Patent Publication Number: US-2004041902-A1

Title: Portable videoconferencing system

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
     [0001] This application claims the benefit of U.S. Provisional Application No. 60/372,201 filed Apr. 11, 2002. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates generally to conferencing systems, and more particularly to a portable videoconferencing system and method.  
       [0004] 2. Discussion of Prior Art  
       [0005] Videoconferencing is rapidly becoming a popular method of communication among corporations and individuals. Aside from face to face conversations between people, videoconferencing is the only available way for people to communicate both visually and audibly in real time. The ability to view gestures, facial expressions and graphical information in real time during a conference has significant advantages over conventional audio-only telephone conferences. In many situations, the use of videoconferencing avoids or significantly reduces the need for time consuming and expensive business travel.  
       [0006] Videoconferencing techniques are used by a wide range of people including, by way of example, engineers discussing designs, medical doctors discussing illnesses, and parents talking with their children in college. For example, engineers working for a company having facilities in the United States, Europe and Asia may advantageously use a videoconferencing system to discuss equipment modifications because they can view the equipment as they discuss it. Without a videoconferencing system the engineers would have to travel to one site where they can both view and discuss the equipment.  
       [0007] A disadvantage with conventional videoconferencing is that all of the sites involved in a conference must have videoconferencing equipment such as that shown in FIG. 1. Typically, a videoconferencing system  100  includes a camera  110 , a display monitor  120 , microphone(s)  130 , speakers  140  and a central processing unit  150 . Videoconferencing system  100  communicates with other devices using standard protocols IEEE 802.3, integrated services digital network (ISDN), T1 and E1. IEEE 802.3 is a standard for wired Local Area Network (LAN) communications such as the Ethernet. ISDN is a communication standard used for sending voice, video and data over digital telephone lines or normal telephone wires at data rate transfers of 64 Kbps. T1 is a dedicated phone connection, used predominantly by businesses, which supports data rates of 1.544 Mbits per second and consists of 24 individual channels, each of which supports 64 Kbits per second. E1 is the European digital transmission equivalent to the T1 Since this type of equipment can be expensive and some companies may not be able or willing to purchase it, this technology has not been fully utilized.  
       [0008] Another disadvantage with conventional videoconferencing system  100  is that its delicate, heavy, and bulky characteristics make it difficult to transport and set up. Consequently it is inconvenient if not impractical to share videoconferencing apparatuses between sites. Since the physical characteristics of current videoconferencing equipment make it impractical to routinely transport such equipment to remote sites and set it up, videoconferences are often not done and someone may have to travel to the remote site. A further disadvantage with conventional videoconferencing system  100  is that it is too bulky and expensive to set up in many offices or homes. Videoconferencing systems  100  are usually located in a meeting or boardroom within a company facility which has a large amount of space.  
       [0009] What is needed is a portable videoconferencing apparatus which is compact and which a user can easily transport to, and set up in, remote sites or in separate locations within a business site.  
       SUMMARY OF THE INVENTION  
       [0010] A portable videoconferencing system comprises a housing; a microphone within the housing for capturing sounds; a video camera within the housing for capturing images; a speaker within the housing for broadcasting sounds; a video display within the housing for displaying images; and, a processing unit within the housing that is coupled to the microphone, the video camera, the speaker and the video display for processing incoming and outgoing audio/video signals. In one embodiment, the videoconferencing system additionally comprises a base unit into which the portable unit or appliance docks. The base unit may contain a power supply and/or network or other I/O connections. In yet another embodiment, the portable videoconferencing system comprises a general purpose notebook computer equipped with a built-in camera, microphone or microphone array, speakers and software for performing real-time protocol conversions between, for example, H.323 and Audio Codec 97.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 shows a prior art stationary videoconferencing terminal,  
     [0012]FIG. 2 is a block diagram of a network useful for videoconferencing;  
     [0013]FIG. 3 is a block diagram showing components in accordance with one embodiment of the invention;  
     [0014]FIG. 4A is a front view of an embodiment of the invention;  
     [0015]FIG. 4B is a rear view of the embodiment of FIG. 4A;  
     [0016] FIGS.  5 A- 5 D are side views of the embodiment of FIGS. 4A and 4B in various positions with and without a base;  
     [0017]FIG. 6 is a block diagram showing hardware components of a videoconferencing pad in accordance with one embodiment of the invention;  
     [0018]FIG. 7 is a flow diagram showing the flow of incoming audio and video streams from a network through the system;  
     [0019]FIG. 8 is a flow diagram showing the flow of incoming audio and video streams from a camera and microphone array through the system;  
     [0020]FIG. 9A is a flowchart showing the software program flow for processing incoming audio and video streams from a network; and  
     [0021]FIG. 9B is a flowchart showing the software program flow for processing incoming audio and video streams from the camera and microphone array. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0022] The present invention provides a system and method for videoconferencing using portable videoconferencing equipment and software which are compact, easy to transport, and easy to set up.  
