#!/bin/bash

journalctl -t mythfrontend.real --since "${1:-3 days ago}" | \
    awk -F '[ :]' '
/Creating TV object/ {
    pid=$7
    startdate=$1 " " $2 " " $3 ":" $4 ":" $5
    starttime=($5+60*($4+60*($3+24*$2)))
}
/Entering main playback loop/ && $7 == pid {
    endtime=($5+60*($4+60*($3+24*$2)))
    printf("%s   %.0f\n", startdate, (endtime - starttime))
}' | less +G