U.S. patent application number 10/771581 was filed with the patent office on 2005-08-18 for customized video processing modes for hd-capable set-top decoders.
Invention is credited to Halgas, Joseph F. JR..
Application Number | 20050180858 10/771581 |
Document ID | / |
Family ID | 34837859 |
Filed Date | 2005-08-18 |
United States Patent
Application |
20050180858 |
Kind Code |
A1 |
Halgas, Joseph F. JR. |
August 18, 2005 |
Customized video processing modes for HD-capable set-top
decoders
Abstract
A method (100; 200) and apparatus (230) for controlling a
display of video being output from a set-top box determines (102)
if a user selected channel contains programming having a first
aspect ratio and stretches (106) automatically video from the user
selected channel having the first aspect ratio, if the user
selected channel contains programming having the first aspect
ratio, to fill a frame having a second aspect ratio that is
different than the first aspect ratio using a predetermined
stretching function. This determining and stretching is initiated
automatically upon tuning (101) to a user-selected channel.
According to another aspect of the present invention, an exemplary
embodiment (200) of a method for controlling video output from a
set-top box, upon receiving a zoom toggle command from a user via a
remote control unit, the method determines (202) if a user-selected
program includes a second aspect ratio different than a first
aspect ratio and ignores (205) the zoom toggle command if the
programming does not include the second aspect ratio. If the
programming does include the second aspect ratio, then the method
selects (206; 208) a next available zoom mode for a first or second
aspect ratio television type if the television type setting is set
for the first or second aspect ratio, respectively, and sets (207;
210) an output format to a mode specified by a first predetermined
output setting.
Inventors: |
Halgas, Joseph F. JR.;
(Huntington Valley, PA) |
Correspondence
Address: |
MAYER, FORTKORT & WILLIAMS, PC
251 NORTH AVENUE WEST
2ND FLOOR
WESTFIELD
NJ
07090
US
|
Family ID: |
34837859 |
Appl. No.: |
10/771581 |
Filed: |
February 4, 2004 |
Current U.S.
Class: |
417/53 ;
348/E5.002; 348/E5.111; 417/572 |
Current CPC
Class: |
H04N 21/440272 20130101;
H04N 7/0122 20130101; G09G 2340/0407 20130101 |
Class at
Publication: |
417/053 ;
417/572 |
International
Class: |
F04B 001/00 |
Claims
1. A method (100) for controlling an image being displayed on a
display from a set-top box comprising: a) tuning (101) to a user
selected channel; b) determining (102) if the user selected channel
includes programming having a first aspect ratio; c) employing
(104) a first output format, if the user selected channel does not
include programming having the first aspect ratio; d) continuing
with steps e) through l), if the user selected channel contains
programming having the first aspect ratio: e) checking (103) an
override setting for the first aspect ratio; f) if the override
setting for the first aspect ratio is not set to a stretch setting,
applying (105) a predetermined procedure for a first aspect ratio
override feature; g) if the override setting for the first aspect
ratio is set to a stretch setting then continuing with steps h)
through l); h) stretching (106) video from the user selected
channel having the first aspect ratio to fill a frame having a
second aspect ratio that is different than the first aspect ratio
using a predetermined stretching function; i) maintaining (107) any
overlaying graphics with their original aspect ratio; k) converting
(108) a resulting video to an output format specified by the first
output format setting, wherein: (i) if the first output format
setting comprises 1080i (109), the stretched video comprises 1080i
(112); (ii) if the first output setting comprises 720p (110), the
stretched video comprises 720p (113); and (iii) if the first output
setting comprises 480p (111), the stretched video comprises 480p
(114); and l) output (115) the stretched and converted video frames
on one or more component video outputs, whereby only a plurality of
primary high definition video outputs display stretched video frame
and a plurality of secondary standard digital video outputs display
4:3 video.
2. A method (100) for controlling an image being output from a
set-top box comprising: determining (102) if a user selected
channel contains programming having a first aspect ratio; and
stretching (106) automatically video from the user selected channel
having the first aspect ratio, if the user selected channel
contains programming having the first aspect ratio, to fill a frame
having a second aspect ratio that is different than the first
aspect ratio using a predetermined stretching function.
3. The method (100) according to claim 2, further comprising
initiating said determining and said stretching upon tuning (101)
to a user selected channel.
4. The method (100) according to claim 2, further comprising:
employing (104) a first output format if the user selected channel
does not contain programming having the first aspect ratio.
5. The method (100) according to claim 2, further comprising:
determining (103), before said stretching, if an override setting
exists for the first aspect ratio, and if the override setting for
the first aspect ratio is not set to a stretch setting then
applying (105)a predetermined procedure for a first aspect ratio
override feature rather than said stretching, and if the override
setting for the first aspect ratio is set to the stretch setting
then performing said stretching (106).
6. The method (100) according to claim 2, further comprising:
maintaining (107) any overlaying graphics with their original
aspect ratio.
7. The method (100) according to claim 6, wherein said overlaying
graphics includes an electronic programming guide and
closed-captioning text.
8. The method (100) according to claim 2, further comprising:
converting (108) a resulting video to an output format specified by
the first output format setting.
9. The method (100) according to claim 8, wherein: (i) if the first
output format setting comprises 1080i (109), the stretched video
comprises 1080i (112); (ii) if the first output setting comprises
720p (110), the stretched video comprises 720p (113); and (iii) if
the first output setting comprises 480p (111), the stretched video
comprises 480p (114).
10. The method (100) according to claim 2, further comprising:
outputting (115) a plurality of stretched and converted video
frames on one or more component video outputs.
11. The method (100) according to claim 2, wherein only a plurality
of primary high definition video outputs display stretched video
frames and a plurality of secondary standard digital video outputs
display video having the first aspect ratio.
12. The method (100) according to claim 11, wherein the plurality
of primary high definition video outputs include YPrPb outputs.
13. The method (100) according to claim 11, wherein the plurality
of secondary standard digital video outputs include one or more
selected from the group of: a composite video output, an S-Video
output and an RF video output.
14. A method (200) for controlling video output from a set-top box
comprising: receiving (201) a zoom toggle command from a user via a
remote control unit; determining (202) if a user-selected program
includes a second aspect ratio different than a first aspect ratio;
determining (203) a television type setting from a user settings
screen; selecting (206) a next available zoom mode for a second
aspect ratio television type if the television type setting is set
for the second aspect ratio and setting (207) an output format to a
mode specified by a first predetermined output setting; selecting
(208) a next available zoom mode for a first aspect ratio
television type if the television type setting is set for the first
aspect ratio, and determining (209) if a zoom mode selected is a
predetermined mode and, if so, setting (211) an output format to an
override mode for the first aspect ratio, otherwise setting (210)
an output format to a mode specified by the first predetermined
output setting; and ignoring (205) the zoom toggle command if the
television type setting is not set for the first aspect ratio or
the second aspect ratio.
15. A method (200) for controlling video output from a set-top box
upon receiving a zoom toggle command from a user via a remote
control unit, said method comprising: determining (202) if a
user-selected program includes a second aspect ratio different than
a first aspect ratio and ignoring (205) the zoom toggle command if
the programming does not include the second aspect ratio; selecting
(206; 208) a next available zoom mode for a first or second aspect
ratio television type if the television type setting is set for the
first or second aspect ratio, respectively, and setting (207; 210)
an output format to a mode specified by a first predetermined
output setting.
16. The method (200) according to claim 15, further comprising:
determining (203) a television type setting from a user settings
screen.
17. The method according to claim 15, further comprising: ignoring
(205) the zoom toggle command if the television type setting is not
set for the first aspect ratio or the second aspect ratio.
18. The method (200) according to claim 15, further comprising:
determining (209) if a zoom mode selected for the first aspect
ratio television type is a predetermined mode and, if so, setting
(211) an output format to an override mode for the first aspect
ratio.
19. An apparatus (220) for controlling a video image output from a
set-top box comprising: a processor (221); a memory (222) being
coupled to the processor and having encoded therein computer
readable instructions causing the processor (221_ to control an
image being output to a display (225) by: determining (102) if a
user selected channel contains programming having a first aspect
ratio; and stretching (106) automatically video from the user
selected channel having the first aspect ratio, if the user
selected channel contains programming having the first aspect
ratio, to fill a frame having a second aspect ratio that is
different than the first aspect ratio using a predetermined
stretching function.
20. The apparatus (220) according to claim 19, further comprising a
remote control unit coupled to the processor (226), wherein said
processor (221) initiates said determining and said stretching upon
receiving a command to tune to a user selected channel from the
remote control unit (226).
21. The apparatus (220) according to claim 19, wherein said
processor (221) employs a first output format if the user selected
channel does not contain programming having the first aspect
ratio.
22. The apparatus (220) according to claim 19, wherein said
processor (221) determines (103), before said stretching, if an
override setting exists for the first aspect ratio, and if the
override setting for the first aspect ratio is not set to a stretch
setting then applies (105) a predetermined procedure for a first
aspect ratio override feature rather than said stretching (106),
and if the override setting for the first aspect ratio is set to
the stretch setting then performs said stretching (106).
