Analyse UDP delay from tcpdump files

Question

I have a video streamer (VLC) which is using RTP to stream video to a client. I have captured the packet trace from both the sender and the receiver side using tcpdump separately.

The streaming produces UDP packets. It is possible that some packets are missing/out of order on the receiver side. Assume that the clocks on both the machines are synchronized.

My task is to find the delay between the packets

Q : Is there any tool which can compare both the dump files and generate UDP statistics, specifically delay?

Answer 1

I had to do it manually. I wrote a python script which

• extracts the packet from each pcap file (sender and receiver)
• compares their payload
• if it's a match and timestamps are causally correct, then delay is calculated
• If a match is not found over a certain window size (I kept it as 100), the packet is assumed to be lost and we move to the next packet

I did this over the entire pcap file and made an average over all the delays. If somebody wants it, I can share the code.

Answer 2

Wireshark offers support for RTP Analysis.

See also these RTP-related Wireshark wiki pages: RTP, RTP Statistics.