rtp:
nalu:
F: 1 bit forbidden_zero_bit. The H.264 specification declares a value of 1 as a syntax violation.
NRI: 2 bits nal_ref_idc. A value of 00 indicates that the content of the NAL unit is not used to reconstruct reference pictures for inter picture prediction. Such NAL units can be discarded without risking the integrity of the reference pictures. Values greater than 00 indicate that the decoding of the NAL unit is required to maintain the integrity of the reference pictures.
Type: 5 bits nal_unit_type. This component specifies the NAL unit payload type as defined in table 7-1 of [1], and later within this memo. For a reference of all currently defined NAL unit types
Type->封包模式
1.单一NAL单元模式，一个RTP包由一个完整的NALU组成。这种情况下RTP NAL头类型字段和原始的H.264的NALU头类型字段是一样的
2.组合封包模式: 可能由多个NAL单元组成一个RTP包，分别有4中组合方式:STAP-A STAP-B MTAP-A MTAP-B
3.分片封包模式：用于把一个NALU单元封装成多个RTP包，存在两种类型FU-A, FU-B 值分别为28,和29
NALU分片：
s = 1分片开始 ，e=1分片结束