Digital Videotechnology 1.Basics a.Analog Video b.Composite, S-Video, Component 2.Digital Video...
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Transcript of Digital Videotechnology 1.Basics a.Analog Video b.Composite, S-Video, Component 2.Digital Video...
Digital Videotechnology
1. Basicsa. Analog Videob. Composite, S-Video, Component
2. Digital Video1. Sampling2. Compression
3. Digital Camera4. DV Format5. Digital TV
Videotechnology: Actual Situation
Studio
Digital Videocompressed MPEG 2Modulated QPSK
Cable Digital64 QAM
Set Top Box
Cable analog
Direct Satellitereceiver
Analog VideoTerrestricalDistribution
Digital VideoTerrestricalOFDM
Introduction to Videotechnology
TV Systems (analog)
Germany, Austria, Poland ...PAL: Phase Alternate Line625 (576 active) Lines, 50 Hz Interlace aspect ratio 4:3
USA, Japan, latin AmericaNTSC: 525 Lines (480 active) 60 Hz Interlaceaspect ratio 4:3
1.Field 2.FieldFrame
Introduction to Videotechnology
= +
Interlace
Introduction to Videotechnology
Interlace
• progressive
• interlaced
Camera CRT or Display
Principle of Videotransmission (analog)
t
V
0.7
Luminance Distribution in one line
Different Screen Format
Introduction to Videotechnology
The Composite Signal
How to transmit Color ?
The Colorcompositing
Additive Colorcompositing Subtractive Colorcompositing
Displays, CRT Print (Paper)
RGB CMYK
Y Luminance
Cr = R-Y
Cb = B-Y
In the Videotechnology people areworking with Component Signals
Y=0.299R+0,587G+0.114B
Matrix
R
G
B
Y
Cr
Cb QAMChrominace
Videosignal(Composite)
Luminance
C
Component signal
Different Video Signals
S-VideosignalY/C -Signal
Introduction to Videotechnology
The Component Signal
Y=0.299R+0,587G+0.114B
Generation of Luminance signal from RGB
100 % intensityRed
kamera 100 % Intensity
100 % IntensitätRot
B/W Kamera 30% Intensity
The Component Signal
Y=0.299R+0,587G+0.114B
Generation of Luminance signal from RGB
100 % IntensityGreen
kamera 100 % Intensity
100 % IntensityGreen
B/W Kamera 59% Intensity
The Component Signal
Y=0.299R+0,587G+0.114B
Generation of Luminance signal from RGB
100 % IntensityBlue
kamera 100 % Intensity
100 % IntensityBlue
B/W Kamera 11% Intensity
Wei
ß Gel
b Cya
n Grü
n Mag
en
da Ro
t
Bla
u Sch
war
z
The Colorbar
How we can explain color bar with RGB ?
Task
We
iß Ge
lb Cy
an Gr
ün
Mag
end
a
Rot
Bl
au
Sch
wa
rz
RU
GU
BU
Y
We
iß Ge
lb Cy
an Gr
ün
Mag
end
a
Rot
Bl
au
Sch
wa
rz
RU
GU
BU
Y
0,891
0,70,59
0,410,3
0,11
We
iß Ge
lb Cy
an Gr
ün
Ma
g.
Rot
Bl
au
Sch
wa
rz
RU
GU
BU
Y
YBU
YRU
Die Chrominanz
QAM: Quadratur Amplitude Modulation
Principle of QAM:
• (R-Y,B-Y) is a vector with angle and lenght :V=0,877(R-Y) und U=0,493(B-Y)
• (U,V)(C,Φ)mit
22 VUC U
V)tan(
QAM: Quadrature Amplitude Modulation
)sin( tU stc
22 UVU c
)arctan( UV
Composite Signal
)sin()( tUtU stc
22 UVU c
)arctan( UV
Saturation
Hue
Farbkreis
Farbkreis
Farbkreis
Introduction to Videotechnology
TV Systems (digital)
SDTV HDTV Digitale Filmkamera
Pixel 720 x 576 1920 x 1080 4096 x 3072
Size for Luminance
0,4 MegaPixel 2,0 MegaPixel 12 MegaPixel
Quantisierung 8 Bit 10 Bit 14 Bit
Sampling 4:2:2 /Y,Cr,Cb 4:2:2 /Y,Cr, Cb 4:4:4/RGB
Datarate 25fps 125 MBit/s 1,485 GBit/s 17,3 Gbit/s
Digital Component Signal
Y, Cr,Cb
•Die Components are digitized
•Quantisation with 10 Bit
Die Norm CCIR 601 4:2:2
Y: Digitalization with 13,5 MHzCr: Digitalization with 6,75 MHzCb: Digitalization with 6,75 MHz
Digital Component Signal
3,375 MHz
4
13,5 MHz
Basic frequency
2
6,75 MHz
Digital Component Signal
Sampling and Quantisation of Component CCIR 601
• Sampling 4:2:2 and Quantisation with 10 Bit
• Datarate 270 Mbit/s
• 1 hour Video material ca. 122 Gbyte
Sampling 4:2:2
Zeile 1
Zeile 2
Zeile 3
Zeile 4
Zeile 5
Zeile 6
4:1:1
Zeile 1
Zeile 2
Zeile 3
Zeile 4
Zeile 5
Zeile 6
Digital Component Signal
DV - Format
576
720
Digital Videoformat
Digitalization of Videosignals
1 Frame
1 Sekunde
2 Frames 3 Frames 25 Frames
How big is the data rate ?
