Podcasting Your Lectures 101: Editing

Last time around in this here little series about podcasting your lecture, we covered the first step in the process: recording (you can read the article here). This time around, we’re going to have a look at what you do after you’ve got your raw audio recorded – the editing process.

Before we get started, I’d like to repeat some caveats that I brought in the first column. First off, I’m using the term “podcasting” generically – meaning (in this context) the online distribution of recorded lecture material. The platform on which the audio file is listened could be an iPod (or another portable MP3 player or mobile internet device), but it could also be via the browser’s built in audio player, or a desktop audio player such as iTunes or Songbird (an open source alternative to iTunes – and one of my favorite apps). Second, I’m not an audio expert. I’ve learned through experimentation, trial and error, and well placed emails to friends and colleagues who are far more up on the art & science of audio than I am. Finally, this isn’t an exhaustive technical step-by-step – its more of a “here are some things you need to think about, go out and dig deeper or experiment for yourself” kind of approach.

Having said all of this, lets get the show on the road.

One of the most important aspects of editing is file management. Editing is a “destructive” process that often can’t be undone if you’ve made a mistake. As a result, you want to keep an original, unedited version of your audio file backed up and untouched. This means that if you screw up with your edits, you always can go back to your original and start anew. When I’m editing, I always have two audio folders – one for the edited file, and one for the raw file. I also use a standardized file naming system. So, for example, I name my original file lecture001raw.mp3 and the edited file lecture001edited.mp3. As a quick side-note, I actually record directly as MP3 (as opposed to .wav). This is a personal choice as automatically encoding the recorded file as an MP3 means it takes up less space on my external recorder’s storage card.

When it comes to the actual editing, the first thing you need to figure out is what application you want to use. For the amateur academic type, I would strongly suggest going with Audacity (http://audacity.sourceforge.net/). It is open source (which is good), free cross platform, and fairly robust in its feature set. There are certainly other apps you could use. I actually use a combination of Audacity and GarageBand. I use Audacity for the “heavy lifting” – trimming, removing dead air, adjusting levels, removing noise, etc. Then I bring that editing audio file into GarageBand for some fine tuning – adding an intro and outtro (both music and speech), and final export. If you are not too terribly concerned with things like intro music, you could stick with Audacity and be just fine.

Once you’ve chosen an editing app, it’s time to get down to actually editing. Here are some things that you should consider doing:

Remove dead air during the lecture. If you’ve got large chunks of dead air in your lecture (if you paused to shuffle around to find something in your bag, for example), you might want to consider cutting it out. Nothing disrupts the flow of a lecture (for the listener) like unexpected dead air (remember, they can’t see you, so if you did something purely visual during the lecture, it will be completely lost in the audio file).

Trim administrative class minutia. This one is always a bit of a quandary for me personally. Should you remove the typical reminders, class announcements, and assignment discussions that typically happen during a lecture (whether at the beginning, the middle or the end of the lecture)? Ultimately, I think this depends on your audience. If you are recording your lectures primarily for the students who are actually in the class, leaving this stuff in is probably a good idea. However, if this recorded lecture is intended for people who aren’t actually in the class, you might want to cut it out. Personally, I’ve gone both ways with this. In the most recent class whose lectures I’m recording (History of the Modern Comic Book – where the recorded lectures are intended both for my students as well as the interested public), I’ve left this stuff in. For students, it’s obviously important. However, for the general public, I personally think it gives context to the class (and adds a more “authentic classroom experience” – which some people appreciate).

Trim the beginning and the end of the lecture. You might be tempted to trim the audio file so that it begins right when the actual audio begins. I often start my recorder a minute or so before I actually start the lecture. This means that I’ve got a lot of dead air at the beginning of the audio file. The challenge here is not to remove so much audio that as soon as the file is loaded the lecture instantaneously starts. Leave a little bit of a cushion of dead air at the beginning of the file – maybe about 3 or 4 seconds

Remove background noise. If you were recording in a noisy environment (open window with a lawnmower going by outside, for example), you probably want to take advantage of noise reduction features available in many audio editors. The kicker is that noise reduction is not intended to remove distinct sounds, like a door slamming or a cough. Instead, it is meant to reduce constant sounds that affect large portions of your track.

Adjust the Volume. This one is particularly important if you use a stationary mic and have a tendency to wander around the classroom (resulting in inconsistent volume – louder when you are close to the mic, softer when you are away from it). It’s also important if the levels of your recording device were set very low when you were actually recording (resulting in an audio file whose volume is really low.). Even though I use a wireless lapel mic, I have a tendency to oscillate between speaking loudly and softly during lecture. As a result, I always end up having to fiddle with the volume at specific points in my audio. The one tip I have for adjusting volume is that you decide upon a level for the entire file, and adjust to that level.

Mixing in music. If you want to add a little extra super duper polish to your podcast, you might want to think about mixing in a little intro and outro music. If you are considering doing this, its incredibly important to realize that you’re entering the domain of copyright and intellectual property. Its safe to say that copyright law, as it relates to digital media, is incredibly complicated. I’m not going to attempt to get into it here (partially because it would probably make everyone’s head explode, but mostly because I’m not a copyright lawyer and am not at all well versed in the issues). If you want to get more info, I would strongly suggest that you check out the Creative Commons Podcasting Legal Guide (http://wiki.creativecommons.org/Podcasting_Legal_Guide).

Next time around, we’ll talk about what you need to do after you’ve actually edited the audio – exporting and distribution. In the meantime, feel free to share your editing tips and tricks, as well as the apps that you use.

Image is by flickr user Jeezny / CC licensed