1.读flv文件jump over9个字节,再jump over4个字节。再读type,datalength,timestamp,streamid。

还是要对照协议看。

The FLV header

9个字节的文件头

 

Field             Type    Comment
Signature         UI8     Signature byte always 'F' (0x46)
Signature         UI8     Signature byte always 'L' (0x4C)
Signature         UI8     Signature byte always 'V' (0x56)
Version           UI8     File version (for example, 0x01 for FLV version 1)
TypeFlagsReserved UB [5]  Shall be 0
TypeFlagsAudio    UB [1]  1 = Audio tags are present
TypeFlagsReserved UB [1]  Shall be 0
TypeFlagsVideo    UB [1]  1 = Video tags are present
DataOffset        UI32    The length of this header in bytes

The FLV File Body

4个字节的PreviousTagSize0，接着是FLVTAG

Field            Type    Comment
PreviousTagSize0 UI32    Always 0
Tag1             FLVTAG  First tag
PreviousTagSize1 UI32    Size of previous tag, including its header, in bytes. \
                         For FLV version 1, this value is 11 plus the DataSize of the previous tag.
Tag2             FLVTAG  Second tag
...

FLV Tag 读type,datalength,timestamp,streamid。type==8是音频，type==9是视频。   VideoTagHeader

结合前文《librtmp发送h264》  ，SendH264Packet函数，SendVideoSpsPps函数就是这样组包的。

 

    //packet attributes
    uint32_t type=0;            
    uint32_t datalength=0;        
    uint32_t timestamp=0;        
    uint32_t streamid=0;            

    FILE*fp=NULL;
    fp=fopen("cuc_ieschool.flv","rb");
    if (!fp){
        RTMP_LogPrintf("Open File Error.\n");
        CleanupSockets();
        return -1;
    }

    //jump over FLV Header
    fseek(fp,9,SEEK_SET);    
    //jump over previousTagSizen
    fseek(fp,4,SEEK_CUR);    
    start_time=RTMP_GetTime();
    while(1)
    {
        if((((now_time=RTMP_GetTime())-start_time)
              <(pre_frame_time)) && bNextIsKey){    
            //wait for 1 sec if the send process is too fast
            //this mechanism is not very good,need some improvement
            if(pre_frame_time>lasttime){
                RTMP_LogPrintf("TimeStamp:%8lu ms\n",pre_frame_time);
                lasttime=pre_frame_time;
            }
            Sleep(1000);
            continue;
        }
        
        //not quite the same as FLV spec
        if(!ReadU8(&type,fp))    
            break;
        if(!ReadU24(&datalength,fp))
            break;
        if(!ReadTime(&timestamp,fp))
            break;
        if(!ReadU24(&streamid,fp))
            break;

        if (type!=0x08&&type!=0x09){
            //jump over non_audio and non_video frame，
            //jump over next previousTagSizen at the same time
            fseek(fp,datalength+4,SEEK_CUR);
            continue;
        }
        
        if(fread(packet->m_body,1,datalength,fp)!=datalength)
            break;

        packet->m_headerType = RTMP_PACKET_SIZE_LARGE; 
        packet->m_nTimeStamp = timestamp; 
        packet->m_packetType = type;
        packet->m_nBodySize  = datalength;
        pre_frame_time=timestamp;

        if (!RTMP_IsConnected(rtmp)){
            RTMP_Log(RTMP_LOGERROR,"rtmp is not connect\n");
            break;
        }
        if (!RTMP_SendPacket(rtmp,packet,0)){
            RTMP_Log(RTMP_LOGERROR,"Send Error\n");
            break;
        }

        if(!ReadU32(&preTagsize,fp))
            break;
            
        if(!PeekU8(&type,fp))
            break;
        if(type==0x09){
            if(fseek(fp,11,SEEK_CUR)!=0)
                break;
            if(!PeekU8(&type,fp)){
                break;
            }
            if(type==0x17)
                bNextIsKey=1;
            else
                bNextIsKey=0;

            fseek(fp,-11,SEEK_CUR);
        }
    }                

    RTMP_LogPrintf("\nSend Data Over\n");
    
    if(fp)
        fclose(fp);

 

 

https://blog.csdn.net/leixiaohua1020/article/details/42104945

 

https://depthlove.github.io/2015/11/13/flv-analysis-in-rtmp-live-play/

https://blog.csdn.net/yeyumin89/article/details/7932368