How to filter out TCP retransmissions

edit

The captured traffic isn't in the readable format of the Wireshark. I have just the header of the captured traffic as the sample above. How can I filter out TCP retransmission myself using the header information?

There is no direct flag transmitted on the wire in the tcp header saying it's a retransmission, it's inferred by sequence number analysis.

You'll have to do tcp reassembly and note when a sequence number is retransmitted.

could you help me with it? how should I check them myself?

Have a look at this SharkFest presentation from @Jasper on tcp analysis.

Thanks @grahamb - but better use the PPT instead, because it has the animations: https://sharkfest.wireshark.org/asset...