Cryptography Reference
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over the network, using the Internet or mobile channels. They can be divided
into two categories. These are:
1. Continuous media which is a series of consecutive units of equal dura-
tion. For instance, audio, They may include video and animation.
2. Discrete media contains one presentation unit, which may be text,
graphics on image.
Multimedia signal processing has the following goals:
(A) high quality,
(B) highly e cient compression,
(C) security-related issues,
(D) error resilient transmission, and
(E) interactivity.
Topics in the topic cover the items from (A) to (D). Part II focuses on items
(A) and (B), Part III and most of Part IV discuss items (A) and (C). A
part of Part IV considers item (D). Item (E) mainly relates to multimedia on
demand (MOD), much of this particular subject exceeds the intended scope
of this topic.
1.1.2 The Need for Multimedia Compression
Multimedia signals contain a great deal of data. The bit rate of the original,
uncompressed data with different formats may be described as follows.
Speech:
8 bit/sample8 Ksample/sec = 64 Kbit/sec
CD audio: selectfont
16 bit/sample/channel 44.1 Ksample/sec 2 channel =1.411 Mbit/sec
Digital TV:
Still picture:
720 pels483 lines2 byte/pixel8 bit/byte = 5.564 Mbit/frame
Motion picture:
5.564 Mbit/frame29.97 frame/sec = 167 Mbit/frame
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