Chapter and HREF Tracks Defined:   A chapter track may contain one or more markers that are tied to specific points along the media time line. Chapter Markers label these points of significance using brief text strings which become a menu in many playback environments. These menus enable rapid, non-linear access to specific points in a video or audio file. Similarly, an HREF track ties hyperlinked text (URL Links) to specific points along the timeline. These URL Links appear as either blue, underlined text or as a graphic button (in iTunes.app) centered atop the lower part of the video. When one of these URL Links is clicked, a web page will open in the default browser. The file name suffix (.m4v or .m4a) is critical for display on Apple devices.

Chapter Tracks in Action:   Chapter track controls will vary by playback environment and file type so we have a separate pair of screencasts showing how chaptered video (.m4v) and enhanced audio (.m4a) files look and behave as well as how they are commonly used in the three major playback environments for mobile, podcastable MPEG-4 files:

• QuickTime Player X: video (.m4v) | enhanced audio (.m4a)
• QuickTime Player 7: video (.m4v) | enhanced audio (.m4a)
• iTunes Application: video (.m4v) | enhanced audio (.m4a)
• The iPhone or iPod touch: video (.m4v) | enhanced audio (.m4a)

HREF Tracks in Action:   HREF Tracks display URL Links along the timeline. These links commonly appear as classical hyperlkinks (blue, underlined text) but, in iTunes.app, appear as an attractive button The following screencasts ilustrate how an HREF Track displays URL Links in the three major playback environments:

• QuickTime Player 7: video (.m4v) | enhanced audio (.m4a)
• iTunes Application: video (.m4v) | enhanced audio (.m4a)
• The iPhone or iPod touch: HREF URL Links Are Not Currently Supported
• QuickTime Player X: HREF URL Links Are Not Currently Supported

The Pedagogy of Chapter Markers and HREF Tracks:   Chapter Markers and HREF hyperlinks provide those faculty, students and staff who want to publish mobile and podcastable learning materials with a number of options that can substantially enhance the value of audio and video files in pursuing important educational objectives. The following is a partial list:

Non-linear access to linear material Content Labeling and Navigation Decision and Collaboration Suppport Foreshadowing, Setting Tone, etc. Rating Reference Paced Instruction Video Annotation Assignment Indicators

Compilations of movies or clips Identify Movements and Other Musical Events Recorded News Events Stepwise Explanations Logical Division of Long Form Video URL: Reference to Further Information URL: Digital Footnotes URL: Supporting Evidence or Argument

Major Applications of Chapter Markers and URL Links:   A track containing chapter markers and URL Links (optional) may be added to MPEG-4 video or audio files in several ways and with different objectives in mind. Once created, they can also be edited by replacement. The following outlines some of the more common application of chapter markers.

• Applications: The primary MacOS X GUI tools capable of doing this kind of work are Subler (donation-ware) and GarageBand (part of the iLife Suite bundled with all new Macs). On Windows, the GUI tool of choice appears to be YAMB. For those who prefer working with a Command Line Interface (CLI), there is MP4Box (Mac or Win: precompiled binaries here).
• Enhancing an Original Video Production
  This is where the person adding the chapter markers is also the author of the video or audio file content. Here is a screencast showing how Garageband is used to add chapter markers and an HREF track to a video file.
• Re-purposing an Extant Video Production
  A DVD title that includes chapter markers can be converted (ripped) to MPEG-4 such that chapter markers and associated timing data are included in a chapter track. This is best done using Handbrake, a free, cross-platform, open source tool. The chapter marker titles may be manually edited either to mirror DVD scene titles or something entirely different. Here is a screencast showing this aspect of Handbrake in action. GarageBand and Subler can be used for subsequent editing of chapter markers or to add additional markers.
• The Audio-annotated Slide Show
  You may also see this referred to as an "Enhanced Audio Podcast." As you saw in the preceeding examples, these podasts are analagous to Apple Keynote or Microsoft PowerPoint slide shows that have been narrated. The chapter markers coincide with the appearance of new slides at arbitrary points along the time line and can also contain a URL hyperlink that, when clicked on, will open a web page with the default browser.
• • Pre, Stand-alone or Post Production
  • The audio-annotated slide show (aka "Enhanced Audio Podcast File") can be authored with GarageBand or a more specialized commercial application called Profcast. These podcast episodes may be used as advance organizers for face-to-face instruction, as stand-alone instruction or as a post-instruction reference and review tool. This screencast shows the basic steps in creating an Enhanced Audio Podcast with GarageBand '09.
  • Live Recording
  • Real-time audio-annotated slideshow podcast files can only be created with ProfCast using the ProfCast playthrough feature. Profcast concurrently captures speaker audio, slide images and slide timing in real-time during a presentation to a "live" audience and thus provides post-instruction reference and review very easily and quickly. Student audio interaction may also be captured if the instructor opts not to pause recording. This screencast shows how Profcast is used in both live and studio recording.
• Notes on HREF Tracks
  Although chapter markers and URL links are implemented as separate tracks in .m4a and .m4v files and could appear independently of one another, this is generally not the case. You will see chapter markers with and without URL links in an HREF Track but it is rare to see a podcast episode with an HREF Track and no corresponding Chapter Track. This may be due to the distraction potential of URL links. As well, URL links present some display inconsistencies that might be objectionable to some designers. The following screencasts illustrate how these inconsistencies are manifested in chaptered video (.m4v) and enhanced audio (.m4a) podcast files so as to facilitate informed decisions on whether to use URL Links or not.
• 
  Finally, we need to recognize the fact that HREF Tracks are currently only implementable in movie containers.