     [0023]FIG. 2 depicts four exemplars of the inventive videoconferencing pad  210  in a network environment interacting with two conventional videoconferencing systems  220 , two gateways  225 , two switches or hubs  230 , a router  233 , a server  235 , two personal computers  237 , an antenna  240 , and a cellular telephone  242 . These network components  220 - 242  communicate according to standards including IEEE 802.11  245 , Bluetooth  250 , direct 2.5G-3G  255 , and DoCoMo  260 . Videoconferencing pad  210  can interface through an IEEE 802.11  245  or Bluetooth  250  interface directly to other videoconferencing devices  220 .  
     [0024] Once a connection to a gateway  225  is established, the gateway establishes a Primary Rate Interface (PRI) link with a switch or hub  230 . A PRI link typically uses four pairs of wires and provides more bandwidth than the usual T1 connections which use two pairs of wires. Switch or hub  230  is then connected to router  233  which routes the videoconference to the appropriate destination(s). Alternatively, videoconference pad  210  can use a high-speed multimedia data and voice 2.5G-3G coupling  255  to interact directly with a receiver such as an antenna  240 . The 2.5G-3G coupling  255  is designed to deliver high-quality audio and video and to have advanced global roaming capabilities. An apparatus using a 2.5G-3G coupling  255  can operate anywhere by automatically handing off its signal to whatever wireless system is available such as a cellular telephone  242  which in turn relays the signal to an antenna using conventional communication standards such as IEEE 802.11  245  (not shown).  
     [0025]FIG. 3 represents an embodiment of videoconference pad system  210  which includes a housing  410 , a video display  310 , a speaker  320 , a video camera  330 , a microphone array  340 , a communication (com) module  345 , a central processing unit (CPU) with memory  350 , a bus  360 , a video and audio input and output (I/O)  370 , software  380 , and general inputs and outputs  390 . Additionally, videoconference pad system  210  includes a battery  395  and a power supply and regulator  397  which can be connected to bus  360  if bus  360  is built to support a power line.  
     [0026] Housing  410  is discussed in more detail below with reference to FIGS. 4A and 4B.  
     [0027] Video display  310  can be a flat panel display, such as an LCD, PLED, plasma screen, or the like, and is capable of simultaneously displaying multiple active windows. Speaker  320  can be a speaker system with stereo capabilities. Camera  330  can be a high resolution CMOS camera mounted to videoconferencing pad  210  and is used to capture video images of videoconferencing participants. Similarly, microphone array  340  can be high performance acoustic sensors and is used to capture sounds in the videoconference room. Com module  345  is used to establish communications and can contain a PCI interface, wireless processing hardware and software, antenna(s), and an additional battery. CPU with memory  350  processes signals received through bus  360  from camera  330 , microphone array  340  and video/audio I/O&#39;s  370 . Software  380  includes an operating system, algorithms for processing video/audio signals and a graphical user interface (GUI) that enables users to control the videoconferencing pad  210 . General I/O&#39;s  390  are used to attach the videoconferencing pad  210  to other electronic devices such as computers and external recording devices. Battery  395  may be a rechargeable battery such as a Lithium Ion, Nickel Cadmium or Nickel Metal Hydride battery.  
     [0028] Housing  410  (FIGS. 4A, 4B) securely houses all of the components in FIG. 3 and battery  395  supplies power to these components, making videoconferencing system  210  portable. Camera  330  and microphone array  340  capture images and sounds in the room where videoconference system  210  is located and produce video and audio signals. Those signals are transmitted via bus  360  and processed by CPU and memory  350  using software  380 , as further described in reference to FIG. 8, before video display  310  displays the video portion of the signal and signals are transmitted through corn module  345 , video/audio input/output  370  and general inputs/outputs  390 . Incoming video signals, generated by a second party participating in a video conference, are received through corn module  345 , video/audio input/output  370  and general inputs/outputs  390 , processed with CPU and memory  350  and software  380 , routed through bus  360 , displayed on video display  310  and broadcast through speaker  320 .  
