Abstract:
A method and system for notifying a viewer of the arrival or presence of one or more video input signals in a video display system, such as a personal computer (PC) or television (TV) system. If a video signal is already present, the system may optionally notify a viewer of the termination or absence of the video signal. The invention further provides the viewer with the opportunity to dynamically select the video source to view. Upon sensing the presence of a new video signal, the system alerts the viewer who may then select whether to view the new video signal or maintain prior viewing status.

Description:
Related Applications  
       [0001]    This application is a continuation, and hereby incorporates by reference the entire disclosure, of co-pending U.S. patent application Ser. No. 09/164,170, entitled “METHOD AND SYSTEM FOR DISPLAYING VIDEO SIGNALS”, which was filed on Sep. 30, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The invention relates generally to the management of video display systems, such as computer monitors. More particularly, the invention relates to the selection of video signals in a video system having multiple input.  
           [0004]    2. Description of the Related Art  
           [0005]    In recent years, the use of multimedia applications has steadily spread to many fields of technology. The term “multimedia” commonly refers to the fusion of information, communications, and visual media in a single processing system. With the evolution of the public Internet, several computer-based systems now offer multimedia applications for the communication and processing of data, voice, image/graphics, and video. Additionally, there are several television-based systems currently in use and development, such as interactive television (TV) or Web TV, which also support multimedia applications. The interactive TV concept combines the Internet and TV to enable viewers to access additional information about the programs they are watching and act on it through the Internet. The interactive TV experience may occur on a personal computer (PC) with a tuner card, such as those used with Intel&#39;s Intercast Technology. Alternatively, interactive TV may also be based on a standard television set with an external device supporting interactive access.  
           [0006]    There are at least two types of display systems available today: one for PC systems, and another for TV systems. The PC display system typically includes a display unit, processing circuit, and display adapter. The display adapter is a device which transforms text, graphics, or video signals from digital form to analog form for display by the display unit. The display unit may be a cathode ray tube (CRT) or liquid crystal display (LCD) device capable of displaying text, graphics, or video. On the other hand, the TV display system typically includes a monitor, demodulator, and tuner. The tuner and demodulator supply one or more video signals for display by the monitor.  
           [0007]    A variety of video standards are used in connection with PC systems, including MDA, CGA, HGC, EGA, PGA, VGA, MCGA, Super VGA, 8514/A, and XGA. In the case of TV systems, a different variety of video standards are used including National Television System Committee (NTSC), Phase Alternating Line (PAL), and Systeme Electronique Couleur Avec Memoire (SECAM).  
           [0008]    As PC and TV systems merge closer together, there is a heightened need to support multiple video inputs to accommodate for a variety of video signals and formats. Moreover, accommodating for multiple video inputs may be required when receiving video signals from dedicated multiple video sources, even though the video signals may be in the same format. When receiving video signals from multiple video sources at the same time (i.e., concurrently), a user has to manually select one video source to override one or more other video sources. For example, when a cable TV signal and a video cassette recorder (VCR) signal are received concurrently, a TV user must press one or more control buttons to select which of the two video signals to display on the TV monitor. In a PC system, a PC user may alternatively instruct the PC (e.g., by specialized programming) to prioritize video input sources in case of concurrent arrival of multiple video signals. Once the user selects a particular video source, the user may not view video signals from other video sources. To view video signals from other sources, the user has to re-press control buttons or reprogram specialized instructions. More particularly, the user is unable to accommodate for recognizing arrival (i.e., new presence) or termination (i.e., new absence) of other video signals into and from the PC or TV system.  
           [0009]    Therefore, there is a need in video display technology to accommodate for concurrent presence of multiple video signals in a PC or TV environment. The new system and method should enable a user to dynamically select multiple video sources as the user desires.  
         SUMMARY OF THE INVENTION  
         [0010]    In accordance with one embodiment, the invention provides a system for displaying video signals. The system comprises at least one detection circuit configured to monitor the arrival or presence of at least one of a plurality of video signals at at least one of a plurality of video inputs. The system further comprises a processing circuit, electrically coupled to the detection circuit, configured to notify the user of the presence of at least one of the plurality of video signals. In the event that only one of the plurality of video signals is present, the processing circuit is configured to automatically select the only one of the plurality of video signals for display. On the other hand, in the event that more than one of the plurality of video signals are present at the plurality of video inputs, the processing circuit is configured to prompt the user to select one of the more than one video signals for display. In another embodiment, the system comprises means for monitoring the arrival or presence of at least one of a plurality of video signals at at least one of a plurality of video inputs. The system further comprises means for notifying the user of the presence of at least one of the plurality of video signals. In the event that only one of the plurality of video signals is present, the notifying means is configured to automatically select the only one of the plurality of video signals for display. In the event that more than one of the plurality of video signals are present at the plurality of video inputs, the notifying means is configured to prompt the user to select one of the more than one video signals for display.  
