在之前两篇关于SkeyeRTMPClient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 = SKEYE_SDK_VIDEO_CODEC_H265;// HEVC;
}
else
{
av_frame.u32AVFrameFlag = SKEYE_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；
SkeyeRTMPClient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。
SkeyeRTMPClient视频帧nalu解析如下代码所示：
int ParserOneVideoNalu(SkeyeRTMPClient_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 == SKEYE_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 == SKEYE_SDK_VIDEO_CODEC_H265&&nalu_type ==e_H265_NAL_UNIT_SPS) ||
av_frame.u32AVFrameFlag == SKEYE_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 == SKEYE_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 == SKEYE_SDK_VIDEO_CODEC_H265&&nalu_type ==e_H265_NAL_UNIT_PPS) ||
av_frame.u32AVFrameFlag == SKEYE_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 == SKEYE_SDK_VIDEO_CODEC_H265&&nalu_type >=e_H265_NAL_UNIT_SLICE_BLA&&nalu_type <=e_H265_NAL_UNIT_SLICE_CRA ) ||
av_frame.u32AVFrameFlag == SKEYE_SDK_VIDEO_CODEC_H264&&nalu_type == e_H264_Frame_Type_Idr)
{
if(av_frame.u32AVFrameFlag == SKEYE_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 = SKEYE_SDK_VIDEO_FRAME_I;
continue ;
}
//H265 以及 H264的P帧解析兼容
else if((av_frame.u32AVFrameFlag == SKEYE_SDK_VIDEO_CODEC_H265&&nalu_type >=e_H265_NAL_UNIT_SLICE_TRAIL_R&&nalu_type <=e_H265_NAL_UNIT_SLICE_TFD ) ||
av_frame.u32AVFrameFlag == SKEYE_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 = SKEYE_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，SkeyeRTMPClient对H264和H265的兼容适配就完成了，我们可以通过SkeyeRTMPClient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。