Video Basics
• Introduction ---- video industry
• Video Imaging ---- video scan, aspect ratio
• Color and Composite & component systems
• From Analog To Digital Video
• Spatial Conversions ---- video formats
• Temporal Conversions
• Mixing And Keying
Onde temos vídeo?
Satellite
DVB-S dow nstream (m ax 90 Mbps)
DS S
Cabl e Modem
Ca ble Ne tw ork
DVB-C down stream (m ax 40 M bps)
OpenCable
H ome Conne ct ion
DS TB
IEEE 1394 / USB
Ethernet 10 M bps…
..
Terrestrial
(Plug&Play , high-data-rate)
DV B -T/ A T SC
Interaction Channe l
DTV set
Di recPC /
Di recDuo
(1-w ay / 2-way) 1. Satellite ( fast PSTN / ISD N
2. Cable Mo dem ( QPSK , TCP / IP ™ for PSTN/ ISDN m odem
3. SD SL / A DSL / VDSL
….
.
Provedores de vídeo
Service Provision
DVB-T
DVB-S
(high speed BB)
DVB-C
(Cable Modem)
POTS Wireless Cable
HFC
(Full Service (xDSL access) (MMDS)
Network)
TCP / IP
Hybrid Services
Residential LAN
(IR, RF, Wired)
DSTB
Aplicações de vídeo digital
‚
’
Pay-per-view
'
ˆ ¯
Surfar, email,..
homebanking
¯
.
RC
Set-Top Box
*Ì
…
e)
Video
… telefonia
......
Multimídia
sob
‚
demanda
‘ •
-
Vantagens de vídeo digital
Open Architecture video systems, meaning the existence of video at
multiple spatial, temporal, and SNR resolution within a single scalable
bitstream
Interactivity
Variable-rate transmission on demand
Easy software conversion from one standard to another
Integration of various video applications
Editing capabilities, such as cutting and pasting, zooming
removal of noise and blur
Robustness to channel noise and ease of encryption
…...
Sistema de vídeo do futuro
SD RAM
Sa tellite
Dual
AD C
Tuner
QPSK
De mod
VC XO
RF
FE C
Modulator
IF
AND/ OR
QP SK
Mod
FEC
De scrambler
OSD
Ca ble
Tuner
AD C
QAM
De mod
MPEG -2
Video
FE C
IF
Terrestr ial
Tuner
AND/ OR
AD C
CO FDM
Trans port
FE C
De mod
SEC AM
Enc ode r
(optional)
MPEG -2
Audio
DA Cs
+ Filters
Graphic s
AV
Sw itch
L
R
CP U
SD RAM
I2 C
Digital Decoder Chip
Flas h/
EPR OM
P1394
Traffic
Controller
NTSC /PAL
Enc ode r
RGB or Y/ C
and CVBS
IR Bu ffer
& Am p
RS 232
IrDA Po rt
Modem
V-Seri es
Sma rt Ca rd
Bu ffer
P1284
SC SI
Imagens e vídeo - definições
Imaging:
normal photography, X-rays, electronic
documents, electronic still pictures, motion
pictures, TV
Video:
a sequence of still pictures of a scene taken at
various subsequent intervals in time
Scanning:
a form of sampling of a continuously varying
two-dimensional signal
Resolução de vídeo
Viewing Ratio (VR):
VR = d /PH
d= viewer’s distance from the screen
PH= picture height
Visible pixels = 3440 /VR
Pixel (Pel) : the smallest detail that can be reproduced in a picture is
about the size of a picture element
Minimum viewing rates
System
Line or pixels/PH
VR
NTSC television
483
7.2
HDTV
1080
3.2
Computer display
768
<4.5
Taxa de refresh e flicker
Persistence of vision,
causes the visual system responds slowly to
rapid changes of illumination
Flicker:
if the illumination varies cyclically at a low
frequency, the eye may perceive an annoying effect
Refresh Rate:
the light output of display devices decays after a
short time, and therefore must be refreshed
periodically to maintain the effect of steady
illumination
Display refresh rates
System
Refresh rate (Hz)
VR
NTSC television
60(59.94)
7
Computer display
72
1-2
Motion picture theater
48
5-10
scanear uma imagem de vídeo
não entrelaçado
scanear uma imagem de vídeo
entrelaçado
Relação largura/altura
IAR (Image Aspect Ratio )is defined as the ratio of picture width to
height
• IAR = w / h
• PAR (pel aspect ratio) =
IAR * vertical_size / horizontal_size
where horizontal_size is the width of the image in terms of pels
and vertical_size is the height of the image in lines
ex. Display IAR = 4:3
Image size = 720 pels * 486 lines
PAR = 4/3 x 486/720 = 0.9
or IAR * display_vertical_size / display_horizontal_size