Image analysis – Applications
Reexamination Certificate
1997-12-31
2002-05-14
Bella, Matthew C. (Department: 2621)
Image analysis
Applications
C345S501000, C345S502000
Reexamination Certificate
active
06389149
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention pertains to a method and apparatus for improving video processing in a computer system or the like. More particularly, the present invention pertains to a method and apparatus for combining video throughput enhancement features into a single computer architecture.
Computer systems are increasingly being used for the capture and display of video images (e.g., in video phone/conferencing applications). An example of a bus architecture for a laptop computer system is shown in
FIG. 1. A
processor
1
(e.g., a PENTIUM® processor manufactured by Intel Corporation, Santa Clara, Calif.) is coupled to a bus
12
. Bus
12
allows communication between processor
11
and a plurality of other components such as graphics subsystem
13
which in turn is coupled to a display
14
(e.g., an active matrix display). Also coupled to bus
12
is a PCMCIA (Personal Computer Memory Card International Association, Release 2.0, September 1991) bridge circuit
15
. PCMCIA bridge circuit
15
is coupled to a number of insertable/removable peripheral components via ports
16
a
,
16
b.
For video applications, a video capture card
17
can be coupled to PCMCIA bridge circuit
15
via port
16
a
, for example. With the video capture device, a camera
18
, for example, generates a video input signal and the video capture device generates video image data. In its raw, uncompressed form, the video image data is typically presented as 30 “frames” per second by video capture card
17
. In actuality, each frame comprises odd and even “fields,” where an odd field represents odd numbered scan lines for the display
14
and the even field represents even numbered scan lines for display
14
. In typical video capture devices for computer applications, one of the fields (e.g., the odd field) is not used and is discarded by video capture card
17
.
Bus
12
will have certain bandwidth restrictions, as well. A video output that comprises 320 picture elements (“pixels”) by 240 pixels for 30 fields per second where each pixel is represented by a two byte value (i.e., 16 bits) requires a bandwidth of 36.884 million bits per second on the bus. To reduce the impact on bandwidth for the bus, video capture card
17
could compress the video image data prior to placing it on the bus. An example of such a product is the CaptureVision PCMCIA card (Nogatech, Inc., Cupertino, Calif.). This PCMCIA card includes a digital signal processor (DSP) which compresses the video image data using any of a variety of compression techniques (e.g., MPEG-I and MPEG-II, International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) 11172-2 and 13818-2). This PCMCIA card, which could be inserted in slot
16
a
, compresses the video image data from camera
18
and sends the data to processor
11
. Processor
11
then acts on the compressed data to decompress this data and transfer it to the graphics subsystem
13
over bus
12
which then outputs the video image to the user at display
14
. In a video phone application, processor
11
will also act to convert the same video image data into a form for transfer over a network
20
(e.g., a telephone system such as plane old telephone system—POTS) to another user (e.g.,“User B”
21
) via a modulator/demodulator (modem)
19
. Processor
11
also acts to convert the video image data from User B
21
over network
20
into a form for display by graphics subsystem
13
. A typical network protocol for transmitting such information over network
20
is the H.261 (International Telecommunication Union—Telecommunications Standardization Sector (ITU-T), March, 1993) standard and the H.263 (ITU-T, Dec. 5, 1995) standard. Processor
11
works on this information to convert it once again into a form that can be transferred over bus
12
to graphics subsystem
13
and to the display
14
.
There are two basic drawbacks to PCMCIA cards of this type. The first drawback is that these cards are expensive, in part because of the digital signal processor component. The second drawback is that the operation of the DSP works to slow down the overall system because of the time that is needed to compress data.
One system to increase throughput of video image data is an extension to the PCMCIA standard that provides a so-called Zoom Video port connection. Referring to
FIG. 2
, a standard Zoom Video system is shown. Again, a processor
31
is coupled to a bus
33
to which is coupled a graphics controller
34
(e.g., a 65554 or 65555 graphics controller from Chips and Technology, Inc.) and the rest of a graphics subsystem
35
. In this example, bus
33
operates according to the Peripheral Component Interconnect (PCI) standard (Rev. 2.1, PCI Special Interest Group, Hillsboro, Oreg., 1995). A video capture card
39
is coupled to a PCMCIA interface, which in turn is coupled to the PCI bus. If the video capture card
39
operates according to the Zoom Video extension, a Zoom Video Bus/port
37
is provided that is coupled between video capture card
39
and the graphics controller chip of the graphics subsystem. The execution of a software driver (e.g., stored in memory
41
) operates as an interface between processor
31
and the PCMCIA bridge
43
as well as graphics controller
34
. Using the software driver, the PCMCIA bridge can receive a command causing it to be placed in a so-called tri-state mode of operation, and video image data output by video capture card
39
(from camera
40
) are not processed by PCMCIA bridge
43
(i.e., not placed onto the PCI bus
33
). Instead, the Zoom Video Bus/Port
37
ID carries the video data signals from video capture card
37
directly to graphics controller
34
and on to the graphics subsystem
35
to display
36
. Though the Zoom Video system can handle
30
frames per second (60 fields per second) in video data, such a system is not effective for processor
31
which does not see the information that is being sent over the Zoom Video bus/port
37
. This is do, in part, to the fact that graphics controller
34
tends to be a one-way device (i.e., data generally flows from the PCI bus
33
and Zoom Video bus/port
37
to the graphics subsystem
35
rather than vice versa).
As described above, the Zoom Video bus/port bypasses the PCI bus since no data is sent on the bus and instead passes as a “side band” signal. To increase the amount of data that can be transmitted to/from peripheral devices (such as a video capture card), the Cardbus interface standard was developed (now part of the PC Card interface; March 1997 release from PCMCIA). An example of a video-conferencing system that uses the Cardbus system is shown in FIG.
3
. Processor
51
once again is coupled to bus
55
operating according to the PCI standard. The bus is further coupled to a modem
57
, a graphics subsystem
58
which includes a graphics controller
59
, and a PC Card bridge
60
. An example of a PC card bridge would be the PCI
1130
bridge from Texas Instruments, Inc. (Dallas, Tex.). PC card bridge
60
serves as an interface to the PCI bus
55
for peripheral components coupled to slots
61
a
and
61
b
. PC Card bridge
60
serves as a PCMCIA interface (a 16-bit interface such as component
43
in
FIG. 2
) and also as a Cardbus interface (a 32-bit interface) depending on the type of component inserted into slots
61
a
and
61
b
. A video capture device
63
operating according to the Cardbus interface can be inserted into slot
61
a
. An example of such a device is the Noteworthy Cardbus video capture card from Toshiba America Information Systems, Inc. In operation, the Noteworthy Cardbus video capture card converts video input signals from camera
65
into video image data that are passed through PC Card bridge
60
, using the Cardbus standard, and onto PCI bus
55
. As in the other systems described above, only one of the fields (odd or even) is sent while the other is typically discarded. Processor
51
then acts to compress these video data signals as described above and send the appropriate image to modem
57
Bella Matthew C.
Intel Corporation
Kenyon & Kenyon
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