     [0029]FIG. 4A shows a front view of the preferred embodiment which includes a housing  410 , a camera  330 , a microphone array including a plurality of microphones  420 ,  421 ,  422 ,  423 ,  424  and  425 , a screen  430  for the video display  310 , speaker  320  units  435  and  436 , a data entry device  440  such as a keypad, an infrared sensor  445 , and a remote control input device  448  separate from the unit. To make videoconferencing pad  210  portable and easy to transport and use, housing  410  has built into it all of the equipment needed to conduct a videoconference, relieving the user of the need to position and connect wires between components such as cameras and speakers. The user can pick up the videoconferencing unit, carry it to another location, and easily set it up. Another advantage of the preferred embodiment is that it can be powered by a rechargeable battery, eliminating the need to locate a power outlet at a remote site.  
     [0030] In the best case setup scenario the user will have a fully charged battery, will choose to use the wireless connection features available on the unit, and will only need to turn the unit ON and use it, without making any connections. In the worst case setup scenario, the user will have an insufficiently charged battery and will choose to make a connection over the Internet through a directly wired LAN or through an external box that can interface with up to 4 ISDN lines using an H.320 link as discussed below with reference to FIG. 4B. In this case the user would need to connect the unit to a network jack and to a power outlet before using video conferencing pad  210 . In either scenario, the set-up procedure is relatively simple and still much easier than wiring several components together.  
     [0031] The camera  330  used to capture the image of the videoconference participants is typically a high resolution CMOS camera positioned at the top center of the housing  410 . System  210  can be equipped with a sensor to track the person talking and the camera  330  can be driven by one or more motor(s) to focus on the person talking or on any object in the room. One embodiment includes a motor drive mechanism that enables panning and tilting camera  330 . In still other embodiments, a zoom feature is included. Panning, tilting and zooming may also be accomplished electronically using a suitably sized imager and a wide-angle lens. The microphones  420 - 425  are positioned on the housing  410  to maximize audio coverage of the room. In one preferred embodiment, four microphones  421 ,  422 ,  423  and  424  are positioned above video screen  425 , and two microphones  420  and  425  are positioned on the sides of video screen  430 . Screen  430  may be an LCD that can be used as a computer monitor when it is not being used in a videoconference call. Keypad  440 , which has a full phone pad layout for speakerphone operation, can be a flip down unit that is securely closed for transportation. Additionally, keypad  440  may have function keys for instant GUI navigation (e.g. select video and audio conferences) as well as arrow keys that allow the user to move between windows and within windows much like the four arrow keys found on a conventional computer keyboard. Remote control device  448  is typically an infrared remote control device that transmits commands through infrared port  445  to the videoconferencing pad  210 . Remote control  448  has the same keys as keypad  440  but allows the user to control the videoconferencing pad  210  from a distance.  
     [0032]FIG. 4A also shows a front view of base unit  450 , which is a detachable part of videoconferencing pad  210 , attached to a power module  452  through a cable  454 . Base unit  450  is a standard base with no additional functionality. It can be replaced by an expanded base unit  457  which has additional functionality as further described with reference to FIG. 4B. Power module  452  converts conventional household electrical AC power, received through an AC power cord  453 , into DC power and transmits the DC power to base unit  450  through cable  454 . Additionally, power module  452  includes a LAN connection  455  and a VGA input  456  which are connected to the base unit  450  through cable  454  giving base unit  450  LAN and VGA access.  
