Multimedia information representation - …userspages.uob.edu.bh/.../ho_multimedia4.pdf · Multimedia information representation 2 Multimedia information representation 2.2Digitization

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Multimedia information representation

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Multimedia information representation

2.2Digitization principles2.2.1 Analog signals2.2.2 Encoder design2.2.3 Decoder design

2.3Text2.3.1 Unformatted text2.3.2 Formatted text2.3.3 Hypertext

2.4Images2.4.1 Graphics2.4.2 Digitized documents2.4.3 Digitized pictures

2.5Audio2.5.1 PCM speech2.5.2 CD-quality audio2.5.3 Synthesized audio

2.6Video2.6.1 Broadcast television2.6.2 Digital video2.6.3 PC video2.6.4 Video content

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Digitization principles

� The conversion of an analog signal into a digital form

� signal encoder.

� signal decoder.

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Signal properties: (a) time-varying analog signal; (b) sinusoidal frequency components;

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Signal properties: (c) signal bandwidth examples; (d) effect of a limited bandwidth transmission channel.

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Signal Encoder Design: Circuit Components

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Signal Encoder Design: Associated Waveform Set

Analog Signal

Low Pass Filtered Version

Clock

Output from Sample & Hold

Quantizer Output

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Alias Signal Generation Due to Under Sampling

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Example 2.1

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Quantization Procedure: Source of Errors

bits ofnumber where22

intervalon quantizatimax == nVq

q

n

( )dBlog20Decibelsin Range Dynamic

minmax10 VVDD

=

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Quantization Procedure: Noise Polarity

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Example 2.2

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Signal Decoder Design: Circuit Components

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Signal Decoder Design: Associated Waveform Set

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Fourier Transform

Multiplyin time Convolution

in Frequency

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Quantization

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