U.S. patent application number 11/180313 was filed with the patent office on 2006-03-23 for multi-instance input device control.
This patent application is currently assigned to Logitech Europe S.A.. Invention is credited to John D. Bateman, Tim Dieckman, Aaron Standridge.
Application Number | 20060064701 11/180313 |
Document ID | / |
Family ID | 25380784 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060064701 |
Kind Code |
A1 |
Bateman; John D. ; et
al. |
March 23, 2006 |
Multi-instance input device control
Abstract
The present invention combines features of an executable process
with the need for multiple application programs to share a single
input device. The present invention provides an executable program
implemented as a process that allows multiple applications to
communicate with a single input device. This is achieved by loading
the input device control executable program as a process. The
executable program is a server thus allowing multiple application
programs to interface with the same input device. The
multi-instance input device control (MIIDC) executable program
responds to each application program request as if the input device
is open for the calling application program. Each application
program is thus enabled to communicate with the input device
instance without interrupting the operation of other application
programs communicating with the input device. The input device
instance keeps track of all the connections to it and multiplexes
and resolves conflicting requests.
Inventors: |
Bateman; John D.; (San
Francisco, CA) ; Standridge; Aaron; (Newark, CA)
; Dieckman; Tim; (San Francisco, CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Logitech Europe S.A.
Romanel-sur-Morges
CH
|
Family ID: |
25380784 |
Appl. No.: |
11/180313 |
Filed: |
July 12, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09882527 |
Jun 15, 2001 |
6918118 |
|
|
11180313 |
Jul 12, 2005 |
|
|
|
09438012 |
Nov 10, 1999 |
6539441 |
|
|
09882527 |
Jun 15, 2001 |
|
|
|
Current U.S.
Class: |
719/328 |
Current CPC
Class: |
G06F 9/542 20130101;
G06F 9/52 20130101; G06F 15/163 20130101; G06F 3/0481 20130101;
G06F 13/10 20130101; G06F 9/4411 20130101; G06F 2209/543 20130101;
G06F 13/102 20130101; G06F 13/12 20130101 |
Class at
Publication: |
719/328 |
International
Class: |
G06F 13/00 20060101
G06F013/00 |
Claims
1. An input device control program which allows multiple client
application programs to simultaneously communicate with a single
input device, wherein said input device control program is loaded
as a process, and wherein all subsequent application programs call
to said process to establish communication with said single input
device.
2. The input device control program of claim 1 wherein said input
device comprises a digital Internet video camera.
3. The input device control program of claim 1 wherein said input
device comprises a microphone.
4. The input device control program of claim 1 wherein said input
device control program comprises routines for: a) video control
methods comprising: i) initializing a video control; ii) taking
digital still images; iii) recording digital video images; iv)
obtaining video driver information; v) setting video camera
properties; and vi) obtaining video camera properties; b) video
camera event notification comprising: i) motion detection
notification; ii) audio visual (AVI) error notification; iii)
camera detached notification; and iv) camera reattached
notification.
5. The input device control program of claim 1 wherein said process
handles all details of network protocols comprising: loading said
input device control program; calling to said input device control
program with relevant input/output data; buffering input and output
to/from said input device control program; executing said input
device control program; and unloading said input device control
program.
6. A input device control program which allows multiple client
application programs to simultaneously communicate with an input
device, wherein said input device control program in response to a
first application program calling for a first connection to be
established to said input device: i) passes said first application
program's calls to a process' application program interface (API);
ii) causes said process' network protocol to load said executable
input device control program onto a process server; iii) causes
said process server to create a single input device instance and
connects said single input device instance to said input device;
iv) causes said process server to create a first input device
control instance and connects said first input device control
instance to said single input device instance; v) causes said
process server to create an interface through which said client
application program communicates with said single input device
instance, and vi) causes a second input device control instance to
be created in response to a call from a second application program
calling for a second connection to a said single input device and
connecting said second input device control instance to said single
input device instance allowing said second application program to
communicate with said same single input device instance.
