1

Kommunikatsiooniteenuste arendusIRT0080

Loeng 3/2008

Avo Otstelekommunikatsiooni õppetool,

TTÜ raadio- ja sidetehnika inst.avo.ots@ttu.ee

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EncoderXX

DecoderX^

Source alphabetDistributionReconstruction alphabetDistortion measure Distortion constraint D: Encoder: Decoder

)(xpX

X̂XX ˆ:)ˆ,( xxd

DxxEd )ˆ,(

Rate-distortion function R(D)= )ˆ;()|ˆ(

minXXI

xxp

LLR X̂}2,....,2,1{ }2,...,2,1{ LRLX

Minimum rate of representing X with distortion D:

Source coding

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TV standardid

• NTS C 525 rida (262.5 rida)60 kaadrit sekundis. Reasagedus fh= 15750 Hz

• Euroopa: 625 rida, (312.5 rida)50 kaadrit sekundisReasagedus fh= 15625 Hz

• HDTV: kaadri formaat 16:9– 720p (1280 x 720 pildipunkti

(pikselit))– 1080i (1920 x 1080 pildipunkti)

Videoriba laius 5.0

MHz(6,0

MHz)

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Üks rida kujutisest

How many lines?

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Television Digital Video• Broadcast Television (analog)

– movie at home - why invent new technology?– mass market– influence of movie on development

• Key Steps– convert pictures to electric signal– send electric signal – convert electric signal to picture

• Comparison with motion picture• High Definition Television - analog digital,

compression• Video conference - travel cost, people cost

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Broadcast Television• Convert picture to electric signal – video

camera– initially only at TV studios, cost not as important– recording media, editing, …– special equipment to convert movie

• Send electric signal – follow radio broadcast, needs spectrum

allocation from – Convert electrical signal to picture

_cathode ray tube_flat panel: LCD, LED, plasma

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Värvuse ülekanne

Y=0.587 G + 0.299 R + 0.114 B Heledussignaal. Ühildavus monokroomsega

U=0.493 (B-Y)

V=0.877 (R-Y)

PAL f=4.433619 Hz

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Analoog/digitaal video

MPEGkooder

Tele-programmi

valmis-tamine

A/D

maatriks

Optilinesõlm ja video-

muundur

Optilinesõlm ja video-

muundur

maatriks

GBR

GBR

YUV

YUV

SDI

Komposiitkooder

Analoogkompo-

siitväljund(PAL)

Digi-taalne

pakitudväljund

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Digitaliseerimine

Komponentide ribalaius kuni 6 MHz

Diskreetimissagedus fd= 13.5 MHz• fd= 864 fh NTSC (Põhja-Ameerika)

• fd= 858 fh PAL (Euroopa)

Kvanteerimine 8 bitti => 13.5* 8 =108 Mbps

Standard ITU-R BT.601 => 720 pildipunkti reas

4 : 2 : 2 => 216 Mbps

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Analoogvideo digitaalseks• Digivideo standard ITU-R BT.601-5,

standardi järgi on kaadri suurus 720x576 (PAL jaoks).

• Ei tarvitse olla 720 pikselit reas. Video digitaliseerimiseks võetav pikselite arv ei pea vastama kuvamise seadme pikselite arvule

• PAL formaadis saab digivideot esitada erinevatel kaadri suurustel 720x480 või 720x576.

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Digivideo vormingud

ITU-R-601 720x480 4:2:2

CIF 360x288 4:2:0

4:3 HDTV 1440x1152 4:2:2, 4:2:0

9:16 HDTV 1920x1152 4:2:2, 4:2:0

4CIF, 16CIF, QCIF

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Digivideosignaal

RGB Kaamera

Maat-riks

13,5 MHz

6,75 MHz

10 bitti27 MHz

takt

Y

U

V

YUV paralleelselt

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Video ja heli

Heliressursi vajadus on suurusjärk väiksem kujutisega võrreldes

(stereoheli kõrgtase 192+192 kbit/s)

Video kodeerimine standardid edastuskiirustele 1,5…60 Mb/s;

MP@ML 15 Mb/s on tavaline(“Main Profile at Main Level”)

Videokooder

Audiokooder

Pakett

Pakett

Programmivoo

MUX

Transpordivoo

MUX

Videoandmed

Audioandmed

Elementidevoog

Andmed

Programmivoog

(DVD)

