This time tomorrow I'll be at the O'Reilly Emerging Technology Conference. Checking out the conference program, I saw that Evan Williams will be hosting a session entitled Odeo -- Podcasting for Everyone. I've noticed the enthusiasm around podcasting among certain bloggers and the media but I am somewhat skeptical of the vision folks like Evan Williams have espoused in posts such as How Odeo Happened.

In thinking about podcasting, it is a good thing to remember the power law and the long tail. In his post Weblogs, Power Laws and Inequality, Clay Shirky wrote

The basic shape is simple - in any system sorted by rank, the value for the Nth position will be 1/N. For whatever is being ranked -- income, links, traffic -- the value of second place will be half that of first place, and tenth place will be one-tenth of first place. (There are other, more complex formulae that make the slope more or less extreme, but they all relate to this curve.) We've seen this shape in many systems. What've we've been lacking, until recently, is a theory to go with these observed patterns.
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A second counter-intuitive aspect of power laws is that most elements in a power law system are below average, because the curve is so heavily weighted towards the top performers. In Figure #1, the average number of inbound links (cumulative links divided by the number of blogs) is 31. The first blog below 31 links is 142nd on the list, meaning two-thirds of the listed blogs have a below average number of inbound links. We are so used to the evenness of the bell curve, where the median position has the average value, that the idea of two-thirds of a population being below average sounds strange. (The actual median, 217th of 433, has only 15 inbound links.)

The bottom line here is that a majority of weblogs will have small to miniscule readership. However the focus of the media and the generalizations made about blogging will be on popular blogs with large readership. But the wants and needs of popular bloggers often do not mirror those of the average blogger. There is a lot of opportunity and room for error when trying to figure out where to invest in features for personal publishing tools such as weblog creation tools or RSS reading software. Clay Shirky also mentioned this in his post where he wrote

Meanwhile, the long tail of weblogs with few readers will become conversational. In a world where most bloggers get below average traffic, audience size can't be the only metric for success. LiveJournal had this figured out years ago, by assuming that people would be writing for their friends, rather than some impersonal audience. Publishing an essay and having 3 random people read it is a recipe for disappointment, but publishing an account of your Saturday night and having your 3 closest friends read it feels like a conversation, especially if they follow up with their own accounts. LiveJournal has an edge on most other blogging platforms because it can keep far better track of friend and group relationships, but the rise of general blog tools like Trackback may enable this conversational mode for most blogs.

The value of weblogging to most bloggers (i.e. the millions of people using services like LiveJournal, MSN Spaces and Blogger) is that it allows them to share their experiences with friends, family & strangers on the Web and it reduces the friction for getting content on the Web when compared to managing a personal homepage which was the state of the art in personal publishing on the Web last decade. In addition, there are the readers of weblogs to consider. The existence of RSS syndication and aggregators such as RSS Bandit & Bloglines have made it easy for people to read multiple weblogs with ease. According to Bloglines, their average user reads just over 20 feeds.

Before going into my list of issues with podcasting, I will point out that I think the current definition of podcasting which limits it to subscribing to feeds of audio files is fairly limiting. One could just as easily subscribe to other digital content such as video files using RSS. To me podcasting is about time shifting digital content, not just audio files.

With this setup out of the way I can list the top three reasons I am not as enthusiastic about podcasting as folks like Evan Williams 

1. Creating digital content and getting it on the Web isn't easy enough: The lowest friction way I've seen thus far for personal publishing of audio content on the Web is the phone posting feature of LiveJournal but it is still a sub optimal solution. It gets worse when one considers how to create and share richer digital content such as videos. I suspect mobile phones will have a big part to play in the podcast creation if it becomes mainstream. On the other hand, sharing your words with the world doesn't get much easier than using the average blogging tool. 
2. Viewing digital content is more time consuming than reading text content: I believe it takes the average person less time to read an average blog posting than to listen to an average audio podcast. This automatically reduces the size of the podcast market compared to plain old text blogging.  As mentioned earlier, the average Bloglines user subscribes to 20 feeds. Over the past two years, I've gone from subscribing to about 20 feeds to subscribing to around 160. However it would be impossible for me to find the time to listen to 20 podcast feeds a week, let alone scaling up to 160.
3. Digital content tends to be opaque and lack metadata: Another problem with podcasting is that there are no explicit or implicit metadata standards forming around syndicating digital media content. The fact that an RSS feed is structured data that provides a title, author name, blog name, a permalink and so on allows one to build rich applications for processing RSS feeds both globally like Technorati & Feedster or locally like RSS Bandit. As long as digital media content are just opaque blobs of data hanging of an item in a feed, the ecosystem of tools for processing and consuming them will remain limited.

This is not to say that podcasting won't go a long way in making it easier for popular publishers to syndicate media content to users. It will, however it will not be the revolution in personal publishing that the combination of RSS and weblogging have been.

I'll need to remember to bring some of these up during Evan Williams' talk. I'm sure he'll have some interesting answers.