7. The input device program of claim 6 wherein said input device
control program is a distributed component object model (DCOM)
executable program which comprises routines for: a) video control
methods comprising: i) initializing a video control; ii) taking
digital still images; iii) recording digital video images; iv)
obtaining video driver information; v) setting video camera
properties; and vi) obtaining video camera properties; b) video
camera event notification comprising: i) motion detection
notification; ii) audiovisual AVI error notification; iii) camera
detached notification; and iv) camera reattached notification.
8. The input device control program of claim 6 wherein said process
is a distributed component object model (DCOM) executable
program.
9. A distributed component object model (DCOM) executable input
device control program which allows multiple client application
programs to simultaneously communicate with a input device, wherein
said program in response to a first application program calling for
a first connection to be established to said input device: i)
passes said first application program's calls to a DCOM application
program interface (API); ii) causes said DCOM's network protocol to
load said executable input device control program onto a DCOM
server and; iii) causes said DCOM server to create a single input
device instance and connects said single input device instance to
said input device; iv) causes said DCOM server to create a first
input device control instance and connects said first input device
control instance to said single input device instance; v) causes
said DCOM server to create an interface through which said; client
application program communicates with said single input device
instance, and vi) creates a second input device control instance to
be created in response to a call from a second application program
calling for a second connection to a said single input device and
connecting said input device instance to said single input device
instance allowing said second application program to communicate
with said same single input device instance.
10. A computer useable medium having computer readable code
embodied therein for causing the simultaneous sharing of an input
device by multiple application programs running on a host and
calling to said input device, said computer readable code
virtualizing an input device driver file, where said computer
readable code is implemented in an executable client-sever
architecture, where each of said application programs is a client,
and where said computer readable code is a server.
11. The computer useable medium of claim 10 wherein said input
device comprises a digital video camera interfaced with said
host.
12. The computer useable medium of claim 10 wherein said input
device comprises a microphone interfaced with said host.
13. The computer useable medium of claim 10 wherein said host is
selected from the group consisting of a personal computer, a
handheld computer, an interactive set-top box, a thin client
computing device, a personal access device, a personal digital
assistant, an internet appliance, an internet connected digital
picture frame and combinations thereof.
14. The computer useable medium of claim 10 wherein said
application programs communicate with said client-server
architecture via a client side mechanism implemented as an input
device portal.
15. The computer user medium of claim 14 wherein said input device
portal is an ActiveX control.
16. The computer useable medium of claim 10 wherein said
application programs communicate with said client-server
architecture via a client side mechanism implemented as a virtual
source filter.
17. A method for allowing multiple client application programs to
communicate with a single input device, said method comprising: i)
passing a first application program's calls to a process'
application program interface (API); ii) causing said process'
network protocol to load an executable input device control program
onto a process server and; iii) causing said process server to
create a single input device instance and connecting said single
input device instance to said single input device; iv) causing said
process server to create a first input device control instance and
connecting said first input device control instance to said single
input device instance;
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
09/882,527, filed Jun. 15, 2001, which is a continuation-in-part
("CIP") of application Ser. No. 09/438,012, filed Nov. 10, 1999,
which are all incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to media source input devices
such as microphones and video cameras, and in particular to the
interfacing of media source input devices to application
programs.
[0003] Traditionally, when one application program connects to a
media source, all other application programs are prevented from
using that media source. In the context of a common personal
computer, when an application program calls to communicate with a
media source, the application program calls to the driver files or
the dynamic link library (DLL or *.dll) files. Typically, a DLL
provides one or more particular functions and a program accesses
the function by creating a link to the DLL. DLL's can also contain
data. Some DLL's are provided with the operating system (such as
the Windows operating system) and are available for any operating
system application. Other DLL's are written for a particular
application and are loaded with the application program (such a
media source control application program). When a media source
control application program calls to connect to a media source, at
that point, the driver checks to make sure that no other
application has opened the particular camera driver file (*.dll),
and if no other has, the driver will open the particular driver
file. Having done so, there now exists a single threaded connection
between the media source (e.g., video camera) and the application
program through the opened media source (e.g., video camera) driver
file as seen in FIG. 1.