           [0011]    In yet another embodiment, the invention provides a method of displaying video signals to a user. The method comprises monitoring the arrival or presence of at least one of a plurality of video signals at at least one of a plurality of video inputs. The method further comprises notifying the user of the presence of at least one of the plurality of video signals. The method further comprises automatically selecting only one of the plurality of video signals for display, provided that only one of the plurality of video signals is present. The method further comprises providing the user with an option to select one of the plurality of video signals for display, provided that more than one of the plurality of video signals are present at the plurality of video inputs. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The above and other aspects, features, and advantages of the invention will be better understood by referring to the following detailed description, which should be read in conjunction with the accompanying drawings, in which:  
         [0013]    [0013]FIG. 1 is a block diagram of an exemplary video system having multiple video inputs.  
         [0014]    [0014]FIG. 2 is a block diagram of one embodiment of the video system of the invention.  
         [0015]    [0015]FIG. 3 is a flowchart describing the steps executed by the video system of FIG. 2.  
         [0016]    [0016]FIG. 4 is a block diagram of one embodiment of the video detect circuit of the video system of FIG. 2.  
         [0017]    [0017]FIG. 5 is an exemplary screen display indicating the presence of one or more video signals in the video system of FIG. 2.  
         [0018]    [0018]FIG. 6 is an exemplary screen display of a control panel of the video system of FIG. 2. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    To better understand the invention, a brief description of functional components of an exemplary video system is first provided. FIG. 1 is a block diagram of an exemplary video system  100  having multiple video inputs. A multiplexer (MUX)  110  receives one or more video input signals (VIS)  104  from one or more video sources (not shown in this figure). The MUX  110  may receive the VIS  104  over copper, fiber-optic, or air media using an appropriate receiver. The MUX  110  may employ any method of coordinating the transfer of concurrent multiple input signals into a single output. For instance, the MUX  110  may comprise an electronic switch which allows connection of a predetermined VIS  104  to the output of the MUX  110 . Alternatively, in more sophisticated systems, the MUX  110  may employ multiplexing techniques such as time division multiplexing (TDM), frequency division multiplexing (FDM), or other similar methods which are known in the art. In case of analog video, the VIS  104  may be in any transmittable video format, such as NTSC, PAL, or SECAM. In case of digital video, the video format of VIS  104  may be in a serial digital interconnect (SDI), serial digital data interconnect (SDDI), Fiber Channel (FC), synchronous digital hierarchy (SDH), or other video formats which are known in the art. In addition to radio frequency (RF) channel medium (e.g., cable, satellite, or VHF/UHF), unconventional transmission methods such as the Internet and/or asynchronous transfer mode (ATM) media may be predominant methods of transmission for all kinds of video signal formats.  
         [0020]    To accommodate for the transmission of video signals over such unconventional transmission media, video information may be compressed using any of a variety of compression techniques which are known in the art. One example of such a compression technique may comply with a motion picture expert group (MPEG) standard. MPEG is an international standard which defines the display of video at 25 images per second having a transmission rate of 150-300 Kbytes per second. MPEG allows the display of full screen and full motion video with CD sound quality using relatively little memory. MPEG-1 is another set of international standards for the compression and decompression of digital video signals. MPEG-1 specifies a video resolution of 352×240 pixels compressed at a rate of 30/25 frames per second over a bandwidth of 150 Kbytes per second. MPEG-2 is yet another standard which specifies a video resolution of 720×480 pixels over a bandwidth ranging from 0.5 to more than 2 Mbytes per second. In general, MPEG-2 may be used for high definition television (HDTV) and digital versatile disk (DVD) drives. DVD is an optical disk having a capacity of up to 17 Gbytes, which contain full-length motion pictures for viewing on a PC.  
         [0021]    If necessary and, particularly, when the VIS  104  is compressed prior to initial transmission, the video system  100  may employ an MPEG decoder  114  to decompress the VIS  104  for processing. In case of analog TV systems, a digital-to-analog converter (DAC)  120  may be required to convert the VIS  104  from digital to analog form. For instance, the DAC  120  may convert SDI signals into NTSC format for further processing. As noted above, a tuner  124  and a demodulator  128  may be used to supply a TV monitor  130  with the appropriate video signal for display by the monitor  130 . In case of digital TV systems (e.g., HDTV), the HDTV may employ appropriate processing circuitry to display digital VIS  104  by a HDTV monitor.  
