H264 封装格式

void ConvertMP4BitstreamToANNB(uint8_t *pdata, const uint32_t size)
{
    auto p = pdata;
    auto end = pdata + size;

    while (p < end) {
        uint32_t nalSize = p[0] << 24 | 
            p[1] << 16 | 
            p[2] <<  8 | 
            p[3];
        p[0] = 0;
        p[1] = 0;
        p[2] = 0;
        p[3] = 1;
        p += 4+nalSize;
    }
}