[0004] FIG. 1 shows an application program connecting with a media
source, which is a video camera. As depicted in FIG. 1, the driver
file 14 is opened by the driver 12 which is called by the calling
application program 10 and gets loaded in the calling application
program's memory. Since the video camera driver file 14 has been
opened by the application program 10, the next application that
attempts to make a call to the video camera is prevented from doing
so. The issues related to conflicts in sharing a media source
between multiple application programs is known as contingency
issues. There will be contingency issues, since typical input
device drivers only allow one application to use the input device
data at any given time. This is because the video camera driver
file has been loaded in the first application program's memory and
is not available to be accessed by another calling program.
Therefore, each application program that potentially makes calls to
a video camera must account for the presence of another application
program possibly already using the camera. Accordingly, such
application programs are encumbered by the need to first check to
determine whether another first application program was executed
that had connected to the video camera, and if so the second
calling program must have routines allowing it to negotiate the
sharing of the camera. However such sharing is a single-instant
one, meaning the that connection between the camera and the first
application program would have to be broken (i.e. the first
application program would have to be shut down or the video camera
turned off) before the connection between camera and the second
application program could be established. Authority, priority, and
other security aspects as well as appropriate error handling must
also be resolved by the communications between the two competing
application programs. Presently, no application program even
attempts to resolve any of these issues, and therefore if a
connection between a calling program and a camera cannot be
established, the unexpected application programs errors are
resolved by the operating system which issues rather inelegant and
undecipherable error messages leaving the ultimate user to only
infer that a proper connection could not be established. At best,
the second calling application program receives a message that the
device being called to is currently in use and not available.
[0005] Application programs have continued to grow in size,
flexibility and usability, and the trend has been to move away from
large monolithic application programs to programs that are made of
many smaller sub-programs. This building block approach provides
many advantages such as ease of later modification and
configurability. Moreover, operating system suppliers, such as
Microsoft, have also adopted such a modular approach and hence
offer many standard sub-programs or objects that handle many
utility-type functions such as queuing files to a printer, and
loading and running printer driver (e.g., DLL) files to print
files. The driver (e.g., DLL) files themselves are objects or
sub-programs. Further, in an effort to allow interoperability
between objects and smaller sub-programs written in different high
level programming languages, operating systems suppliers have
developed models for executable programs, which can be compatible
with each other at the binary level. One such model for binary code
developed by the Microsoft Corporation is the component object
model (COM). The COM enables programmers to develop objects that
can be accessed by any COM-compliant application. Although many
benefits can be realized by transitioning from large monolithic
application programs to sets of smaller sub-programs and objects,
those advantages must be balanced against the burdens imposed by
the need for the additional routines allowing for inter process
communications amongst these sub-programs and objects.
[0006] Besides growing in complexity and usability, multi-unit
application programs have been migrating from single-host sites to
multiple host heterogeneous network environments. Consequently, it
is now not unheard of to have a single application program be
comprised of many different routines, each written in different
high level programming languages and each residing on a separate
computer, where all those computers are connected to each other
across a network. In such implementations, the demands for
efficient intra and inter-network and inter-process communications
can take on a life of their own, detracting from the programmer's
primary function of writing an application program. The programmer
also has to handle the communications issues posed by spreading
application programs across a network. Once again, operating
systems suppliers have realized this challenge and potential
detraction and have addressed it in various ways. For example,
Microsoft has extended the COM functionality by developing the
distributed component object model (DCOM). DCOM is an extension of
COM to support objects distributed across a network. Besides being
an extension of COM, DCOM provides an interface that handles the
details of network communication protocols allowing application
programmers to focus on their primary function of developing
application specific programs. DCOM is designed to address the
enterprise requirements for distributed component architecture. For
example, a business may want to build and deploy a customer order
entry application that involves several different areas of
functionality such as tax calculation, customer credit
verification, inventory management, warranty update and order
entry. Using DCOM the application may be built from five separate
components and operated on a web server with access via a browser.
