PSM的当前时间解析

来源：https://www.cnblogs.com/feixiang-energy/p/17735762.html
00 00 01 BC 00 5A E0 FF 00 24 40 0E 48 4B 00 00
17 9D 3E B4 60 00 00 FF FF FF 41 12 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 2C
1B E0 00 10 42 0E 00 00 A0 21 05 00 02 D0 12 1C
3F 00 1C 21 0F C0 00 0C 43 0A 00 00 FE 00 FA 03
01 F4 03 FF BD BD 00 00 BF BF 00 00 00 00 00 00  

4byte    start: 00 00 01 BC
2byte    packlen: 00 5A    = 90
2byte    packinfo: E0 FF
2byte    program_strem_info_len: 00 24 = 36
36byte   descriptor: 40 0E 48 4B 00 00 17 9D 3E B4 60 00 00 FF FF FF 41 12 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    aa 0x40 表示当前为BASIC信息
    aa+1 0x0E = 14 BASIC信息长度
    aa+2~aa+3 0x48 0x4B 公司描述符
    aa+6~aa+11 0x17 0x9D 0x3E 0xB4 0x60 0x00 0x00 当前年月日时分秒及加密类型
    
    bb 0x41 表示当前为DEVICE信息
    bb+1 0x12 = 18 DEVICE信息的长度
    bb+4~bb+19 设备ID号

2byte    elementary_stream_map_length: 00 2C = 44
1byte    stream_type: 1B    0x1B --> H264    0x24 --> H265
1byte    elementary_stream_id: E0       0xE0 --> 视频   0xC0 --> 音频
2byte    elementary_stream_info_len: 00 10 = 16
16byte   descriptor: 42 0E 00 00 A0 21 05 00 02 D0 12 1C 3F 00 1C 21
    aa 0x42 表示当前为VIDEO信息
    aa+1 0x0E = 14 VIDEO信息长度
    aa+2~aa+3 0x00 0x00 编码器版本
    aa+4~aa+5 0xA0 0x21 编码器年月日
    aa+6~aa+7 0x05 0x00 = 1280 图像宽度
    aa+8~aa+9 0x02 0xD0 = 720 图像高度
    aa+10 0x12 是否隔行扫描,b帧数目,是否为SVC码流,是否使用e帧,最大参考帧数目
    aa+11 0x1C 水印类型,显示时是否需要反隔行
    aa+12 0x3F JPEG的Q值
    aa+13~aa+15 0x00 0x1C 0x21 以1/90000s为单位的两帧间时间间隔,是否使用固定帧率

1byte    stream_type: 0F        0x90 --> g711 0x0F --> aac
1byte    elementary_stream_id: C0       0xE0 --> 视频   0xC0 --> 音频
2byte    elementary_stream_info_len: 00 0C = 12
12byte   descriptor: 43 0A 00 00 FE 00 FA 03 01 F4 03 FF
    dd 0x43 表示当前为AUDIO信息
    dd+1 0x0A AUDIO信息长度
    dd+2~dd+3 0x00 0x00 音频帧长度
    dd+4 0xFE 音频声道数
    dd+5~dd+7 0x00 0xFA 0x03 音频采样率
    dd+8~dd+10 0x01 0xF4 0x03 音频比特率

2byte 私有数据信息 BD BD
4byte CRC校验 00 00 BF BF

size_t clock_extension_descriptor_write(uint8_t* data, size_t bytes, int64_t clock)
{
    struct tm* t;
    time_t seconds;
    if (bytes < 16)
        return 0;

    seconds = (time_t)(clock / 1000);
    t = localtime(&seconds);

    data[0] = 0x40;
    data[1] = 0x0E;
    data[2] = 0x48;
    data[3] = 0x4B;
    data[4] = 0x01;
    data[5] = 0x00;
    data[6] = (uint8_t)(t->tm_year + 1900 - 2000); // base 2000
    data[7] = (uint8_t)((t->tm_mon + 1) << 4) | ((t->tm_mday >> 1) & 0x0F);
    data[8] = (uint8_t)((t->tm_mday & 0x01) << 7) | ((t->tm_hour & 0x1F) << 2) | ((t->tm_min >> 4) & 0x03);
    data[9] = (uint8_t)((t->tm_min & 0x0F) << 4) | ((t->tm_sec >> 2) & 0x0F);
    data[10] = (uint8_t)((t->tm_sec & 0x03) << 6);
    data[11] = 0x00;
    data[12] = 0x00;
    data[13] = 0xFF;
    data[14] = 0xFF;
    data[15] = 0xFF;
    return 16;
}