Hypertext, Hypermedia & MHEG Standards

Explanation

Linear media forces users into sequential consumption (like reading a traditional novel from page 1 to 100). Hypertext and hypermedia decouple this, allowing dynamic, non-linear navigation across heterogeneous nodes. MHEG-5 was standardized to define object-oriented multimedia presentations in digital TV set-top boxes with low computational resources, specifying exact screen coordinates, audio playback cues, and interactive remote control buttons using declarative bytecode.

Key points

• Hypermedia: Extension of hypertext integrating audio, video, graphics, and animations into the linked non-linear document structure.
• Dexter Hypertext Reference Model: Foundational model defining three layers: Storage Layer (nodes and links), Within-Component Layer (content structures), and Runtime Layer (presentation and user interaction).
• MHEG (Multimedia and Hypermedia Information Coding Expert Group): ISO/IEC international standard defining declarative interactive multimedia objects for digital broadcasting (DVB/IPTV).
• HTML5 Multimedia Extensions: Standardized declarative tags (, , ) replacing proprietary plugins (Flash, Silverlight).

Example

Code examples

<!-- Modern HTML5 Hypermedia Integration -->
<video controls width="640" poster="/images/poster.jpg">
  <source src="/media/lecture.mp4" type="video/mp4">
  <source src="/media/lecture.webm" type="video/webm">
  <track kind="subtitles" src="/subs/en.vtt" srclang="en" label="English" default>
  Your browser does not support HTML5 video.
</video>

Exam questions

• [7 Marks] Differentiate between Hypertext and Hypermedia. Describe the three layers of the Dexter Hypertext Reference Model.
• [5 Marks] What is MHEG? Explain its historical role and technical features in interactive digital television broadcasting.