Media diagnostics · Primary-source explanation; examples are illustrative. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Keep transport and codec boundaries separate
RFC 6184 defines several ways to carry H.264 Network Abstraction Layer units in RTP. It includes fragmentation units which distribute one NAL unit across multiple packets, as well as aggregation forms. Therefore a packet capture cannot be read by assuming every payload is one complete independently decodable frame. A packet boundary, a NAL unit boundary and a picture boundary are related technical structures rather than interchangeable counts.
Follow an original fragment example
Imagine one permitted diagnostic NAL unit carried across three consecutive fragmentation packets. A receiver needs the relevant ordered fragments to reconstruct that unit according to the payload format. Seeing three packets does not establish three pictures. This invented example explains the counting problem, not a measured stream. Keep the actual sequence information, start and end indications and observed gaps when an authorised maintainer investigates incomplete delivery.
Do not blame every fragment for corruption
Fragmentation is a documented transport representation and is not itself evidence that the source file is damaged. Missing required pieces can create a different condition which needs actual packet evidence. Avoid inferring visible damage solely from a payload type name, or copying private media payloads into a public report. This article supplies a narrower interpretation of H.264 RTP diagnostics and does not promise recovery, establish decoder support for every mode or claim that UK IPTV uses this packet format.