Each component can reside on a different computer accessing a
different database. The programmer can focus on application
development and DCOM is there to handle the inter process
communications aspects of the separate components of the
application program. For example, DCOM would handle the integration
of component communication with appropriate queues and the
integration of component applications on a server with HTML-based
Internet applications.
[0007] Thus, while many computer system operating system suppliers
are providing many standardized models for executable programs,
even such executable programs can only interface with a media
source input device on a one-on-one basis. A standardized device
driver file, once linked to an application program, is no longer
available for use by another program. There is a need to allow
multiple application programs to share a single media source input
device, which most commonly is a video camera or microphone.
SUMMARY OF THE INVENTION
[0008] The present invention combines features of an executable
process with the need for multiple application programs to share a
single input device, such as video camera or a microphone. An input
device such as a video camera or a microphone is a peripheral
device that is opened and remains open in response to a call from
an application programs. The present invention provides an
executable program implemented as a process that allows multiple
applications to communicate with a single input device. This is
achieved by creating a virtual interface (an instance) to the
physical input device and by loading the input device control
executable program into a process. An instance is an actual usage
and the resulting virtual creation of a copy of an entity loaded
into memory. The executable program process acts as a server thus
allowing multiple application programs to interface with the same
input device. This executable program, which as used herein is
referred to as the multi-instance input device control (MIIDC)
executable program responds to each application program request as
if the input device is open for the calling application program.
Each application program is thus enabled to communicate with the
input device instance without interrupting the operation of other
application programs communicating with the same input device. In
other words, the MIIDC virtualizes an input device by creating s
client-server architecture, where each calling application program
is a client and where the MIIDC is the server, serving the driver
file to each calling application program.
[0009] The MIIDC and the method of virtualizing an input device are
implementable on many computing platforms running various operating
systems. A media source input device such as a video camera or a
microphone is commonly interfaced with a host computer. The host
computer is most commonly a personal computer, such as the commonly
available PC of Mac computers. However, since advancements in
technology are blurring the boundaries between computing and
communication devices, a host computer as used herein is synonymous
with an intelligent host, and an intelligent host as used herein is
meant to include other examples of any host having a processor,
memory, means for input and output, and means for storage. Other
examples of intelligent hosts, which are also equally qualified to
be used in conjunction with embodiments of the present invention
include a handheld computer, an interactive set-top box, a thin
client computing device, a personal access device, a personal
digital assistants, and an internet appliance.
[0010] In one implementation on a PC host running a common
Windows-based operating system, the (MIIDC) executable program can
be a DCOM object. DCOM can also serve as an interface that allows
multiple application programs to communicate with a single input
device. The DCOM interface handles all interfacing operations such
as: loading, executing, buffering, unloading and calling to the
executable program. In the DCOM-based implementation, the MIIDC
object itself is a DCOM server. The MIIDC program works by
connecting to the input device in a DCOM object implemented as an
executable server. Consequently, the MIIDC becomes a DCOM object
implemented as an executable program, meaning that MIIDC is a
process--like any other operating system (O/S) process--sharable by
many applications. By placing the input device access program into
a separate executable process, the input device is capable of being
shared by multiple application programs. The DCOM interface appears
to the application program as if it is being opened just for the
application that calls to the DCOM object, while there's only one
instance of the input device.
[0011] MIIDC is implemented so that for each actual hardware input
device, the DCOM server creates a single input device instance and
connects to the hardware device. When an application program
connects with the input device control--which is an executable DCOM
server--the DCOM server creates a MIIDC instance (and an interface)
through which the application program communicates with the single
input device instance. Data is provided for output by the single
input device instance for each instance of the input device
control, thus allowing simultaneous multiple applications to
communicate with a single input device. Global settings are (MIIDC)
instance specific. Additionally, the input device instance is
protected so that multiple instances of the input device control
program cannot perform tasks that would interfere with processing
in another instance. Using this new approach, applications can be
written which do not need to account for the presence of another
application possibly already using the same input device.