23. The apparatus (220) according to claim 19, wherein said
processor (221) maintains any overlaying graphics with their
original aspect ratio.
24. The apparatus (220) according to claim 19, wherein said
processor (221) converts a resulting video to an output format
specified by the first output format setting.
25. The apparatus (220) according to claim 19, wherein said
processor outputs a plurality of stretched and converted video
frames on one or more component video outputs.
26. The apparatus (220) according to claim 19, further comprising a
plurality of primary high definition video outputs which include
stretched video frames and a plurality of secondary standard
digital video outputs which include video having the first aspect
ratio.
27. An apparatus (230) for controlling video comprising: a remote
control unit (226); a receiver (223) to interact with the remote
control unit (226) and to receive a zoom toggle command from a user
via said remote control unit (226); a processor (221) determining
if a user-selected program includes a second aspect ratio different
than a first aspect ratio and ignoring the zoom toggle command if
the programming does not include the second aspect ratio; and a
graphical user interface (224) via which a user can enter a
television type setting via a user settings screen, wherein said
processor (221) determines the television type setting from the
user settings screen, and selects a next available zoom mode for a
first or second aspect ratio television type if the television type
setting is set for the first or second aspect ratio, respectively,
and sets an output format to a mode specified by a first
predetermined output setting.
28. The apparatus (230) according to claim 27, wherein said
processor (221) ignores the zoom toggle command if the television
type setting is not set for the first aspect ratio or the second
aspect ratio.
29. The apparatus (230) according to claim 27, wherein said
processor (221) determines if a zoom mode selected for the first
aspect ratio television type is a predetermined mode and, if so,
sets an output format to an override mode for the first aspect
ratio.
30. A method (200) for controlling a display of video having a 16:9
aspect ratio image using a set-top box, comprising: cycling (206)
among a plurality of selectable zoom modes upon receiving a zoom
toggle command from a remote control; and moving (206) to a top of
a list of the plurality of selectable zoom modes upon reaching a
bottom of the list of the plurality of selectable zoom modes,
wherein the plurality of selectable zoom modes includes: (1) a "No
Zoom" mode to remove all ASTB Zoom Mode processing to view video
broadcast "as is"; (2) a zoom mode that takes a centered 14:9
cutout of a 16:9 broadcast image and horizontally stretches the
16:9 broadcast image to fill a 16:9 frame of a display; (3) a zoom
mode that takes a centered 4:3 cutout of a 16:9 broadcast image and
horizontally stretches the 16:9 broadcast image to fill a 16:9
frame of a display; and (4) a zoom mode that takes a centered 4:3
cutout of a 16:9 broadcast image and horizontally and vertically
stretches the 16:9 broadcast image to fill a 16:9 frame of a
display; and (5) a zoom mode that takes a centered 4:3 cutout of
the 16:9 broadcast and converts the output format of the ASTB to a
known 4:3 format (either 480i or 480p).
31. A method (24) for controlling an image being output from a
set-top receiver to a display comprising: receiving (241)
information as to an aspect ratio of the display to which the
set-top receiver is connected; manipulating (242) a received video
image in the set-top receiver using a stretch/zoom technique to
provide at least one customized zoom mode guaranteed to fill an
entire screen of the display and to provide one or more additional
zoom modes that are independent of the aspect ratio of the display;
outputting (243) the manipulated video image using one or more ATSC
formats; receiving (244) input from a viewer to select one of the
at least one customized zoom mode or the one or more additional
zoom modes, or setting the zoom mode automatically based on the
aspect ratio of the display without requiring additional input from
the user.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed generally to methods and
apparatuses for processing video signals at user premises, and more
particularly to a method and apparatus for processing a video
signal at a user premises, in which the video signal originates at
a broadcast location.
BACKGROUND
[0002] The transition from NTSC standard definition to ASTC high
definition broadcasting means that consumers are no longer watching
only 4:3 aspect ration programs. With the transition to widescreen
high definition broadcasts, programs can be broadcast in 4:3 or
16:9 aspect ratios. Of those broadcast in 16:9 high definition
formats, the actual video may not fill the entire 16:9 screen.
There will be black bars to the left and right of the image. These
black bars can cause fading issues with televisions and can be
annoying to viewers.
[0003] The present invention is therefore directed to the problem
of developing a method and apparatus for controlling presentation
of video images to limit the use of black bars on television
screens when an image is being displayed on a screen for which the
image is not optimal.
SUMMARY OF THE INVENTION
[0004] The present invention solves these and other problems by
providing inter alia a method and apparatus for controlling a
display of video being output from a set-top box.
[0005] According to one aspect of the present invention, an
exemplary embodiment of a method for controlling an image being
output from a set-top box determines if a user selected channel
contains programming having a first aspect ratio and stretches
automatically video from the user selected channel having the first
aspect ratio, if the user selected channel contains programming
having the first aspect ratio, to fill a frame having a second
aspect ratio that is different than the first aspect ratio using a
predetermined stretching function. This determining and stretching
is initiated automatically upon tuning to a user-selected
channel.
[0006] According to another aspect of the present invention, an
exemplary embodiment of a method for controlling video output from
a set-top box, upon receiving a zoom toggle command from a user via
a remote control unit, the method determines if a user-selected
program includes a second aspect ratio different than a first
aspect ratio and ignores the zoom toggle command if the programming
does not include the second aspect ratio. If the programming does
include the second aspect ratio, then the method selects a next
available zoom mode for a first or second aspect ratio television
type if the television type setting is set for the first or second
aspect ratio, respectively, and sets an output format to a mode
specified by a first predetermined output setting.
[0007] According to still another aspect of the present invention,
an exemplary embodiment of an apparatus for controlling a video
image output from a set-top box includes a processor and a memory.
The memory is coupled to the processor and stores encoded, computer
readable instructions that cause the processor to control an image
being output to a display by: determining if a user selected
channel contains programming having a first aspect ratio; and
stretching automatically video from the user selected channel
having the first aspect ratio, if the user selected channel
contains programming having the first aspect ratio, to fill a frame
having a second aspect ratio that is different than the first
aspect ratio using a predetermined stretching function.
[0008] According to yet another aspect of the present invention, an
exemplary embodiment of an apparatus for controlling video includes
a remote control unit, a receiver, a processor and a graphical user
interface. The receiver interacts with the remote control unit to
receive a zoom toggle command from a user via said remote control
unit. The processor determines if a user-selected program includes
a second aspect ratio different than a first aspect ratio and
ignores the zoom toggle command if the programming does not include
the second aspect ratio. The graphical user interface enables a
user can to enter a television type setting via a user settings
screen. The processor determines the television type setting from
the user settings screen and selects a next available zoom mode for
a first or second aspect ratio television type if the television
type setting is set for the first or second aspect ratio,
respectively, and sets an output format to a mode specified by a
first predetermined output setting.
[0009] Other aspects of the present invention will be apparent to
those reviewing the following drawings in light of the
specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 depicts a screen image having a widescreen 16:9
aspect ratio.
[0011] FIG. 2 depicts the screen image of FIG. 1 in a standard 4:3
aspect ratio.
[0012] FIG. 3 depicts the screen image of FIG. 1 in a hybrid 14:9
aspect ratio.
[0013] FIG. 4 depicts a letterbox display of a widescreen image on
a standard screen HDTV.
[0014] FIG. 5 depicts a full screen display of a widescreen image
on a standard screen HDTV.
[0015] FIG. 6 depicts pillarbox display of a standard screen image
on a widescreen HDTV.
[0016] FIG. 7 depicts an example of screen fade on a widescreen
HDTV.
[0017] FIG. 8 depicts a linear stretch display of a standard screen
image on a widescreen HDTV.
[0018] FIG. 9 depicts a zoom display of a standard screen image on
a widescreen HDTV.
[0019] FIG. 10 depicts DTV output formats and corresponding aspect
ratios.
[0020] FIG. 11 the common 15:9, 14:9 and 4:3 hybrid aspect ratio
broadcasts.
[0021] FIG. 12 depicts representative images used to illustrate the
ASTB 16:9 zoom Modes according to one aspect of the present
invention.
[0022] FIGS. 13-15 depict the representative images from FIG. 12
for the various zoom Modes for 16:9 aspect ratios according to
another aspect of the present invention.
[0023] FIGS. 16-18 depict the representative images from FIG. 12
for the various zoom Modes for 4:3 aspect ratios according to
another aspect of the present invention.
[0024] FIG. 19 depicts an exemplary embodiment of a method for
controlling a display of an image from video being output by a set
top box according to still another aspect of the present
invention.
[0025] FIG. 20 depicts an exemplary embodiment of a method for
controlling a display of an image from video being output by a set
top box according to yet another aspect of the present
invention.
[0026] FIG. 21 depicts an exemplary embodiment of an apparatus for
controlling a display of an image from video being output by a set
top box according to still another aspect of the present
invention.
[0027] FIG. 22 depicts an exemplary embodiment of a method for
controlling a display of an image from video being output by a set
top box according to yet another aspect of the present
invention.
