The Glories of the Command Line

Let’s say you have a middling to lousy Internet connection, but you still want to take advantage of an online video language course. What’s the solution? Download the videos, obviously; my processor is much faster than streaming them over my middling to lousy connection.

The videos, however, are streamed under the “mms” protocol. This doesn’t mean that they can’t be downloaded (they are free to view, by the way); it just means that you can’t download them directly, you have to stream them and save them as they’re streamed. (Essentially, this is downloading them in real time; so saving the thirty-two minute video takes thirty-two minutes.) While I’m at it, I want to convert them from the execrable Windows Media format they’re provided in to a different, free, and good format; namely, Ogg Theora. What to do?

Well, Video LAN Client, or VLC, provides the answer. This cross-platform media player can handle playlists and deals with just about every media format known to man. ffmpeg, on the other hand, will be used for converting the video to Ogg Theora. There are plenty of tutorials online explaining how to use VLC to save a streaming mms video to disk, and plenty explaining how to use ffmpeg to convert a video to Theora. (I’ll show you all in a minute, only I’ll do it in a better way.) It involves navigating lots of menus; it takes several seconds per video, which is fine when you’re only doing a video or two.

Thing is, this is a multi-part language course. With fifty-two parts. Downloading them all individually, one by one, when it takes half an hour to do each, and then converting them all manually with ffmpeg, would be a hideous nightmare. However, VLC is a Unix application by birth and by choice, and consequently it has a fully developed command-line interface. This means that it can be scripted. Which means that I can get all this done without a fuss or a bother; in the time it takes to download one video manually, or even less, I can write a script which will handle each and every one for me, and convert them all to Theora while it’s at it. But how, you ask?

RTFM! I went into the documentation and learned how to tell VLC to save a streaming video while it streams when invoking it on the command line, and how to tell vlc to exit when it’s done. (Check the script below!) This took about ten minutes. I then hammered out the script; I had to look up the syntax for while loops in a bash script, which took another ten minutes or so. I then ran it, corrected a couple of errors, and ran it again. About a half hour of work, and I was able to download and convert all fifty-two videos without a lick of trouble, while not even looking at the computer the entire time unless I wanted to. Without the scriptability of the command line, I would have had to nurse the whole process for well over twenty-four hours to get it done.

Yes, the command line is superior, if you read the documentation and take a few minutes to do it right instead of doing it easy. That’s the way with all fields; why should computers be any different? An automatic transmission is easy as pie; but a standard gets better gas mileage and provides better control.

It’s the same way with computers. A graphical interface is shiny and lets you pointy-clicky and probably after a few minutes accidentally stumble on whatever you need to do, then immediately forget how you did it until you pointy-clicky your way back to it again the next time. But the command line gets you more control, more facility, once you’ve learned how to use it. Learning how to use it requires work; there’s no two ways about it. But that work will pay off once you do it.

So here’s the script. Enjoy it in all its ugly wonder.

#!/bin/bash
# +AMDG

i="0"

while [ $i -lt 53 ]
do
     i=$[$i+1];
     if [ $i -lt 10 ]; then
	vlc --sout videos_{$i}of52.wmv mms://video_path_0$i.wmv vlc://quit;
	ffmpeg -i videos_{$i}of52.wmv -sameq -acodec libvorbis videos_{$i}of52.ogg;
     fi
     if [ $i -ge 10 ]; then
	vlc --sout videos_{$i}of52.wmv mms://video_path_$i.wmv vlc://quit;
	ffmpeg -i videos_{$i}of52.wmv -sameq -acodec libvorbis videos_{$i}of52.ogg;
     fi
done
exit;

Of course, this puts actual curly braces in the final file name, something I didn’t intend. But a quick line of bash, using the rename Perl script (standard on every Linux distribution I’ve used), took care of all that; another half-minute. Big whoop.

The condition is necessary because the videos are named in the form “video_$number.wmv”, where $number is always two-digit, even when it’s less than ten. They do this simply by adding a leading zero (as in “03″). That makes it show up in numerical order in file listings (instead of that annoying “video29, video3, video 30″ listing you’d get otherwise), but it did necessitate two different statements, one if there was a leading zero and one if not. I could have made this just one, but it was more work than it was worth, as this worked splendidly.

Learn the command line! It’s better!

Praise be to Christ the King!