What is the memory amount for storing 1 hour Video ?
Digitalization of Videosignals
DV Format MPEG 2 Standard
DVD
DVBDigital Video Broadcasting
Camcorder
Digitalization of Videosignals
• DV- Format was establish by Consortium of
the leading Broadcast Companies
(Sony, Thomson, Panasonic, Philips)
• Standard since 1994
• Applications: Recording Video im consumer field
• Compression algoritm is optimized of constant Byte/Frame
Intraframe Codierung /DV Format
• Resolution: 720*576 /25Hz (Luminanz)
• Sampling 4:2:0 und Quantization 8 Bit
• Input data rate : ca 125 Mbit/s
• Compression 5:1 ; Discrete Cosinus Transformation DCT
• Constant Outputdata rate: 25 Mbit/s
Intraframe Codierung /DV Format
Matrix
R
G
B
Y
Cr
Cb
Sampling(4:2:0)
& Quantization
125 Mbit/s
Y Cr Cb
Intraframe Coding /DV Format
Preprocessing
Zeile 1
Zeile 2
Zeile 3
Zeile 4
Zeile 5
Zeile 6
Intraframe Codierung /DV Format
Digitalization of Videosignals 4:2:0 Grid
Huffman-Codierer
011010101
DCTTransformation
Huffman-Decodierer
Inverse-Transformation
TresholdCoeffizients with small Energy
are omitted
Intraframe Codierung /DV Format
DV Compression: DCT Transformation
185 191 204 62
98 110 116 112
101 108 104 106
100 99 97 101
A00A04
273,6 111,8 12,1 1,6
94,1 74,2 -3,8 1,2
-1,4 0,4 0,3 -0,6
0,5 0,7 0,2 0,125
274 11 0 0
9 7 0 0
0 0 0 0
0 0 0 0
17
DCT
Tresholdweighting & Quantization
DV (JPEG) : CodierungMuster der 2 dimensionalen DCT
Intraframe Codierung /DV Format
274 112 0 0
94 74 0 0
0 0 0 0
0 0 0 0
274, 112, 94, 0, 74, 0, 0, 0, 0, 0 ,0 ,0 ,0 ,0 ,0 ,0
274, 112, 94, 0, 74, 0, ! ,11RLE Coding
Coeffizienten Matrix
Intraframe Coding/DV Standard
Zig Zag Process
Zig Zag Process
Block 1Block 2Block N
Huffman Codierung
DPCM
RLE
DC
011010101
Intraframe Codierung/DV Standard
Exsample of DV Compressions
Intraframe Codierung/DV Standard
Rekonstruktion 26,6 KBOriginal 133,5 KB
Compression 1:5
Examples of DV Compression
Intraframe Coding/DV Standard
Reconstruktion 26,6 KBOriginal 133,5 KB
Compression 1:5
Examples of DV Compression
Intraframe Coding/DV Standard
Rekonstruktion 3,8 KBOriginal 133,5 KB
Kompression 1:35
Examples of DV Compression
Intraframe Coding/DV Standard
Rekonstruktion 2,26 KBOriginal 133,5 KB
Compression 1:60
DV Format
Intraframe Verarbeitung, Block shuffling
• 5 Makroblöcke aus unterschiedlichen Bereichen des Bildes werdenzu einem Videosegment zusammengefasst 1 Videosegment =5*384Bytes=1920 Bytes
• 1 Frame 324 Videosegmente
• Block Shuffling bewirkt gleichmäßige Verteilung der Kompressionseffekte
M1M2
M5M3
M4
IntraframeMacroblock-
Shuffling
M1 M2 M3 M4 M5
1 Videosegment1920 Bytes
Intraframe Processing, Block shuffling