     [0033]FIG. 4B shows a rear view of the embodiment of FIG. 4A which includes an inset handle  460 , a remote control slot  463 , multiple internal slots for NTT DoCoMo mobile link cards  465 ,  466 ,  467 ,  468 , a back stand  470 , a DC power cord  473 , PCMCIA slots  475  and  476  and a base interface  480 . Inset handle  460 , which can be detachable or permanently attached to housing  410 , is for picking up and carrying pad  210 . Remote control slot  463  is for securely storing the remote control device  448  so that it can be transported safely. Internal slots for the NTT DoCoMo mobile link cards  465 - 468  are used to access wireless services through the NTT DoCoMo service provider. Back stand  470  supports videoconferencing pad  210  in an upright position and has one end hinged to the rear of pad  210  while the other end can be pulled out to rest on a horizontal surface, as shown in FIGS. 5A, 5B and  5 D. DC power cord  473  is used to power videoconferencing pad  210  as well as to charge the rechargeable battery in videoconferencing pad  210 . PCMCIA slots  475  and  476  are for using an IEEE 802.11 interface to connect to a LAN. Base interface  480  is a set of interconnects, such as gold-plated electrical connection pads, that allows videoconferencing pad  210  to be easily docked into interconnect  497  of the expanded base  457 . A zero insertion force connection may advantageously be provided between videoconferencing pad  210  and base  450  and  457  because gravity may, in some embodiments, be the only force holding the two together. This feature makes videoconferencing pad  210  a “grab-and-go” device because the user only needs to pick up the videoconferencing pad  210  and carry it to a different location.  
     [0034]FIG. 4B also shows a rear view of one preferred embodiment of the extended base unit  457  which includes a Universal Serial Bus (USB) connector  485 , an H.320 link  487 , a serial I/O port  489 , a VGA output port  491 , a VGA input port  493 , two audio/video I/O ports  495  and  496  and a base electrical interconnect  497 . The relationship between videoconferencing pad  210  and base unit  457  is much like the relationship between a lap top computer and a docking station. To dock portable videoconferencing pad  210  it is placed on top of base unit  457  so that the electrical interconnects  480  on pad  210  line up with the base electrical interconnect  497  on base unit  457 . Videoconferencing pad  210  weighs enough to maintain it securely on base unit  457 . Base unit  457  expands the functionality of videoconferencing unit  210  by providing a USB connector  485  which is a hardware interface for low-speed peripherals such as a keyboard, mouse, joystick, scanner, printer or telephony devices. The USB connector  485  interface supports MPEG-1 and MPEG-2 digital video and has a maximum bandwidth of 12 Mbits/sec. H.320 link  487  facilitates videoconferencing over ISDN communication lines. Serial I/O port  489  allows base unit  457 , along with videoconferencing pad  210 , to be interfaced through an RS232 connection to external RS232 devices (not shown) such as cameras for image capturing and personal computers for purposes of debugging, programming or configuring base unit  457  and videoconferencing pad  210 . VGA output  491  allows hooking up an external video monitor, such as a larger monitor for better viewing. VGA input  493  allows capturing of images from a computer, such as a laptop, for transmission to remote sites. Two audio and video Inputs/Outputs  495  and  496  enable the user to attach videoconferencing pad  210  to external devices such as videocassette recorders for recording a videoconference.  
     [0035] Additionally, FIG. 4B shows power module  452  with AC power cord  453  attached to extended base unit  457  through cable  454 . The details of power module  452  were discussed above with reference to FIG. 4A.  
     [0036] Videoconferencing pad  210  can be transported by turning it OFF, picking it up by inset handle  460  and carrying it in the same way one would carry a laptop computer. Setting it up at its destination is done by turning it ON and, if a wireless connection is not available, connecting it to a communication port such as a phone jack. If the videoconferencing pad&#39;s battery  395  is not charged then power cord  473  must be plugged into a power outlet.  
     [0037]FIGS. 5A, 5B,  5 C and  5 D are side views of videoconferencing pad  210  in several positions. FIG. 5A shows pad  210  supported upright with a back stand  470  and mounted on a standard base  450  in a desktop position. Videoconference pad  210  connects to the standard base through the interconnects on base interface  480 . Standard base unit  450  contains power and recharge circuitry along with VGA output  456 , and LAN connections  455 , and has a single output cable which contains a power cord, VGA in and LAN connections. FIG. 5B shows pad  210  mounted on an extended base  457  in a desktop position. In the embodiment illustrated in FIG. 4B, the extended base  457  has a USB port  485 , a Polycom H.320 link  487  for attachment to H.320 peripherals (Quad BRI, PRI, etc.), a serial I/O  489 , a VGA output  491 , and additional audio/video I/O  495  and  496 . FIG. 5C shows pad  210  mounted on a standard base  450  and supported in an upright position by a wall (not shown). Finally, FIG. 5D shows pad  210  supported upright by a back stand  470  in a desktop position without a base.  