         [0022]    In case of PC systems, a large amount of video information may be communicated among a video card, a video processor (e.g., CPU), and a system memory over a video interface. A video interface may be defined as the medium by which a video processor and memory communicate with the rest of the PC. The video interface may comprise a local bus  134 , which may be an industry standard architecture (ISA), VESA local (VLB), peripheral component interconnect (PCI), an accelerated graphics port (AGP), or other similar video bus which is known in the art. As noted above, a display adapter  140  (e.g., a video card) may be used to transform text, graphics, or video signals from digital form to analog form for display by a PC monitor  150 . The PC monitor  150  may be a cathode ray tube (CRT) or liquid crystal display (LCD), or any other device which is capable of displaying text, graphics, or video.  
         [0023]    [0023]FIG. 2 is a block diagram of one embodiment of the video system of the invention. The video system  200  may comprise an analog or digital video system which is based on a TV or PC system architecture. A multiplexer (MUX)  210  may receive one or more video input signals (VIS)  204  for processing. Depending on its multiplexing technique, the MUX  210  communicates one of the VIS  204  to a multimedia processing circuit (MPC)  220  which may include some or all of the functional blocks illustrated in the video system  100  of FIG. 1. The MPC  220  may also include a processor programmed with instructions to perform or cause performance of video signal processing functions described above. Such a processor may be adapted for video signal processing, such as those used in PC or digital TV systems. An example of such a processor may be the Mpact media processor by Chromatic Research, Inc.  
         [0024]    Moreover, the video system  200  comprises one or more video detect circuits (VDC)  230  which monitors the activity of the VIS  204  ports. As used herein, the term “activity” refers to any signal activity associated with or related to video signals (i.e., VIS  204 ) including, without limitation, arrival, presence, termination, or absence of the VIS  204  at its respective port. The VDC  230  monitors the presence and absence of VIS  204  signals arriving into the video systems  200 . Each VDC  230  is electrically coupled to its respective VIS  204 . In this embodiment, three VIS  204  and three respective VDC  230  are depicted in FIG. 2. However, depending on the desired application, the video system  200  may employ any number of VIS  204  and VDC  230 . Moreover, in this embodiment, one VDC  230  monitors one VIS  204 . However, several VDC  230  may be implemented as one video detect unit to monitor one or more VIS  204 . Finally a general processor input/output (GPIO)  240  communicates with the one or more VDC  230  to monitor and reset each VDC  230  after it detects a VIS  204 . The GPIO  240  may be a 37M707 processor manufactured by SMC.  
         [0025]    Upon detecting the presence of a VIS  204 , the respective VDC  230  may generate an interrupt in a form of one or more logic level signals to the MPC  220 . If the presence of only one VIS  204  is detected, then the MPC  220  instructs the MUX  210  to connect the port receiving the active VIS  204  to the output of the MUX  210 . The MPC  220 , in turn, processes and displays the active VIS  204  using a display monitor (not shown in this figure). If, on the other hand, two or more VDC  230  detect the presence of two or more VIS  204 , then the two or more VDC  230  may generate two or more interrupts to the MPC  220 . Accordingly, the MPC  220  may alert (i.e., prompt) a system user with a message on the display monitor to select one of the two or more VIS  204  for viewing. The user may then respond to the MPC  220  by pressing one or more control buttons (located on the screen or elsewhere) or clicking a mouse. Upon selecting a VIS  204  to view, the MPC  220  may instruct the MUX  210  accordingly.  
         [0026]    It is sometimes desirable to prompt the user to select a video port each time a new VIS  204  is detected by the respective VDC  230 . For instance, if a user is viewing a VIS  204   a , and a video signal is detected at the VIS  204   c  port, then the MPC  220  will prompt the user to select whether to view the newly detected VIS  204   c  or continue viewing VIS  204   a . Alternatively, if the user is already viewing a VIS  204 , the MPC  220  may optionally be configured not to prompt the user to select a video port even if another VIS  204  is newly detected. This option may allow the user to view a video source without interruption due to the presence or arrival of another VIS  204 .  
