Skip to content
Skip to main content

About this free course

Become an OU student

Download this course

Share this free course

Exploring communications technology
Exploring communications technology

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

3 Perceptual source-coding and lossy compression

3.1 Introduction

Source coding is the representation of a phenomenon such as a sound or an image in a form suitable for communication or storage. You are probably familiar with the example of digital sampling for creating digital representation of sounds or images. Prior to transmission, such representations often have error control incorporated, as you saw earlier. There is more to source coding than just sampling, though, because of the desirability of representing a source as efficiently as possible. Usually this means using as few bits as possible, consistent with achieving a desired level of fidelity to the original source. This raises the issue of data compression, and in particular lossy compression which I will look at shortly. Lossy compression is widely used in the source coding of sound, images and video. MP3 and JPEG files use lossy compression. Usually this compression relies on human perceptual characteristics that enable some data to be discarded with no apparent degradation.

In this introductory audio, Allan Jones talks to Laurence Dooley, the author of Section 3, about some of the issues from this section.

Download this video clip.Video player: tm355_openlearn_003-640x360.mp4
Copy this transcript to the clipboard
Print this transcript
Show transcript|Hide transcript
 
Interactive feature not available in single page view (see it in standard view).