     [0038]FIG. 6 is a block diagram of videoconferencing pad  210  in the preferred embodiment  600 , which includes an expansion connector  605 , details of CPU with memory  350 , LCD  310 , details of speaker system  320  (including two internal speakers  435  and  436 ), a video/audio input/output  370 , local power regulator  397 , and battery  395 . CPU with memory  350  (FIG. 3) further includes a microphone array interface  607 , a camera interface  609 , a Blue Tooth interface  611 , an IR and LED interface  613 , a keyboard interface  615 , flash memory  617 , an RS232 interface  619 , an audio D/A converter  621 , a serializer-deserializer (SerDes)/Transceiver  623 , all connected to a field programmable gate array (FPGA) interface  627 . Additionally, CPU with memory  350  includes a mid-range amp  629 , a woofer amp  631 , a PCI-PC Card Bridge  643 , two PCI-PC slots  645  and  647 , an SDRAM  649 , a reset point  651 , a boot ROM  653 , an address EPLD  655  and a programmable multi-media processor  657 .  
     [0039] FPGA  627  interfaces with the various external inputs. As also shown in FIG. 8, the microphone array interface  607  receives its audio input from microphone array  340  and outputs it to FPGA  627  which routes it through the SerDes Transceiver  623  to the video/audio input/output  370  which in turn transmits it to the other calling parties. Camera interface  609  receives its video input from camera  330  and outputs it to the FPGA  627  in which splitter  830  splits the signal and routes part of it to LCD  310  and the other part through the SerDes Transceiver  623  to the video/audio input/output  370  which transmits it to the other calling parties. The Blue Tooth interface  611  interfaces FPGA  627  with devices that use the Blue Tooth open standard to transmit digital voice and data short ranges between mobile devices. Signals from external devices such as the remote control  448  are relayed through I/O  390  and IR and LED interface  613  to the FPGA  627  while signals from the keyboard or keypad  440  are relayed through I/O  390  and the keyboard interface  615  to the FPGA. Flash memory interface  617  connects flash memory (not shown), which stores recorded information such as accessing information, to the FPGA  627 . RS232 interface  619  connects and controls FPGA  627  with external electronic RS232 devices (not shown) such as computers, cameras and electronic white boards for image capture.  
     [0040] After FPGA  627  processes information received from microphone array interface  607  and digital camera  609 , the processed signals are transmitted to audio D/A converter  621 , SerDes/Transceiver  623  and LCD  310 . Audio D/A converter  621  processes the received signals and supplies them to mid-range amplifier  629  and bass amplifier  631  which drive internal speakers  435  and  436 . The LCD  310  receives signals directly from FPGA  627  and uses them to display images on an electronic screen.  
     [0041] Both the LCD  310  and audio D/A converter  621  receive, through FPGA  627 , signals which originated from another party or parties involved in the videoconference. Signals incoming from other members of a videoconference arrive through video/audio input/output  370 , go through SerDes Transceiver  623  and are received by FPGA  627 .  
     [0042] Base interface  480  also supports charging of battery  395 . Docking videoconferencing pad  210  on base unit  450  forms a connection dedicated to charging battery  395 . The energy used to charge the battery flows from a typical 110 volt AC electrical outlet to the base unit  450  or  457  where the voltage and current are converted from AC to DC. The DC electrical energy flows to the local power regulation unit  397  which may control the current and/or voltage to avoid overcharging or otherwise damaging battery  395 .  
     [0043] Programmable multi-media processor  657 , which controls SDRAM  649  and several inputs and outputs such as video in and video out, has a boot ROM  653  and an address EPLD  655  and can be reset with the use of the reset point  651 . Expansion connector  605  connects both the PCI-PC card bridge  643  and the programmable multi-media processor  657  to an external personal computer or to one instantiation of the NTT DoCoMo interface. The programmable multi-media processor  657  is used in debugging of videoconferencing pad  210 , typically with a personal computer. For example, an external computer can be used to debug the firmware by connecting the computer through the RS232 interface  619  to programmable multimedia processor  657  so that a programmer can monitor firmware execution and appropriately change code in the firmware.  
