Podcasting for the Penguin!
Kelly Penguin Girl and I have been producing the weekly GNU/Linux User Show podcast (www.linuxuser.thepodcastnetwork.com) since June 2005. We're just about to hit show #30, which I think makes us one of the oldest running GNU/Linux podcasts aimed specifically at new GNU/Linux users. We've moved on to other things and no longer host the show, but it's been a long, fun journey, and we've learned a lot.
The technical aspects of podcasting on GNU/Linux are on par with podcasting on any other OS, but there are some cultural differences. Podcasting to the Free/Libre/Open-Source Software (FLOSS) community requires a sensitivity of the community's values. In short, a podcaster that intends to podcast to the FLOSS community should really be part of the community. The community wants to be talked with, not talked at. Trespassers will be shot.
We record our shows on either a Kanotix or Linspire box (depending on where we are in the house) using a set of $25 US NeXXt headsets and two pairs of Y-cables. We thought about getting a mixer, but so far the Y-cables have performed flawlessly, so we don't see the need to spend the extra money on unnecessary gear.
I always find it quizzical why so many podcasters recommend spending $200 US or more on gear. We've spent less than $100 US since day one on three sets of headsets and a standalone microphone. One of the lessons that blogging has taught us is that content is king, not the pretty bells and whistles around the content. Although there is certainly a minimum level of quality expected by listeners, the content is what drives the show, not the benefits of shiny microphones and mixers.
Application-wise, we use Audacity to record and edit the show, and EasyTag to insert the ID tags in preparation for file upload.
The real workhorse of our show is Audacity. Audacity is a wonderful digital audio workstation (DAW) application that is not only licensed under the GNU GPL and available on SourceForge, but it is also available for all major OS platforms. Audacity has served us well for recording our shows, editing the audio streams, adding effects, importing and aggregating other audio streams and formats, and finally allowing us to export our show in a variety of different formats. Audacity supports Ogg Vorbis encoding out of the box, and it will support MP3 encoding via the LAME encoder (separate download).
One of the killer features of Audacity is the wide range of audio formats it is capable of importing. Over time, we've had to incorporate audio from many sources, such as individual listeners, promo clips from advertisers, audio clips from other shows and downloaded clips from the Internet. Without Audacity's ability to import everything we've thrown at it, we would have been dead in the water many times over.
We generally record the show in many parts. Some are recorded days apart, and some only seconds apart. Regardless, Audacity represents each of these parts as a graphic sound wave, and each of these waves can be manipulated individually (Figure 1).
This intuitive feature makes the post-production of our shows a snap. The tools we use the most are the time-shifter, which allows movement of individual audio parts to snug them up together and kill any dead space, and the insert silence tool. The insert silence tool may sound innocuous, but it's very handy for extending little dead spots to fit around another sound clip.
Audacity also features a very complete set of options that allow granular control of the final audio file quality and size (Figure 2).
Podcasts generally are mostly speech and can therefore be exported at low quality without any appreciable degradation. The Podcast Network's standard is 48Kbps and 22KHz. We used to put out only MP3s of our show, but after Richard M. Stallman came on lucky show #13 and asked us also to produce Ogg Vorbis files, we started doing that as well. It took me a while to understand the Ogg Vorbis compression technique, and our first few Oggs were twice as big as the same show's MP3 file. That didn't make us very popular, let me tell you! Here's the secret: in Audacity, there is no bit rate setting for Ogg Vorbis files. Rather, there is a slider from 0 to 10. A setting of 0, although counter-intuitive, creates a perfectly usable Ogg Vorbis file.