EasyRTMPClient扩展支持HEVC(H.265)解决方案之兼容H264和H265帧数据解析详解

在之前两篇关于EasyRTMPClient扩展支持HEVC(H.265)解决方案的文章中，我们已经完成了对H265的支持，本文主要阐述将H26和H265支持兼容起来，实现不同视频编码格式的自适应兼容适配。

1. 根据CodecId判断数据编码类型

根据视频编码ID判断视频编码类型，如果视频编码ID==FlvCodeId_Hevc（12）,则判断视频编码格式为H265，反之则为H264（因为目前我们只支持这两种编码格式的视频推送），如下代码所示：

    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 = EASY_SDK_VIDEO_CODEC_H265;// HEVC;
	} 
	else
	{
		av_frame.u32AVFrameFlag = EASY_SDK_VIDEO_CODEC_H264;// 默认h264, 其他类型是否需要判断?!;
	}

2. 数据帧头部判断

根据FLV/RTMP扩展支持H265标准，支持HEVC的VideoTagHeader定义如下图所示：

即 当CodecID == 12时，AVCPacketType为HEVCPacketType：

• 如果HEVCPacketType为0，表示HEVCVIDEOPACKET中存放的是HEVC sequence header；

• 如果HEVCPacketType为1，表示HEVCVIDEOPACKET中存放的是HEVC NALU；

• 如果HEVCPacketType为2，表示HEVCVIDEPACKET中存放的是HEVC end of sequence，即HEVCDecoderConfigurationRecord；

而当CodecID == 7时，AVCPacketType为AVCPacketType：

• 如果AVCPacketType为0，表示HEVCVIDEOPACKET中存放的是AVC sequence header；

• 如果AVCPacketType为1，表示HEVCVIDEOPACKET中存放的是AVC NALU；

• 如果AVCPacketType为2，表示HEVCVIDEPACKET中存放的是AVC end of sequence，即AVCDecoderConfigurationRecord；

EasyRTMPClient对sequence header的解析函数如下代码段所示：

int ParserVideoSequencePacket(FlvCodeId video_code_id, char *buf,int len)
{
	int parser_offset = 0;
	char *parser_config = buf;
	if (video_code_id == FlvCodeId_Hevc)
	{
		if(len <= sizeof(Parser_HEVCDecoderConfigurationRecord))
		{
			return -1001;
		}			
 		......’
		//Parser HEVCDecoderConfigurationRecord 
		......
		rtmpclient_h265_decode_sps((unsigned char *)sps_buf_, sps_len_, width_, height_);	
	} 
	else
	{
		if(len <= sizeof(parser_AVCDecoderHeader))
		{
			return -1001;
		}
 		......’
		//Parser HEVCDecoderHeader
		......
		rtmpclient_h264_decode_sps((unsigned char *)sps_buf_, sps_len_, width_, height_);
	}

    return 0;
}

3. 视频数据体帧数据nalu类型判断

根据FLV/RTMP扩展支持协议标准，支持H265的VideoTagBody定义如下, 扩展后的VideoTagBody如下图所示(红色字体为HEVC新增内容)：：

当CodecID为12时，VideoTagBody中存放的就是HEVC视频帧内容。
EasyRTMPClient视频帧nalu解析如下代码所示：

int ParserOneVideoNalu(EasyRTMPClient_AV_Frame& av_frame,char *buf,int len,char* processbuf)
{
    if(processbuf == NULL || buf == NULL || len == 0)
    {
        return -3001;
    }
    if(sps_len_ == 0 || pps_len_ == 0)
    {
        printf("do not get sequence head yet\n");
        return -3002;
    }

