You may know this already, but your connection must be setup as a monitor / mirror port on the switch. Or set it up as a trunk and monitor each virtual interface in a different process.
UPDATE: Sorry I did not read carefully, you already have the pcap file.
I actually have ~ 2TB worth and they all have the vlan tag, unfortunately the program that i'm trying to import them into do not like vlans so I want to remove the tag and thought the easiest way may be to just write a script that would take care of this.