• Bilding Makroblocks
• 1 Makroblock contain 6 DCT Blocks (8*8 or 2*4*8 Blocks)
• The Size of Makroblocks is 6*8*8 Byte=384 Bytes
• 1 Makroblock contain 4 Luminance and 2 Crominanzblocks
Intraframe Codierung/DV Standard
Makroblocks
• 1 Makroblock contains 6 DCT Blöcke (8*8 Blöcke)
• 1 Makroblock : 4 Luminance and 2 Crominance
• The Size of the Makroblocks ist6*8*8 Byte=384 Bytes
Intraframe Codierung/DV Standard
1 2 3 4 5 6
Y Cr Cb
4:2:0
Y Cr Cb
Intraframe-Block Shuffling
DCT Buffer Quanti-sierung VCL
Analyse
feste Videodatenrate25 Mbit/s
Feed Forward Steuerung
Intraframe Codierung/DV Standard
Videoblock
DV Format
Verschiedene Herstellerformate
DV DVCAM DVCPro DVCPro50
Y-Bandbreite 5,75 MHz 5,75 MHz 5,75 MHz 5,75 MHz
C-Bandbreite 2,75 MHz 2,75 MHz 1,37 MHz 2,75 MHz
Pegelauflösung 8 bit 8 bit 8 bit 8 bit
Abtastraster 4:2:0 4:2:0 4:1:1 4:2:2
Signal/Rausch-abstand
>56dB >56dB >56dB >56dB
Datenreduktionsfaktor 5:1 5:1 5:1 3,3:1
Aufzeichnungsrate 42 Mbit/s 42 Mbit/s 42 Mbit/s 84 Mbit/s
Videodatenrate 25 Mbit/s 25 Mbit/s 25 Mbit/s 50 Mbit/s
Anzahl der Zeilen/Halbbild
288 288 288 288
Anzahl der Audio Kanäle
2/4 2/4 2 4
Artefakte bei DV
•Durch Farbreduktion 3 Probleme:
1.Mosquito Noise
2.Quilting (Diskontinuität benachbarter DCT-Blöcke)
3.Motion Blocking
Artefakte bei DV
• Mosquito Noise
Artefakte bei DV
• Quilting beihorizontalen Linien
Artefakte bei DV
• Motion Blocking
Artefakte bei DV
• Dropout
Artefakte bei DV
• Dropout
MPEG Moving Pictures Expert Group
• 1988 gegründet
• Ziel: Normierung von Kodiervorgängen für Bewegtbilder unddazugehörigen Tonsignalen
• Offener Standard
• Zur Zeit bereits standardisiert: MPEG1, MPEG2, MPEG4
• In der Planung MPEG7, MPEG21
MPEG Moving Pictures Expert Group
• MPEG Algorithmus basiert auf Hybride DCT
eine Kombination von DPCM und DCT
• Bei der DPCM wird die closed loop DPCM verwendet
+
P
Huffmancoder
Huffmandecoder
iS
1iS
–iS
+p
iS
1iS
+
Open-Loop DPCM
iS
1iSSchätzwert
Diiferenzwert
1 iii SSS
Rekonstruktionswert
1 iii SSS
MPEG Moving Pictures Expert Group
Huffmancoder
Huffmandecoder
Methoden der Bildcodierung
Close-Loop DPCM
+p
iS + iS
+
P
iS
1 iS
–Q
+
iS+
1'iS
Q
1 iS
aktuelles Bild vorhergehendes Bild
Differenz
Methoden der Bildcodierung
Interframe DPCM
aktuelles Bild
vorhergehendes Bild
Bewegungsschätzung und
kompensation
BK Bild
Bewegungsvektor
vorhergehendes Bild
BK Bild
Bewegungsschätzung und
kompensation
Diff. Bild Diff. Bild
Methoden der Bildcodierung
Interframe DPCMEncoder Decoder
MPEG Moving Pictures Expert Group
DCT
Q
DCT
Q
DCT
Q
DCT
Q
P P P P
MPEG Moving Pictures Expert Group
DCT
Q
B
GOP Group of Picture
B- Frames
Profiles & Levels MPEG 2