PATENT ABSTRACT
A workstation for processing and producing a video signal comprises a video input system, a video graphics processor, and a video output system. The video input system may comprise a video input module, a first video pipeline, and a second video pipeline. The video output system may comprise a receiver, a video pipeline and a video output module. In addition, the video input system may comprise a video input module having a specific configuration and a video processing module having a connector for coupling the video input module, the specific configuration of the video input module setting the characteristics of the video processing module. The video output system may comprise a video processing module having a connector for coupling a video output module and a video output module having a specific configuration, the specific configuration of the video output module setting the characteristics of the video processing module.

PATENT DESCRIPTION
PRIORITY 
   This application claims priority from co-pending provisional U.S. Patent Application Ser. No. 60/147,668, filed Aug. 6, 1999, entitled “GRAPHICS WORKSTATION” and bearing, the disclosure of which is incorporated herein, in its entirety, by reference and co-pending provisional U.S. Patent Application Ser. No. 60/147,609, filed Aug. 6, 1999, entitled “DATA PACKER FOR GRAPHICAL WORKSTATION” and bearing, the disclosure of which is incorporated herein, in its entirety, by reference. 
   CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is related to U.S. patent application Ser. No. 09/632,662, filed on even date herewith, entitled “SYSTEM AND METHOD FOR PRE-PROCESSING A VIDEO SIGNAL” and, naming Jeff S. Ford and David J. Stradley as inventors, the disclosure of which is incorporated herein, in its entirety, by reference, U.S. patent application Ser. No. 09/632,452, filed on even date herewith, entitled “SYSTEM AND METHOD FOR PRODUCING A VIDEO SIGNAL” and, naming Jeff S. Ford and Claude Denton as inventors, the disclosure of which is incorporated herein, in its entirety, by reference, U.S. patent application Ser. No. 09/632,605, filed on even date herewith, entitled “VIDEO CARD WITH INTERCHANGEABLE CONNECTOR MODULE” and, naming Jeff S. Ford and Jeff Belote as inventors, the disclosure of which is incorporated herein, in its entirety, by reference, U.S. patent application Ser. No. 09/632,443, filed on even date herewith, entitled “SYSTEM AND METHOD FOR FRAME RATE MATCHING” and, naming Jeff S. Ford as inventor, the disclosure of which is incorporated herein, in its entirety, by reference, and U.S. patent application Ser. No. 09/632,451, filed on even date herewith, entitled “SYSTEM AND METHOD FOR PACKING AND UNPACKING VIDEO DATA” and, naming Jeff S. Ford, Arthur McKinney and Craig Jordan as inventors, the disclosure of which is incorporated herein, in its entirety, by reference. 

