Mine

  if ($dll(WinAmpI.dll, GetSongLength, 0) == unknown) { 
    set %track $dll(WinAmpI.dll, GetSongPosition, 0) $+ / $+ Unlimited (Radio)
    tokenize 58 $dll(WinAmpI.dll, GetSongPosition, 0) | if ($3) { set %track $asctime($calc($2 * 60 + $3),hh:nn:ss) $+ / $+ Unlimited (Radio) }
  }
  elseif ($dll(WinAmpI.dll, GetSongLength, 0) !== unknown) { 
    set %track $dll(WinAmpI.dll, GetSongPosition, 0) $+ / $+ $dll(WinAmpI.dll, GetSongLength,0)
    set %position $dll(WinAmpI.dll, GetSongPosition, 0)
    tokenize 58 $dll(WinAmpI.dll, GetSongPosition, 0) | if ($3) { set %position $asctime($calc($2 * 60 + $3),hh:nn:ss) }
    tokenize 58 $dll(WinAmpI.dll, GetSongLength, 0) | if ($3) { set %endtime $asctime($calc($2 * 60 + $3),hh:nn:ss) }
    if (%endtime) { set %track %position $+ / $+ %endtime }
    unset %position
    unset %endtime
  }