Makes a select tag (1-30min with 30 sec intervals)

convert_to_duration.rb

def convert_to_duration(fixnum)
  min = (fixnum / 60).to_s.rjust(2, '0')
  sec = (fixnum % 60).to_s.rjust(2, '0')
  "00:#{min}:#{sec}"
end

(1.minute..30.minutes).step(30).collect { |s| convert_to_duration(s) }

# 00:01:00
# 00:01:30
# 00:02:00
# 00:02:30

view.rhtml

<% durations = ['Choose One']
   durations << (1.minute..30.minutes).step(30).collect { |s| convert_to_duration(s) }
   durations.flatten!
%>
<%= select_tag("duration", options_for_select(durations)) %>