DETAILED DESCRIPTION
[0028] It is worthy to note that any reference herein to "one
embodiment" or "an embodiment" means that a particular feature,
structure, or characteristic described in connection with the
embodiment is included in at least one embodiment of the invention.
The appearances of the phrase "in one embodiment" in various places
in the specification are not necessarily all referring to the same
embodiment.
[0029] Introduction
[0030] The exemplary embodiments of the present invention relate to
video processing features for digital set-top boxes (e.g., the
DCT-5100 High-Definition digital cable set-top box) and television
receivers. During the transition to all-digital television
broadcasts, there remains considerable confusion regarding the
various resolutions, aspect ratios, and scan formats inherent in
the new ATSC Digital Television (DTV) standard. The consumer
electronics industry remains without agreement on the optimal
manner to process the large number of video broadcast formats that
are now in use. Presented with more viewing choices than ever
before, in terms of what programming is available for viewing and
in what format programming may be viewed, consumers will remain
faced with a significant learning curve to become comfortable with
digital television. In response to this confusion, the exemplary
embodiments herein include features for a digital set-top box that
provide for greater viewing flexibility for a wide variety of
consumers who own a wide variety of HDTV sets.
[0031] The embodiments herein are also applicable to any set-top
boxes or receivers that include high definition decoding
capabilities.
[0032] ATSC Video Formats
[0033] The ATSC has defined 18 Digital television (DTV) formats
that include High Definition, Enhanced Definition, and Standard
Definition resolutions. The formats represent a combination of
picture resolutions, aspect ratios, and scan modes. The 18 ATSC DTV
formats are presented in Table 1 with the most commonly-used
formats shaded in gray.
1TABLE 1 Vertical Horizontal Frame Rate Pixels Pixels Pixel Shape
Aspect Ratio Scan Mode (frames/second) HD 1080 1920 Square 16:9
Progressive 24 1080 1920 Square 16:9 Progressive 30 1080 1920
Square 16:9 Interlaced 30 720 1280 Square 16:9 Progressive 24 720
1280 Square 16:9 Progressive 30 720 1280 Square 16:9 Progressive 60
ED 480 704 Rectangular 16:9 Progressive 24 480 704 Rectangular 16:9
Progressive 30 480 704 Rectangular 16:9 Progressive 60 480 704
Rectangular 4:3 Progressive 24 480 704 Rectangular 4:3 Progressive
30 480 704 Rectangular 4:3 Progressive 60 480 640 Square 4:3
Progressive 24 480 640 Square 4:3 Progressive 30 480 640 Square 4:3
Progressive 60 SD 480 704 Rectangular 16:9 Interlaced 30 480 704
Rectangular 4:3 Interlaced 30 480 640 Square 4:3 Interlaced 30
[0034] Each format has a clearly defined vertical resolution,
horizontal resolution, pixel shape, aspect ratio, scan mode and
associated frame rate.
[0035] Picture Resolution
[0036] The resolution of an ATSC DTV image is measured in
horizontal and vertical pixels. A pixel is a tiny piece of the
overall image. The greater the number of pixels, the more detail
and sharpness an image will have. The original NTSC analog
television format measured resolution in terms of the number of
vertical lines, but in an effort to begin merging televisions and
computer monitors under a single standard, the ATSC has opted to
define video resolution in pixels. The HD video formats have a
vertical resolution or either 720 pixels or 1080 pixels. The ED and
SD video formats have a vertical resolution of 480 pixels.
[0037] Pixel Shape
[0038] Early models of analog televisions used pixels that were
rectangular in shape that were taller than they were wide. This was
mostly due to the way that cathode ray tubes were able to draw
images on the screen and not necessarily an intentional
characteristic. When computer monitors were developed, cathode ray
tube technology was further advanced and they were able to generate
pixels that were square in shape. In an effort to bring designs for
televisions and computer monitors closer together, the ATSC has
defined some DTV formats that specifically use square pixels (such
as the HD video formats). DTV-capable televisions must be able to
draw both square and rectangular pixels on their screens, which
allows them to display both television and computer video
images.
[0039] Aspect Ratio
[0040] Aspect ratio is the measure of an image's width to its
height and is generally expressed as (w:h). The original NTSC
analog television standard specified a single aspect ratio that was
4:3. Since there was only one aspect ratio available, television
manufacturers built their sets to have display screens that matched
the 4:3 images. As a result, the overwhelming majority of
television sets and television programs have the 4:3 aspect ratio.
As a result, the 4:3 aspect ratio is often referred to as the
"standard screen" or "full screen" format.
[0041] The ATSC DTV formats can have one of two possible aspect
ratios--either 4:3 or 16:9. Since the ATSC was primarily concerned
with reinventing the way that people watch television, and to
further increase the visual improvements of the new HD formats, the
ATSC opted to institute the 16:9 (as referred to as "widescreen")
aspect ratio for the new HD formats. Images with 16:9 aspect ratios
are typically more impressive and attractive to the human eye since
the field of vision of a human eye is much more broad than it is
high. Widescreen images tend to fill more of our field of vision
and create a more panoramic viewing experience, which is why most
motion pictures are filmed in widescreen formats. A side-by-side
comparison of widescreen and standard screen aspect ratios is
presented below in FIG. 1 and FIG. 2.
[0042] To further complicate issues, broadcasters have adopted
several "hybrid" aspect ratios to help bridge the gap and ease the
transition from the NTSC 4:3 standard to the eventual ATSC 16:9
standard. These hybrid aspect ratio programs are actually broadcast
in a 16:9 format, however, the video within the 16:9 frame does not
fill the entire frame. One very popular hybrid aspect ratio format
is the 14:9 format, since it is the mathematical "halfway point"
between a 4:3 standard screen image and a 16:9 widescreen image.
Since the active video does not fill the entire widescreen frame,
the broadcaster embeds black sidebars, also known as curtains, at
the edges of the frame to fill the 16:9 aspect ratio. The 14:9
format is depicted in FIG. 3. Notice that in comparison to the
images shown in FIGS. 1-2, the hybrid aspect ratio is wider than a
standard screen image but narrower than a true widescreen
image.
[0043] Scan Mode
[0044] There are two ways to draw video images on a television or
monitor screen. The first method, the older of the two, is referred
to as the interlaced scan mode. In the interlaced scan mode, the
image is drawn in two separate passes. In the first pass, all of
the odd "lines" of the image are drawn from left to right and from
top to bottom. In the second pass, all of the even "lines" of the
image are drawn from left to right and from top to bottom. Each
pass results in a portion of the image known as a field. Two fields
combined together create a frame, which is the entire image. All
analog televisions drawn images on the screen in this fashion.
[0045] Computer monitors were able to take advantage of
advancements in CRT technology and in addition to using square
pixels also adopted the progressive scan modes. In the progressive
scan mode, every line of the image is drawn in a single pass, from
left to right and from top to bottom. The frame is drawn all at
once without dividing it into two separate fields as is done in the
interlaced scan mode. This results in much less flicker in the
video and smoother motion across the screen. Once again, in an
effort to bring televisions and computer monitors closer together,
the ATSC has created a number of DTV formats that take advantage of
the progressive scan mode. Since motion pictures are filmed and
viewed in what is essentially a progressive scan format, the ATSC
wanted to capture the "movie theater effect" in some of the DTV
formats as well. For backwards compatibility, several DTV formats
still use the older interlaced scan mode.
[0046] Frame Rate
[0047] As discussed above, the interlaced and progressive scan
modes use different methods to draw a complete picture frame on the
screen. Interlaced scan methods draw a complete field every
60.sup.th of a second, and since two fields are used to create a
complete frame, the frame rate is equal to 30 frames per second
(fps). The most common progressive scan rate is 60 fps, meaning
that the complete image is drawn once ever 60.sup.th of a second.
However, the ATSC has also defined additional progressive scan
frame rates within the DTV standard. Most notable among these frame
rates is the presence of 24 fps. This happens to be the frame rate
at which motion pictures are filmed and presented in movie
theaters. The film is projected onto the theater screen at a rate
that equals 24 complete picture frames every second. In an effort
to provide DTV modes that capture the "movie theater effect" the
ATSC defined several formats that use 24 fps progressive scan
modes.
[0048] Aspect Ratio Mismatches
[0049] With the adoption of the ATSC DTV formats which include both
16:9 and 4:3 aspect ratios, and the introduction of widescreen
televisions to augment the existing population of standard screen
televisions, it becomes readily apparent that viewing situations
will arise when the tuned video program has an aspect ratio that is
different from that of the television's display screen. The
consumer electronics industry has developed techniques for handling
these aspect ratio mismatches. These techniques include:
[0050] Letterbox displays
[0051] Pillarbox displays
[0052] Stretch displays
[0053] Zoom displays
[0054] Televisions and set-top decoders apply these techniques in
very specific scenarios that rely greatly on the DTV format of the
tuned video program. As a result, the formats in Table 1 will be
referred to constantly throughout this section, particularly the
most common DTV formats which appear in the table shaded in
gray.
