Transcript lecture8-Intro to Video

Introduction to Multimedia
Lecture #9
Intro to Video
Instructors:
Mohamed MAGANGA
Today’s Agenda
3 Topics Left
•Video (pt.2)
•Sound (1)
•Review (1)
1.
2.
3.
Announcements
Warm Up
Today’s Lecture
 Lect 9: Intro to Video
“A good film
is when the price of the dinner, the
theatre admission and the babysitter were worth it.”
 Alfred Hitchcock
Major Assignment - 10%
Marking Criteria:
1. Technical: file organization, file names (lower case)
2. Color creativity
3. Website Design: content, layout, style, links
4. Video – Word Overlay, transitions, music, style
5. Animation: creativeness and how it was incorporated in the website
EVERYTHING MUST BE WORKING
TEST IT ALL
3
Warm Up Questions
Which of the following terms means:
“seeing two or three of the previous frames in
order to predict where to put the next frame”
a) Tweening
b) Onion Skin
c) Morphing
Tweening: Process of
___________________________ to give the
appearance that the first image evolves
smoothly into the second image.
Onion Skin: Creating animated cartoons and
editing movies to see
____________________
Morphing: Process of blending
together _______________ into a
series of images
4
Warm up Questions:
1.
Question: How many frames per second should we have
when building an animation for display on a computer?
2.
Question:
A.
B.
C.
D.
3.
Which type of animation uses frames:
Cel Based
Path Based
Both
Neither
Question:
If an animation is 40 frames long and the fps is
5, how long will the animation take to play?
Today’s Agenda
Video – Part 1
 What is Video
 Capturing Video
 Firewire vs USB
 Editing Video
 How TV Works
 Review
6
What is Video?
Video uses the power of Motion and Sound
A sequence of still images or frames that create the
illusion of movement when played in succession.
Movies
Display at ______ fps
Computer Displayed Video
Display at ________ fps for
smoothness
2 Types of Video:
Analog: Smooth ___________ waves ex. Conventional TV
Digital: Each frame is a _____________, stored
as 0s and 1s
Digital Video
Digital Video is composed of a series of bitmap
graphics, each one called a ____________.
Characteristics:
• Bits store color and brightness data for each video
frame.
• Retains image quality no matter how many times it is
copied.
• Easily manipulated on a pc because stored in digital
format
“Digital Technology is the same revolution as adding sound to pictures
and the same revolution as adding color to pictures. Nothing more
and nothing less.”
- George Lucas, film maker of STAR Wars
What kinds of Digital Videos?
Classified by its platform or application (how it will
be delivered)
1.
Desktop video (DTV)
•
2.
Web-based video
•
3.
Incorporated in Web pages and accessed with a
browser
DVD-video
•
4.
Videos constructed and displayed using a personal
computer
A DVD format used for commercial DVDs that contain
feature-length films.
PDA video
•
Small-format video designed to be viewed on a PDA
or cell phone screen
How much planning goes into
making a movie before the first
scene is ever shot?
http://www.youtube.com/watch?v=FvQV21hkMjI&feat
ure=related (we will just watch the first 2 minutes)
10
Creating Digital Video
11
Ready to Make a Video –
Assumption: you took the footage
Let’s take a closer look!
Capture
Video
•Download video
from camcorder
to computer
12
Edit
Digital Video
(using Computer,
Digital Video software
ex. Adobe Premiere, Avid)
 Edit it
 Add all kinds of cool titles
 Filters, transitions
 Superimpose clips
 Synchronize audio with video
 Authoring software: create
menus and interactivity
Output Video
•Output to
different file
formats
•Back out to tape,
the Web, CD,
DVD
Capturing the Video with
Camcorders

If we use an:

Analog Camcorder,:
•
Electronic impulses are recorded
Must convert it to digital BEFORE we can put it on our computer
to edit.
To convert analog video to digital video we need a ___________
•
•
 Digital Video Camcorder:
•
•
Information is sent as _____________
Thus no need to convert!
Capturing Video –
Download video from camcorder to computer
To use video in a multimedia application,
it must be in digital
form (0s and 1s)
So how do you get a camcorder video into digitized form?
Analog
Video
camera
Video
card
Connecting
Leads:
14
Digital
camera
Firewire or
USB cable
Software:
Capturing,
Editing,
Outputting
Digital Video Camcorders


Most Digital Video Camcorders (DV Camcorders), do a
little bit of compression right inside the camera.
common DV compression used by today’s camcorders:
DV25 is the most

DV25 Format Specs:
Pixel Dimension is 720 X 480 (note this is 3:2 ratio)
 Frame Aspect Ratio either 4:3 or 16:9
 Data Rate: 25 mega bits per second (that’s why it
is DV25)
 Frame Rate: 29.97 fps
 Colour Sampling: YUV 4:1:1

Colour Compression
In The Camera


For still images RGB is commonly used
For video the model is YUV (YIQ) or YCbCr (for MPEG
compression)



Y  luminanace (brightness)
UV (CbCr)  chrominance (color/hue)
Question: Black and White TV only used the _____ signal (fill in the
blank with Y, U or V)
Answer: ______________________

Question: Which one will the human eye detect changes in more
easily? How does this help us with compression?
Answer:________________
Color Sampling Method for Video
-compression technique

You may see that the compression used

4:1:1 4:2:0 4:4:4
What does this mean?