     [0044] PCI-PC card bridge  643  controls PC card slots  645  and  647 , which may be a PCMCIA card, used to run LAN or Ethernet connections. PC card slots  645  and  647  can be IEEE 802.11 wireless LAN and IEEE 1394 card slots which allow for direct connection to an IEEE 1394 hard drive for digital recording of images captured in a local conference room or received from remote sites. Videoconferencing pad  210  can also connect to the LAN through the LAN connection  455  in the power module  452  when videoconferencing pad  210  is connected to the base  457  and  457 .  
     [0045]FIG. 7 is a block diagram showing the path of audio and video signals incoming from the network interface  623 , through the FPGA  627 . The block diagram includes a TCP/UDP/IP  710 , a media router  720 , an audio decoder  730 , a video decoder  740 , an audio D/A converter  621  and a video display  310 . The incoming audio and video streams, which originated at one or more remote conference sites and represent the sounds and images of that site, are received through video/audio input/output  370  (FIG. 6), processed through serdes/transceiver  623  (FIG. 6) and processed by the TCP/UDP/IP stack  710 , which performs error checking and removes header information from the incoming audio and video streams. Once the header information is removed by the TCP/UDP/IP stack  710 , the audio and video streams are directed to the media router  720  which sends the audio stream to the audio decoder  730  and the video stream to the video decoder  740 .  
     [0046] Media router  720  supplies the audio stream, minus the headers, to the audio decoder  730  which decodes the audio stream so that an audio D/A converter  621  can process it. Additionally, if multiple incoming audio streams are received, as would be the case with a multi-point videoconference, the audio decoder  730  mixes or switches the audio streams. The audio decoder  730  then transmits the decoded audio stream to audio D/A converter  621  which converts the digital signals to analog signals and passes the analog signals through amplifiers  629  and  631  to loudspeakers  435  and  436  that reproduce and broadcast the sounds from other remote videoconferencing sites.  
     [0047] Media router  720  sends the incoming video stream to the video decoder  740 , which decodes the video stream. Video decoder  740  may also perform mixing or switching services if there are multiple video streams from different remote videoconferencing sites. The decoded video stream is subsequently transmitted to video display  310  which displays the images embodied in the decoded video stream in a window on a screen.  
     [0048]FIG. 8 is a block diagram showing the path  800  of the audio and video signals, which originate in the videoconference pad&#39;s  210  own microphone array  340  and video camera  330  respectively, through the FPGA  627 . The path  800  includes an audio encoder  810  which is part of microphone array interface  607 , a video encoder  820  which is part of camera interface  609 , and details of FPGA  627 . FPGA  627  further includes a splitter  830 , a communications module  840 , a TCP/UDP/IP  850  and a video decoder  860 .  
     [0049] Audio signals originating from the microphone array  340  first go through the audio encoder  810  which encodes the audio stream with the appropriate protocol such as H.323 and may then go through a USB connection to communications module  840 . The communications module packetizes the audio stream and passes the packets to a TCP/UDP/IP stack  850  which attaches header information to the audio stream and outputs the stream through SerDes  623  and video/audio input/output  370  for transmission over the Internet to one or more remote conference endpoints.  
     [0050] Video signals originating from the video camera  330  first go through the video encoder  820  which encodes the video stream with the appropriate protocol such as H.323 and then to splitter  830 . Splitter  830  generates identical copies of the original signal and transmits one copy to the communication module  840  and the other copy to video decoder  860 . The communications module processes the video stream copy in a manner similar to how the audio decoder  730  processes the audio stream. Communication module  840  packetizes the video stream and passes it to the TCP/UDP/IP stack  850  which attaches header information to the video stream and places the stream, through serdes/transceiver  623 , on the video/audio input/output  370  for transmission over the Internet to one or more remote conference endpoints. The second copy of the video stream, transmitted to the video decoder  860 , is decoded and transmitted to the video display  310 , which displays the image embodied in the local video stream.  
     [0051] Splitter  830  enables the video stream from the camera  330  both to be transmitted to other videoconferencers and to be displayed on the user&#39;s own video display  310  so that he/she can view himself/herself. In some embodiments, the audio stream is not duplicated and played back to the user because it tends to interfere with the conversation.  