[0055] Letterbox Displays
[0056] Letterbox displays are not new to the general viewing
public. While some viewers may dislike the letterbox display
format, almost everyone has seen it at one time or another. The
letterbox technique is used to display images on a television
screen when the image itself has an aspect ratio that is wider than
the display screen. The image is scaled down in size (and
resolution) until its width fits the physical width of the display
screen. As a result, the image cannot fill the physical height of
the display screen. In order to "frame" the picture on the screen
and reduce any visual distraction, the portions of the screen above
and below the image that are not filled with active video are
usually set to black. The letterbox technique is depicted in FIG.
4, where the widescreen image from FIG. 1 is shown being displayed
on a 4:3 standard screen television.
[0057] The letterbox technique allows the viewer to see the entire
video image as it was originally filmed without any portions of the
picture being cropped and discarded in order to fill the entire
screen. Whenever a video that was originally filmed in a widescreen
format is reformatted to fill a 4:3 standard screen television,
portions of the image must be cropped from each video frame. The
full screen version of the widescreen image as presented on the
same 4:3 television is presented below in FIG. 5.
[0058] A quick comparison of the television displays shown in FIGS.
4 and 5 reveals that the letterbox technique effectively maintains
the original aspect ratio of the video program, but at the expense
of lower picture resolution and black static areas on the
television screen. The full screen display does in fact fill the
entire screen and takes advantage of the full vertical resolution
of the television, but significant portions of the original video
program must be cropped and cannot be enjoyed by the viewer. While
some viewers wish to view widescreen programs in their original
aspect ratios regardless of any loss in resolution or the presence
of static black bars, other viewers insist that they have a full
screen picture at all times even if it means they are not able to
view the entire image as originally filmed.
[0059] Referring to Table 1, it is clear that all HD formats are
defined to have an aspect ratio of 16:9. As a result, all 4:3
standard screen HDTVs will show HD programming in the letterbox
format as seen in FIG. 4. There is no other way for a 4:3
television to show a widescreen image on its display screen.
Whenever the television is fed with either 1080i or 720p video
signals, the display will automatically switch to the letterbox
format with static bars above and below the active video. Given
this information, it is easy to ask why do television manufacturers
even offer HDTVs that have 4:3 display screens. The reason is
fairly simple: the vast majority of television programming
available today is still in a 4:3 format, and these programs will
fill the entire screen of a 4:3 HDTV (as seen in FIG. 5) which is
the expected behavior by some viewers. However, all HD programming
will have to be viewed in the letterbox format on these sets.
[0060] Pillarbox Displays
[0061] The pillarbox display, unlike the letterbox display, is
relatively new to the viewing public since the adoption of the ATSC
DTV standard. Whereas the letterbox display is used to fit
widescreen programming on a 4:3 screen (though programs that are
wider than 16:9 will also be shown as letterbox on a widescreen
TV), the pillarbox format is used to fit 4:3 programming on a
widescreen display. Since a 4:3 image is too narrow to fill the
width of a widescreen television, the television typically will
center the image on the screen and place dark bars to the left and
right of the image. A typical pillarbox display on a widescreen
HDTV is depicted below in FIG. 6. The image is centered and scaled
vertically to fit the physical height of the display screen, and
the portions of the screen that are not filled with active video
are usually set to black.
[0062] The pillarbox technique is one method used to display
standard screen 4:3 images on a widescreen display. Television
manufacturers who make widescreen HDTVs already know that the vast
majority of television programming is still in the 4:3 aspect
ratio. Therefore, the manufacturers have designed their widescreen
televisions to work with standard screen images in a number of
ways. The only method to display 4:3 content in its original aspect
ratio without any distortion or video cropping on a widescreen HDTV
is to apply the pillarbox format.
[0063] Stretch Displays
[0064] Widescreen television manufacturers took into consideration
the fact that 90-95% of the content available on television today
is 4:3. HDTVs use a number of different display technologies,
including cathode ray tubes (CRTs), liquid crystals, plasma cells,
and digital light processing. Some of these display technologies
are susceptible to phenomena known as "screen burn" and "screen
fade." This typically occurs in phosphor-based display technologies
such as CRTs and plasma cells. Referring to FIG. 6, and keeping in
mind that 90-95% of the television content today is still 4:3, it
becomes clear that the left and right sidebars will be present a
great deal of the time. The center portion of the television screen
is constantly exercised and illuminated (and as such slowly fades
in brilliance and clarity over time) but the sidebars remain
unexercised and in a like-new state. This is known as screen fade.
When a widescreen image is finally displayed on the HDTV, the
portion of the picture in the areas where the black sidebars
usually reside will be noticeably brighter and crisper than the
center area of the screen. A depiction of screen fade on a
widescreen HDTV that has been primarily used to watch 4:3 video in
the pillarbox format is shown below in FIG. 7.
[0065] Most widescreen HDTV manufacturers recommend (particularly
on expensive plasma displays and any CRT-based display) that the
pillarbox format be used for less than 20% of total viewing. Since
90% or more of the content available today is in 4:3 format,
widescreen HDTVs have been designed with several ways of "fitting"
4:3 video to their 16:9 screens. These methods include the stretch
display, which will be discussed here, and the zoom display, which
will be discussed in the next section.
[0066] Most widescreen HDTVs have implemented one or more types of
stretch modes. These modes allow the viewer to fill the 16:9 screen
with active video so that no static black bars reside on the
display. The reason for this is twofold: the potential for screen
fade is greatly reduced when the pillarbox display mode is used
less frequently, and some viewers actually prefer to always have
video fill their entire television screen regardless of any
distortion or cropping that takes place. In discussing any kind of
stretch mode on a widescreen HDTV, the industry understanding is
that the stretch only takes place in the horizontal direction and
that there is no processing that takes place in the vertical
direction. Zoom modes, which are discussed in the next section,
apply horizontal and vertical processing to fit the video to the
display screen. In general, stretch modes imply processing along
the horizontal width of the screen only.
[0067] There are a number of ways to perform a horizontal stretch
of an image on a widescreen display. Television manufacturers use
the quality of their stretch and zoom modes as key differentiators
in the marketplace. While the complexity of the stretch algorithms
varies greatly between HDTV models, fundamentally stretch modes are
implemented using linear processing or nonlinear processing.
[0068] Linear stretch--Horizontal distortion is uniform across the
entire image
[0069] Nonlinear stretch--Horizontal distortion is focused on the
edges of the image
[0070] An example of a linear stretch mode is depicted below in
FIG. 8. In this example, the 4:3 content that is shown in FIG. 6 is
linearly stretched by the widescreen HDTV to fill the entire
display.
[0071] A comparison of FIGS. 6 and 8 shows some of the horizontal
distortion that occurs when a linear stretch mode is invoked by the
HDTV. The white house in the center of the picture is much wider
than it would appear if viewed in person (or in the pillarbox
format which preserves the proper aspect ratio). For inanimate
objects, such as the house in this picture, the distortion that is
introduced by the HDTV does not look that odd to the human eye.
However, scenes that contain human beings (and particularly human
faces) can look very strange to the human eye when viewed in a
stretch mode, since we have fairly fixed notions of what a "normal"
human being or human face looks like. When stretched to fill a
widescreen HDTV, humans on-screen can look very distorted and can
immediately cause the reaction that there is excessive distortion
in the picture, even more than if the exact same stretch method is
applied to a scene containing inanimate objects such as in FIG.
8.
[0072] Zoom Displays
[0073] In addition to the stretch modes (linear and nonlinear) that
widescreen television manufacturers have implemented on their
products, an alternate display mode known as a "zoom display" has
started to appear with increasing frequency on many widescreen HDTV
sets. The zoom mode is basically a two-dimensional stretch. The
image is stretched horizontally to fill the width of the display
screen, but is also stretched vertically so that the amount of
horizontal distortion is greatly reduced. However, once-viewable
portions of the picture at the top and bottom are in effect
"zoomed" off the screen and are basically cropped.
[0074] The zoom display is an alternative to the basic stretch
display that some viewers may not enjoy because of the horizontal
distortion that is introduced, particularly when viewing people in
this manner. The zoom display stretches the picture in both
directions, though depending on the manufacturer, the amount of
stretch in both directions may be very similar or very different.
An example of a zoom mode (where equal amounts of stretch are
applied horizontally and vertically) is shown below in FIG. 9.
[0075] To see the difference between the zoom display and the
stretch display, compare the television displays in FIGS. 8 and 9.
There are several noticeable differences between the two images. To
illustrate these differences, compare the white house in the center
of the picture, the street sign on the left of the picture, and the
concrete post at the lower left of the picture. In the zoom
display, the house and the sign have no appearance of horizontal
distortion and appear in the normal (original) aspect ratio. This
appears to be an advantage over the linear stretch display.
