EdX Bundler

These scripts will help you create an edX course whose video and subtitle assets reside locally, for example, on a DVD.

You might want this if, for example, you're trying to use the course in a location whose Internet connection doesn't support streaming video.

Note, this only "localizes" the video and subtitles. It expects that the rest of the course will be served through the edX platform as usual.

Requirements

Because I'm lazy, this uses all four major scripting languages -- shell, Ruby, Python, and Perl. Deal with it. You therefore need:

• bash
• Ruby 1.9+ (ruby -v to check)
• The Nokogiri gem (gem list nokogiri to see if you have it; gem install nokogiri, possibly as root, if you don't)
• Perl, any version >=5 (perl -v to check)
• The youtube-dl Python script (which in turn relies on Python 2.6+; python --version to check)
• Comfort using shell scripts and other power tools, and a standard god-fearing Unix environment with the usual command-line utilities available (find, etc). No GUI here. If step 1 below looks alien to you, stop and get help.

What to do

There are three main sets of steps:

0. Modify the course definition (XML) to point to videos locally rather than on YouTube
1. Download the actual videos from YouTube
2. Run a local Web server to serve those videos from local storage when you open the course

Modify the course definition

The first set of steps modifies the XML files exported by Studio to point to local copies of the videos and video transcript (.srt) files. As a side effect, it also converts the XML markup in the .xml files describing video assets to use what appears to be the newer XML schema exported by Studio. (At the end of this file are the details of what this means.)

0. Install the contents of this repo in a directory of your choice, which we'll refer to as $BUNDLE_PATH henceforth.
1. Export your edX course from Studio as a tar archive, un-gzip it, and change into its toplevel directory. You should see subdirectories video and drafts in particular.
2. From within the toplevel directory of the course export, run this command:

find video drafts/video -name '*.xml' | xargs ruby $BUNDLE_PATH/edx-localize.rb

If all goes well, run the following command to delete the backup files:

find video drafts/video -name '*.bak' -delete

Tar up the course directory and re-import it into Studio.

You should now have a course that can be deployed as usual (on Edge or wherever) but expects to find all its videos on a web server listening on localhost:8000.

Download all the videos

The next set of steps downloads the actual videos from YouTube. This could take a long time to run, since it will download '''every video in your course''' to local storage:

5. Make sure youtube-dl is in your $PATH.
6. From the toplevel directory of the exported course, run ./download-videos.sh. This will attempt to create a new subdirectory mp4/ and download all the videos into it. It will take a long time.

Run a local webserver

Finally, change to the mp4 directory (or wherever you moved all the downloaded videos to) and run either ruby -run -ehttpd . -p8000 or if you prefer python -m SimpleHTTPServer 8000. Either will run a static HTTP server on port 8000. You'd better be running a firewall so that the only access to this webserver is from localhost. If you prefer a different one-line web server, here's a whole list of them.

Appendix: old vs. new

Especially for older courses that predate Studio authoring, the video tags sometimes look like this (newlines added for clarity):

<video display_name="Video (5:59)" 
       download_track="true" 
       download_video="true" 
       source="http://s3.amazonaws.com/BESTech/CS169/download/CS169_v13_w1l1s2.mp4" 
       track="http://s3.amazonaws.com/BESTech/CS169/srt/CS169_v13_w1l1s2.srt" 
       youtube="1.00:ifajo-fiRXo" 
       youtube_id_1_0="ifajo-fiRXo">
  <track src="http://s3.amazonaws.com/BESTech/CS169/srt/CS169_v13_w1l1s2.srt"/>
</video>

As best I can tell, the source attribute identifies the video file and the track attribute (if present) identifies the transcript file. I don't know why there is sometimes a redundant <track> element and sometimes not.

When a video file is inserted via Studio, the exported markup looks like this--the html5_sources attribute appears to be an XML-escaped list of video source files (though I've yet to see an example where the list has more than 1 element), the sub attribute appears to be the root filename, the youtube element is gone, the youtube_id_1_0 element is present but empty, and the track attribute has been removed in favor of leaving only the <track> element:

<video 
    display_name="Video" 
    download_track="true" 
    download_video="true" 
    html5_sources="[&quot;http://localhost:8000/ifajo-fiRXo.mp4&quot;]"
    source="" 
    sub="ifajo-fiRXo" 
    track="http://localhost:8000/CS169_v13_w1l1s2.srt" 
    youtube_id_1_0="">
  <source src="http://localhost:8000/ifajo-fiRXo.mp4"/>
  <track src="http://localhost:8000/CS169_v13_w1l1s2.srt"/>
</video>

The edx-localize.rb script uses Nokogiri to perform this simple transformation.