Assume we have 4 pixels 
Color Sampling:
Refers to technique in digital video –compression technique
BACKGROUND: in Video we do not store record all color in an image
• Color Sampling allows Averages out pixels to cut down on bandwidth
(faster transfer rates)
• Eye senstivity:
• Rods – light vs. dark, black vs. white -- not color
• Cones – see color
• We can detect brightness better than color (more rods)
Color Sampling Method for Video

http://dvxuser.com/articles/colorspace
/
You may see that the compression used 4:1:1 Color Sampling
Method, What does this mean?

Assume we have 4 pixels 
Red, Orange, Blue, Purple
red + blue = Purple
• 4:1:1
• Blocks of 4 pixels
averaged out
• 4 x 1 block
Result:
So all four pixels get forced to
become purple (shades of
brightness)
Blocks of 4 pixels averaged out
•4:2:0
•Blocks of 4 pixels
averaged out
•2x2 grid
block
Color Sampling Method for Video
http://dvxuser.com/a
rticles/colorspace
Color
Sampling
Method
Amount of
Y
(luminance)
Amount of U
(color or hue)
Amount of V
(color or hue)
Amount of
Compression
4:4:4
4 samples
4 samples
4 samples
None
12 samples for
each group of 4
pixels
4:2:2
4 samples
2 samples
2 samples
Reduced from
12 samples to 8,
33% reduction
in storage
4:2:0
4 samples
2 samples of either U or V, one 12 to 6, 50%
scan line of U, then one scan
reduction in
/
Used in
Digital Betacam
format
HDV, MPEG-1,
DVD, MPEG-2,
Connection Types:
Video
•S video
(better quality)
•Yellow RCA
Audio
Firewire
connection
Sony Hi-8
20
TRV-80
To get the video off of your camera
onto a computer you must use either:
USB
cables
Firewire
Video Capture Card
Plugs directly
• Converts video
from
ANALOG TO
DIGITAL
21
Firewire (4 pin)
USB
Capturing Video –Video Capture Device
Download video from camcorder to computer
Firewire ( ________, _________)

A means by which information could be sent from the camcorder
directly to the computer
 A high-speed digital serial _________that allows the output of
the camera to be fed directly into a computer in digitized form
 Digital Video footage requires 13GB of storage per hour of
video.
 All major manufacturers agreed to use a common digital tape
format and a method -- Firewire (universal standard)
•4-pin to 4-pin plugs
•4-pin to 6-pin plugs
22
•6-pin to 6-pin plugs
Summarizing Analog vs Digital
1983
1994
ANALOG (Older Technology )
DIGITAL (Newer Technology)
• Records electrical
signals/pulses directly onto a
medium (like a tape) with a
magnetic encoding.
• Disadv: Picture loses quality
Video capture card needed
to convert video from analog
to digital for your computer
23
• Records a binary code (string
of 1s and 0s) compressed on
magnetic tape or other media
• Adv: No image degradation
Plug your video camera directly
into your computer via a
Firewire (aka i.Link) or USB
connection.
These are digital connections
and allow you to "dump" footage
straight from the camera to
hard drive.
Solid State
Media Card
- Memory
Sticks
A little history on TVs
Digital video often adheres to standards for TV
broadcasting – 2 standards

NTSC Standard:
 Regular Analog TV broadcasting began in the
United States in 1939 and carried through to today
 Frame rate was originally 30fps but when color
was introduced, needed to go down to _______ fps
to accommodate for colour information.

PAL Standard:
 Britain, Europe and other countries
 Frame rate is set for _________ fps
A little history on TVs

Experiments with High Definition TV began in
the late 40s and 50s but it wasn’t adopted by a
single station till 1996.

Before 1996 ALL TV was broadcast using
_________________(see next slide)

The original ANALOG video choices made
about TV display (frames per second, frame
size, etc..) affect the standards that were picked
for DIGITAL video and applied today!
How did the
original TV display work?



Our eyes see phosphor dots on the screen.
An electron beam (gun) activates the dots.
The gun scans through the dots horizontally
A complete scan is when the gun starts at the
top left and scans several times horizontally
till it gets to the bottom right

The scan only draws every OTHER line
(1,3, 5, …479) then starts back at the top
and draws the even lines (2,4,…480).
 Thus two passes
 Each pass is called a field
 The process is called Interlaced
display

This way it can cheat the eye, while the
phosphor dots are disappearing, it is
drawing the line underneath.
How did the
original TV display work?
Increasing the frame rate in the old
days required a lot more bandwidth, so
they “cheated” and used interlacing to
trick the eye
Interlacing effect (old TVs)
Line 1,3,5,7,
Line 2,4,6,8..
Progressive effect
( not interlaced)
(now used by Flat Screens
because of the panel)
Line 1,2,3,4,5,6,7..
http://www.crutchfield.com/Learn/learningcenter/home/understanding-resolution.html
NTSC Standards
NTSC Standard DV Frame:
 For NTSC  720 X 480 pixels
For Pal  720 X 576 pixels
 Pixels are distorted (not square)
because 720:480 is actually 3:2
ratio
High Definition for NTSC:





