NAL_UNIT_VPS     1901 source/encoder/encoder.cpp     list.serialize(NAL_UNIT_VPS, bs);
NAL_UNIT_VPS      100 source/encoder/nal.cpp     else if (!m_numNal || nalUnitType == NAL_UNIT_VPS || nalUnitType == NAL_UNIT_SPS || nalUnitType == NAL_UNIT_PPS)