   FIELD OF THE INVENTION 
   The invention generally relates to a video graphics workstation and, more particularly, the invention relates to the pre-processing of a video signal and the production of a video signal. 
   BACKGROUND OF THE INVENTION 
   In general, a video graphics workstation is a system of hardware and software that allows a user to process a video signal for use in a number of different applications. For example, the user may process a video signal for display on a computer monitor, for storage on a computer-readable storage medium, for display on a television, or for storage on a video tape. 
   Typically, however, video graphics workstations are designed to process particular video signals. Thus, most video graphics workstations are not scalable. In other words, most video graphics workstations are not designed to adapt to the changing needs of the workstation&#39;s user. 
   SUMMARY OF THE INVENTION 
   In accordance with one aspect of the invention, a workstation for processing and producing video signals comprises a video input system and a video graphics processor. The video input system comprises a video input module, a first video pipeline, and a second video pipeline. The video input module receives and forwards one or more live video signals, producing a forwarded video signal for each received live video signal. The first video pipeline pre-processes VS 1 , wherein VS 1  is a first stored video signal or one of the forwarded video signals produced in the video input module, producing a first pre-processed video signal. The second video pipeline pre-processes VS 2 , wherein VS 2  is the same video signal being pre-processed in the first video pipeline, one of the other forwarded video signals produced in the video input module or a second stored video signal, producing a second pre-processed video signal. The video graphics processor processes VS 3 , wherein VS 3  is a third stored video signal, the first pre-processed video signal, or the second pre-processed video signal, producing a processed video signal. 
   In a further embodiment of the invention, the workstation may further comprise a video output system, the video output system producing a formatted video signal. The video output system may further comprise a receiver for receiving VS 4 , wherein VS 4  is the first pre-processed video signal, the second pre-processed video signal, or the processed video signal, a video pipeline for post-processing VS 4 , the video pipeline operating in conjunction with the video graphics processor and producing a post-processed video signal, and a video output module for converting the post-processed video signal, the video output module producing the formatted video signal. 
   In accordance with another aspect of the invention, a workstation for processing and producing video signals comprises a video graphics processor for processing a video signal, the video graphics processor producing a processed video signal, and a video output system. The video output system comprises a receiver for receiving the processed video signal, a video pipeline for post-processing the processed video signal, the video pipeline producing a post-processed video signal, and a video output module for converting the post-processed video signal, the video output module producing a formatted video signal. 
   In accordance with still another aspect of the invention, a workstation for processing and producing video signals comprises a video graphics processor for processing a video signal, the video graphics processor producing a processed video signal, and a video output system. The video output system comprises a video processing module for post-processing the processed video signal, the video processing module producing a post-processed video signal and having a connector for coupling a video output module, and a video output module for converting the post-processed video signal, the video output module having a specific configuration and producing a formatted video signal, the specific configuration of the video output module setting the characteristics of the video processing module. 
   In a further embodiment of the invention, the video output module may further comprise a buffer for storing the post-processed video signal, a processor for converting the post-processed video signal into the formatted video signal, and a transmitter for transmitting the formatted video signal. 
   In accordance with yet another aspect of the invention, a workstation for processing and producing a video signal comprises a video input system and a video graphics processor. The video input system comprises a video input module for converting a live video signal, the video input module having a specific configuration and producing a formatted video signal, and a video processing module for pre-processing the formatted video signal, the video processing module producing a pre-processed video signal, the video processing module having a connector for coupling the video input module, the specific configuration of the video input module setting the characteristics of the video processing module. The video graphics processor processes the pre-processed video signal, producing, a processed video signal. 
   In a further embodiment of the invention, the video input module may further comprise a first receiver for receiving the live video signal, a processor for converting the live video signal into the formatted video signal, and a buffer for storing the formatted video signal. 
   In accordance with still yet another aspect of the invention, a workstation for processing and producing a video signal comprises a video input system and a video output system. In one embodiment of the invention, the video input system comprises a video input module for receiving and forwarding one or more live video signals, the video input module producing a forwarded video signal for each received live video signal, a first video pipeline for pre-processing VS 1 , wherein VS 1  is a first stored video signal or one of the forwarded video signals produced in the video input module, the first video pipeline producing a first pre-processed video signal, and a second video pipeline for pre-processing VS 2 , wherein VS 2  is the same video signal being pre-processed in the first video pipeline, one of the other forwarded video signals produced in the video input module, or a second stored video signal, the second video pipeline producing a second pre-processed video signal. In this embodiment, the video-output-system comprises a receiver for receiving VS 3 , wherein VS 3  is a third stored video signal, the first pre-processed video signal, or the second pre-processed video signal, a video pipeline for post-processing VS 3 , the video pipeline producing a post-processed video signal, and a video output module for converting the post-processed video signal, the video output module producing a formatted video signal. 
   In another embodiment of the invention, the video input system comprises a video input module for converting a live video signal, the video input module having a specific configuration and producing a formatted video signal, and a video processing module for pre-processing the formatted video signal, the video processing module producing a pre-processed video signal, the video processing module having a connector for coupling the video input module, the specific configuration of the video input module setting the characteristics of the video processing module. In this embodiment, the video output system comprises a video processing module for post-processing the pre-processed video signal, the video processing module producing a post-processed video signal and having a connector for coupling a video output module, and a video output module for converting the post-processed video signal, the video output module having a specific configuration and producing-a formatted video signal, the specific configuration of the video output module setting the characteristics of the video processing module. 
   In alternate embodiments for all aspects of the invention, the video input system may include an ancillary data extractor for removing ancillary data from at least one of the live video signals, and the video output system may include an ancillary data injector for inserting ancillary data into the post-processed video signal. The video output system may also include a generator locking device. 
   In other alternate embodiments for all aspects of the invention, the live video signal may be an analog composite video signal, an analog component video signal, a serial digital composite video signal, a serial digital component video signal, a parallel digital composite video signal, or a parallel digital component video signal. Further, the pre-processed video signal may be an RGB encoded video signal, an RGBA encoded video signal, a YUV-Type encoded video signal, or a YUVA-Type encoded video signal. In addition, the formatted video signal may be an analog composite video signal, an analog component video signal, a serial digital composite video signal, a serial digital component video signal, a parallel digital composite video signal, or a parallel digital component video signal. 
   In still other, alternate embodiments for all aspects of the invention, the process of pre-processing may include changing the sample rate of the video signal being pre-processed, gamma removal, gamma insertion, color space conversion, dithering, and scaling. In addition, the process of pre-processing may include addressing on a frame-by-frame basis the video signal being pre-processed. Further, the video input system may be a Peripheral Component Interconnect circuit board. 
   In-yet other alternate embodiments for all aspects of the invention, the process of post-processing may include region of interest selection, frame rate matching, scaling, framing, letter boxing, changing the sample rate of the video signal being post-processed, gamma removal, gamma insertion, color space conversion, and changing frames of video data into interleaved fields of video data. In addition, the process of post-processing may include addressing on a frame-by-frame basis the video signal being pre-processed. Further, the video output system may be a Peripheral Component Interconnect circuit board. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects and advantages of the invention will be appreciated more fully from the following further description thereof with reference to the accompanying drawings wherein: 
       FIG. 1  shows a block diagram of an exemplary video graphics workstation for implementing the various embodiments of the invention. 
       FIGS. 2   a  through  2   b  show various exemplary embodiments for a video input system for use in a video graphics workstation. 
       FIG. 3  shows an exemplary embodiment for a scalable video input system for use in a video graphics workstation. 
       FIGS. 4   a  and  4   b  show various exemplary exploded views for mounting an interchangeable connector module to a video processing module. 
       FIG. 5  shows an exemplary embodiment for a video output system for use in a video graphics workstation. 
       FIG. 6  shows an exemplary embodiment for a scalable video output system for use in a video graphics workstation. 
       FIG. 7  shows an exemplary video graphics workstation for carrying out various exemplary video graphics applications. 
       FIG. 8  shows an exemplary process in a video graphics workstation for video signal frame rate matching. 
       FIGS. 9   a  and  9   b  show an exemplary process in a video graphics workstation for packing and unpacking pixels. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In accordance with one embodiment of the invention, a video graphics workstation includes three sub-systems—a video input system, a video graphics processor, and a video output system. In general, the video input system pre-processes video signals, the video graphics processor processes and/or displays video signals and graphics input, and the video output system produces video signals. The video signals processed and produced may be analog video signals or digital video signals. 
     FIG. 1  shows a block diagram of an exemplary video graphics workstation for implementing the various embodiments of the invention. Video graphics workstation  100  includes central processing unit  102 , chipset  104 , memory  106 , two Peripheral Component Interconnect (“PCI”) buses—a 64-bit PCI bus and a 32-bit PCI bus, and an Accelerated Graphics Port (“AGP”). Video input system  110  and storage medium  120  connect to chipset  104  via the 64-bit PCI bus. Video graphics processor  130  connects to chipset  104  via the AGP. Video output system  140  connects to chipset  104  via the 32-bit PCI bus. In addition, video input system  110  connects to video graphics processor  130  via local bus  182  and video output system  140  connects to video graphics processor  130  via local bus  184 . 
   A. Video Input System 
     FIGS. 2   a  through  2   b  show various exemplary embodiments for video input system  110 . In particular,  FIG. 2   a  shows an exemplary embodiment for pre-processing a live video signal in video input system  110 . The process of pre-processing a video signal includes, among other things, up sampling, down sampling, gamma insertion, gamma removal, color space conversion, scaling and dithering. For purposes of understanding and reference, and without intending to limit the meaning the above-identified processes have to a person of ordinary skill in the art, listed below are definitions for the above-identified processes: 
   
     
       
             
             
             
           
         
             
                 
                 
             
             
                 
               PROCESS 
               DEFINITION 
             
             
                 
                 
             
           
           
             
                 
               Up Sampling 
               Process of increasing the amount of 
             
             
                 
                 
               digital data used to represent an image 
             
             
                 
               Down Sampling 
               Process of decreasing the amount of 
             
             
                 
                 
               digital data used to represent an image 
             
             
                 
               Gamma Insertion 
               Process of inserting a value to 
             
             
                 
                 
               compensate for the non-linear 
             
             
                 
                 
               characteristics of an output device 
             
             
                 
                 
               (e.g., a computer monitor) 
             
             
                 
               Gamma Removal 
               Process of removing a value inserted to 
             
             
                 
                 
               compensate for the non-linear 
             
             
                 
                 
               characteristics of an output device 
             
             
                 
                 
               (e.g., a computer monitor) 
             
             
                 
               Color Space 
               Process of converting between 
             
             
                 
               Conversion 
               different color encoding schemes (e.g., 
             
             
                 
                 
               between a component color scheme 
             
             
                 
                 
               and a composite color scheme) 
             
             
                 
               Scaling 
               Process of changing the resolution of 
             
             
                 
                 
               an image 
             
             
                 
               Dithering 
               Process of combining colors to trick 
             
             
                 
                 
               the eye into seeing more colors than 
             
             
                 
                 
               the system can actually display 
             
             
                 
                 
             
           
        
       
     
   
   In addition, pre-processing may include addressing on a frame-by-frame basis the video signal being pre-processed. In video, a frame is a single complete image. In frame-by-frame addressing, video input system  110  may pre-process one frame of a video signal different than, for example, the next frame of the video signal. 
   In the embodiment shown in  FIG. 2   a , video input system  110  includes video input module  200 , input multiplexer  212 , input multiplexer  222 , pipeline  210 , pipeline  220 , output multiplexer  214 , and output multiplexer  224 . Video input module  200  receives a live video signal and forwards the live video signal to, for example, a buffer (not shown) for transfer to pipeline  210  and/or pipeline  220 . The live video signal may be an analog video signal or a digital video signal. If the live video signal is an analog video signal, then video input module  200  converts the live video signal into a computer-readable format. 
   The input multiplexers, multiplexer  212  and multiplexer  222 , route the respective video signal to the pipelines. In particular, multiplexer  212  routes video signals to pipeline  210  and multiplexer  222  routes video signals to pipeline  220 . The pipelines, pipeline  210  and pipeline  220 , pre-process the forwarded video signal. The output multiplexers, multiplexer  214  and multiplexer  224 , route the pre-processed video signals to, for example, various output buffers (not shown) accessible to video graphics workstation  100 . For example, the pre-processed video signal may be forwarded, via the 64-bit PCI bus and the AGP, to video graphics processor  130 . Or, the pre-processed video signal may be forwarded, via the 64-bit PCI bus and the 32-bit PCI bus, to video output system  140 . The pre-processed video signal may also be forwarded, via the 64-bit bus, to storage medium  120 . 
     FIG. 2   b  shows an exemplary embodiment for pre-processing a live video signal and a stored video signal in video input system  110 . In this embodiment, pipeline  210  and pipeline  220  pre-process a live video signal and/or a stored video signal. Typically, the stored video signal is forwarded from, for example, storage medium  120 , to a buffer (not shown) to allow for efficient transfer of the stored video signal to video input system  110 . 
   With two pipelines, a single live, or stored, video signal may reach pipeline  210  and pipeline  220 . Thus, two versions of a single live, or stored, video signal may be generated at the same time. For example, video input system  110  may receive a television signal and pre-process the televison signal via pipeline  210  for display on a computer monitor and via pipeline  220  for storage on storage medium  120 . In addition, using frame-by-frame addressing, video input system  110  may pre-process more than two video signals substantially at the same time. In this embodiment, the frames of the different video signals are interleaved and routed to pipeline  210  and pipeline  220 . Moreover, video input system  110  may pass a video signal, either live or stored, through pipeline  210  and/or pipeline  220  without pre-processing the video signal. 
   In a further embodiment of video input system  110 , video input module  200  receives and forwards more than one live video signal to, for example, a buffer (not shown) for transfer to pipeline  210  and/or pipeline  220 . The live video signals may be analog video signals or digital video signals. If the live video signal is an analog video signal, then video input module  200  converts the live video signal into a computer-readable format. For each received live video signal, video input module  200  produces a forwarded video signal. 
   In a further embodiment of these exemplary embodiments, video input module  200  includes an ancillary data extractor for removing ancillary data from a live video signal. Typically, the ancillary data is removed from the live video signal prior to receipt of the live video signal in the input multiplexers, multiplexer  212  and multiplexer  214 . Ancillary data includes, among other things, audio data and close captioning data. 
     FIG. 3  shows an exemplary embodiment for a scalable video input system  110 . In this embodiment, video input system  110  includes video input module  300  and video processing module  350 . Video input module  300  includes receiver  302 , processor  304 , and buffer  306 . Receiver  302  receives a live video signal and forwards the live video signal to processor  304 . Processor  304  converts the received video signal into a video signal having a common video data format. The formatted video signal is then forwarded to buffer  306  for transfer to video processing module  350 . In alternate embodiments of the invention, video input module  300  may include an ancillary data extractor for removing ancillary data from a live video signal. 
   Video processing module  350  includes input multiplexer  352 , pipeline  354 , and output multiplexer  356 . As discussed above in regard to the embodiments shown in  FIG. 2 , video processing module  350  pre-processes the formatted video signal and/or a stored video signal and routes the pre-processed video signal to, for example, a buffer (not shown) accessible to video graphics workstation  100 . Video processing module  350  may have two pre-processing pipelines. In addition, the pre-processed video signal may be forwarded to video graphics processor  130 , video output system  140 , and/or storage medium  120 . 
   The common video data format may be an organized bit stream. As noted above, a frame is a single complete image. An image, in turn, is composed of a raster of picture elements, referred to as pixels. A pixel is represented by some number of bits stored, for example, in memory. Pixels are the smallest “units” on a screen that can be given a color (represented with color data) and an opacity (represented with alpha data). Thus, an organized bit stream may include color data, alpha data, or color data and alpha data. For example, a bit stream with color data may include 20-bits for color data. In contrast, a bit stream for alpha data may include 10-bits for alpha data. Pipeline  354  may pre-process color data separate from alpha data. In this embodiment, a color data bit stream may be forwarded on a output different from the output used to forward alpha data. 
   In these exemplary embodiments, video input module  300  and video processing module  350  are separate modules coupled together via, for example, male/female cables. In one embodiment, video input module  300  is a daughterboard that plugs into video processing module  350 . The separation of the various functions of a video input system into a video input module and a video processing module allows for the separation of video input module  300  and video processing module  350 . 
   In turn, the separation of video input module  300  from video processing module  350  allows for the configuration of various video input modules, each configured to receive and process different video signal formats. Because the “input” functions of video input system  110  have been separated from the “processing” functions of video input system  110 , video input module  300  may be “exchanged” without the need to replace video processing module  350 . Thus, when a user wants to input, for example, a serial digital component video signal into video input system  110  instead of an analog composite video signal, the user “exchanges” the video input module configured for the analog composite video signal with a video input module configured for the serial digital component video signal. In turn, processor  304  (on the “new” video input module) signals video processing module  350  of the new configuration. 
     FIGS. 4   a  and  4   b  show various exemplary exploded views for mounting an interchangeable connector module, such as video input module  300 , to a processing module, such as video processing module  350 . In  FIG. 4   a , interchangeable connector module  400  includes connectors  402  and mounting holes  404 . Circuit board  450  includes plate  455 . Plate  455  includes connector holes  452  and mounting holes  454 . Plate assembly  430  includes plate  435   a  and two screws (not shown). Plate  435   a  includes connector holes  432   a  and mounting holes  434   a . Connectors  402  are designed to fit through connector holes  432  and  452 . The two screws, passing through mounting holes  434   a  and mounting holes  454 , secure interchangeable connector module  400  to circuit board  450  via mounting holes  404 . 
   In  FIG. 4   b , plate assembly  430  further includes plate  435   b  and gaskets  436 . Gaskets  436  are designed to improve electromagnetic shielding. For example, gaskets  436  may be composed of a rubber compound with embedded silver. For the exemplary embodiments shown in both  FIG. 4   a  and  FIG. 4   b , in operation, interchangeable connector module  400  would also be coupled (not shown) to processing module  450 . 
   B. Video Graphics Processor 
   Various exemplary embodiments of a video graphics processor are disclosed in the following: 
   1. U.S. patent application Ser. No. 09/353,495, filed Jul. 15, 1999, and entitled “MULTIPROCESSOR GRAPHICS ACCELERATOR,” the disclosure of which is hereby incorporated, in its entirety, by reference; 
   2. U.S. patent application Ser. No. 09/354,462, filed Jul. 15, 1999, and entitled “APPARATUS AND METHOD OF DIRECTING GRAPHICAL DATA TO A DISPLAY DEVICE,” the disclosure of which is hereby incorporated, in its entirety, by reference; 
   3. U.S. patent application Ser. No. 09/353,420, filed Jul. 15, 1999, and entitled “WIDE INSTRUCTION WORD GRAPHICS PROCESSOR,” the disclosure of which is hereby incorporated, in its entirety, by reference; and 
   4. U.S. patent application Ser. No. 09/353,419, filed Jul. 15, 1999, and entitled “SYSTEM FOR DISPLAYING A TELEVISION SIGNAL ON A COMPUTER MONITOR,” the disclosure of which is hereby incorporated, in its entirety, by reference. 
   C. Video Output System 
     FIG. 5  shows an exemplary embodiment for video output system  140 . In  FIG. 5 , video output system  140  includes receiver  500 , pipeline  510 , and video output module  520 . Receiver  500  receives a video signal and forwards the received video signal to, for example, a buffer (not shown) for transfer to pipeline  510 . The received video signal may be formatted in one of many different video data formats. For example, the received video signal may be an RGB encoded video signal or an RGBA encoded video signal. An RGB encoded video signal encodes an image in accordance with the amount of red, green, or blue contained in the image. An RGBA encoded video signal further encodes an image in accordance with the amount of opacity contained in the image. 
   The received video signal may also be a “YUV-Type” encoded video signal or a “YUVA-Type” encoded video signal. A “YUV-Type” encoded video signal encodes an image in accordance with the amount of luma (black and white) and color differences contained in the image. A “YUVA-Type” encoded video signal further encodes an image in accordance with the amount of opacity contained in the image. A “YUV-Type” encoded video signal includes, among other things, a YUV encoded video signal, a YCbCr encoded video signal, and a YPbPr encoded video signal. A “YUVA-Type” encoded video signal includes, among other things, a YUVA encoded video signal, a YCbCrA encoded video signal, and a YPbPrA encoded video signal. 
   Pipeline  510  post-processes the forwarded video signal and forwards the post-processed video signal to video output module  520 . The process of post-processing includes, among other things, region of interest selection, frame rate matching, spatial adaptation, up sampling, down sampling, gamma insertion, gamma removal, and color space conversion. Spatial adaptation includes, among other things, scaling and picture framing. Picture framing includes, among other things, letter boxing. For purposes of understanding and reference, and without intending to limit the meaning the above-identified processes have to a person of ordinary skill in the art, listed below are definitions for the above-identified processes not previously defined: 
   
     
       
             
             
             
           
         
             
                 
                 
             
             
                 
               PROCESS 
               DEFINITION 
             
             
                 
                 
             
           
           
             
                 
               Region of Interest 
               Process of selecting a portion of an 
             
             
                 
               Selection 
               image for post-processing 
             
             
                 
               Frame Rate 
               See Section E. 
             
             
                 
               Matching 
             
             
                 
               Picture Framing 
               Process of positioning an image on a 
             
             
                 
               and Letter Boxing 
               background image 
             
             
                 
                 
             
           
        
       
     
   
   In addition, post-processing may include addressing on a frame-by-frame basis the video signal being post-processed. In frame-by-frame addressing, video output system  140  may post-process one frame of a video signal different than, for example, the next frame of the video signal. Also, post-processing may include changing a frame of video data into interlaced fields of video data. In using this process, video output system  140  “blends” single or multiple lines from a frame in an input video signal into a single line in an output video signal, e.g, 3:2 pull-down. 
   Video output module  520  converts the post-processed video signal to a formatted video signal. The formatted video signal may be an analog video signal or a digital video signal. 
   Typically, video output system  140  also includes a generator locking device, referred to as a genlock, which allows the synchronized display of graphics and video. A genlock may lock video output system  140  to, for example, video graphics processor  130 . In addition, regardless of whether video output system  140  is locked to video graphics processor  130 , a genlock may lock video output module  520  to another source, e.g., an external clock, an internal clock, etc. 
   In a further embodiment of these exemplary embodiments, video output module  520  includes an ancillary data injector for inserting ancillary data into the post-processed video signal prior to conversion of the post-processed video signal. As noted above, ancillary data includes, among other things, audio data and close captioning data. 
     FIG. 6  shows an exemplary embodiment for a scalable video output system  140 . In this embodiment, video output system  140  includes video processing module  600  and video output module  650 . Video processing module  600  includes receiver  602  and pipeline  604 . As discussed above in regard to the embodiments shown in  FIG. 3 , video processing module  600  receives a video signal, post-processes the received video signal, and forwards the post-processed video signal to video output module  650 . Video processing module  600  may include a generator locking device for locking video processing module  600  to, for example, video graphics processor  130 . 
   Video output module  650  includes buffer  652 , processor  654 , and transmitter  656 . Video processing module  600  forwards the post-processed video signal to buffer  652  for transfer to processor  654 . Processor  654  converts the post-processed video signal into a formatted video signal, e.g., an analog composite video signal, a parallel digital component video signal, etc. The formatted video signal is then forwarded to transmitter  656 . In alternate embodiments of the invention, video output module  650  may include an ancillary data injector for inserting ancillary data into the post-processed video signal. 
   In these exemplary embodiments, video output module  650  and video processing module  600  are separate modules coupled together via, for example, male/female cables. In one embodiment, video output module  650  is a daughterboard that plugs into video processing module  600 . The separation of the various functions of a video output system into a video output module and a video processing module allows for the separation of video output module  650  and video processing module  600 . 
   In turn, the separation of video output module  650  from video processing module  600  allows for the configuration of various video output modules, each configured to process and produce different video signal formats. Because the “output” functions of video output system  140  have been separated from the “processing” functions of video output system  140 , video output module  650  may be “exchanged” without the need to replace video processing module  600 . Thus, when a user wants to output, for example, a serial digital component video signal instead of an analog composite video signal, the user “exchanges” the video output module configured for the analog composite video signal with a video output module configured for the serial digital component video signal. In turn, processor  654  (on the “new” video output module) signals video processing module  600  of the new configuration. 
   As an interchangeable connector module, video output module  650  may be mounted on video processing module  600 , a processing module, in the manner shown in  FIGS. 4   a  and  4   b.    
   D. Exemplary Video Graphics Applications 
     FIG. 7  shows an exemplary video graphics workstation implementing one embodiment of the invention for carrying out various exemplary video graphics applications In this embodiment, video input system  730  includes two pipelines, pipeline  732  and pipeline  734 . In addition, video output system  750  forwards a formatted video signal to a video tape recorder for recordation. 
   In one application, video graphics workstation  700  captures a live video signal. First, video graphics workstation  700  receives the live video signal. Next, the received video signal is pre-processed in pipeline  732  of video input system  730 . Then, the pre-processed video signal is forwarded, via the 64-bit PCI bus, to storage medium  720 . 
   In another application, video graphics workstation  700  captures and displays a live video signal. First, video graphics workstation  700  receives the live video signal. Next, the received video signal is pre-processed in both pipeline  732  and pipeline  734  of video input system  730 . Then, the pre-processed video signal from pipeline  732  is forwarded, via the 64-bit PCI bus, to storage medium  720 . In the interim, the pre-processed video signal from pipeline  734  is forwarded, via local bus  782 , to video graphics processor  740  for display on computer monitor  760 . The pre-processed video signal from pipeline  734  may also be forwarded to video graphic processor  740  via the 64-bit PCI bus and the AGP. In alternate embodiments, the pre-processed video signal from pipeline  734  may be forwarded, via the 64-bit bus and the 32-bit bus, to video output system  750  for recordation on video tape recorder  770 . 
   In another application, video graphics workstation  700  plays back a stored video signal. First, video graphics workstation  700  forwards a stored video signal, via the 64-bit PCI bus to video input system  730 . Next, the stored video signal is pre-processed in pipeline  732 . Then, the pre-processed video signal is forwarded, via local bus  782 , to video graphics processor  740  for display on computer monitor  760 . In an alternate embodiment, the pre-processed video signal may also be forwarded, via local bus  784 , to video output system  750  for recordation on video tape recorder  770 . 
   In another application, video graphics workstation  700  processes a stored video signal, for example, performs a two-dimensional or three-dimensional effect on the stored video signal, and displays the processed video signal. First, video graphics workstation  700  forwards a stored video signal, via the 64-bit PCI bus, to video input system  730 . Next, the stored video signal is pre-processed in pipeline  732 . Then, the pre-processed video signal is forwarded, via local bus  782 , to video graphics processor  740  for “effects” processing and display on a computer monitor  760 . In an alternate embodiment, the processed video signal may also be forwarded, via local bus  784 , to video output system  750  for recordation on video tape recorder  770 . 
   In another application, video graphics workstation  700  pre-processes a stored video signal and saves the pre-processed video signal. First, video graphics workstation  700  forwards a stored video signal, via the 64-bit PCI bus, to video input system  730 . Next, the stored video signal is pre-processed in pipeline  732 . Then, the pre-processed video signal is forwarded, via the 64-bit PCI bus, to storage medium  720 . In alternate embodiments, the pre-processed video signal may be forwarded, via the 64-bit PCI bus, to central processing unit  715  or to memory  710 . 
   In another application, video graphics workstation  700  processes a stored video signal and saves the processed video signal. First, video graphics workstation  700  forwards a stored video signal, via the 64-bit PCI bus, to video input system  730 . Next, the stored video signal is pre-processed in pipeline  732 . Then, the pre-processed video signal is forwarded, via local bus  782 , to video graphics processor  740  for “effects” processing. Last, the processed video signal is forwarded, via local bus  782 , to video input system  730 . Video input system  730  may pre-process the processed video signal, for example, to convert the processed signal to a format better suited for saving, or forward the processed signal, via the 64-bit PCI bus, to storage medium  720 . 
   In another application, video graphics workstation  700  combines a live video signal, a stored video signal, and graphics information and records the combined video signal. First, video graphics workstation  700  receives a live video signal. Next, the received video signal is pre-processed in pipeline  732  of video input system  730 . In the interim, video graphics workstation  700  forwards a stored video signal to video input system  730 . Next, the stored video signal is pre-processed in pipeline  734 . Then, graphics information (via the AGP), the pre-processed video signal from pipeline  732  (via local bus  782 ), and the pre-processed video signal from pipeline  734  (via local bus  782 ) are forwarded to video graphics processor  740  for “effects” processing. Last, the processed video signal is forwarded, via local bus  784 , to video output system  750  for recordation on video tape recorder  770 . 
   E. Frame Rate Matching 
   As discussed above, a frame is a single complete image. Typically, a frame is represented, in a video graphics workstation, with frame data. In general, frame rate is how fast a new frame of frame data, in other words, an new image, is available for processing or display. The process of frame rate matching includes, among other things, matching the frame rate of, for example, a video signal to the frame rate of, for example, an output device. Typically, in a video graphics workstation, the process of frame rate matching occurs in the video output system. 
     FIG. 8  shows an exemplary process in a video graphics workstation for video signal frame rate matching. The process begins at step  800 , in which the video graphics workstation fills a first buffer with a sequence of frame data. Next, at step  810 , the workstation reads out the frame data in the first buffer and, at substantially the same time, fills a second buffer with the next sequence of frame data. The process continues at step  820 , in which the video graphics workstation determines whether all of the frame data has been read out of the first buffer. If yes, the video graphics workstation fills the first buffer with the next sequence of frame data. If no, the video graphics workstation, at step  830 , fills the third buffer with the next sequence of frame data. 
   Next, at step  840 , the video graphics workstation determines whether all of the frame data in the first buffer has been read out of the first buffer. If no, the video graphics workstation begins to fill the second buffer with the next sequence of frame data. If yes, the video graphics workstation, at step  850 , determines whether the second buffer or the third buffer has the most current and most complete frame data. If the second buffer has the most current and most complete frame data, the video graphics workstation, at step  860 , reads the frame data out of the second buffer. If the third buffer has the most current and most complete frame data, the video graphics workstation, at step  870 , reads the frame data out of the third buffer. 
   In a further embodiment of the invention, the buffer determined not to have been filled with the most current and most complete frame data becomes a remainder buffer. In this embodiment, the video graphics workstation fills the remainder buffer with the next sequence of frame data. Then, if all of the frame data has not been read out of the buffer determined to have been filled with the most current and most complete frame data, the video graphics workstation fills the first buffer with the next sequence of frame data. The video graphics workstation continues to alternate between the remainder buffer and the first buffer until all of the frame data has been read out of the buffer determined to have been filled with the most current and most complete frame data. 
   Thus, in operation, the three buffers change “roles.” For example, the buffer now being filled may, depending upon the circumstances, next become either the buffer being read or the buffer not being either filled or read. Or, the buffer now being read may, depending upon the circumstances, next become either the buffer being filled or the buffer not being either filled or read. Or, the buffer now not being either filled or read may, depending upon the circumstances, next become either the buffer being read or the buffer being filled. 
   In both embodiments of the invention, a buffer may contain the most complete frame data when the buffer is less than 100% full. Typically, however, a buffer contains the most complete frame data when the buffer is 100% full. In addition, a buffer may contain one or more frames of frame data. Typically, however, a buffer contains one frame of frame data. 
   Further, both embodiments of the invention are scalable. In other words, both embodiments of the invention may be used to match any frame rates. For example, a frame rate to be matched may be 24/1.001 frames/second, or 24 frames/second, or 25 frames/second, or 29.97 frames/second, or 30/1.001 frames/second, or 30 frames/second, or 50 frames/second, 60/1.001 frames/second, 60 frames/second or 75 frames/second. Also, the frame rates being matched may be the same frame rate. Or, in the alternative, the frame rates being matched may be multiples of each other. 
   F. Packing and Unpacking Video Data 
   As discussed above, an image is composed of a raster of picture elements, referred to as pixels. Pixels are the smallest “units” on a screen that can be given a color (represented with color data) and an opacity (represented with alpha data). In general, a pixel is represented by some number of bits stored, for example, in memory. For example, a pixel may be 1-bit in length, 8-bits in length, 10-bits in length, 24-bits in length, or 32-bits in length. 
   In turn, memory stores data in segments, with each segment being some number of bits. For example, memory may be capable of storing data in 32-bit segments or 64-bit segments. It may inefficient, however, to store, for example, one 8-bit pixel in a 32-bit memory segment. But, four 8-bit pixels may be “packed” in a 32-bit memory segment. In the same way, four 24-bits pixels may be packed in three 32-bit memory segments. Typically, in a video graphics workstation, the process of packing and unpacking pixels occurs in the video input system. 
     FIGS. 9   a  and  9   b  show an exemplary process in a video graphics workstation for packing and unpacking pixels. In particular,  FIG. 9   a  shows an exemplary process in a video graphics workstation for unpacking pixels. The process begins at step  900   a , in which the video graphics workstation loads a shift-down register with the pixel data contained in a first memory device. In this embodiment, the first memory device has a bit storage capacity smaller in size than the bit storage capacity of the shift-down register. For example, the first memory device may be 64-bits in length and the shift-down register may be 80-bits in length. Next, at step  910   a , the video graphics workstation shifts one complete pixel of pixel data down the shift-down register. For example, one 24-bit pixel is shifted down the shift-down register. 
   Then, at step  920   a , the video graphics workstation determines whether the shift-down register contains another complete pixel of pixel data. If yes, the video graphics workstation shifts another complete pixel of pixel data down the shift-down register. If no, the video graphics workstation, at step  930   a , loads a shift-up register with the pixel data contained in a second memory device. In this embodiment, the second memory device is contiguous with the first memory device and has the same bit storage capacity as the first memory device. Also, the shift-up register has the same bit storage capacity as the shift-down register. 
   Next, at step  940   a , the video graphics workstation shifts the pixel data in the shift-up register up the number of bits of pixel data remaining in the shift-down register. For example, if the shift down register has 16 bits of pixel data remaining, then the video graphics workstation shifts the pixel data in the shift-up register up 16 bits. Then, at step  950   a , the video graphics workstation moves the pixel data in the shift-up register to the shift-down register, placing the shifted-up pixel data in the same bit locations in the shift-down register the shifted-up pixel data occupied in the shift-up register. For example, if the shifted-up pixel data occupied bit locations  16  through  63  in the shift-up register, then the video graphics workstation moves the shifted-up pixel data to bit locations  16  through  63  in the shift-down register. 
     FIG. 9   b  shows an exemplary process in a video graphics workstation for packing pixels. In this embodiment, the memory device in which the pixel data will be packed has a bit storage capacity smaller in size than the bit storage capacity of the shift-up register. For example, the memory device may be 64-bits in length and the shift-up register may be 80-bits in length. 
   The process begins at step  900   b , in which the video graphics workstation shifts one complete pixel of data up a shift-up register. Next, at step  910   b , the vide graphics workstation determines whether the shift-up register has capacity to hold another complete pixel of pixel data. If yes, the video graphics workstation shifts another complete pixel of pixel data up the shift-up register. If no, the video graphics workstation, at step  920   b , moves the pixel data in the uppermost bit locations of the shift-up register to a shift-down register, placing the moved pixel data in the same bit locations in the shift-down register the moved pixel data occupied in the shift-up register. For example, if the moved pixel data occupied bit locations  16  through  63  in the shift-up register, then the video graphics workstation moves the shifted-up pixel data to bit locations  16  through  63  in the shift-down register. 
   The amount of pixel data moved from the uppermost bit locations in the shift-up register depends upon the bit storage capacity of the memory device in which the pixel data will be packed. For example, if the memory device is 64-bits in length, then the video graphics workstation moves the 64 uppermost bits of the shift-up register to the shift-down register. Also, the shift-down register has the same bit storage capacity as the shift-up register. 
   Next, at step  930   b , the video graphics workstation shifts the pixel data in the shift-down register down the number of bits of pixel data remaining in the shift-up register. For examples, if the shift-up register has 16 bits of pixel data remaining, then the video graphics workstation shifts the pixel data in the shift-down register down 16 bits. Then, at step  940   b , the video graphics workstation moves the contents of the shift-down register to the memory device. 
   In all embodiments of the invention, one complete pixel of pixel data may include a bit stream of color data, a bit stream of alpha data, or a bit stream of color data and alpha data. The color data may be RGB encoded or “YUV-Type” encoded. In addition, the color data and alpha data may be RGBA encoded or “YUVA-Type” encoded. 
   The various embodiments of the invention may be implemented in any conventional computer programming language. For example, the various embodiments may be implemented in a procedural programming language (for example, “C”) or an object-oriented programming language (for example, “C++” or JAVA). The various embodiments of the invention may also be implemented as preprogrammed hardware elements (for example, application specific integrated circuits or digital processors), or other related components. 
   The various embodiments of the invention may be also implemented as a computer program product for use with a computer system. Such implementation may include a series of computer instructions fixed either on a tangible medium, such as a computer readable media (for example, a diskette, CD-ROM, ROM, or fixed disk), or transmittable to a computer system via a modem or other interface device, such as a communications adapter connected to a network over a medium. The medium may be either a tangible medium (for example, optical or analog communications lines) or a medium implemented with wireless techniques (for example, microwave, infrared or other transmission techniques). The series of computer instructions preferably embodies all or part of the functionality previously described herein with respect to the system. Those skilled in the art should appreciate that such computer instructions can be written in a number of programming languages for use with many computer architectures or operating systems. Furthermore, such instructions may be stored in any memory device, such as semiconductor, magnetic, optical or other memory devices, and may be transmitted using any communications technology, such as optical, infrared, microwave, or other transmission technologies. It is expected that such a computer program product may be distributed as a removable medium with accompanying printed or electronic documentation (for example, shrink wrapped software), pre-loaded with a computer system (for example, on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the network (for example, the Internet or World Wide Web). 
   Although various exemplary embodiments of the invention have been disclosed, it should be apparent to those skilled in the art that various changes and modifications can be made which will achieve some of the advantages of the invention without departing from the true scope of the invention. These and other obvious modifications are intended to be covered by the appended claims.