Transcript Chapter 6 Review - Siena Computer Science Department

Chapter 6 Review
Which of the following is the
television broadcast standard for
the U.S. and Japan?
A. NTSC
B. PAL
C. SECAM
Which of the following is the
television broadcast standard for
most of the Asian countries?
A. NTSC
B. PAL
C. NSTC
D. SECAM
Which of the following compression
methods works best with large areas
of solid color, such as in a cartoon
animation?
A. QuickTime Animation
B. Cinepak
C. MPEG-1
D. MPEG-2
Run Length Encoding (again)
• Some digital image compression algorithms,
such as Run-length encoding (RLE) and JPEG
compression are used. Codecs that use spatial
compression and RLE are QuickTime
Animation, QuickTime PlanarRGB, and
Microsoft RLE. RLE works well for video with
large areas of solid colors, such as most
cartoon animation.
Which of the following compression
methods achieves higher compression
for videos without much motion
difference, such as for talking heads?
A. spatial compression
B. temporal compression
C. lossless compression
D. asymmetric compression
Which of the following is the most
common color model for video?
A. RGB
B. HSV
C. CIE XYZ
D. luminance-chrominance
The frame rate for the NTSC system
is _____ fps.
A. 24
B. 25
C. 28.9
D. 29.97
E. 30
The frame rate for the PAL system
is _____ fps
A. 24
B. 25
C. 28.9
D. 29.97
E. 30
Frame rates (again)
•
•
•
•
NTSC 29.97
PAL 25
SECAM 25
Motion-picture film 24
The scan mode of a CRT computer
monitor is _____.
A. interlaced
B. progressive
• Computer monitors (CRTs) display the picture by
displaying the lines from top to bottom in one
pass, i.e. progressive scan
– Same thing for flat panel computer displays LCD and
Plasma, but the refresh is so fast, it more of a burst
than a progressive scan.
• Television monitors (CRTs) display in two passes,
interlacing.
– Allowed the broadcast signal to be “cut in half”
– Otherwise, early signal would have been 15 fps.
The scan mode of a CRT television
set is _____.
A. interlaced
B. progressive
Clarification
• Plasma and LDC TV’s can be either progressive
scan or interlaced.
• However, interlaced displays were only made
because Broadcast TV is interlaced
• However, the plasma and LCD technology is
better suited for progressive display
• We are seeing a shift to progressive signals
and displays
Interlaced scan displays the frame
by scanning the lines of a frame
_____.
A. in one pass from top to bottom
B. in two passes: even-numbered lines in one
pass and odd-numbered lines in the second
The comb-like artifact in a digital video, as
shown here, occurs in the _____ video.
A. interlaced
B. progressive
C. both A and B
Overscan is _____.
A. the area where critical content and text
titles should be placed
B. the area where the significant action takes
place
C. the area that is outside of the television
screen
True/False: There is no sampling
and quantization involved in
capturing motion in digital video.
The frame size of a video refers to
the video’s _____.
A. aspect ratio
B. pixel aspect ratio
C. resolution
D. ppi
True/False: The pixel per inch (ppi)
is an important attribute for video
resolution and should be set
correctly when working with digital
video in video-editing programs.
Clarification
• The frame size of a NTSC standard definition
DV frame is 720 × 480 pixels. However, based
on these numbers, its width to height ratio is
720:480, i.e, 3:2.
• It does not match the frame aspect ratio
quoted above; it is neither 4:3 nor 16:9.
• What is missing here?
720 X 480 is 3:2
• For pixel aspect ratio = 0.9,
width : height =
720 × 0.9 : 480 =
648 : 480
4:3
• For pixel aspect ratio = 1.2,
width : height =
720 × 1.2 : 480 =
864 : 480
16:9
Pixel aspect ratio means _____.
A. the ratio of a frame’s width (in pixels) to the
height (in pixels)
B. the ratio of a frame’s height (in pixels) to
the width (in pixels)
C. the ratio of a pixel’s width to its height
D. the ratio of a pixel’s height to its width
The pixel aspect ratio of a widescreen format DV is _____.
A. 4:3
B. 16:9
C. 1.0
D. 0.9
E. 1.2
The pixel aspect ratio of a standard
format DV is _____.
