Mainstream consumers are starting to embrace audio content delivered as podcasts. According to Bridge Ratings latest research “The Podcasting Audience Project”, the number of weekly podcast listeners in the US is expected to almost triple from 2007 to 2010 to more than 7 million listeners.

Fig 1 – U.S. Weekly Podcast User Estimates 2005 vs. 2006
Source: “The Podcasting Audience Project”, Dave Van Dyke, Bridge Ratings, 9/30/06

There are several key drivers across both the supply and demand side of this podcasting explosion. On the supply side, podcasting has lowered the barriers to both creating and distributing content. For many topic experts, creating a podcast is even easier than typing a blog, with some even recording podcasts from their cellphones. Web hosts have put together packages that make is simple to create, upload and list podcasts in major directories – at prices as low as $5 per month, for example, with’s Quick Podcast package. Podcast supply and demand is also being driven by ad-insertion technologies from companies such as Podtrac, which enable even major media brands to offer top syndicated content to consumers for free.

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These key factors have driven an explosion of available podcast content. While no one can seem to keep a good count of the available supply of podcasts, at least one indicator is the number of podcasts available in the iTunes podcast directory, which was reported to have increased by 10x from Q3 of 2005 to Q3 of 2006 to over 80,000 podcasts, each with an average of over 6 episodes.

On the demand side, consumers are increasingly expecting the ability to timeshift their media content. In the broadcast video media arena, devices such as the Tivo have solved the programming hassles of VCRs and led to an increase in consumer video timeshifting. With audio media content, there is really no counterpart to the Tivo, although there are some PC-based timeshifting packages with radio tuners for the really tech-savvy. However, podcasting can provide many of the same timeshifting benefits to consumers. With audio podcasting, consumers can put together their own set of favorite programs in any sequence they desire. And since consumers can more easily multiplex with audio content, there are more potential listening hours to fill with timeshifted audio programs than with video as you can’t drive, shave, or write and email while watching a video, but you certainly can with audio podcasts!

According to a recent Aribitron report (“The Infinite Dial: Radio’s Digital Platforms, 2006”), more than 22 percent of Americans recognize the term podcast, but only half as many have ever listened to a podcast. So what is holding back podcast usage? According to Dave Van Dyke, of Bridge Research, “consuming podcasts is difficult; the process needs to simplify”. Finding, subscribing, storing and managing content for mobile listening are steps which many have found overwhelming. Fortunately, there are new sites and software emerging which help tackle these challenges. Let’s take a look at each of these steps.

1) Finding audio podcast content – Podcast content normally consists of two parts – one part is the audio itself packaged as an MP3 file, and the other is the text file which describes the audio author, title, episode summary, duration, and url location of the actual MP3 file. The text file is in a standard format known as RSS, which stands for Really Simple Syndication.

Podcast authors submit the RSS text file to various podcast directories, which can be standalone web sites such as and, or applications with built-in directories such as iTunes and Juice (formerly iPodder). These directories let you search the RSS files by genre/title or by keyword search. goes a step further – searching for keywords within the audio of the MP3 file, using patented speech recognition software originally developed for defense applications. Podzinger can help you identify podcast episodes which might cover a very specific topic which the author didn’t list in the more general text file summary.

With the explosion in the number of podcasts, it is also helpful to get some other tools to identify those which best match your needs and interests. In iTunes, you can see a popularity index next to each podcast. When you select a podcast, you will also see an Amazon-style “listeners of this podcast also subscribed to…” list. These two tools help you narrow down and prioritize which podcasts to download and review. Another new tool set of tools are emerging from social networking sites such as In the podcast beta area, site users can add podcasts to the directory, vote for their favorites, and even post comments about specific episodes.

2) Subscribing – once you find some podcasts, users typically use a podcatcher application to “subscribe” to the podcast series. To subscribe, a user can copy the url for the podcast RSS file, usually identified by the orange RSS icon, into their podcatcher subscription list. Other applications such as iTunes simplify this step with a subscribe button. A growing set of applications and sites let users export a list of their favorite podcast descriptions in a standard format known as Output Processor Markup Language (OMPL). This feature enables podcast listeners to share their favorite subscriptions with friends and can be used to migrate these favorites to another podcast application, if it supports OPML import.

3) Capturing and syncing your podcasts – To enjoy the timeshifting convenience of podcasts, most users want to take their favorite podcasts mobile. The traditional method involves two steps – moving the podcast audio content from an author’s server to a listener’s desktop hard drive and then copying the same file from the listener’s desktop to a mobile device. To get the most current episode, the first step must be performed as close as possible to the time that new podcast episodes are published by the author. Not too bad if your podcatcher application is running on an “always on – always connected” desktop computer, but can be a challenge for a roving laptop user.

When a listener subscribes to a lot of podcasts, another constraint is disk storage space. Podcast authors sometimes record in CD quality bit rates, which means that a single episode of a half-hour show can consume as much disk space as an entire digitized CD. Again, this is increasingly a challenge as more consumers utilize laptops with smaller disk drives.

Once all of the desired episodes are on the hard drive, a listener needs to select which ones to take mobile. Mobile devices typically contain memory which is a small fraction of the size of a hard drive due to power and price limitations. As a result, a podcast listener sometimes needs to manually delete older files to make room for podcast episodes to be transferred from the PC drive. If a user gets behind on listening, this can lead to episode voids where a user can’t download the latest episode or deletes an unheard prior episode in order to make room for the freshest content.

All of this copying to get from the podcast server to the mobile podcast player can cost a user in terms of added memory. As shown in Fig 2, memory prices range from a little over a dollar per Gigabyte for laptop drives to over $10 per Gigabyte for mobile device memory. Fortunately, new mobile applications are now available which simplify this process. For example, the latest SelectRadio® software for newer Windows Mobile PDAs and smartphones lets you stream podcasts directly from the podcast server, without the need to subscribe, download or sync to your PC. The software utilizes advanced buffering approaches to stream through the handheld device network connection using only a small amount of temporary buffer memory and no PC in between.

With SelectRadio software, there is no need to worry about your PC being connected at the right time to download the freshest episode of your favorite podcast. Instead, you just click on the podcast title and you will see a list of available episodes, including the freshest available. You can even click to play all of the available episodes sequentially – like a “virtual channel” of your favorite topics. When an episode plays, the summary description text is scrolled across your display and you are only a click away from selecting another podcast or another episode.

SelectRadio software includes presets for a variety of popular podcast programs ranging from lifestyle topics like movie, wine, cigar and concert reviews, to endurance training and ski reports. You can also import your own OPML format podcast lists created in iTunes or your account. Or you can import lists directly from OPML links on a growing number of websites such as’s “Top 50 podcasts” or even your friend’s podcast lists.

Audio podcasting use is poised to reach the tipping point in 2007 thanks to a variety of technologies, techniques and business model innovations. You too can harness this vast universe of content to easily become your own “program director” of a personalized daily soundtrack with fresh, informative and entertaining content on your topics, on your schedule, and without the early adopter hassles.

Jim Kearns is president of CardonWare, a consumer wireless software company.