Hi ,
i need to convert this comand shell to python :


sudo tshark -n -r $pcap -Y "rtp && rtp.ssrc == $ssrc" -T fields -e rtp.payload | sed "s/:/ /g" | perl -ne 's/([0-9a-f]{2})/print chr hex $1/gie' >>  $pcap.$ssrc.raw

i do this :
p2 = sub.Popen(('sudo', 'tshark','-n','-r',pcap,'-Y','rtp and rtp.ssrc=='+pa[n],'-T','fields','-e', 'rtp.payload','|',' sed','s','/',':','/',' /','g' ,'|',' perl',' -ne', 's','/,','([0-9a-f]{2}),','/','print',' chr',' hex',law,'/gie',' >>',pcap+'.'+pa[n]+'.raw'),stdout=sub.PIPE)


is there some one who can help me please ? 
 best regards 
amani