1440 X 1080
1280 X 720
Frame Aspect Ratio is 16:9
1440:1080  ratio is 1.333
(pixels are not square)
1280:720  ratio is 16:9
(pixel are square )
Frame aspect ratio
is the ratio of width
to height of the
image frame.
4:3 Frame aspect ratio
16:9 Frame aspect ratio
How do we see images on a CRT
Display TV vs Flat Screen
29
http://www.crutchfield.com/Lea
rn/learningcenter/home/underst
anding-resolution.html


Older TVs 480 Scan Lines
New Plasma, Flat Screen  720 or 1080 lines
 progressive not interlaced
OLDER
TECHNOLOGY
-Screen
resolution
__________
-Electron gun
beam activates
the dots
http://www.crutchfield.com/learn/learningcenter/home/tv_flatpanel.html?page=2
http://www.crutchfield.com/S-EMMmc3InSom/learn/learningcenter/home/tv_flatpanel.html
http://www.crutchfield.com/Learn/learningcenter/home/understanding-resolution.html?page=2
PLASMA or
LCD
Screen
resoluiton sof
_________
_________
Flat grid of
pixels
How do we see images on a
Don’t need to know
Flat Panel TV
more detail for the
exam
Most flat-panel TVs are progressive displays
• Illuminating a fixed grid of
tiny pixels.
• Every pixel has three
sub-pixels: (RGB)
• Color and brightness
information controlled at
the sub-pixel level
• Uses progressive display
Screen resolutions of
1080p (progressive)
1080i (interlacing)
Capturing Video –
Download video from camcorder to computer
Resolution Comparison
Format
Lines of Resolution
(measurement of
image quality)
VHS, VHS-C
240 lines
8mm
240 lines
Hi 8mm
400 lines
Most older TVs
(standard,
SDTV)
480 lines
DV 8mm, Mini
DV
480 lines
High Definition
(HD) TV
720 lines
Or 1080 lines
32
Digital Advantage:
higher resolution
(# of horizontal lines)
Depending on features of individual unit,
you may be able to achieve:
Newer TVs

http://www.crutchfield.com/Lea
rn/learningcenter/home/underst
anding-resolution.html
Question: On a newer HD TV, what
does the circled area mean?
Firewire vs. USB
It used to take A LONG time to move video from your
camcorder to your computer (Hours and Hours)

Firewire
 Firewire initiated by Apple and
the IEEE in the late 80s.
 It is a high speed data transfer
technology.
 Transmitted originally at
400Mbps
 Apple wanted to charge 1 dollar
for every machine that was
going to use it, this caused most
PC manufacturers to decide
against it, in favour of USB 1.1.

USB
 USB 1.1. could transmit at
12Mbps
 Used for mice, keyboards,
printers, _____________
 USB 2.0 came along, backward
compatible, transmitted at
480Mbps (could beat with
Firewire400 and do video)
Currently, we have Firewire 800,
transmits at 800 Mbps, at some point
in the future, they expect new
34Firewire will transmit at 3.2 Gbps! Apple IPODS no longer have firewire ports

Capturing Video
Download video from camcorder to computer
Benefits of Digital
• No Loss of Quality – Digital Videotape can be copied almost indefinitly.
Important consideration in Postproduction sessions that require numerous
generations of video effects.
• No need of analog-to-digital conversion
Digital material can be directly uploaded to digital editing systems
• Reduces or eliminates problems such as dropouts due to
error-correction circuitry associated with digital electronics
• Archival (long-term) storage.
Digital videotapes are better suited for longer periods
• Quality of digital recordings is significantly better than analog
recordings
35
Capturing Video
Download video from camcorder to computer
Controlling the Transfer Process
• Video Capture software: Doesn’t matter if you are using
an analog or digital camera
Software Should have Features:
• Start and stop the transfer
• Select a file format for storing your video footage
• Specify file name for each video clip
• Video capture software is supplied with video editing
software and with video capture devices
36
TIP: Videos are easier to edit if you divide them into
several files, each containing a one or two minute
video clip.
In Lab – MovieMaker
Learning to edit your video
Capture Video
Edit
Digital Video
(using video capture card)
from camcorder to
computer

(using Computer,
Digital Video software
ex. Adobe Premiere, Avid)
 Edit it
Add all kinds of cool titles

Filters, transitions and FX

Superimpose clips

Synchronize audio with
video
Output in different file
formats

37
Output Video
(back out to tape, the
Web, CD, DVD)
In Lab – MovieMaker
Movie on Adobe Premier
Let’s Review

When would you use Firewire?



Which of the following is a benefit of using a digital
video recorder?




38
If you have a digital camcorder
If you have an analog camcorder
No loss of data
Can edit digital footage on a computer, you can NOT edit analog
footage on a computer.
You don’t need a video capture card
All of the above are benefits of going digital.