However, it can also be seen that the chimney of the white house is
much closer to the top of the display screen and a sizable portion
of the concrete post has disappeared from the display screen
entirely. Portions of the top and bottom of the original image are
therefore cropped from view and cannot be seen by the viewer. While
in this scene the effect of losing the upper and lower portions of
the screen is negligible, scenes that focus on "close-ups" on
dialogue and such may crop signification portions of the actors'
faces and heads from view. Some viewers may find that to be
visually disruptive and may prefer to watch those scenes in a
stretch display or a pillarbox display. The choice is left to the
viewer to decide what they believe "looks best" and the widescreen
HDTV manufacturers have attempted to provide a number of options to
suit the various preferences of the viewers.
[0076] ASTB Video Output Formats
[0077] The Advanced Set-top Boxes (ASTBs) are equipped with a
number of video outputs. These outputs include component video
ports, an s-video port, a composite video port, and an RF output.
Since the component video ports are intended to be the primary
connection used with an HDTV, and the majority of the proposed
video features deal with DTV formats (which the component video
ports alone can accommodate), the embodiments herein will focus on
the component video (YPbPr) outputs.
[0078] An exemplary embodiment of a set top box, such as the
DCT-5100, is capable of generating video outputs in any one of five
different ATSC DTV formats. These formats are shown in Table 1
shaded in gray and are referred to as 1080i, 720p, 480p (16:9),
480p (4:3), and 480i. The numeric portion of the video format
refers to the number of vertical pixels, the "p" refers to the
progressive scan mode, and the "i" refers to the interlaced scan
mode. Each of these formats has a single defined aspect ratio
except for the 480p format. The aspect ratio restrictions are
depicted FIG. 10.
[0079] FIG. 10 depicts the aspect ratios that are defined for each
of the five DTV output formats included in the exemplary embodiment
of an ASTB. Therefore, it is impossible for this embodiment to
generate a 1080i 4:3 picture, for example. Since these five DTV
formats are the only formats available on the component video
outputs of the DCT-5100, any proposed video features will
essentially boil down to a generated video output in one of these
five formats. It is essential to understand how different HDTVs
(widescreen and standard screen) display each of these five DTV
formats in order to understand the resultant output that will be
generated by each proposed video feature. For example, many
widescreen HDTVs automatically stretch 480p signals to fill the
display screen, regardless of whether the video source signal has a
4:3 480p format or a 16:9 480p format. The reason that the
televisions do this is fairly straightforward: 480p is the output
format generated by all progressive scan DVD players, and the TV
manufacturer assumes that if the consumer has purchased a
widescreen television, the consumer must also be watching
widescreen (anamorphic) DVDs with their progressive scan DVD
player. As a result, the television stretches the 480p signal to
fill the screen, which is the proper choice when viewing anamorphic
DVDs on a progressive scan DVD player. However, this "auto-stretch"
by the widescreen TV may produce a very different effect from the
one desired from the exemplary embodiment.
[0080] Current ASTB User Settings
[0081] The exemplary embodiment of the ATSB provides to the
consumer a "User Settings" screen that allows the consumer to
configure the ASTB to work with their specific model of HDTV and
set some general viewing preferences. An exemplary embodiment of an
ASTB configuration menu is shown below in Table 2. The default
values for each option as defined in the ASTB firmware are shown
first (16:9, 1080i, 480i) and the additional values that can be
selected are shown in parentheses.
2TABLE 2 USER SETTINGS TV TYPE 16:9 (4:3 LETTERBOX, 4:3 PAN-SCAN)
YPbPr OUTPUT 1080i (720p, 480p, 480i) 4:3 OVERRIDE 480i (480p, OFF)
CLOSED CAPTION DISABLED OPTIONS: PEN SIZE AUTO FONT STYLE AUTO
FOREGROUND COLOR AUTO FOREGROUND OPACITY AUTO BACKGROUND COLOR AUTO
BACKGROUND OPACITY AUTO SERVICE SELECTION AUTO SETTINGS AUTO
RESTORE DEFAULTS
[0082] The three options used primarily for configuring the ASTB
are known as TV Type, YPbPr Output, and 4:3 Override. These options
allow the consumer to configure the exemplary embodiment of the
ATSB to work with their particular model of HDTV and control the
manner in which SD and HD content in viewed on the HDTV. The
options perform the following functions:
[0083] TV Type--Specifies the type of HDTV connected to the
ASTB.
[0084] YPrPb Output--Specifies the output video format on the
set-top's component video ports except when the 4:3 Override is in
effect.
[0085] 4:3 Override--Specifies the output video format on the
set-top's component video ports when the ASTB is tuned to a 4:3
program.
[0086] The 4:3 Override feature is one type of automatic output
switching and addresses a number of issues such as postage stamped
displays and screen burn/fade.
[0087] One of the advantages of the exemplary embodiment of the
User Settings screen is that it has been designed with a "set and
forget" approach, meaning that once the consumer finds the
selections that work best with his/her particular model of HDTV,
there is never a need to go back into the menu to change settings.
As a result, the driving requirement for any addition that is to be
made to the User Settings screen is that it must be implemented as
a "Set And Forget" style option.
[0088] Video Features
[0089] The embodiments of the ATSB implement various stretch and
zoom modes to provide more viewing options to the consumers and to
counteract static black areas embedded in HD programs by some
broadcasters.
[0090] ASTB 4:3 Stretch Mode
[0091] The exemplary embodiment of the ATSB incorporates some type
of stretch mode for viewing true 4:3 programs on a 16:9 widescreen
HDTV. This feature can be provided in addition to the standard 4:3
Override feature, and therefore can be implemented in such a
fashion as to be complementary to the 4:3 Override feature. The
ASTB Stretch Mode is not intended to be used with 4:3 content that
is broadcast in a 16:9 format in the pillarbox mode.
[0092] Assumptions
[0093] The assumptions that were made in order to come up with the
embodiments herein for implementation of the ASTB Stretch Mode are
listed below.
[0094] The Stretch Mode should apply to consumers with 16:9
HDTVs
[0095] The Stretch Mode should not apply to consumers with 4:3
HDTVs
[0096] The Stretch Mode should augment the 4:3 Override Feature
[0097] The Stretch Mode should be invoked when the ASTB is tuned to
4:3 content
[0098] The Stretch Mode should not be invoked when the ASTB is
tuned to 16:9 content
[0099] On widescreen HDTVs, the stretch modes are used to fill the
16:9 screen with 4:3 video content. The stretch algorithms can
vary, but the final result is a filled display screen. Standard
television screens with 4:3 aspect ratios have no need for a
stretch feature because the display screen matches the aspect ratio
of 4:3 video content. Since the 4:3 Override feature is a standard
feature on the ASTB product line, and any ASTB Stretch Mode would
also deal with 4:3 video content, the Stretch Mode should be
implemented in a complimentary fashion to the 4:3 Override.
[0100] Problems Addressed
[0101] The problem that this feature primarily addresses is any
widescreen television that either does not have its own stretch
mode for viewing 4:3 full screen, or a widescreen television that
does a poor job of creating stretch displays. By incorporating this
feature on the exemplary embodiments of ASTBs, the set-top boxes
provide yet another viewing option that will enhance the feature
set of the product and potentially improve the viewing experience
of the consumer. Additionally, widescreen televisions that use
phosphor-based display technologies are susceptible to screen burn
& fade. The implementation of a stretch feature on the ASTB
also serves to provide a safeguard against possible screen damage
to a costly HDTV.
Exemplary Embodiment
[0102] The ASTB 4:3 Stretch Mode is not envisioned to be a
frequently-toggled feature like the ASTB 16:9 Zoom Mode. It is
envisioned that the consumer will use the ASTB Stretch Mode on a
widescreen HDTV if either the widescreen HDTV itself does not
supply a stretch mode or if the HDTV does a poor job with its
stretch display. In that case, the consumer has the option of using
the ASTB to perform the stretch instead.
[0103] Since most television manufacturers recommend viewing
content that causes static black areas on the screen (such as
pillarbox displays) less than 20% of the time to reduce any chance
of screen fade, it is likely that the ASTB 4:3 Stretch Mode will
not be toggled on and off frequently by the consumer. If the
consumer decides to use the ASTB Stretch Mode, it will likely
become the default mode for viewing 4:3 content on a 16:9
widescreen HDTV. If the consumer prefers the stretch modes offered
by the HDTV, then the standard ASTB 4:3 Override feature will be
used to provide 4:3 video formats to the HDTV to stretch on its
own.
[0104] Due to the likelihood that the ASTB Stretch Mode will be an
"all or nothing" type of feature, meaning that the consumer will
either use it the majority of the time or hardly at all, it is not
critical that this feature be toggled from a remote control button.
Though a remote control button provides a cleaner user experience
to toggle the stretch feature on and off, as opposed to entering
the User Setting screen and toggling the feature there, it is not
deemed to be an absolute necessity in order to implement the ASTB
Stretch Mode Feature.
[0105] The ASTB Stretch Mode can be added neatly and intuitively to
the 4:3 Override menu selection in the User Settings screen. A
"STRETCH" option can appear as an additional option next to 480i,
480p, and OFF. Since this feature is intended only for widescreen
HDTVs, the STRETCH option under 4:3 OVERRIDE can be made so that it
is only accessible if the TV TYPE is set to 16:9. If the TV TYPE is
set to 4:3 (either Letterbox or Pan Scan) then the ASTB Stretch
Mode should not be accessible as it provides no advantage over the
existing 4:3 Override feature.