    int parse_offset = 0;
    int nalu_len = 0;
    int nalu_type = 0;
    int processlen = 0;
    while(parse_offset < len - 4)
    {
        nalu_len = ntohl(*(int*)(buf + parse_offset));  
        parse_offset += 4;
        //如果视频帧编码类型为H265
		if(av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H265)
		{
			nalu_type = (buf[parse_offset] >> 1) & 0x3F;
			if(nalu_type == e_H265_NAL_UNIT_VPS)
			{
				ASSERT_PARSER(nalu_len,MAX_VPS_LEN);
				memcpy(vps_buf_,buf + parse_offset,nalu_len);
				vps_len_ = nalu_len;
				parse_offset += nalu_len;
				continue;
			}
		}else{
			nalu_type = buf[parse_offset]&0x1F;
		}
       //H265 以及 H264的SPS头解析兼容
        if((av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H265&&nalu_type ==e_H265_NAL_UNIT_SPS) || 
			av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H264&&nalu_type == e_H264_Frame_Type_Sps)
        {
            ASSERT_PARSER(nalu_len,MAX_PPS_LEN);
            memcpy(sps_buf_,buf + parse_offset,nalu_len);
            sps_len_ = nalu_len;
            parse_offset += nalu_len;

			if(width_ == 0 && sps_len_ > 0)
			{
				if(av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H265)
					rtmpclient_h265_decode_sps((unsigned char *)sps_buf_, sps_len_, width_, height_);
				else
					rtmpclient_h264_decode_sps((unsigned char *)sps_buf_, sps_len_, width_, height_);
			}
            continue;
        }
		       //H265 以及 H264的PPS头解析兼容
		else if((av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H265&&nalu_type ==e_H265_NAL_UNIT_PPS) || 
			av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H264&&nalu_type == e_H264_Frame_Type_Pps)
        {
            memcpy(pps_buf_,buf + parse_offset,nalu_len);
            pps_len_ = nalu_len;
            parse_offset += nalu_len;
            continue;
        }

       //H265 以及 H264的I帧解析兼容
		else if((av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H265&&nalu_type >=e_H265_NAL_UNIT_SLICE_BLA&&nalu_type <=e_H265_NAL_UNIT_SLICE_CRA ) || 
		av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H264&&nalu_type == e_H264_Frame_Type_Idr)
        {
			if(av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H265)
			{
				memcpy(processbuf + processlen,nalu_head_,4);
				processlen += 4;
				memcpy(processbuf + processlen,vps_buf_,vps_len_);
				processlen += vps_len_;
			}
			.......
			//拷贝SPS和PPS以及Idr nalu
			......
			av_frame.u32VFrameType = EASY_SDK_VIDEO_FRAME_I;
            continue ;
        }
       //H265 以及 H264的P帧解析兼容
		else if((av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H265&&nalu_type >=e_H265_NAL_UNIT_SLICE_TRAIL_R&&nalu_type <=e_H265_NAL_UNIT_SLICE_TFD ) || 
			av_frame.u32AVFrameFlag == EASY_SDK_VIDEO_CODEC_H264&&nalu_type == e_H264_Frame_Type_Slice)
        {
            memcpy(processbuf + processlen,nalu_head_,4);
            processlen += 4;
            memcpy(processbuf + processlen,buf + parse_offset,nalu_len);
            processlen += nalu_len;
            parse_offset += nalu_len;

			av_frame.u32VFrameType = EASY_SDK_VIDEO_FRAME_P;
            continue ;
        }
        else
        {
            parse_offset += nalu_len;
            continue;
        }
    }

    av_frame.pBuffer = (uint8_t *)processbuf;
    av_frame.u32AVFrameLen = processlen;
    return 0;
}

至此，EasyRTMPClient对H264和H265的兼容适配就完成了，我们可以通过EasyRTMPClient拉取任意编码格式为H264或者H265的RTMP进行拉流，均能取得完整的视频帧数据进行解码和播放。

欢迎大家下载EasyPlayer测试播放支持H265的RTMP流：
https://github.com/EasyDSS/EasyPlayer-RTMP-Win
https://github.com/EasyDSS/EasyPlayerPro-Win

有任何技术问题，欢迎大家和我进行技术交流：
[email protected]

大家也可以加入EasyPlayer流媒体播放器 QQ群进行讨论：
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