On PHPMaster.com there's a tutorial posted that walks you through the creation of a podcast feed based around a Slim framework application and this skeleton application.

In this article, I’ll demonstrate how to use PHP to generate a podcast feed. We’ll create a simple administrative interface to configure the podcast metadata, add and list episodes, and then go through the generation of the podcast feed itself (which is simply an RSS document).

He walks you through the full process - setting up the application, creating the various management pages and making the associated views to add more information to the feed. He also includes the code/markup you'll need for adding episodes and generating the actual XML RSS feed output. You can download the full app if you want to see how it's all laid out.

The Zend Developer Zone has a new tutorial from Vikram Vaswani looking at the reading and writing of metadata for mp3s and images with two handy PECL extensions.

It's just that every time I sit down to have a go at [finding something in my photo or mp3 library], the sheer volume of data overwhelms me and I take the command decision to deal with something easier instead. Sounds familiar? If it does, help is at hand, in the form of PHP's ID3 and EXIF extensions. These extensions can help you organize and catalog your digital media collection so that it's easier to navigate and search. Keep reading, and I'll show you how.

He installs the ID3 package first (via the pecl command line tool) and gives a few sample scripts to pull the metadata information out of a mp3 file as well as update/remove the information that's already there. He even sets up a simple SQLite database to store the information he's retrieved.

The second part of the tutorial looks at grabbing the image metadata via the EXIF extension. This can yield all sorts of information including date/time the photo was taken, the resolution, the model of the camera and various camera settings at the time. He includes a sample script that automatically makes thumbnails for the images via the exif_thumbnail function.