNORE 0/* if bResume TRUE */ //resume时需要指定的字段,用于帮助流定义resume的位置uint8_t initialFrameType; //定位的帧的类型,即是视频帧还是音频帧uint32_t nResumeTS; //定位的帧的时间戳char *metaHeader; //要resume的流的metedata数据char *initialFrame; //定位的帧的datauint32_t nMetaHeaderSize; //要resume的流的metadata数据的尺寸uint32_t nInitialFrameSize; //定位的帧的data lengthuint32_t nIgnoredFrameCounter;uint32_t nIgnoredFlvFrameCounter;} RTMP_READ;typedef struct RTMP_METHOD{AVal name;int num;} RTMP_METHOD;//表示一个RTMP流,用于保存这个RTMP流的相关参数typedef struct RTMP{int m_inChunkSize; //接收max chunk sizeint m_outChunkSize; //发送max chunk sizeint m_nBWCheckCounter; //带宽检测计数器int m_nBytesIn; //接受到的字节的总数量int m_nBytesInSent; //发送的字节的总数量int m_nBufferMS; // 当前缓冲的时间长度,以MS为单位int m_stream_id; /* returned in _result from createStream */ //Message Stream IDint m_mediaChannel; //当前media使用的chunk Stream iduint32_t m_mediaStamp; //当前media的时间戳uint32_t m_pauseStamp; //当前media暂停时的时间戳int m_pausing; //是否暂停状态int m_nServerBW; //window sizeint m_nClientBW; //Set Peer Bandwidth Message中的window sizeuint8_t m_nClientBW2; //Set Peer Bandwidth Message中的limit typeuint8_t m_bPlaying; //当前是否playuint8_t m_bSendEncoding;uint8_t m_bSendCounter;int m_numInvokes; //记录RTMP发起的invoke的数量int m_numCalls; //m_methodCalls中的数量RTMP_METHOD *m_methodCalls; /* remote method calls queue */int m_channelsAllocatedIn;int m_channelsAllocatedOut;RTMPPacket **m_vecChannelsIn;RTMPPacket **m_vecChannelsOut;int *m_channelTimestamp; /* abs timestamp of last packet */double m_fAudioCodecs; /* audioCodecs for the connect packet */double m_fVideoCodecs; /* videoCodecs for the connect packet */double m_fEncoding; /* AMF0 or AMF3 */double m_fDuration; /* duration of stream in seconds */int m_msgCounter; /* RTMPT stuff */int m_polling;int m_resplen;int m_unackd;AVal m_clientID;RTMP_READ m_read; // RTMP_Read()操作的上下文RTMPPacket m_write; // RTMP_Write()操作使用的可复用报文对象RTMPSockBuf m_sb; // RTMP_ReadPacket()读包操作的上下文RTMP_LNK Link; // RTMP连接上下文} RTMP;