[0106] The exemplary embodiments of the ATSB can be configured so
that the primary output format, set via the YPrPb OUTPUT menu
option, is one of the two available HD formats (720p or 1080i). In
these cases, the STRETCH option should be available as one of the
4:3 OVERRIDE settings. Additionally, the STRETCH option should be
available if the YPrPb OUTPUT is set to 480p. Currently, if the
YPrPb OUTPUT is set to 480i, the 4:3 OVERRIDE automatically
switches to OFF and becomes inaccessible. This same behavior should
continue with the addition of the ASTB Stretch Mode, since in this
instance the consumer has forced the ASTB to output a known 4:3
video mode in 480i and there is no need for the stretch mode.
[0107] The addition of the STRETCH option to the 4:3 OVERRIDE
submenu is shown in Table 3. In the exemplary embodiment, the
STRETCH feature is toggled from the User Settings screen and is
enabled whenever the ASTB is tuned to true 4:3 content. In effect,
the ASTB 4:3 Stretch Mode becomes an augmentation of the standard
4:3 Override feature that is easily turned off and on by the
consumer by accessing the User Settings display.
3TABLE 3 Addition of the ASTB Stretch Mode to the User Settings
Menu USER SETTINGS TV TYPE 16:9 (4:3 TVs have no need to view 4:3
video stretched) YPbPr OUTPUT 1080i, 720p, or 480p (480i defaults
the 4:3 Override to OFF) 4:3 OVERRIDE STRETCH (the consumer can
still choose 480i, 480p, or OFF)
[0108] The ASTB 4:3 Stretch Mode can then be instantiated whenever
the ASTB is tuned to a 4:3 service, regardless of whether it was an
analog service or a digital service. The ASTB can recognize that it
had been tuned to a 4:3 service, stretch the 4:3 video to fill a
16:9 viewing frane, and output the resultant widescreen video in
the output format specified by the YPbPr OUTPUT setting in the User
Settings screen. An exemplary embodiment of a logical process that
would be invoked after a channel change is shown in FIG. 19.
[0109] In step 101, a user-selected channel is tuned to.
[0110] In step 102, the determination is made if the service is a
4:3 service. If the service is not a 4:3 service, in step 104 the
YPrPb OUTPUT format is used and the process ends. If the service is
a 4:3 service, the process moves to step 103, in which the override
setting is determined.
[0111] If the override setting is not set to STRETCH, in step 105,
the existing logic for the 4:3 Override feature is applied and the
process ends. If the override setting is set to STRETCH, the
process moves to step 106, in which the 4:3 video is stretched to
fill a 16:9 frame. This stretching function can be a linear
stretching function or a non-linear stretching function.
[0112] In step 107, any overlaying graphics (such as electronic
programming guide information or closed-captioning text) is not
stretched to avoid distortion.
[0113] In step 108, the video is converted to the output format
specified by the YPrPb OUTPUT setting. For example, if the YPrPb
OUTPUT setting is 1080i (determination made in step 109), the
stretched video is 1080i (step 112). If the YPrPb OUTPUT setting is
720p (determination made in step 110), the stretched video is 720p
(step 113). And, if the YPrPb OUTPUT setting is 480p (determination
made in step 111), the stretched video is 480p (step 114).
[0114] In step 109, the stretched and converted video frames are
output on the component video outputs. Only the primary High
Definition video outputs (YPrPb) include stretched video frames.
The secondary standard digital video outputs (e.g., Composite,
S-Vid, RF) include 4:3 video.
[0115] One embodiment of the ASTB Stretch Mode utilizes a linear
stretch algorithm, while others may utilize nonlinear stretch
algorithms. Nonlinear stretch algorithms can reduce the perceived
amount of distortion by the viewer and promote a more enjoyable
viewing experience.
[0116] Advantages
[0117] There are some inherent advantages to this particular
implementation of the ASTB Stretch Mode.
[0118] Advantages:
[0119] The ASTB Stretch Mode fits very neatly into the "Set And
Forget" theme of the User Settings menu as one of the selectable
ways to watch 4:3 content.
[0120] The ASTB Stretch Mode does not force a switch of the YPrPb
output format, so there is no visible re-synch that must occur on
the HDTV to reacquire and display the new format.
[0121] The ASTB Stretch Mode can be augmented to include several
different stretch algorithms if necessary (linear and nonlinear
methods) that drop neatly into the User Setting
[0122] The ASTB Stretch Mode would automatically protect expensive
widescreen HDTVs from damage caused by screen bum and screen fade
since it would be invoked as soon as the set-top tuned to known 4:3
content.
[0123] Drawbacks:
[0124] The ASTB Stretch Mode cannot provide an "instant
gratification" toggle for the consumer without a new remote control
key.
[0125] Overall, it appears that the proposed implementation offers
even more viewing options for consumers who own widescreen HDTVs
and can help to reduce the chance of causing damage to any
phosphor-based displays. Some consumers may decide that they do not
like the way that the set-top performs the stretch based on their
own personal viewing preferences, but since the ASTB 4:3 Stretch
Mode is not a default setting and can be easily turned off, this is
not an issue.
[0126] ASTB 16:9 Zoom Modes
[0127] The exemplary embodiments of the ATSB incorporate some type
of zoom feature for viewing widescreen 16:9 broadcasts that have
hybrid aspect ratio video. This feature would be provided in
addition to the standard 4:3 Override feature, and therefore is
implemented in such a fashion as to be complementary to the 4:3
Override feature. The ASTB Zoom Modes are intended to provide the
consumer with several different options for viewing hybrid aspect
ratio programming.
[0128] Assumptions
[0129] The assumptions that were made in order to come up with the
proposed implementation of the ASTB 16:9 Zoom Modes are listed
below.
[0130] The Zoom Modes should apply to consumers with 16:9 HDTVs
[0131] The Zoom Modes should apply to consumers with 4:3 HDTVs
[0132] The Zoom Modes should complement the 4:3 Override
Feature
[0133] The Zoom Modes should be toggled via remote control
[0134] The Zoom Modes should not be toggled via the User Settings
menu
[0135] The Zoom Modes should be selectable when the ASTB is tuned
to 16:9 content
[0136] The Zoom Modes should not be selectable when the ASTB is
tuned to 4:3 content since this case is covered by the 4:3 Override
and ASTB Stretch features
[0137] The ASTB Zoom Modes will be used primarily to fill the
entire display screen on 16:9 HDTVs and as much of the display
screen as possible on 4:3 HDTVs whenever the tuned HD programming
contains static black areas embedded in the video. The vast
majority of television content recorded over the last 5 decades has
been in the standard screen 4:3 aspect ratio. There is not yet
enough true widescreen 16:9 HD programming for a DTV broadcaster to
fill an entire day, so often the older 4:3 content is upconverted
to a DTV format and broadcast with black sidebars (known as the
pillarbox display) to fill the required 16:9 video frame for an HD
transmission.
[0138] Problems Addressed
[0139] The ASTB 16:9 Zoom Modes can offer viewers several different
options when viewing HD broadcasts that do not have a full 16:9
frame worth of active video. The video is narrower than the 16:9
broadcast frame, and in order to comply with the 16:9 aspect ratio
requirement specified by the ATSC DTV standard, static black bars
are placed to the left and the right of the video to fill the width
of the 16:9 frame (see FIG. 5). Static black bars that are embedded
in the broadcast are typically of great concern to HDTV owners
because until now there has been no way to counteract them. There
are two reasons why a viewer would like to be able to counteract
the embedded black bars in a widescreen broadcast: 1) they prefer
to view "fullscreen" displays as often as possible and dislike any
static black areas, or 2) the black areas can contribute over time
to a phenomenon known as "screen burn" or "screen fade" which can
damage an HDTV display, particularly the very costly plasma
HDTVs.
Exemplary Embodiment
[0140] Since the ASTB Zoom Modes would in all likelihood be toggled
by the viewer as he/she flips through the available channels to
suit the program they have selected at that moment, a static menu
setting such as the one used for the ASTB Stretch Mode would not be
practical. This would force the viewer to enter the User Settings
screen every time they tuned to a hybrid aspect ratio program which
the viewer wished "to zoom" in some fashion. In order for the ASTB
Zoom Modes to work intuitively and in a fashion consistent with the
rest of the consumer electronics industry, the zoom modes must be
toggled via the remote control.
[0141] In studying the most common hybrid aspect ratios used by DTV
broadcasters today, the three used most often are the 15:9 hybrid,
the 14:9 hybrid, and the 4:3 hybrid. In these cases, all of the
video frames are in fact 16:9, yet the frames are filled with
(centered) video that is either 15:9, 14:9, or 4:3. Since all three
of these aspect ratios are narrower than 16:9, static black bars
appear to the left and the right of the active video to center it
within a 16:9 video frame. Examples of these three common hybrid
aspect ratio broadcasts are depicted in FIG. 11. The static black
areas to the left and right of the active video are actually part
of the total video frame that is being transmitted by the
broadcaster.
