7.3. Additional De-Packetization Guidelines

The following additional de-packetization rules may be used to implement an operational H.264 de-packetizer:

Intelligent RTP receivers (e.g., in gateways) may identify lost coded slice data partitions A (DPAs). If a lost DPA is detected, after taking into account possible retransmission and FEC, a gateway may decide not to send the corresponding coded slice data partitions B and C, as their information is meaningless for H.264 decoders. In this way, a MANE can reduce network load by discarding useless packets without parsing a complex bitstream.
Intelligent RTP receivers (e.g., in gateways) may identify lost FUs. If a lost FU is found, a gateway may decide not to send the following FUs of the same fragmented NAL unit, as their information is meaningless for H.264 decoders. In this way, a MANE can reduce network load by discarding useless packets without parsing a complex bitstream.
Intelligent receivers having to discard packets or NALUs should first discard all packets/NALUs in which the value of the NRI field of the NAL unit type octet is equal to 0. This will minimize the impact on user experience and keep the reference pictures intact. If more packets have to be discarded, then packets with a numerically lower NRI value should be discarded before packets with a numerically higher NRI value. However, discarding any packets with an NRI bigger than 0 very likely leads to decoder drift and SHOULD be avoided.