Digital Audio Distro: Getting your work out there.

Evan Henshaw-Plath

Producing your audio piece is just the first step in a much larger process of distribution and promotion. Once you have an interview, song, or radio program, you need to get it out there. This article is a quick overview of what's required to produce audio for distribution including the formats you want to use for sharing audio over the internet and what role Free and Open Source Software (FOSS) can play. Finally I will address where you can host your audio files and how to build a podcast.

Your first step is record and produce the audio. The primary application you'll use is Audacity. It's a standard audio editing application. The most important thing to know about audio formats is there are two primary sets of audio formats.

Lossy and Lossless Audio Formats
Some are audio formats are lossless, meaning the quality of the audio does not get lost when it gets reopened and edited. Lossless file formats are good for files which are going to be edited again, or remixed in to other files. You will want to save your files in a lossless format while you create, edit, and mix your audio production. The disadvantage is that lossless files is that they are very large. Popular lossless audio formats are WAV, AIFF and FLAC.

The second audio format is what you will want to use for distribution for play over the radio and the net. The file format is much smaller and can be of good quality for the listener. The most popular lossy format is mp3, but there are others like AAC, MP4, and WMA which are also lossy. The FOSS option for lossy codecs is generally referred to as Ogg. Ogg is the container used for the Vorbis codec and as such audio is encoded in this was is referred to as Ogg Vorbis, or Ogg for short.

Lossy codecs sound good when played back but not when you edit them. Mixing lossy formats like mp3 to make new audio files greatly reduces the quality. Think of it like a VHS cassette. Each time you copy from one cassette to another it gets worse. After the 3rd copy the quality becomes so bad it's unlistenable. The advantage of mp3 and all lossy formats is they can be 10% or smaller in comparison to the full quality lossless formats. Most audio distributed over the internet is done as mp3's and it's recommended that unless you plan on people remixing / editing your audio files, to use mp3.

Some applications like Audacity and Rezound support saving as either lossy or lossless file formats. One application for windows users for transcoding to different media file formats is Media Coder, on Mac you can use Max. They are setup to translate audio files from any format to another. Think about the download implications and intended uses when choosing file formats. Remember that any translation to or from a lossy format will result is lost audio quality.

Understanding Audio File Formats
Audio files have a number of aspects which are important to know and will effect the size and quality of the audio you produce. Audio files have a sample rate and a bit rate. The higher the number the bigger the file, and higher quality. Lower numbers generate smaller files at worse quality. Music requires more quality than spoken word. Make sure that your sample rates are one of the following, 11, 22, or 44 khz (that's 11,000 hz). That way the broadest range of audio players will be able to play your files without sounding like Alvin and the Chipmonks. The other number you are going to have to decide in your setting, especially for mp3's and related formats is the bitrate. The bitrate is the primary thing which will make your files large or small. Most music should be set between 128 and 190 bits. Most talk and spoken word pieces should be between 32 and 64. When you are trying to really save bandwidth you can use as little as 16, but it will not sound good. For audio which will be rebroadcast over AM radio, a bitrate of 32 is fine. Because of it's file size, most people distribute audio files over the internet as mp3's.

Hosting your Files
There are two issues you will face in putting your audio files online. First is uploading your files, and the second one is hosting. Audio files are big, they require a lot of space on the server to host them, and then a lot of bandwidth when they are downloaded.

Uploading files
There are two primary ways in which you can upload files. The first option is to use your web browser and a form with a file upload. This is the easiest way of uploading, and will work with all the sites mentioned below. The problem is that it requires a faster internet connection. Web browsers are not great at posting large files over 50 megabytes. That's an hour long mp3 at medium quality. Uploading from a web browser does not, most of the time, give you a progress bar indicating time remaining, nor does it let you continue an upload if you loose your connection. Uploading using a web browser over a dial up modem internet connection is unlikely to work for files bigger than a megabyte or two.

The second way you can upload files is using an ftp client. FTP stands for File Transfer Protocol, and it's an application you can run to transfer files to websites and other servers. FTP allows for you to see your progress in uploading a file and restart transfers which get interrupted. If you have an unstable internet connection, or are using a dial up connection, I highly recommend using FTP.

There are two sites profiled in this article which allow you to upload files using FTP, radio4all.net and archive.org. Many hosting accounts websites also support uploading files via FTP.

So, now that we have talked about how to post your files online, we need to know where to put them. The first possibility is to just put them on the same server as your website, if you have one. There are two problems with this. First, most website hosting accounts have a limited amount of space. Mp3's are smaller than lossless formats like WAV, but they are still huge in comparison to html and images. Many accounts only provide 100 megs of storage. While that's plenty for websites, it's less than 2 hours of decent quality audio. It is really important that you understand how you pay for bandwidth. Many accounts allow up to several gigabytes of traffic a month, but after that you have to pay fairly steep overuse penalties. If your audio becomes popular, this could run up a bill of hundreds or thousands of dollars.