[0142] The ASTB 16:9 Zoom Modes should provide some benefit to
consumers who own either a widescreen 16:9 HDTV or a standard
screen 4:3 HDTV. Although the consumers who own the more expensive
widescreen TVs which are more susceptible to screen burn and screen
fade have more to gain from the implementation of the ASTB Zoom
Modes, viewers with 4:3 HDTVs should also benefit from these zoom
modes. However, since 16:9 HDTVs and 4:3 HDTVs display widescreen
programming in very different fashions, the ASTB Zoom Modes should
be implemented so that they behave differently for 16:9 HDTVs and
4:3 HDTVs.
[0143] ASTB 16:9 Zoom Modes on Widescreen HDTVs
[0144] Through the TV TYPE setting in the User Settings screen, the
ASTB can determine that it is connected to either a 16:9 HDTV or a
4:3 HDTV. Using this information, the ASTB can tailor the ASTB Zoom
Modes to what makes the most sense for the particular television
connected to it. In the case of the widescreen HDTVs, the ASTB 16:9
Zoom Modes should be able to counteract the three commonly
encountered hybrid display formats shown in FIG. 11. Since the 15:9
and 14:9 hybrid formats are so similar to each other in terms of
width, there is little need to have a zoom mode to support the 15:9
format and a separate mode to support the 14:9 format. A zoom mode
to support the 14:9 format alone will also handle the 15:9 format
as well, though there will be very slender strips of video cropped
off the screen in the 15:9 hybrid scenario. The 15:9 and 14:9
formats are fairly close in width to the full 16:9 video frame.
While the term "zoom" in the consumer electronics industry
typically implies a two dimensional stretch of an image
horizontally and vertically (to reduce distortion in any one
direction), the 15:9/14:9 zoom mode would implement a
"horizontal-only" stretch to fill the entire 16:9 frame with active
video with very little horizontal distortion (as opposed to
stretching a 4:3 image to fill a 16:9 frame).
[0145] The 4:3 hybrid aspect ratio is quite a bit narrower than the
15:9 and 14:9 hybrid formats and as a result should be handled by
two different "zoom" formats. The first mode would perform a
horizontal stretch of the 4:3 video to fill the 16:9 frame. The
second mode would apply horizontal and vertical stretch to fill the
width 16:9 video frame with little or no distortion, but there
would be some cropping of the top and bottom of the original video
image as it was stretched vertically to minimize horizontal
distortion.
[0146] To summarize, exemplary embodiments of ASTB Zoom Modes for a
widescreen 16:9 HDTV would include four selectable zoom modes that
can be cycled through using the remote control and would "wrap"
around to the top of the list with consecutive remote control
button presses:
[0147] 16:9 Zoom Mode #1: A "No Zoom" mode to remove all ASTB Zoom
Mode processing to view the broadcast "as is."
[0148] 16:9 Zoom Mode #2: A zoom mode that takes a centered 14:9
cutout of the 16:9 broadcast and horizontally stretches it to fill
a 16:9 frame.
[0149] 16:9 Zoom Mode #3: A zoom mode that takes a centered 4:3
cutout of the 16:9 broadcast and horizontally stretches it to fill
a 16:9 frame.
[0150] 16:9 Zoom Mode #4: A zoom mode that takes a centered 4:3
cutout of the 16:9 broadcast and horizontally and vertically
stretches it to fill a 16:9 frame.
[0151] ASTB 16:9 Zoom Modes on Standard Screen HDTVs
[0152] Through the TV TYPE setting in the User Settings screen, the
ASTB can determine that it is connected to either a 16:9 HDTV or a
4:3 HDTV. Using this information, the ASTB could tailor the ASTB
Zoom Modes to what makes the most sense for the particular
television connected to it. In the case of the 4:3 standard screen
HDTVs, the ASTB Zoom Modes should be able to counteract the three
commonly hybrid aspect ratios shown in FIG. 11. However, 4:3 HDTVs
are not designed to display 16:9 broadcasts as full screen images
like the widescreen HDTVs are. As a result, every 4:3 HDTV
available today must display 16:9 widescreen programming in the
letterbox format (see FIG. 4). Whenever a 4:3 HDTV is fed with a
1080i or 720p input signal, which it understands to use the 16:9
aspect ratio, it will automatically switch to a letterbox type of
display. This is an important fact to keep in mind when discussing
the ASTB Zoom Modes for a 4:3 HDTV.
[0153] Hybrid aspect ratio broadcasts will display as a "postage
stamp" display on a 4:3 HDTV. Where a 16:9 widescreen TV would only
display the black bars on the left and right of the active video, a
4:3 standard screen TV would display black bars on all four sides
of the active video. This occurs because the broadcaster has
embedded black bars to the left and the right of the active video
to fill a 16:9 video frame, and the 4:3 HDTV must use the letterbox
display with black bars above and below the active video to fit the
widescreen program to its standard screen display. This limits the
effectiveness of the ASTB 16:9 Zoom Modes discussed for widescreen
HDTVs previously because a 4:3 HDTV would always show black bars
above and below the active video as a result of its own letterbox
requirements. The zoom modes discussed for widescreen HDTVs would
eliminate the postage stamp display on a 4:3 HDTV, but none of them
could counteract the letterbox display.
[0154] In order to provide a degree of usefulness in the ASTB 16:9
Zoom Modes for owners of 4:3 HDTVs, an additional zoom mode that is
only available for 4:3 HDTVs could be made available. It would
provide the viewer with a fullscreen display, but at the cost of
definition and panorama. Essentially, the final zoom mode designed
for 4:3 HDTVs would force the ASTB output to a known 4:3 video
format (either 480i or 480p) and display a centered 4:3 cutout of
the 16:9 video frame on the screen. This would be the equivalent of
a "cropped" display as opposed to a pan & scan display. The 4:3
cutout would be centered on the 16:9 video frame. Since the zoom
modes are intended to counteract the hybrid aspect ratios with
black areas to the left and right of the screen, the amount of
active video that is actually being "cropped" in this case may be
very little (for the 15:9 and 14:9 cases) or none at all (for the
4:3 case). This provides the 4:3 HDTV viewer with a level of
functionality that is particularly useful for their television
displays.
[0155] To summarize, an exemplary embodiment of ASTB Zoom Modes for
a widescreen 16:9 HDTV would include four zoom modes that can be
cycled through using the remote control:
[0156] 4:3 Zoom Mode #1: A "No Zoom" mode to remove all ASTB Zoom
Mode processing to view the broadcast "as is."
[0157] 4:3 Zoom Mode #2: A zoom mode that takes a centered 14:9
cutout of the 16:9 broadcast and horizontally stretches it to fill
a 16:9 frame.
[0158] 4:3 Zoom Mode #3: A zoom mode that takes a centered 4:3
cutout of the 16:9 broadcast and horizontally stretches it to fill
a 16:9 frame.
[0159] 4:3 Zoom Mode #4: A zoom mode that takes a centered 4:3
cutout of the 16:9 broadcast and converts the output format of the
ASTB to a known 4:3 format (either 480i or 480p).
[0160] If the ASTB 4:3 Stretch Mode is implemented as well, then
there is the possibility that the 4:3 OVERRIDE could be set to
STRETCH in certain cases. Since it has been proposed that the ASTB
16:9 Zoom Modes utilize the 4:3 OVERRIDE setting in certain cases
to decide what format output to generate to display on the HDTV, it
is worthwhile to cover this scenario in a bit more detail. The ASTB
4:3 Stretch Mode is intended for use by consumers who own
widescreen 16:9 HDTVs only. There is no need for a stretch feature
for 4:3 standard screen HDTVs. As a result, the 4:3 OVERRIDE option
can only be set to STRETCH if the TV Type is 16:9. Likewise, the
zoom modes tailored to a 4:3 HDTV are only invoked via the remote
control if the 4:3 OVERRIDE option is set to either 4:3 Letterbox
or 4:3 Pan-Scan. In this case, the "STRETCH" option is not
accessible for the 4:3 OVERRIDE menu and they only available
options are 480i, 480p, or OFF. The logical process covers the
expected behavior for each of these three allowable settings.
[0161] Logical Process for the ASTB 16:9 Zoom Modes
[0162] The exemplary embodiment of the ASTB 16:9 Zoom Mode feature
is a complex feature that provides a great amount of control to the
viewer over how they wish to view 16:9 programming on their HDTV.
The ASTB 16:9 Zoom Modes are envisioned primarily to allow the
viewer to remove static black areas embedded in a 16:9 broadcast in
order to provide a more pleasant viewing experience or to reduce
the possibility of screen damage to a costly widescreen HDTV.
[0163] An exemplary embodiment 200 of a logical process for the
ASTB 16:9 Zoom Mode feature as follows would be invoked via a
remote control button press is shown in FIG. 20.
