MKV 文件的簇大小是经过编码的？

Question

元素 ID（也称为 EBML ID），以 ID 本身开头，后跟数据大小。

数据大小（以八位字节为单位）也使用类似于 UTF-8 的系统进行编码。

如何解码十进制的数据大小

Answer 1

您可以在以下位置找到简单的示例代码 https://github.com/wangf1978/DumpTS/blob/master/Matroska.h

static uint64_t UnpackUnsignedIntVal(CBitstream&bs, uint8_t max_octs = 8, bool unPackVal=true, uint8_t* pcbValLen=nullptr)
{
    uint8_t nLeadingZeros = 0;
    uint64_t u64Val = bs.GetByte();
    for (uint8_t i = 0; i < max_octs; i++)
        if ((u64Val&(1ULL << (7 - i))) == 0)
            nLeadingZeros++;
        else
            break;

    if (nLeadingZeros >= max_octs)  // Unexpected
        return UINT64_MAX;

    if (unPackVal)
        u64Val &= ~(1 << (7 - nLeadingZeros));

    for (uint8_t i = 0; i<nLeadingZeros; i++)
        u64Val = (((uint64_t)u64Val) << 8) | (uint8_t)bs.GetBits(8);

    if (pcbValLen != nullptr)
        *pcbValLen = nLeadingZeros + 1;

    return u64Val;
}

virtual int Unpack(CBitstream& bs)
{
    // Read the element ID
    uint64_t u64Val = UnpackUnsignedIntVal(bs, 4, false);
    if (u64Val == UINT64_MAX)
        return -1;

    ID = (uint32_t)u64Val;

    if ((u64Val = UnpackUnsignedIntVal(bs)) == UINT64_MAX)
        return -1;

    Size = u64Val;

    //printf("ID: 0X%X, Size: %lld(0X%llX)\n", ID, Size, Size);

    return 0;
}

MKV 文件的簇大小是经过编码的？

MKV file cluster size which is encoded?

c++

hex

ascii

mkv

webm