Noise in Multimedia System - Essay Example

Noise is defined as any unwanted thing in the desired one. Though in some special cases in electronics like oscillator where noise is intentionally introduced but, most of the times they create hindrance to the actual motto. Suppose after faithful encoding data is sent over transmission medium. Spurious electrical signals from environment may interfere to the original signal resulting noise. In other cases noise appears as flicker of screen. For portable devices developers need to design layout for the target device and developing pixels of precise width and resolution sometimes give erroneous result.

Again, online content developers who work independently for target devices finally come out with objects which have problem in mapping. This paper explicitly concentrates on various noise sources and their effect on multimedia products. It also outlines ways to overcome it. Noise in one sense is defined as measurable amount of loss of data. It is a random parameter that can be measured by its statistical properties. In telecommunication channel noise is generally gets added in medium during transmission.

Figure 1 shows such a transmission channel. In between transmitter to receiver there is the medium. It can be either wire in case of line communication or free space for wireless communication. Signal gets interfered by noise in the medium by various means e.g. thundering, signal from other sources if two signals are close to each other and from mismatch between transmitter and receiver. Shannon defined the limit of transmission in a noisy channel for a given channel capacity in order to maximize the signal-to-noise (SNR) ratio1.

But it does not guarantee noise free transmission. This is nothing but the post transmission noise and before it gets received.Different methods exist to detect any error has arisen and if so, to correct it. The seven layer OSI model works well for error detection and correction in any computer communication process. From multimedia perspective transmission and reception methods are somewhat more complex where; total display is fragmented into different components and then all together information is sent to the target end maintaining timing constraint.

SMIL is a language format used for encoding multimedia presentations for transmission over the web. It's a structured composition of autonomous media objects. Figure 2 shows one basic timing containers2. In SMIL seq container begin time is relative to predecessor's end. Par container has begin time relative to the containing par but for excl object a is started whenever object x (not shown) is activated and object b, c are started when object y and z (not shown) are activated. It is to be noted that no two common timeline should be used to model the relationship between a, b and c.

If it's not maintained then there will be overlap between the objects that will turn to give timing mismatch, which may appear as noise in display. Other than this, before transmission objects are encoded into convenient form. During encoding data might get lost. For example if it's an image then it might have been encoded into jpg form where loss of data and as a result noise can get introduced. This noise will be incorporated throughout its processing and appear finally in