Üksikuprogrammitranspordi

voog

VideoPES

AudioPES

PES – programmi elementide voog

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Kujutisest signaal

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Signaali (heledus) esitus

T= 1 (ajaühik)

T0 T1

t

U

f

0 1 3 5

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Heledusastmed

10 0111 00

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Kujutis läbi madalpääsfiltri

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Kujutis läbi kõrgpääsfiltri

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DV plokid

• 4:2:2 YUV–16x16 macroblock–8x8 pixel blocks–8 bits/sample = 16 bits/pixel = 4Kbits/macroblock

• 4:1:1 YUV–3Kbits/macroblock–12 bits/pixel

Y3

U1

U2 V2

V1Y1 Y2

Y4

macroblock

Y3

U VY1 Y2

Y4

30 fps * 720 * 480 * 1.5 * 8 = 124 Mb/s

•9:16 HDTV

–30 fps * 1920 * 1152 * 1.5 * 8 = 796Mb/s

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Color Space Conversion• RGB to YUV or (YCrCb)

• Y luminance component (brightness).

Y = 0.299 R + 0.587 G + 0.144 B

• U, V

U = B – Y

V = R - Y

Y U V

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0

2

4

6

8

02

46

8

-10

0

10

20

col

row

DC

T C

oe

ffic

ien

ts

02

46

8

0

2

4

6

80

2

4

6

8

10

colrow

Gra

ys

ca

le L

ev

el

Image block DCT Coefficients

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Kahemõõtmeline kujutis

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Ruumiline “aeg”

1 0 1 0

0 1 0 1

1 0 1 0

0 1 0 1

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Ruumiline “sagedus”

0.5 0.7 0.2 0.05

0.6 0.5 0.07 0

0.1 0.08 0.01 0

0.01 0 0 0

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JPEG

8x8 blockDCT Quantization

Quantizationtables

Difference coding

Run length coding

Entropycoding

Header

Tables

Data

DC

AC

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Makroblokk (8 * 8)

124 125 122 120 122 119 117 118

121 121 120 119 119 120 120 118

126 124 123 122 121 121 120 120

124 124 125 125 126 125 124 124

127 127 128 129 130 128 127 125

143 142 143 142 140 139 139 139

150 148 152 152 152 152 150 151

156 159 158 155 158 158 157 156

-4 -3 -6 -8 -6 -9 -11 -10

-7 -7 -8 -9 -9 -8 -8 -10

-2 -4 -5 -6 -7 -7 -8 -8

-3 -4 -3 -3 -2 -3 -4 -4

-1 -1 0 1 2 0 -1 -3

15 14 15 14 12 11 11 11

22 20 24 24 24 24 22 23

28 31 30 27 30 30 29 28

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Koosinusteisendatud

39.88 6.56 -2.24 1.22 -0.37 -1.08 0.79 1.13

-102.43 4.56 2.26 1.12 0.35 -0.63 -1.05 -0.48

37.77 1.31 1.77 0.25 -1.50 -2.21 -0.10 0.23

-5.67 2.24 -1.32 -0.81 1.41 0.22 -0.13 0.17

-3.37 -0.74 -1.75 0.77 -0.62 -2.65 -1.30 0.76

5.98 -0.13 -0.45 -0.77 1.99 -0.26 1.46 0.00

3.97 5.52 2.39 -0.55 -0.051 -0.84 -0.52 -0.13

-3.43 0.51 -1.07 0.87 0.96 0.09 0.33 0.01

,

DC AC AC AC AC …

AC AC AC AC

AC AC AC

AC AC …

AC

…

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JPEG 2000Features• Improved compression efficiency (vs. JPEG)• Highly scalable embedded data streams• Progressive lossy to lossless compression

within a single data stream• Arbitrarily crop images in the compressed domain• Selectively enhance quality of spatial “regions of

interest”• Support for very large images

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0

20

40

60

80

100

Mb

it/s

ek

Resolutsioon

MPEG-2 kihid ja profiilid

Lihtne profiil

PõhiprofiilSNR mastabeeritav

Ruumiline mastabeeritavusKõrgprofiil

Liikuva kujutise edastusvariandid

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Lõpulingidhttp://en.wikipedia.org/wiki/Source_coding

http://www.chiariglione.org/mpeg/http://www.jpeg.org/jpeg2000/

http://en.wikipedia.org/wiki/YUVhttp://www.iec.ch/http://www.itu.int/rec/R-REC-BT.601/enhttp://www.ebu.ch/http://en.wikipedia.org/wiki/Video_codec