关于c++:SkeyeRTMPClient拉取RTMP流扩展支持HEVCH265解决方案

不久前咱们曾经在RTMP推送端扩大反对了HEVC(H.265 后文统称H265)编码格局，然而，因为RTMP官网指定的协定格局曾经不再更新，官网的播放器的Flash播放器并不反对H265格局的编码数据进行解码播放；当初，咱们须要在播放器端解析RTMP流时对H265编码格局进行扩大反对。

首先，咱们能够通过扩大ffmpeg，让其反对拉H265封装的RTMP流进行解码播放，咱们能够通过金山云对FFmepg的扩大反对H265来解决。

而后，咱们通过批改SkeyeRTMPClient的代码实现对H265 的反对，因为咱们曾经实现了推送端的扩大反对，所以，播放端反对则绝对比较简单；不过仍然有几个方面咱们须要留神；上面将对整个扩大流程进行介绍。

1. 扩大编码ID

和推送端一样，须要先扩大反对H265的编码ID，咱们定义为12，如下代码所示：

enum FlvVideoCodecId
{
    e_FlvVideoCodecId_None     = 0,
    e_FlvVideoCodecId_Jpeg     = 1,
    e_FlvVideoCodecId_H263     = 2,
    e_FlvVideoCodecId_Screen   = 3,
    e_FlvVideoCodecId_Vp6      = 4,
    e_FlvVideoCodecId_Vp6Alpha = 5,
    e_FlvVideoCodecId_ScreenV2 = 6,
    e_FlvVideoCodecId_Avc      = 7,
    // RTMP扩大反对HEVC(H.265) 
    e_FlvVideoCodecId_Hevc      = 12, 

};


enum FlvCodeId
{
    FlvCodeId_Jpeg = 1,
    FlvCodeId_Sorenson = 2,
    FlvCodeId_ScreenVideo = 3,
    FlvCodeId_On2Vp6 = 4,
    FlvCodeId_On2Vp6Alpha = 5,
    FlvCodeId_ScreenVideoV2 = 6,
    FlvCodeId_AVC = 7,
    // RTMP扩大反对HEVC(H.265)
    FlvCodeId_Hevc      = 12,
};

2. 扩大H265特有头部数据结构VPS

因为H264只有SPS和PPS，所以在兼容H265的时候，咱们须要定义其特有的头VPS:

    char    vps_buf_[MAX_VPS_LEN];//256
    int        vps_len_;    

3. MetaData解析扩大反对H265

在推送端，咱们扩大H265发送的MetaData构造定义如下：

typedef struct HVCCNALUnitArray {
    uint8_t  array_completeness;
    uint8_t  NAL_unit_type;
    uint16_t numNalus;
    uint16_t *nalUnitLength;
    uint8_t  **nalUnit;
} HVCCNALUnitArray;

typedef struct HEVCDecoderConfigurationRecord {
    uint8_t  configurationVersion;
    uint8_t  general_profile_space;
    uint8_t  general_tier_flag;
    uint8_t  general_profile_idc;
    uint32_t general_profile_compatibility_flags;
    uint64_t general_constraint_indicator_flags;
    uint8_t  general_level_idc;
    uint16_t min_spatial_segmentation_idc;
    uint8_t  parallelismType;
    uint8_t  chromaFormat;
    uint8_t  bitDepthLumaMinus8;
    uint8_t  bitDepthChromaMinus8;
    uint16_t avgFrameRate;
    uint8_t  constantFrameRate;
    uint8_t  numTemporalLayers;
    uint8_t  temporalIdNested;
    uint8_t  lengthSizeMinusOne;
    uint8_t  numOfArrays;
    HVCCNALUnitArray *array;
} HEVCDecoderConfigurationRecord;

