How to extract payload information and the ratio of incoming / outgoing packets from a pcap file?

Question

I have a very large pcap file and I want to create a script that will give me (in addition to the attributes that wireshark gives me) the payload and the number of incoming / outgoing packets.

I was thinking of using something like this below, but I'm not sure if there is a more efficient way to do this? :

from scapy.all import *
data = "Eavesdrop_Data.pcap"
a = rdpcap(data)
os.system("tshark  -T fields -e _ws.col.Info -e http -e frame.time -e"
      "data.data -w Eavesdrop_Data.pcap > Eavesdrop_Data.txt -c 1000")
os.system("tshark -r Eavesdrop_Data.pcap -Y Eavesdrop_Data_http.pcap")
sessions = a.sessions()
i = 1
for session in sessions:
  http_payload = ""
  for packet in sessions[session]:
    print packet