[0012] Other aspects of the present invention are directed towards
the client-side mechanisms that enable an application program to
communicate with the input device server executable. As described
above, the MIIDC executable is implemented under a client-server
architecture, where each application program is a client.
Naturally, a client must be able to communicate with the server.
The method of the present invention provides several mechanisms
that enable an application program to communicate with the MIIDC
server. In a PC/Windows environment, a first client-side mechanism
is delivered via an ActiveX control called an input device portal.
A second client-side mechanism also under a PC/Windows environment,
is delivered via a DirectShow.TM. video capture source filter.
[0013] The client side mechanisms under the portal approach include
communicating with the MIIDC server and supplying user-interface
elements to an application. With the portal approach, all
functionality of virtualizing an input device is performed by the
MIIDC server, and thus, application programs communicating with the
MIIDC server will require user-interface programming. To accomplish
this, under the video-portal approach, a template is provided to
allow various application program providers to generate their own
custom input-device portal.
[0014] The client-side mechanism under the second approach (i.e.
DirectShow approach) takes advantage of the standardized DirectShow
modular components called filters. This second client-side
mechanism replaces the standard source (media input) filter with a
virtual source filter, which communicated directly with the MIIDC
server. The virtual source filter is a client to the MIIDC server.
With this mechanism, a DirectShow application cannot distinguish
between the "real" and the "virtual" source filter. The advantage
of this second client-side mechanism is that any application
program written to function in a DirectShow environment, will be
able to readily share an input device without the need for any
additional user-interface programming before being able to
communicate with the MIIDC server.
[0015] For a further understanding of the nature and advantages of
the present invention, reference should be made to the following
description in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a block diagram showing the prior art method of a
single application program communicating with a single video camera
device.
[0017] FIG. 2 is a block diagram depicting one embodiment of the
present multi-instance input device control program.
[0018] FIG. 3 is a flow chart showing the steps involved in an
application connecting to a single input device.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0019] FIG. 2 shows a block diagram depicting one embodiment of the
present multi-instance input device control program (MIIDC) in a
PC/Windows environment. In this embodiment, the input device is a
video camera, and the executable program is a DCOM executable
server. This figure shows how multiple application programs may
share a single video camera. Once a first application program 100
calls to connect to the video camera 108, the call is passed to the
DCOM application program interface (API) 102. The appropriate
Microsoft documentation or the Microsoft website may be referred to
for a more detailed description of DCOM. The DCOM API 102 handles
the loading of the DCOM executable program and establishes a
connection from the application program to the DCOM executable
program 200. The DCOM server 200 creates a single video camera
instance 106 and a first MIIDC instance 104. Next, the DCOM server
200 connects the single video camera instance 106 to the video
camera driver 107, the video camera driver 107 to the video camera
device 108 and the first MIIDC instance 104 with the single video
camera instance 106. The video camera instance 106 is a virtual
interface to the physical video camera device 108. An instance is
an actual usage and the virtual creation of a copy of an entity
loaded into memory. In this embodiment all instance memory is
allocated in the executable server. Finally the connection 300 is
established allowing client application 100 to interact through the
newly instantiated DCOM interface (single video camera instance)
106 with the video camera device 108.
[0020] Once a second application program 110 calls to connect to
the video camera 108, the DCOM server 200 creates a second MIIDC
instance 114, and connects it to the single video camera instance
106 thus allowing the second client application 110 to interact
through the single video camera instance 106 with the video camera
device 108 via the second established connection 310. Subsequent
application program calls 120, et. seq. also interact through the
DCOM instantiated single video camera instance interface 106 with
the video camera device 108 via the subsequently established
connections 320, et seq.