     [0052] Videoconferencing pad  210  may be additionally be used to transmit and view slide shows. The slide shows can be a collection of digital images captured by a digital camera or a collection of images generated with a computer software application such as Microsoft PowerPoint™ presentation software. Slide shows, which are typically stored in the memory of a personal computer, may be transferred to videoconferencing pad  210  through general I/O port  390 . Once the signals reach videoconferencing pad  210  they may be processed and transmitted as ordinary video signals described with reference to FIG. 8 above. Furthermore, slide show images may be received and processed similarly to the video signals described with reference to FIG. 7 above.  
     [0053]FIG. 9A shows the software components  380  which may be used by CPU  350  to process signals from video camera  330  and microphone array  340 . The components illustrated include a graphical user interface (GUI)  910 , a video/audio CoDec (Coder-Decoder) driver  915  that converts analog sound or video to digital code (analog to digital) and vice-versa (digital to analog), a video/audio encoder driver  920 , a media switch driver  925 , a TCP/UDP/IP STACK driver  930 , a PCMCIA driver  935  and a network or Ethernet card driver  940 .  
     [0054] The user interacts with the videoconferencing pad  210  through GUI  910  which allows the user to use a pointer/selector such as an infra-red remote control or an internal keyboard to manipulate the screens. The user can enter data through conventional keyboard or keypad  440 , remote control keypad  448 , or a soft keyboard that allows the user to enter keyboard characters by selecting keyboard elements on the screen with a pointer-selector device such as, for example, a light pen, touch pad, mouse, joystick or touch screen. Alternatively, an external keyboard or pointing device could be used to control the videoconferencing pad. Once information has been entered through the GUI, the operating system translates the entered information into commands to be executed by the firmware and software which run the videoconferencing pad  210 . Although one preferred embodiment of videoconferencing pad  210  uses a custom operating system, it may use a conventional operating system such as Microsoft Windows® or Linux which may be configured for a videoconferencing application.  
     [0055] The audio/video output signals from the camera  330  and microphone array  340  are first processed by audio and video CoDec driver  915  respectively. After video/audio CoDec driver  915  has converted analog signals to digital signals the video/audio encoder driver  920  encodes the audio and video signals. The audio encoder  810  follows instructions from audio encoder driver  920  for applying the encoding protocol of ITU Recommendation G.711 (“Pulse Code Modulation (PCM) of Voice Frequencies”) to the local audio stream generated by microphone array  340  and audio CoDec driver  915 . The G.711 protocol utilizes a PCM scheme to compress the local audio stream. Audio encoder driver  920  may be configured to support additional audio encoding algorithms, such as MPEG-1 audio and ITU Recommendations G.722, G.728, G.729 and G.723.1 or other proprietary or non-proprietary algorithms. The video encoder driver  920 , which runs the video encoder  820 , includes instructions for encoding common intermediate format (CIF) images in the local video stream supplied by video camera  330 , in accordance with Recommendation H.263 (“Video CoDec for Audiovisual Services at px64 kbit/s”, incorporated herein by reference) of the ITU. As is known in the art, H.263 is a video source-coding algorithm which uses a hybrid of inter-picture prediction to utilize temporal redundancy and transform coding of the remaining signal to reduce spatial redundancy. Video encoder driver  920  may be additionally configured to support alternative video encoding protocols, such as H.261 common intermediate format (CIF), or proprietary formats.  
     [0056] After the audio and video streams have been encoded, media switch driver  925  prepares the streams for transmissions. Media switch driver software  925  packetizes encoded audio and video streams in accordance with Real-time Protocol (RTP). Media switch software  925  includes instructions for implementing the media stream packetization functions of ITU Recommendations H.225.0 (“Call Signaling Protocols and Media Stream Packetization for Packet-Based Multimedia Communication Systems”) and H.245 (“Control Protocol for Multimedia Communications”) which are incorporated by reference. These recommendations are well known in the art, and hence a detailed description of the functions implemented by communications processes is not included.  
     [0057] In order to transmit audio and video streams a communication protocol is established by the TCP/UDP/IP driver  930 , which is a communication protocol, typically embedded in the operating system, for accessing the Internet. TCP is Transmission Control Protocol, UDP is User Datagram Protocol and IP is an Internet Protocol. The TCP/UDP/IP Stack also handles error checking and addressing functions in connection with communications received and transmitted through video/audio input/output  370 . TCP/UDP/IP driver  930  is well known in the art, and hence a detailed description of its functions implemented by communications processes is not included here. Alternatively, other protocols such as session initiation protocol (SIP) and 3G Call Control Protocol can be used instead of the TCP/UDP/IP  930 .  
