Slicing and Dicing a sniffer trace

[netdetective]

I have a large sniffer trace (over 28,000 packets) and am looking for a way to remove every 3rd packet. When I captured the trace it had a duplicate response for every packet sent to it. It has something to do with sniffing a trunk port on a Cisco switch and HSRP. Without getting bogged down in the reasons for this behavior I'd like to know if anyone has any ideas on how I can slice and dice my sniffer trace to the effect of removing every 3rd packet? It is an exact duplicate of another packet, same mac, same everything so display filters are not an option. I'm thinking that there must be a way to export into a spreadsheet type format and manipulate the data that way. Any ideas?

 

[PalmTest]

Perhaps ProConvert can help you to convert your trace to a raw frame dump.

http://www.wildpackets.com/products/other_products/proconvert/features

 

[netdetective]

I gave it a try but my problem is that I have to be able to slice it up and return it to trace file format. Once you convert to the hex dump you are unable to convert it back into a trace file format. So far I haven't found any combination that works.