Basic control over Ruby elements, specially command line scripting.
There are several ways to subtitle a movie nowadays, and one of the most well known format is the SubRip format (http://en.wikipedia.org/wiki/SubRip). It has entries like these:
645
01:31:51,210 --> 01:31:54,893
the government is implementing a new policy...
646
01:31:54,928 --> 01:31:57,664
In connection with a dramatic increase
in crime in certain neighbourhoods,
Each line has an increasing integer identification, then comes the time range (start and end time) in the format “hours:minutes:seconds,milliseconds”. The decimal separator used is the comma. Finally there are the subtitles themselves and a line break marks the end of an entry.
Sometimes the timing is shifted for a small amount, 2 or 3 seconds. Then comes the trouble when you need to shift everything a few seconds back or ahead.
The goal is to create a small command line script in Ruby that will read an SRT file, and output another one with the new calculated times.
So, for example, if I want to shift everything 2,500 (2 seconds and 500 milliseconds) ahead, I would start with this:
01:32:04,283 --> 01:32:07,769
and end up with:
01:32:06,783 --> 01:32:10,269
The command line should accept arguments such as:
shift_subtitle --operation add --time 02,110 input_file output_file
This means “--operation” can accept either ‘add’ or ‘sub’ to add or subtract times. The “--time” will accept the amount of time to shift in the format 11,222 where “11″ is the amount of seconds and “222″ the amount of milliseconds.
Requirements: This has to be a pure Ruby script, using only the Ruby Standard Libraries (meaning, no external Gems).
It has to implement “optparse” to parse the command line arguments.
As an observation, bear in mind that the first thing that you might attempt will look like this:
a = Time.at(04,283)
b = a + 2.500
puts b.usec
=> 500283
This is wrong, the proper result should’ve been “783″ (as in the example in the previous section). So it means that you will have to find another way out.
Extras (Optional): If you want:
It would be interesting to exercise the process of a Gem creation. So you would have to package your script. Another thing that would be good is to have RSpec unit tests covering your code, to exercise software development best practices. (Note that the above two points are optional and not a requirement).