Managing Multimedia Devices and Mass Storage on PCs: A+ Guide (6e) - Prof. Angelo J. Gero, Study notes of Electrical and Electronics Engineering

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A+ Guide to Managing and

Maintaining your PC, 6e

Chapter 10

Multimedia Devices and Mass Storage

(v1.0)

Multimedia on a PC

•^

Goal: generate output that emulates reality

-^

Differences between cyberspace and realspace^ – Sights and sounds in reality are continuous

(analog)

• Computer data is binary (discrete and

digital)

•^

Challenge: bridge world of cyberspacewith reality

Multimedia on PC’s

•^

PC as a hub for other devices^ – MP3 players– Cell phones– Digital cameras

Streaming Data

•^

Flow and/or the processing of datacannot be interrupted without affectedthe quality

-^

Examples:^ – audio & video

CPU Technologies for Multimedia

•^

Operations a CPU can perform^ – MMX and SSE help with repetitive looping– SSE improves 3D graphics

-^

Pentium 4 can use MMX, SSE, SSE2,SSE3, HT

-^

AMD uses 3DNow!, HyperTransport!,PowerNow!

Digitizing Analog Data

•^

Data must be converted from analogformat to a digital format

-^

Sampling rate & resolution

Sampling Rate

•^

How often an analog signal (video oraudio) is sampled.

-^

Measured in hertz

-^

Higher sampling rates = better fidelitybut generate more data (larger files)

Sampling Rates

Example

•^

Digitize a 60 second audio clip at asampling rate of 4 Khz and aresolution of 8 bits^ –

(8 bits x 4,000 hz x 60 seconds) / 8 = 240,000 bytes

Example

•^

Digitize the same 60 second audio clipat a sampling rate of 44.1 khz at aresolution of 16 bits^ –

(16 bits x 44,100 hz x 60 seconds) / 8 = 5,292,000 bytes

A+ Guide to Managing and Maintaining your PC, 6e

Why is it needed?

•^

Multimedia files are very large

-^

Need to conserve disk space and networkbandwidth

-^

The multimedia features on the Internet rely ondata compression^ – Video streaming (You Tube)– Digital Audio (iTunes, Napster)

A+ Guide to Managing and Maintaining your PC, 6e

Example #1: Bit Mapped Graphics

•^

Example: 1024 x 768 x 24 bit color depth image^ –

1024 x 768 x 24 / 8 =

2,359,296 bytes

Basic Compression Technologies^ •^

Based on data having repeated patterns

-^

Lossless^ – No loss of information when the data is

compressed

•^

Lossy^ – Some loss of data when data is compressed

Compression Ratio

•^

How much is a file compressed

-^

Expressed as ratio^ – Uncompressed size is 100K– Compressed size is 25K–

Compression ratio is 4:1 or 1: