Abstract:
A videoconference system can automatically transmit first and second images from a local site to a remote site where the first image is a high-resolution live image and the second image may be transmitted either as a high-resolution live or still frame image. Two video streams representing the first and second images are transmitted together to the remote site within a single carrier channel. The second image is transmitted as a still image whenever the second image is static to conserve bandwidth.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application Serial No. 60/278,305 filed on Mar. 22, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates generally to video conferencing, and more particularly to transmission of alternate image sources through a graphics side channel.  
           [0004]    2. Description of Related Art  
           [0005]    Videoconferencing systems provide a means for users at a local site to conference with users at a remote site by way of audio and video transmissions. These systems typically consist of a video source and an audio source that transmit images and sound from the local site for viewing and listening by the users at the remote site.  
           [0006]    Due to bandwidth limitations, current videoconferencing systems can display either a conference camera image, typically showing the conference participants (i.e., the normal videoconference source), or a document camera image (e.g., an alternate video source), typically showing a computer screen display. They cannot, however, simultaneously display an alternate video source that can be displayed along with the normal videoconference source of the system.  
           [0007]    Moreover, although some videoconferencing systems have the capability to preview an alternate video source, the user is forced to manually select whether the alternate video source should be transmitted as a live or still frame image. Even in systems where preview and send are automatic, the user is forced to view the live source in lower resolution than the still frame image. In all prior art systems, however, the normal conference video source is lost during the display of the alternate video source.  
           [0008]    These prior art systems have several disadvantages. First, in many systems the user must manually select and send a live preview. Second, even if a live previewed image can be automatically transmitted, it is not transmitted in a high-resolution image format. Finally, the normal conference room video and the alternate video source cannot be viewed at the same time.  
           [0009]    Based on the foregoing discussion, there currently exists a need to provide videoconferencing systems with the capability to display alternate video sources without the need for manual user intervention. There is also a need for the alternate video sources to have the capability to be displayed in a high-resolution format. Finally, there is a need to provide a system that will not sacrifice the loss of the normal conference video when the alternate video source is selected.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention provides an alternate video source in a videoconference system that can automatically transmit a second image from a local site to a remote site of a videoconference. The image may be transmitted as a high-resolution live or still frame image. The alternate video source is transmitted along with a live view of a normal conference video source.  
           [0011]    Using the present invention, each time the alternate video source is changed, the alternative video source will be displayed to the remote site as a live image and will share bandwidth of the normal conference video. Conversely, when the alternate video source is static, the alternative video source will be displayed as a still image. This way, the channel bandwidth of the normal conference video is affected only when necessary. The alternate video source can be displayed either on a separate second monitor or in conjunction with the normal videoconference using picture-in-picture (PIP) on a single monitor. Additionally, the user is not required to manually select when and how to view the alternate video source since this is done automatically.  
           [0012]    The present invention thus allows alternate video sources, such as presentations, documents and the like, to be used with normal conference video in videoconferencing. An example of an alternate video source is a document camera or personal computer. Using the present invention, alternate video sources can be seen at the remote site of a videoconference as a high resolution live or still image as appropriate while the normal conference video continues.  
           [0013]    The present invention works by allowing two separate video streams, a conference video stream and an alternate video stream, to share the bandwidth of a standard video channel. For example, the conference video stream can carry live video captured by a video camera of a local videoconference unit, including images of the users at the local site. Simultaneously, the alternate video stream can carry video captured from an alternate source, such as a VGA output of a computer.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings where like reference numerals frequently refer to similar elements and in which:  
         [0015]    [0015]FIG. 1 shows a schematic diagram of a videoconferencing system utilizing a high resolution graphics videoconference accessory module according to the present invention;  
         [0016]    [0016]FIG. 2 depicts the basic components of a video signal generated by the videoconference accessory module of the present invention;  
         [0017]    [0017]FIG. 3 is a schematic diagram illustrating the operation of the videoconference accessory module; and  
         [0018]    [0018]FIG. 4 exemplifies an alternate embodiment of the videoconference accessory module of the present invention.  
     
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0019]    [0019]FIG. 1 shows a videoconference unit  120  located at a local site  100 . The videoconference unit  120  captures live video images  105  and audio of users at a local site  100 . The videoconference unit  120  then transmits the live video images  105  and the audio to a communications interface  140  through a carrier channel  130 . The communications interface  140  transmits the signals to a remote site  160  by way of a communications path  150 . Examples of the communications path  150  include, for example, ISDN, Internet, etc. The users of the videoconference unit  120  at the local site  100  can thus communicate both visually and audibly with users of a similar videoconference system at the remote site  160 . The users at the remote site  160  will see and hear the video and sound generated by the users of the videoconference unit  120  at local site  100 . Because the videoconference unit  120  operates bi-directionally, users of a similar videoconference unit at the remote site  160  can likewise transmit video and sound to the users at the local site  100 . In this way, meetings between parties who are separated over large distances can take place in real time.  
         [0020]    [0020]FIG. 1 also shows an exemplary videoconference accessory module  110  connected to the videoconference system  120 . Using the videoconference accessory module  110  of the present invention in conjunction with the videoconference system  120 , the users at the local site  100  can also transmit alternate video sources along with the live video and sound described above. The videoconference accessory module  110  accepts an alternate image source signal  124  from an alternate image source  122 . The videoconference accessory module  110  also accepts a sound source signal  125  from one or more microphone pods  121 . Subsequently, the videoconference accessory module  110  processes these inputs and utilizes a side channel  111  to transmit the input data to the videoconference system  120 . The videoconference unit  120  takes the input from the side channel  111  and incorporates the input into an output of the carrier channel  130 , which is then transmitted to the remote site  160  as described above. For the convenience of the users at the local site  100 , the videoconference accessory module  110  also has an output to a projector  123 .  
         [0021]    [0021]FIG. 2 shows the inputs and outputs of the videoconference accessory module  110  and the videoconference system  120 . As shown, the alternate image source signal  124  and the sound source signal  125  from FIG. 1 are input into the videoconference accessory module  110 . The videoconference accessory module  110  processes these signals according to the discussion below in reference to FIG. 3.  
         [0022]    After processing, the videoconference accessory module  110  outputs the side channel  111  to the videoconference system  120 . The side channel  111  includes the processed alternate image source signal  124  and the processed sound source signal  125 , which are output as an alternate video component  210  and a sound component  220 , respectively. In addition to the side channel  111 , the videoconference unit  120  receives the live video images  105 . All three components, the alternate video component  210 , the sound component  220 , and the live video images  105  are incorporated by the videoconference unit  120  to generate the carrier channel  130 . The carrier channel  130  consists of a video subchannel  230 , which carries video image data, and an audio subchannel  240 , which carries sound or audio data.  
         [0023]    The video subchannel  230  is further made up of two video streams: a normal conference video stream  231  and an alternate video stream  232 . The normal conference video stream  231  carries the live video images  105  captured by the videoconference system  120 , including images of the users at the local site  100  (FIG. 1). The alternate video stream  232  carries image data from the alternate video component  210  of the side channel  111  that originated from the alternate image source  122  (FIG. 1). Advantageously, the present invention can facilitate simultaneous transmission of the normal conference video stream  231  within the same channel as the alternate video stream  232 . Additionally, the alternate video stream  232  transmits these images in a high-resolution format (e.g., 4 times common intermediate format (CIF), or 704×480 National Television Standards Committee (NTSC) format and 704×576 phase alternating line (PAL) format).  
         [0024]    To achieve simultaneous transmission of the normal conference video stream  231  with the alternate video stream  232 , total bandwidth of the video subchannel  230  must be conserved and optimized. For this reason, the alternate video stream  232  carries a live image only when the image from the alternate image source  122  changes. At all other times, when the image from the alternate image source  122  is static, the alternate video stream  232  carries a still image.  
         [0025]    The data transmitted through the normal conference video stream  231  and the alternate video stream  232  can be displayed using two separate monitors, a single monitor that can switch back and forth between channels, or a single monitor with multi-channel picture-in-picture (PIP) capability.  
         [0026]    [0026]FIG. 3 shows an exemplary internal architecture of the videoconference accessory module  110  according to one embodiment of the present invention. Preferably, the videoconference accessory module  110  includes an RGB analog-to-digital (A/D) converter  310 , a field programmable gate array (FPGA)  320 , a processor  330 , a memory  340 , a sound A/D converter  350 , and various input ports. As shown in FIG. 3, the videoconference accessory module  1   10  has one or more audio input ports  352  for inputting the sound source signals  125  from one or more of the microphone pods  121 . The videoconference accessory module  110  also has a video graphics array (VGA) input  353 , a local area network (LAN) input  354 , and a projector output  370 .  
         [0027]    The videoconference unit  120  captures live video images  105  from the local site  100  (FIG. 1) and transmits the images to the communications interface  140  (FIG. 1) using the normal conference video stream  231  of the carrier channel  130 . The microphone pods  121  capture live sound waves from the local site  100  and generate the sound source signals  125 . These sound source signals  125  pass through the audio inputs  352  of the videoconference accessory module  110  and are processed by the sound A/D converter  350 . The sound A/D converter  350  converts the source signals from analog to digital format, creating the sound component  220  of the side channel  111 , which carries the signals to the videoconference system  120 . As described above in reference to FIG. 2, the videoconference unit  120  attaches these sound signals to the audio subchannel  240  of the carrier channel  130 .  
         [0028]    The VGA input port  353  accepts the alternate image source signal  124  from the alternate image source  122 , which can be any source having the capability of generating images. For example, the alternate image source  122  can be a computer generating images in RGB format, allowing the users at the local site  100  to send the VGA output from the computer to the VGA input port  353 . The alternate image source signal  124  then passes through the RGB A/D converter  310  and is sampled and digitized. The digitized signal then is sent to the FPGA  320 . The FPGA  320  converts and compresses the digitized RGB image into YUV format.  
