Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1999-09-03
2002-12-24
Le, Vu (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C375S240250
Reexamination Certificate
active
06498816
ABSTRACT:
TECHNICAL FIELD
The invention relates generally to image processing circuits and techniques, and more particularly to a circuit and method for formatting each of a series of encoded video images into respective first and second regions. Such formatting facilitates the subsequent overlaying of another image, such as an electronic program guide, onto the video images.
BACKGROUND OF THE INVENTION
FIG. 1
is a video image
6
, which is a video frame that includes a first region
7
and a second region
8
. Although described as a video frame for example purposes, the image
6
may also be a video field. Furthermore, although shown as two rectangles in a top-bottom arrangement, the number, shape, and respective locations of these regions is arbitrary.
Typically, one views a sequence of video frames
6
in their respective entireties. But one may sometimes wish to view another image, i.e., an overlay image, in one of the regions
7
and
8
. For example, one may wish to view an electronic program guide (EPG) in the region
8
while he/she is watching a program in the region
7
(and also in the region
8
if the EPG is transparent). Or, one may wish to view an internet order menu in the region
8
while he/she is viewing merchandise for sale in the region
7
(and also in the region
8
if the menu is transparent). Thus, the overlay image is typically a partial frame that is the same size as or that is smaller than the frame region that it overlays, although the overlay frame can overlay an entire video frame. But for simplicity, both partial and full overlay frames are referred to as “overlay frames”.
FIG. 2
is a block diagram of a conventional television receiver system
10
, which includes a set-top box
11
such as a cable TV (CATV) or satellite TV box, a remote control
12
, and a digital video display
13
. Generally, the box
11
allows one to view overlay images—such as those that compose an EPG—in the respective regions
7
of a sequence of video frames
6
(FIG.
1
). The box
11
includes a processing circuit
14
, which receives an encoded, multiplexed broadcast video signal on an input terminal
15
, receives command signals from the remote control
12
on a command terminal
16
, and generates a video display signal on an output terminal
17
. The broadcast video signal includes one or more broadcast channels and one or more overlay frames such as the frames that compose an EPG, and is encoded according to a compression standard such as the Moving Pictures Experts Group (MPEG) standard (discussed below). In response to channel-select and overlay commands from the remote control
12
, the circuit
14
blends the video frames from the selected channel with the appropriate overlay frame or frames and generates the display signal as a sequence of these blended video frames. The display
13
receives the display signal from the terminal
17
and decodes and displays the sequence of blended video frames.
More specifically, the processing circuit
14
includes a command decoder
18
, which decodes the commands from the remote control
12
and generates corresponding control signals, such as an overlay signal, that control other portions of the processing circuit
14
. A channel selector
20
receives the broadcast signal from the terminal
15
and, in response to a channel-select signal from the command decoder
18
, demultiplexes the selected channel from the broadcast signal. In response to an overlay signal from the decoder
18
, the selector
20
also demultiplexes the selected overlay frames from the broadcast signal. For example, the selector
20
may demultiplex the EPG that corresponds to the selected channel. A video decoder
22
decodes the video frames of the selected channel into pixel-domain frames, i.e., frames of pixel luminance and chromanance values. In response to the overlay signal, the video decoder
22
also decodes the selected overlay frames into the pixel domain, and an overlay/video combiner
24
blends the decoded video frames with the decoded overlay frames. Conversely, if the command decoder
18
does not generate an overlay signal, then the selector
20
does not demultiplex the overlay frames, and thus the combiner
24
merely passes through the decoded video frames from the decoder
22
. In one embodiment, the output terminal of the combiner
24
is coupled directly to the output terminal
17
. But because it is sometimes undesirable to couple decoded video frames (blended or unblended) directly to the display
13
, in another embodiment the circuit
14
includes an optional re-encoder
26
, which re-encodes the decoded video frames from the combiner
24
before providing them to the display
13
. Although shown as including a number of separate circuit blocks, the processing circuit
14
may include one or more processors that perform the functions of the above-described circuit blocks
18
,
20
,
22
,
24
; and
26
.
Still referring to
FIG. 2
, in operation during a period when a viewer does not want to view an overlay frame, he selects a channel with the remote control
12
, which generates a corresponding control signal. The control terminal
16
, which is typically an infrared detector, receives the control signal and couples it to the command decoder
18
. In response to the control signal, the decoder
18
generates the channel-select signal, which causes the channel selector
20
to recover the encoded video signal of the selected channel by demultiplexing the broadcast signal. The video decoder
22
decodes the recovered video signal into frames of pixel values, and the combiner
24
passes these frames to the optional re-encoder
26
, which re-encodes the frames and provides a re-encoded video signal to the display
13
. If, however, the re-encoder
26
is omitted, then the combiner
24
passes the decoded frames directly to the display
13
.
In operation during a period when the viewer wants to view an overlay frame, he selects a channel as described above and also selects an overlay frame or a series of overlay frames, such as an EPG, with the remote control
12
. The decoder
18
generates the channel-select signal and an overlay signal, which together cause the channel selector
20
to recover both the encoded video signal of the selected channel and the encoded video signal containing the overlay frame or frames. The overlay signal causes the video decoder
22
to decode the recovered channel and overlay video signals from the channel selector
20
into respective sequences of frames, and causes the combiner
24
to blend the overlay frames with the channel frames to generate blended frames. The optional re-encoder
26
re-encodes these blended frames and provides them to the display
13
, which decodes the re-encoded blended frames. If, however, the re-encoder
26
is omitted, then the combiner
24
provides the blended frames directly to the display
13
.
Unfortunately, the set-top box
11
cannot utilize the decoding ability of the display
13
, and thus includes its own redundant decoding circuitry, which often adds significant size and cost to the box
11
. Typically, the display
13
includes channel-select and full decoding circuitry respectively similar to the channel selector
20
and the decoder
22
of the box
11
. Thus, the display
13
typically can directly receive the encoded, multiplexed broadcast video signal, recover the encoded video signal of the selected channel, and decode and display the video frames of the recovered video signal. But the display
13
typically cannot blend overlay frames with the video frames. Therefore, to allow such blending, the box
11
includes the same decoding capability (the decoder
22
) as the display
13
. The viewer, however, typically requests the display of overlay frames for only a small portion of the time that he/she spends watching a program. Therefore, because the blending abilities of the box
11
are needed only a small part of the time, the decoding abilities of the box
11
are redundant to those of the display
13
most of the time. That is, the viewer paid for
Easwar Venkat V.
Gove Robert J.
Natarajan Ramachandran
O'Donnell John S.
Equator Technologies Inc.
Graybeal Jackson Haley LLP
Le Vu
Senfi Behrooz
LandOfFree
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