#old string

awk -v len=40 '{ if (length($0) > len) print substr($0, 1, len-3) "..."; else print; }'

#new string

awk -v len=40 '{ if (length(dbus[0]["xesam:title"] ) > len) print substr(dbus[0]["xesam:title"], 1, len-3) "..."; else print; }'

#what I am trying in awk program

format = mediainfo["Audio"]["Format"] == "MPEG Audio" && mediainfo["Audio"]["Format profile"] == "Layer 3" ? "MP3" : mediainfo["Audio"]["Format"]
    printf "%s / %s / %s\n", awk -v len=40 '{ if (length(dbus[0]["xesam:title"]) > len) print substr(dbus[0]["xesam:title"], 1, len-3) "..."; else print; }' , mediainfo["Audio"]["Bit rate"], format