[0164] In step 201 a zoom mode toggle command is received from the
remote control, after which in step 202 a determination is made as
to whether the currently tuned service is a 16:9 broadcast. If the
service is not a 16:9 service, then the zoom toggle is ignored in
step 205 and the process ends. If the service is a 16:9 service,
then the zoom toggle is allowed and the process continues.
[0165] In step 203, the TV TYPE setting is determined from the User
Settings screen entered via a graphical user interface.
[0166] If the TV TYPE is 16:9, in step 206, each toggle press moves
to the next mode available for that TV Type, and in step 207 the
output format is set to the mode specified by the YPrPb OUTPUT. The
process then ends
[0167] If the TV TYPE is 4:3 Letterbox or 4:3 Pan Scan, in step 208
each toggle press moves to the next mode available for that TV
Type.
[0168] In step 209, the determination is made as to whether the
fourth zoom mode is selected (i.e., 4:3 Zoom Mode #4: A zoom mode
that takes a centered 4:3 cutout of the 16:9 broadcast and converts
the output format of the ASTB to a known 4:3 format (either 480i or
480p)). If not, in step 211 the output format is set to the mode
specified by the YPrPb OUTPUT and the process ends. If so, the
output format is set to the mode specified by the 4:3 override
setting.
[0169] The 4:3 OVERRIDE format provides a means for the ASTB 16:9
Zoom Mode feature to know what the user's preference is for viewing
4:3 video on their 4:3 HDTV. If the user has selected 480i, then
the 4.sup.th zoom mode for 4:3 HDTVs should output the cropped
video in the 480i format. If the user has selected 480p, then the
4.sup.th zoom mode for 4:3 HDTVs should output the cropped video in
the 480p format. If the user has selected OFF, then the ASTB 16:9
Zoom Mode feature should toggle automatically to the 1.sup.st zoom
mode for 4:3 HDTVs (which is the "no zoom" mode).
[0170] Graphical Representation of the ASTB 16:9 Zoom Modes
[0171] Since a picture is worth a thousand words, and it can be
difficult to visualize the displays that will result on the HDTV
screen as the user cycles through the zoom modes, several tables in
the figures depict the resulting displays on the television screen
for each combination of HDTV type (widescreen or standard screen),
hybrid aspect ratio broadcast formats, and ASTB Zoom mode.
[0172] FIG. 12 contains three images that will be used to represent
the three popular hybrid aspect ratio formats that are commonly
used by broadcasters today. Each image represents a specific
broadcast format. From left to right these images represent the
15:9 hybrid aspect ratio format, the 14:9 hybrid aspect ratio
format, and the 4:3 hybrid aspect ratio format respectively. These
images will be used in FIGS. 13-18 to show that the set-top has
tuned to a program that is being broadcast in one of these three
hybrid formats.
[0173] FIGS. 13-18 depict the displays that are produced on an HDTV
screen when the user cycles through the various ASTB 16:9 Zoom
Modes for each of the three popular hybrid aspect ratio formats
shown above. FIGS. 13-15 show the displays produced on a widescreen
(16:9) HDTV. FIGS. 16-18 show the displays produced on a standard
screen (4:3) HDTV. Note that the tables do not show the displays
for Zoom Mode #1, which is the "no zoom" mode and has no effect on
the display that is produced on the HDTV screen, which is the
version shown as the tuned program in each figure.
[0174] Advantages
[0175] There are some inherent advantages to this exemplary
embodiment of the ASTB 16:9 Zoom Mode feature.
[0176] The ASTB Zoom Mode feature is tailored to provide benefits
to owners of both style of HDTV (16:9 and 4:3).
[0177] The ASTB Zoom Mode feature can provide "instant
gratification" with a remote control button press.
[0178] The ASTB Zoom Mode feature can counteract static black bars
embedded by broadcasters which could damage expensive widescreen
HDTVs over time.
[0179] The ASTB Zoom Mode feature offers several different modes to
accommodate a range of viewer preferences.
[0180] The ASTB Zoom Mode feature utilizes the options selected in
the User Settings menu to enhance the logical process.
[0181] Overall, the exemplary embodiment offers even more viewing
options for consumers who own widescreen and standard screen HDTVs
and can help to reduce the chance of causing damage to any
phosphor-based displays, particularly the expensive widescreen
televisions. Consumers who own 4:3 HDTVs can fully eliminate the
"postage stamp" display at any time with a couple of remote control
button presses. Some consumers may decide that they do not like the
way that the set-top applies the zoom processing based on their own
personal viewing preferences, but since the ASTB Zoom Mode is not a
default setting and can be easily toggled using the remote control,
this is not an issue.
[0182] ASTB 4:3 Stretch Feature Support
[0183] The existing ASTB hardware (such as BCM 7035) is capable of
supporting this feature on the primary video outputs (YPbPr or DVI)
of the set-top box. The 7035 supports linear scaling factors, but
linear and non-linear scaling factors can be used in other
exemplary embodiments. The ASTB 4:3 Stretch feature may be
augmented to take advantage of the non-linear scaling
capabilities.
[0184] The video quality that will result on the secondary video
outputs (s-video, composite, and RF) can be affected when the
stretch feature is in use. In one embodiment, the stretch
processing is applied to the main video pipeline for presentation
over the primary video outputs. In this case, the video for the
secondary outputs needs to be "de-stretched" before presentation on
the secondary video outputs.
[0185] ASTB 16:9 Zoom Feature Support
[0186] The existing ASTB hardware (BCM 7035) is capable of
supporting this feature on the primary video outputs (YPbPr or DVI)
of the set-top box. The 7035 supports linear scaling factors that
may be applied horizontally and/or vertically to provide a simple
"stretch" effect or a two-dimensional "zoom" effect. The exemplary
embodiment takes a centered "cutout" of a 16:9 frame and applies
the scaling factors to that cutout. Once that cutout has been made
(either 14:9 or 4:3 depending on the zoom mode), then the
application of the horizontal and/or vertical scaling factors is a
relatively straightforward process.
[0187] The video quality that will result on the secondary video
outputs (s-video, composite, and RF) may be affected when the
stretch feature is in use. As in the above-mentioned embodiment,
the zoom processing is applied to the main video pipeline for
presentation over the primary video outputs. The video for the
secondary outputs needs to be "de-zoomed" before presentation on
the secondary video outputs. The secondary outputs would also need
to show a different style of output than the primary video outputs
due to the inherent video cropping that takes place in the zoom
modes (for example, the primary outputs may present a zoomed 4:3
image whereas the secondary outputs may be expected to present a
4:3 letterboxed output).
[0188] FIG. 21 depicts an exemplary embodiment 230 for implementing
the above processes and methods. A set-top box 220 receives the
incoming video from a cable or other source. A video processor 221
performs the above-mentioned processes based on programming stored
in its memory 222. The converted video is output to a display 225.
A remote control 226 activates the zoom toggle feature discussed
above via a receiver 223 in the set-top box 220. A graphical user
interface 224 interacts with the user to set the television type
and other settings mentioned above.
[0189] In general, using the present invention a high definition
capable set top receiver is informed of the aspect ratio of the TV
it is connected to (4:3 or 16:9), and using this information the
set top receiver manipulates the received video image using
stretch/zoom techniques. The manipulated video image is then output
to the display using one or more ATSC formats. The set top receive
receives input from the user via front panel, RF, or IR remote
control, for example, to select one or more zoom modes. The set top
receiver will provide at least one customized zoom mode guaranteed
to fill the entire screen of display or television to which the set
to receiver is connected. The set top receiver will also provide
additional zoom modes that are agnostic or independent of the
aspect ratio of the display or television to which the set top
receiver is connected. The set top receiver will then select the
appropriate customized zoom mode automatically based on the aspect
ratio of the display or television without requiring additional
input from the user.
[0190] An exemplary embodiment of a method 240 for controlling the
display of an image in a video signal being output to a display is
shown in FIG. 22. The set top receiver receives information as to
an aspect ratio of the display to which the set-top receiver is
connected (step 241). The set top receiver then manipulates the
received video image using a stretch/zoom technique to provide at
least one customized zoom mode guaranteed to fill an entire screen
of the display, as well as to provide one or more additional zoom
modes that are independent of the aspect ratio of the display (step
242). The manipulated video image is output to the television or
display using one or more ATSC formats (step 243). Input from a
viewer is then used to select one of the at least one customized
zoom mode or the one or more additional zoom modes (step 244). In
the case of no input from the viewer, the zoom mode is set
automatically based on the aspect ratio of the display without
requiring additional input from the user (step 244).
SUMMARY
[0191] The present invention includes exemplary embodiments
implementing the ASTB Stretch Mode and the ASTB Zoom Mode features
for the set-top boxes. Although various embodiments are
specifically illustrated and described herein, it will be
appreciated that modifications and variations of the invention are
covered by the above teachings and are within the purview of the
appended claims without departing from the spirit and intended
scope of the invention. For example, certain aspect ratios are
discussed, however, the present invention is applicable to other
aspect ratios. Furthermore, this example should not be interpreted
to limit the modifications and variations of the invention covered
by the claims but is merely illustrative of possible
variations.
* * * * *