If hosting your files on your own server is not a good idea, where can you host them? There are a few options:

• Archive.org - The Internet Archive has a section for hosting large multimedia files provided the are licensed under a Creative Commons license. The system supports both web and FTP upload. Archive.org also supports automatic transcoding to high and low quality versions of your files to support people with low bandwidth connections. The only downside to using archive.org is the rather slow signup and cumbersome process for uploading and categorizing the files. Archive.org does not create podcast feeds automatically for easy distribution of your files. Archive.org receives some support from Amazon.com's Alexa search engine and as a result has very good bandwidth and extensive capacity to handle files. There is a wait period of a day or two between when you apply for an account and get approved.
• OurMedia - OurMedia uses archive.org and you must have both accounts to use ourmedia. What ourmedia provides is an easier and cleaner interface to archive.org and the ability to create your own page listing your audio contributions.
• radio4all - A community radio site for sharing community radio programs. Radio4all is unfunded and grassroots, but it has been around for a long time and provides an easy interface for uploading via the web and FTP. It works well and automatically generates podcast feeds for you as well as allowing direct linking to the mp3's. Radio4all is primarily aimed at sharing radio programs and has limited bandwidth for their servers. Their service works well, but they are overtaxed and often serve files slowly.
• Radio.indymedia.org - And Other indymedia servers. Indymedia is an activist network which allows anybody to post audio, text, photos, and video about social justice related issues. You can use the web form to post files to your local Indymedia site and then link to them from your website. Some Indymedias generate a single podcast feed of all audio posted, but it doesn't let you build your own specific feed or update the files once they have been posted. In terms of capacity, Indymedia is somewhere between radio4all and archive.org.
• Odeo.com - A commercial service which is provided for podcasting and audio sharing over the internet. Odeo allows free uploading of files to their servers. Odeo lets you link directly to the mp3, but also generates many flash players for listening to your audio from within your webpage. Odeo keeps simple stats on the plays via streaming and download. By default Odeo places a 'bumper' with Odeo branding on uploaded files, but if you request, this can be removed for all NGO's.
• Others - There are many other places you can host audio content on the internet. The primary things you should be looking for are the following: Can i post things easily, via FTP or through the web? Can i edit my files once they are posted? Will it automatically make low quality versions for easy download? Will it generate podcast feeds or is that a separate step? Many applications such as Drupal, Loudblog and Wordpress support file uploading and generating podcasts, but you need to make sure that your bandwidth costs stay under control.

Podcasting
What is podcasting? It's a way of distributing audio files automatically over the internet. Think of it as your favorite radio program getting downloaded when ever a new episode is released. It is easy to do and has become very popular in the last year. Many people have become 'podcasters' and like community radio DJ's and journalists they have created their own radio like programs. Many podcasts are actually repurposed radio programs which are distributed over the internet rather than the airwaves. Podcasting is popular because you can put the programs on your computer or portable mp3 player, like an ipod, for later listening. Although it is not actually broadcasting, you don't need an ipod to do it, and Apple was not at all involved in the creation of podcasting, the name stuck as an abbreviation of i-pod-broad-casting.

Getting podcasts.
There are a lot of applications you can use to listen to podcasts. The first application which started podcasting is the open source juice client. It works on Mac, Windows, and Linux. There are many others, but the one I recommend is Songbird (sonbirdnest.com) which is a cross-platform open source music player with podcast client capability. It's the open source version of iTunes. With either of these, or other clients you need to subscribe to a feed. It's a special RSS file which just has a list of the most recent episodes, with links. The client automatically downloads the latest shows and puts them in to your mp3 library. Juice puts it in iTunes or an xmms play list, while Songbird has it's own mp3 library. When you want to listen to a show, it's already downloaded. You can also automatically transfer it to your portable mp3 player. This makes the process of finding and keeping up to date with many podcasts (radio programs) easy.

Making podcasts.
To make a podcast you need two things. First you need to have your audio files up on the internet. Secondly you need to make something called a podcast RSS feed which has 'enclosures'. An RSS file is a machine readable format which lists articles, blog posts, or related content. Each article can have something called an enclosure, which is a link to a file. All a podcast file is a specific format for linking to a list of your audio files. Many applications automatically create podcast feeds if you link to an mp3. Those include Wordpress and Drupal. Other times your software will not support it automatically. If you have an RSS feed already for your site, you can link to your mp3's and then provide that feed to feedburner.com which will 'podcastify' it for you. Once you have a podcast feed you need to include a link to it and submit it to podcast directories so people can find your audio content.

Conclusion
Whilst getting your audio out there on the net still takes some technical skills the bar is being lowered everyday. With a bit of patience and work you can take advantage of these new technologies to to bypass the traditional media gatekeepers and get your voice heard.

You can find more out about podcasting at odeo.com and
Wikipedia

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