         [0029]    To enhance the throughput and performance of the video conversion and compression process, the FPGA  320  works in conjunction with the processor  330  and the memory  340 . The FPGA  320  uses the memory  340  as a buffer, storing several images of RGB data into the memory  340  before converting the images to YUV format. Additionally, the processor  330  is used to offload as much of the processing from the FPGA  320  as possible.  
         [0030]    After the compression and conversion of the alternate image source signal  124  to YUV format, the videoconference accessory module  110  outputs the processed image to the videoconference unit  120  by way of the alternate video component  210  of the side channel  111 . As described above in reference to FIG. 2, the alternate video component  210  is output as the alternate video stream  232  of the carrier channel  130  by the videoconference unit  120  and transmitted to the communications interface  140  (not shown).  
         [0031]    Referring back to FIG. 3, the videoconference accessory module  110  also has a LAN input port  354 . LAN input port  354  provides a standard network connection between the alternate image source  122  and the videoconference accessory module  110  so that multiple image sources  122  may be used, or so that such sources may be used from remote locations. The videoconference accessory module  110  also includes a projector output  370 . The users at the local site  100  can connect the projector  123  to this port in order to provide a larger, room-size view of the image being generated by the alternate image source  122 .  
         [0032]    Using the principles of the present invention, and referring back to FIG. 1, a videoconference system located at remote site  160  will receive the carrier channel  130  sent by the communications interface  140  of the videoconference system  120 . As discussed above, the carrier channel  130  carries the live video images  105  captured by the videoconference unit  120  on the normal conference stream  231  (FIG. 2), the sound captured by the microphone pods  121  on the audio subchannel  240  (FIG. 2), and the images from the alternate image source  122  on the alternate video stream  232  (FIG. 2). The videoconference system used by the remote site  160  receives all three signals. As mentioned above, because the videoconference system is bi-directional, the process is merely reversed in order to transmit sight, sound, and image data from the remote site  160  to the local site  100 .  
         [0033]    Referring now to FIG. 4, an alternate embodiment of the present invention is illustrated. In this embodiment, the videoconference accessory module  110  (FIG. 1) is substituted with a videoconference interface card  410  that is connected to the alternate image source  122 . For example, the alternate image source  122  is a laptop computer and the videoconference interface card  410  is a PCMCIA card. A cable from the videoconference interface card  410  connects to the microphone pod  121 . The videoconferencing system  120  receives data from the microphone pod  121  by way of the side channel  111 . As discussed above in reference to FIG. 2, the side channel  111  consists of the alternate video component  210  and the sound component  220  (not shown).  
         [0034]    The videoconference unit  120  captures the live video  105  at the local site  100  and transmits the images on the normal conference video stream  231  (FIG. 2) of the carrier channel  130  to the communications interface  140 . Further, the microphone pod  121  captures live sound waves from the local site  100  and transmits these signals to the videoconference unit  120  by way of the sound component  220  (FIG. 2) of the side channel  111 . The videoconference unit  120  then sends these signals to the communications interface  140  by way of the audio subchannel  240  (FIG. 2) of the carrier channel  130 .  
         [0035]    Images from the alternate image source  122  are digitized, compressed, and converted into YUV format by the videoconference interface card  410  using similar technology as described above with reference to the videoconference accessory module  110  of FIG. 3. The converted images are transmitted through the microphone pod  121  to the videoconference unit  120  by way of the alternate video component  210  (FIG. 2) of the side channel  111 . The videoconference unit  120  then sends these signals to the communications interface  140  by way of the alternate video stream  232  (FIG. 2) of the carrier channel  130 . Subsequently, the communications interface  140  transmits the data on the carrier channel  130  to the remote site  160 .  
         [0036]    The videoconference interface card  410  includes a flash memory. The flash memory is preloaded with application software necessary to make the videoconference interface card  410  operable with the alternate image source  122  and the videoconference system  120 . Additionally, the videoconference interface card  410  is a “hot-swappable” card, meaning that it can be inserted without the need to reboot the alternate image source  122 , and is instantaneously operable upon insertion. The user is not required to load or run external software.  
         [0037]    When the videoconference interface card  410  is inserted into the alternate image source  122 , the alternate image source identifies the interface card  410  as a storage device, such as a hard disc drive. Because the videoconference interface card  410  looks like a storage device to the alternate image source  122 , the alternate image source will perform identical I/O operations on the videoconference interface card  410  as if the interface card  410  were a hard disc drive. Thus, most standard read and write functions available to a hard disc drive are used to operate the videoconference interface card  410 . This provides a user with familiar, intuitive, and user-friendly commands when using this embodiment of the invention.  
         [0038]    As preferred embodiments of the present invention are described above with reference to the aforementioned drawings, various modifications or adaptations of the methods and or specific structures described may become apparent to those skilled in the art. All such modifications, adaptations, or variations that rely upon the teachings of the present invention, and through which these teachings have advanced the art, are considered to be within the spirit and scope of the present invention. Hence, these descriptions and drawings are not be considered in a limiting sense as is understood that the present invention is in no way limited to the embodiments illustrated.