A. 4:3
B. 16:9
C. 1.0
D. 0.9
E. 1.2
The frame aspect ratio of a widescreen format DV is _____.
A. 4:3
B. 16:9
C. 1.0
D. 0.9
E. 1.2
The frame aspect ratio of a
standard format DV is _____.
A. 4:3
B. 16:9
C. 1.0
D. 0.9
E. 1.2
The frame aspect ratio of a
standard format DV is _____.
A. 4:3
B. 16:9
C. 1.0
D. 0.9
E. 1.2
True/False: The signals of digital
television are broadcast or
transmitted digitally.
Clarification
• While one could argue that a signal wave (radio,
electrical, etc.) is analog.
• Digital refers to how the signal is translated or
interpreted.
• Hard drives can have arbitrary levels of
magnetism but we interpret only two levels.
– Magnetized, not magnetized
• If the signal is interpreted as binary, it’s a digital
signal even though the signal itself can transmit
analog data.
HDTV is in _____ format.
A. MPEG-1
B. MPEG-2
C. MPEG-3
D. MPEG-4
E. QuickTime
F. AVI
True/False: The frame aspect ratio
of all six HDTV formats is 16:9.
Several high definition video camcorders
are available to record 720p and 1080i
formats. The number in the format name—
720 or 1080—designates the _____.
A. data rate of the video
B. width (in pixels) of the frame size
C. height (in pixels) of the frame size
D. ppi of the video
E. none of the above; they are model numbers of
different companies
Several high definition video camcorders are
available to record 720p and 1080i formats. The
letters “p” and “i” in each format name stand for
_____ and _____ respectively.
A. pixels; inches
B. proprietary; infrastructure
C. progressive; interlaced
D. ppi; ppi
For a one-minute QuickTime video file with a file
size of 100 MB, its playback on a 48x CD-ROM
drive very likely will be _____. (Hint: The data
rate for a 48x CD-ROM drive is about 7 MB/s.)
A. smooth
B. choppy
Playback  Bandwidth
• 100 MB needs to be moved in 60 seconds
• 100MB/60 seconds = 1.66 MB/sec
• If your playback or bandwidth is greater than
1.66, it’ll play smooth (on playback devices
like DVD) or it can stream live (if you are
downloading it).
For a five-second QuickTime video file with a file
size of 100 MB, its playback on a 48x CD-ROM
drive very likely will be _____. (Hint: The data
rate for a 48x CD-ROM drive is about 7 MB/s.)
A. smooth
B. choppy
Playback (again)
• 100MB needs to be moved in 5 seconds.
• 20MB per second.
• If device or network can decode/transfer
20MB second, you have two choices…
– Wait (for download)
– Skip data (choppy)
What does the term codec
stand for?
Code and Decode
• Captured video is coded into a file format
• The file format needs to be decoded for
playback or editing.
_____ refers to the type of compression method
that aims at compacting individual frames.
A. asymmetric compression
B. lossless compression
C. lossy compression
D. spatial compression
E. temporal compression
_____ refers to the type of compression
method that exploits the repetitious image
content over time.
A. asymmetric compression
B. lossless compression
C. lossy compression
D. spatial compression
E. temporal compression
_____ refers to the type of compression method in
which the amount of time and the complexity
required to compress and decompress are
significantly different.
A. asymmetric compression
B. lossless compression
C. lossy compression
D. spatial compression
E. temporal compression
_____ refers to the type of compression
method that exploits the repetitious image
content over time.
A. asymmetric compression
B. lossless compression
C. lossy compression
D. spatial compression
E. temporal compression
_____ refers to the type of compression
method that exploits the repetitious image
content over time.
A. asymmetric compression
B. lossless compression
C. lossy compression
D. spatial compression
E. temporal compression
symmetrical codec vs asymmetrical
• A symmetrical codec requires about the same
amount of time to compress as to decompress a
video.
• asymmetrical codecs: the amount of time
required to compress and decompress are
significantly different
• Fast decompression is preferable for video,
– makes the playback much better—less wait time.
– many codecs fall into the asymmetrical category
because it takes much longer to compress a video
than to decompress.