5.3: Coding and decoding multimedia systems

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Page ID: 14855

Harrison Njoroge
African Virtual University

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Introduction

This section introduces the learner to the fact that Multimedia data which is voluminous in nature needs to be coded and decoded so that it can be transmitted fast on the existing media

Activity Details

In multimedia system design, storage and transport of information play a significant role. Multimedia information is inherently voluminous and therefore requires very high storage capacity and very high bandwidth transmission capacity. There are two approaches that are possible - one to develop technologies to provide higher bandwidth (of the order of Gigabits per second or more) and the other to find ways and means by which the number of bits to be transferred can be reduced, without compromising the information content. There are two approaches that are possible - one to develop technologies to provide higher bandwidth (of the order of Gigabits per second or more) and the other to find ways and means by which the number of bits to be transferred can be reduced, without compromising the information content, i.e. data compression.

Data compression is often referred to as coding, whereas coding is a general term encompassing any special representation of data that achieves a given goal. Information coded (compression) done at the source end has to be correspondingly decoded at the receiving end. Coding can be done in such a way that the information content is not lost; that means it can be recovered fully on decoding at the receiver. However, media such as image and video (meant primarily for human consumption) provide opportunities to encode more sufficiently but with
a loss. Coding (consequently, the compression) of multimedia information is subject to certain quality constraints. For example, the quality of a picture should be the same when coded and, later on, decoded.

Coding and compression techniques are critical to the viability of multimedia at both the storage level and at the communication level. Some of the multimedia information has to
be coded in continuous (time dependent) format and some in discrete (time independent) format. In multimedia context, the primary motive in coding is compression. By nature, the audio, image, and video sources have built-in redundancy, which make it possible to achieve compression through appropriate coding. As the image data and video data are voluminous and act as prime motivating factors for compression, our references in this chapter will often be to images even though other data types can be coded (compressed).

Conclusion

This section has informed the learner the reasons why compression is necessary in multimedia data, that is why coding and decoding are necessary in multimedia data transmission. processes like coding, compression and decoding were learned.

Assessment

1. What is multimedia? is content that uses a combination of different content forms such as text, audio, images, animation, video and interactive content

2. Define the terms;

Coding; is the process of putting a sequence of characters (letters, numbers, punctuation, and certain symbols) into a specialized format for efficient transmission or storage.

Decoding; the conversion of an encoded format back into the original sequence of characters.

Compression; is a reduction in the number of bits needed to represent data. Compressing data can save storage capacity, speed file transfer, and decrease costs for storage hardware and network bandwidth.