     [0058] Since the local area network (LAN) is accessed through the Ethernet via power module  452  or a network card connected to the PCMCIA card slot  475  and  476 , a PCMCIA driver  935  for the PCMCIA card and a network or Ethernet driver  940  for the network or Ethernet card are both required. Both the PCMCIA driver  935  and the network or Ethernet driver  940  are well known in the art, and hence a detailed description of their functions is not included.  
     [0059]FIG. 9B shows the software components used to process video and audio streams arriving through a network. The software components include a user interface  950 , a network or Ethernet card driver  955 , a PCMCIA driver  960 , a TCP/UDP/IP STACK driver  965 , a media router driver  970 , a video/audio decoder  975 , and a video/audio CoDec  980 . The program flow for processing audio and video streams received from the network is almost the reverse of that for processing audio and video streams received from the videoconference pad&#39;s  210  own microphone array  340  and camera  330 . The audio and video streams are received through the LAN and accessed through the Ethernet via a network card connected to the PCMCIA card slot. Therefore, PCMCIA drivers  960  are required for operating the PCMCIA card slot and network or Ethernet drivers  955  are required for operating the network or Ethernet card. Furthermore, TCP/UDP/IP stack driver  965  establishes a communication protocol, performs error checking and removes header information from the incoming audio and video streams. The LAN stack will be embedded in the rest of the software running on the multimedia processor.  
     [0060] Media router driver  970 , which runs media router  720 , separates the modified incoming audio and video streams into their appropriate audio and video components. The audio stream is directed towards the audio decoder  730  whereas the video stream is directed towards the video decoder  740 . Audio decoder software  975 , which runs audio decoder  730 , includes instructions for decoding one or more incoming compressed audio streams received from remote conference endpoints. Audio decoder software  975  may be configured to decode audio streams encoded in accordance with the G.711 protocol, and may additionally be configured to decode audio streams encoded using other protocols, such as G.722, G.728, G.729, G.723.1, and MPEG-1 audio. Additionally, audio decoder software  975  can be configured to apply an echo cancellation algorithm to the incoming audio stream to remove components of the incoming audio signal attributable to acoustic feedback between the loudspeaker and microphone located at the remote conferencing terminal. Since echo cancellation techniques are well known in the art, they need not be discussed here. Video decoder software  975 , which runs video decoder  740 , includes instructions for decoding local and remote video streams encoded in accordance with the H.261 QCIF protocol. Additionally video decoder software  975  may include instructions for decoding video streams encoded using alternative protocols, such as H.261 CIF, H.263, or proprietary protocols. Finally, the decoded incoming audio and video signals are converted from digital to analog using audio and video CoDec software  980  and transmitted to internal speakers  435 ,  436  and monitor  310  of the videoconferencing pad  210 .  
     [0061] In yet another embodiment, videoconferencing pad  210  may be implemented in a general-purpose, microprocessor-based, notebook computer. The notebook computer may preferably comprise a built-in, digital camera, one or more speakers and audio amplifiers, and a microphone or microphone array. Alternatively, remote speakers and/or microphone arrays may be connected to the notebook computer through, for example, a USB port for improved audio quality. Protocol conversions such as, for example, between H.323 and Audio Codec 97 and/or MPEG may be accomplished by software routines running on the notebook computer. In one particularly preferred embodiment, the notebook computer is equipped with a microprocessor having advanced video processing capabilities such as the Intel Pentium™ 4 processor. In still another embodiment, certain videoconferencing-specific components such as, for example, a pan/tilt/zoom camera and a microphone array are included in a videoconferencing docking station for the notebook computer.  
     [0062] It will also be recognized by those skilled in the art that, while the invention has been described above in terms of preferred embodiments, it is not limited thereto. Various features and aspects of the above-described invention may be used individually or jointly. Further, although the invention has been described in the context of its implementation in a particular environment and for particular applications, those skilled in the art will recognize that its usefulness is not limited thereto and that the present invention can be utilized in any number of environments and implementations.