[0021] FIG. 3 is a flowchart depicting the process of FIG. 2. Once
a client application program calls to connect to the video camera
device (step 103), the application program's call is sent to the
DCOM API (step 203). Next, the DCOM API determines whether the DCOM
implemented MIIDC executable is loaded or not. Typically the first
client application program causes the MIIDC executable to be
loaded. If the MIIDC executable server is not loaded, the DCOM API
takes the call and causes the DCOM server to load the DCOM
implemented MIIDC executable server (step 403). Next, the MIIDC
server creates an input device control instance (step 503). If the
MIIDC executable server had already been loaded, step 403 becomes
unnecessary, and the next step after step 303 would be step 503.
The MIIDC server next creates a single video camera instance and
connects it to the video camera device, and connects the input
device control instance to the single video camera instance (step
603). Finally, the MIIDC server creates an interface through which
the first client application program communicates with the single
camera instance (step 703).
[0022] The video camera instance 106 depicted on FIG. 2 is an
interface with the video camera device that maintains the state of
the input device control's instance. The input device instance 106
is a block of memory that maintains the necessary accounting of the
number of connections that have been established with the video
camera device, and the particular states of each of these
connections. The video camera instance 106 also incorporates the
logic necessary to prioritize the requests from each input device
control instance connection and multiplex and resolve conflicting
requests. Since the MIIDC server exists as a separate process,
video (and audio) data must be replicated for each client requiring
access to the video (and audio) data. To reduce data replication,
the MIIDC server is designed to record video (and audio), detect
motion, save pictures, as well as other functions which are typical
of a media source capture device. The MIIDC server thus limits the
data replication to only those applications requiring direct access
to media source (e.g., video and audio) data.
[0023] For example, the first input device instance may be
requesting a video stream having a resolution of 640 by 480 pixels,
while the second and third instances may be requesting video
streams having 320 by 480 and 160 by 120 pixel resolutions
respectively. In such a scenario, the video camera instance 106
would then decide to capture video at the largest resolution of 640
by 480 pixels and then scale it or crop it down to the lower
resolutions being requested by the second and third instances.
Following the same logic, if consequently the first video instance
disconnects from the video camera, the video camera instance 106,
would then resolve the requests from the second and third instances
requesting 320 by 480 and 160 by 120 pixel resolutions
respectively, by capturing video at the highest requested
resolution of 320 by 480 pixels to satisfy the second instance's
request and then scaling down or cropping the 320 by 480 pixels
video stream down to 160 by 120 pixels to satisfy the third
instance's request.
[0024] In another example involving three input device control
instances, the first input device control instance may be sending a
motion detection command to the virtual video camera device, while
the other two instances are only requesting video streams. Now the
video camera instance 106 would capture video at the highest
demanded resolution and only pass that video stream through a
motion detection calculation for the first input device control
instance.
[0025] In yet another example involving three input device control
instances, the second input device control instance may be
requesting a text overlay on the video image, while the other two
instances are only requesting video stream captures. Now, the video
camera instance 106 would capture video at the highest demanded and
only add the text overlay to the stream flowing to the second input
device request.
[0026] While the embodiments described thus far were generally
described in the context of a video camera that is interfaced with
a personal computer host, the scope of the present invention is not
meant to be limited solely to a video camera or even a particular
type of personal computer host. As described above, the embodiments
of the present invention are directed towards the simultaneous
sharing of an input device by several application programs by
virtualizing a device driver file which is in turn achieved by
implementing the input device control program as an executable
server. While the input device described above is a video camera,
another input device that can be configured to be simultaneously
shared is a microphone. Thus, the input device instance (106 on
FIG. 2) incorporates the logic necessary to prioritize the requests
from each input device control instance and multiplex and resolve
conflicting requests. Extending the sharing capabilities of video
source to also include an audio input source, is not only a natural
one, but it is also almost mandatory, since video and audio are
most commonly bundled together as naturally complementary media
sources.
