The difference between h264 and h265 decoding

Simply explain the difference between h264 and h265 decoding

h264

I used the analysis tool to parse the h264 file and found:

In fact, it is SPS+PPS+SEI+IDR+P+B+P+B+P+B...SPS+PPS+I+P+B+P+B... This cycle, in which SEI only needs to be sent once, that is, at the time of the first frame, IDR and I frame are both so-called I frames. In order to distinguish the first I frame, it is called IDR frame. SEI only needs to be brought before the IDR frame, followed by every other period.There will be an I frame in time, and the rest are P frame + B frame cycles.

h265

h265 is actually a sequence with an additional vps, video parameter set, which is mainly used to transmit video rating information, which is conducive to the expansion of compatible standards in scalable video coding or multi-view video.It becomes VPS+SPS+PPS+SEI+IDR+P+B+P+B...VPS+SPS+PPS+SEI+CAR+P+B+P+B..., CAR is similar to I frame, type=19, 20, are all I frames, and 21 is CAR.

At this point, we found that h265 sends VPS and SEI every time, and it is not necessarily I frames that are sent in a loop.

NALU

Each SPS, PPS, IDR is a NALU, and the normal format of NALU is: start code+NALU header+NALU data.So to get the stream, you only need to parse out the NALU and get the header information normally, which is very simple.
The start code is usually 00 00 01 or 00 00 00 01, and the NALU header data can be used to determine whether it is VPS, SPS, or PPS.But it should be noted that the h264 header length is different from the h265 header length.

How to judge whether the video stream is H264 or H265

Usually it is to judge whether the type decimal in the NALU header is 32 (VPS) and it is h265, or whether the SEI decimal is 6 or 39, 6 is h264, etc.