前言

rtmp即Real Time Messaging Protocol（實時訊息傳輸協議）的首字母縮寫，它是由Adobe公司提出的一種應用層的協議，用來解決多媒體資料傳輸流的多路複用（Multiplexing）和分包（packetizing）的問題。
目前現在流行的是直播技術， 大部分都是採用該協議；本文件重點用C++開發實現了RTMP直播推流sdk部分，並使之跨平臺通用。
簡單的結構如下：

主要介面設計

class  SRLibRtmpInterface
{
public:    
    virtual int Connect(const char* url) = 0
 
;
    virtual int StartRtmpSend(int EnableVideo, int EnableAudio) = 0;
    virtual int InitVideoParams(SR_VideoCodecSetting videoCodecSetting) = 0;
    virtual int InitAudioParams(SR_AudioCodecSetting audioCodecSetting) = 0;
    virtual int SetAudioDelay(int msecs) = 0;
    virtual int StartRecordMp4File() = 0
 
;
    virtual int StopRecordMp4File() = 0;
    virtual int SendYUVCapture(unsigned char * yuvframe, int  yuvframeLen, unsigned long nTimeStamp) = 0;
    virtual int SendPCMFrame(unsigned char * pcmframe, int  frameLen, unsigned long nTimeStamp) = 0;
    virtual int Close() = 0;

    SRLibRtmpInterface(){};
    virtual
 
 ~SRLibRtmpInterface() = 0;

}

• 使用者直接設定需要連線的url 例如騰訊雲的推流地址
• 使用者直接輸入yuv和pcm資料，推流sdk打包推送到各個平臺
• 使用者可以錄製本地推送的流到mp4 檔案

H264編碼

int i_frame_size_byte = x264_encoder_encode(_enc, &nalu, &num_nals, &xpic, &oxpic);

    if(i_frame_size_byte < 0)
    {
        xbase::XLog::Printf("EncodeX264", xbase::XLOG_ERR, "x264 encode failed");
        return -1;
    }

    if(num_nals <= 0)
    {
        xbase::XLog::Printf("EncodeX264", xbase::XLOG_ERR, "frame delayed in encoder.");
        return -2;
    }

    _frameNbr++;


    for(int i = 0; i < num_nals; i++)
    {
           //unsigned char nalu_header[4] = { 0, 0, 0, 1 };
            //fwrite(nalu_header, 1, 4, fp_h264);
            //fwrite(nalu[i].p_payload, 1, nalu[i].i_payload, fp_h264);
        x264_nal_t &nal = nalu[i];

        if (nal.i_type == NAL_SPS)
        {
            uint8_t * h264Data = nal.p_payload;

            if (video_broadcaster)
            {
                base::DataBuffer* RecvdataBuf = new base::DataBuffer(h264Data, nal.i_payload);
                video_broadcaster->PreSendVideoDataPacket(RecvdataBuf, nTimeStamp, true);
            }

        }

        if (nal.i_type == NAL_PPS)
        {

            uint8_t * h264Data = nal.p_payload;

            if (video_broadcaster)
            {
                base::DataBuffer* RecvdataBuf = new base::DataBuffer(h264Data, nal.i_payload);
                video_broadcaster->PreSendVideoDataPacket(RecvdataBuf, nTimeStamp, true);
            }

        }

        if (nal.i_type == NAL_SLICE_IDR)
        {
            uint8_t * h264Data = nal.p_payload;

            if (video_broadcaster)
            {
                base::DataBuffer* RecvdataBuf = new base::DataBuffer(h264Data, nal.i_payload);
                video_broadcaster->PreSendVideoDataPacket(RecvdataBuf, nTimeStamp, true);
            }
        }



        if (nal.i_type == NAL_SLICE)
        {
            uint8_t * h264Data = nal.p_payload;

            if (video_broadcaster)
            {
                base::DataBuffer* RecvdataBuf = new base::DataBuffer(h264Data, nal.i_payload);
                video_broadcaster->PreSendVideoDataPacket(RecvdataBuf, nTimeStamp, false);
            }

        }
    }

分發器

本sdk加入了分發器的概念， 同一個流可以推動多個平臺

rtmp打包

RTMP 協議棧的實現，這裡使用的 srs-libRTMP，它提供的使用demo很多，程式碼設計也很精煉

聯絡

點選連結加入群【rtmp直播交流學習合作】：https://jq.qq.com/?_wv=1027&k=4Aqm21F
qq群號：559425694
email:[email protected]/690759587