[0027] For example, referring back to FIG. 2, it is expected to
consider that a microphone (not shown) is also recording sound
while the device 108 is recording video. Then for example, the
first input device instance may be requesting audio having a bit
depth of 16-bits at 44.1 kHz, while the second instance may be
requesting audio streams having an 8-bit depth at 11.025 kHz. In
such a scenario, the input device instance will then decide to
capture audio at the highest sampling rate and bit depth and then
scale, or compress it down to the lower bit depth or sampling rate
being requested by the second instance.
[0028] The MIIDC and the method of virtualizing an input device are
implementable on many computing platforms running various operating
systems. A media source input device such as a video camera or a
microphone is commonly interfaced with a host computer. The host
computer is most commonly a personal computer, such as the commonly
available PC of Mac computers. However, since advancements in
technology are blurring the boundaries between computing and
communication devices, a host computer as used herein is synonymous
with an intelligent host, and an intelligent host as used herein is
meant to include other examples of any host having a processor,
memory, means for input and output, and means for storage. Other
examples of intelligent hosts, which are also equally qualified to
be used in conjunction with embodiments of the present invention
include a handheld computer, an interactive set-top box, a thin
client computing device, a personal access device, a personal
digital assistants, and an internet appliance.
[0029] Other aspects of the present invention are directed towards
the client-side mechanisms that enable an application program to
communicate with the input device server executable. As described
above, the MIIDC executable is implemented under a client-server
architecture, where each application program is a client.
Therefore, a client must be able to communicate with the server.
The method of the present invention provides several mechanisms
that enable an application program to communicate with the MIIDC
server. In a PC/Windows environment, a first client-side mechanism
is delivered via an ActiveX control called an input device portal.
A second client-side mechanism also under a PC/Windows environment,
is delivered via a DirectShow video capture source filter.
[0030] The client side mechanisms under the portal approach include
communicating with the MIIDC server and supplying user-interface
elements to an application. With the portal approach, all
functionality of virtualizing an input device is performed by the
MIIDC server, and thus, application programs communicating with the
MIIDC server will require user-interface programming. To accomplish
this, under the video-portal approach, a template is provided to
allow various application program providers to generate their own
custom input-device portal.
[0031] The client-side mechanism under the second approach (i.e.
DirectShow approach) takes advantage of the standardized DirectShow
modular components called filters. DirectShow.TM. services from
Microsoft.TM. provide playback services for multimedia streams
including capture of multimedia streams from devices. At the heart
of the DirectShow.TM. services is a modular system of pluggable
components called filters. These modular components can be
classified as a source, transform or renderer. Filters operate on
data streams by reading, copying, modifying or writing the data to
a file or rendering the file to an output device. The filters have
input and output means and are connected to each other in a
configuration called a filter graph. Application programs use an
object called the filter graph manager to assemble the filter graph
and move data through it. The filter graph manager handles the data
flow from an input device to the playback device. A further
description of DirectShow.TM. services and the Microsoft.TM.
DirectX.TM. media software development kit can be obtained by
referring to appropriate documentation as is known to those of
skill in the art.
[0032] This second client-side mechanism replaces the standard
source (media input) filter with a virtual source filter, which
communicates directly with the MIIDC server. The virtual source
filter is a client to the MIIDC server. With this mechanism, a
DirectShow application cannot distinguish between the "real" and
the "virtual" source filter. The advantage of this second
client-side mechanism is that any application program written to
function in a DirectShow environment, will be able to readily share
an input device without the need for any additional user-interface
programming before being able to communicate with the MIIDC
server.
[0033] As will be understood by those skilled in the art, the
present invention may be embodied in other specific forms without
departing from the essential characteristics thereof. For example,
the MIIDC could be implemented as any other executable process
other than a DCOM based process and any other interfacing protocol
other than the DCOM interface could be used to allow multiple
application programs to communicate with that process. These other
embodiments are intended to be included within the scope of the
present invention, which is set froth in the following claims.
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