当初咱们须要从MetaData外面讲VPS，SPS和PPS解析进去，首先，判断视频编码格局：

    parser_VideoTag *video_tag = (parser_VideoTag*)(buf+parser_offset);
    FlvCodeId video_code_id = (FlvCodeId)(video_tag->code_id&0x0f);
    if (video_code_id == FlvCodeId_Hevc)
    {
        av_frame.u32AVFrameFlag = SKEYE_SDK_VIDEO_CODEC_H265;// HEVC;
    } 
    else
    {
        av_frame.u32AVFrameFlag = SKEYE_SDK_VIDEO_CODEC_H264;// 默认h264, 其余类型是否须要判断?!;
    }

而后，判断视频帧格局为H265后，咱们从MetaData中获取VPS,SPS和PPS，如下代码所示：

         char *parser_config = buf;
        Parser_HEVCDecoderConfigurationRecord *decoder_header = (Parser_HEVCDecoderConfigurationRecord*)((char*)parser_config);
        parser_offset += sizeof(Parser_HEVCDecoderConfigurationRecord);
        int nNumOfArrays = decoder_header->numOfArrays;
        for (int i=0; i<nNumOfArrays; i++)
        {
            Parser_HVCCNALUnitArray* pNALUnit = (Parser_HVCCNALUnitArray*)((char *)parser_config+parser_offset);
            parser_offset += sizeof(Parser_HVCCNALUnitArray);
            int numNalus = ntohs(*(unsigned short *)((char *)parser_config + parser_offset));  
            parser_offset += 2;
            for (int nI=0; nI<numNalus; nI++)
            {
                //     uint16_t *nalUnitLength;
                //     uint8_t  **nalUnit;
                ps_len = *pNALUnit[i]->nalUnitLength;
                if (pNALUnit[nI]->NAL_unit_type == 0x20)
                {
                    //获取VPS
                    memcpy(vps_buf_, *pNALUnit[i]->nalUnit, ps_len);
                    vps_len_ = ps_len;
                } 
                else if (pNALUnit[nI]->NAL_unit_type == 0x021)
                {
                    //获取SPS
                    memcpy(sps_buf_,*pNALUnit[i]->nalUnit, ps_len);
                    sps_len_ = ps_len;
                }
                else if (pNALUnit[nI]->NAL_unit_type == 0x22)
                {
                    //获取PPS
                    memcpy(pps_buf_,*pNALUnit[i]->nalUnit, ps_len);
                    pps_len_ = ps_len;
                }    
                parser_offset += ps_len;
            }
        }
        //从H265的SPS头部构造中获得视频长宽
        rtmpclient_h265_decode_sps((unsigned char *)sps_buf_, sps_len_, width_, height_);    

4. 视频数据帧Nalu解析扩大反对H265

首先，判断如果是H265视频帧，则须要解析视频帧是否携带VPS：

        if(av_frame.u32AVFrameFlag == SKEYE_SDK_VIDEO_CODEC_H265)
        {
            nalu_type = (buf[parse_offset] >> 1) & 0x3F;
            if(nalu_type == e_H265_NAL_UNIT_VPS)
            {
                memcpy(vps_buf_,buf + parse_offset,nalu_len);
                vps_len_ = nalu_len;
                parse_offset += nalu_len;
                continue;
            }
        }else{
            nalu_type = buf[parse_offset]&0x1F;
        }

而后，对于SPS和PPS，以及Idr帧、P帧的nalu数据单元的解析，该局部解析和H264解析办法统一，就不做过多赘述。

上面咱们通过SkeyeScreenLive来推H265编码格局的RTMP流到SkeyeSMS，通过skeyplayer（ffmpeg拉流）和skeyeexpeedplayer(SkeyeRTMPClient拉流)播放，如下图所示：

咱们发现通过网页播放咱们推送的基于H265编码的RTMP是播放不了的，而通过SkeyePlayer则胜利播放了进去，阐明咱们通过SkeyeRTMPClient拉取RTMP流扩大反对H265的计划曾经完满解决。