How to judge the video frame type in h265 in golang development

Many of our projects are through Golang Compilation of , such as EasyNVR、EasyGBS、EasyDSS etc. , about Golang Use , We've always been studying . stay Golang in , The corresponding parsing package is provided in the requirements , for example h265parser.

You can use the corresponding analytic function ParseSliceHeaderFromNALU Returns the corresponding frame type ：

    payloads, _ := h265parser.SplitNALUs(payload)
    payloadsLen := len(payloads)
    if payloadsLen == 0 {
        return
    }
    sliceType, e := h265parser.ParseSliceHeaderFromNALU(payloads[5])
    if e == nil {
        if sliceType == h265parser.SLICE_I {
        } else if sliceType == h265parser.SLICE_P {
        } else {
            log.Printf("Not support %s", sliceType.String())
        }

        log.Printf(sliceType.String())
    }

Under the analysis of h265 stream ( Byte stream mode ),nal How units are divided into types .

Here's our last paragraph h265 Code stream fragment of ：

Look at the nal Cell segmentation .

seek 0x000001 perhaps 0x00000001, The following rules ： Every NALU There is a start code in front 0x000001,3bits. If NALU The type is vps,sps,pps, Or the decoding order is the first AU One of the first NALU, Add another... Before the start code 0x00. The first video stream NALU Add... Before the start code of 0x00.

In practical analysis , It doesn't have to be so complicated , Just find 0x000001 perhaps 0x00000001 that will do .

We also take the content in the figure above for analysis , The above code stream nal Split into ：

First frame : 0000 0001 4001 0c01 ffff 0160 0000 0300 0003 0000 0300 0003 00ba 9702 40 Second frame ： 00 0000 0142 0101 0160 0000 0300 0003 0000 0300 0003 00ba a00f 0804 47f9 65e4 91b6 1c5e 4924 fe79 fcf2 ffff ffcf e7f3 f3f9 d9 Frame 3 : 00 0000 0144 01c1 9095 8112 The fourth frame : 0000 0126 01af 1380 790b dc5c 557c 74…

Here are NAL Type analysis ：

The type judgment method is the value that the first byte after the separator is shifted one bit to the right First frame ：0x40 >> 1, obtain 0x20, Decimal system 32, by NAL_VPS Second frame ：0x42 >> 1, obtain 0x21, Decimal system 33, by NAL_SPS Frame 3 ：0x44 >> 1, obtain 0x22, Decimal system 34, by NAL_PPS The fourth frame ：0x26 >> 1, obtain 0x13, Decimal system 19, by NAL_IDR_W_RADL