[FFmpeg-devel] How to implement pcap ffmpeg format?

[sonntex]

I want to implement something which helps me to play rtp stored in pcap
files.

tcpdump -i lo udp port 50000 -s0 -w - | ffplay <codec options> -i -

The specification of pcap files is really simple and I could create a new
ffmpeg format, but don't know how to process rtp packets extracted from
pcap, because it seems that all functions for rtp parsing are private.

Need a good example of inner ffmpeg formats processing.