         [0027]    Moreover, upon detecting the absence of one or more VIS  204 , the respective one or more VDC  230  may generate one or more interrupts in a form of one or more logic level signals to the MPC  220 . Consequently, the MPC  220  may notify the user with a message on the user&#39;s display monitor. The message may comprise, among other things, the code or name which identifies one or more video sources whose absence is detected. The user may acknowledge such notification by pressing one or more control buttons or clicking a mouse. The MPC  220  may notify the user of the absence of a VIS  204  port each time a new absence of a VIS  204  is detected by the respective VDC  230 . Alternatively, however, if the user is already viewing a VIS  204 , the MPC  220  may optionally be configured not to notify the user to select a video port even if the absence of another VIS  204  is newly detected. This option may allow the user to view a video source without interruption due to the absence or termination of another VIS  204 .  
         [0028]    [0028]FIG. 3 is a flowchart describing the steps executed by the video system  200 . The process begins at step  300  when the video system  200  is powered-up or initialized. At step  310 , the VDC  230  monitors the arrival or, if already present, termination of one or more video signals (i.e., VIS  204 ) from one or more video sources. At step  320 , the VDC  230  determines whether one or more new VIS  204  are detected at an input port. Hence, if one or more VIS  204  are already present, the VDC  230  takes no affirmative action. The VDC  230  returns to the monitoring step at  310 . The duration of time between two consecutive monitoring steps may be determined and programmed as desired by the system operator. On the other hand, if the arrival of one or more new VIS  204  is detected at step  310 , then the process proceeds to step  330 . At step  330 , the VDC  230  generates one or more interrupts to notify the MPC  220  of the presence (or absence) of one or more VIS  230 .  
         [0029]    At step  340 , the MPC  220  records the one or more interrupts and determines if more than one VIS  204  is detected. If the arrival of only one VIS  204  is detected, and no other VIS  204  are active, then the MPC  220  may automatically display the only active video source at step  350 . Alternatively, however, the system operator may desire to instruct the video system  200  to always prompt the user to select to view a VIS  204 , even if only one VIS  204  is active. On the other hand, if the arrival of more than one new VIS  204  is detected, then the MPC  220  may prompt the user to select the video source the user desires to view. Consequently, at step  370 , the video system  200  displays the desired VIS  204  to the user. The process terminates at step  380 . In practice, unless instructed otherwise, the video system  200  returns to the monitoring step at  310  and, hence, does not terminate.  
         [0030]    [0030]FIG. 4 is a block diagram of one embodiment of the VDC  230  of the video system  200 . It is worth noting that, depending on the technical specifications of the video system, there may be many variations of the VDC  230  which will appear obvious from the following description to one having ordinary skill in the art. In this description, an industry standard architecture (ISA) based video system is used to implement the VDC  230 . However, any other types of systems having an interrupt scheme may be used including, without limitation, extended ISA (EISA) and peripheral component interconnect (PCI).  
         [0031]    As shown in FIG. 4, the VDC  230  comprises one or more bandpass filters (BPF)  410  electrically connected to one or more video sources (not shown in this figure) supported by the video system  200 . For instance, the video system may support TV broadcasting channels, vertical sync channels, and many others. Hence, a BPF 410a may be used to detect video signals in the very high frequency (VHF) range of about 30-300 MHz. A BPF 410b may be used to detect video signals in the ultra high frequency (UHF) range of about 300-3000 MHz. A BPF 410c may be used to detect video signals directly received in the range of 50-100 Hz. Typically, a video cassette recorder (VCR) provides an output on VHF channels  3  and  4 . Hence, a VCR output may be connected to a circuit with a VHF BPF (i.e., BPF 410a). A satellite video signal may be in a MPEG format and, hence, may be connected through a filter with a BPF covering MPEG frequencies, i.e., 90 (MPEG1)-64 (MPEG4) kHz.  
         [0032]    It is desirable to have the output signal of a BPF 410 conform to the logical state levels recognized by the video system  200 . For instance, if the video system is a 5-Volt based system (i.e., one that recognizes 0 V as a low logical state and 5 V as the high logical state), it is desirable to have the output of a BPF 410 be in the range of 0-5 volts. Moreover, the BPF 410 is selected so that, whenever there exists any minimal video activity by a VIS  204 , its output signal is able to activate, drive, or trigger a subsequent component such as a transistor. Bandpass filters having lower and upper cutoff frequencies in various ranges of frequencies are known in the art.  
         [0033]    The VDC  230  further comprises one or more interrupt generation circuits (IGC)  420  electrically connected to the one or more BFP 410. Upon detecting a VIS  204 , the IGC  420  issues an interrupt signal to the MPC  220  (FIG. 2). The IGC  420  may comprise a set of resistors and capacitors coupled to a digital generation logic. Hence, the design of the IGC  420  may be accomplished in a variety of ways. Moreover, the following description is for an IGC  420 , which detects and generates an interrupt for a single VIS  204 . Hence, using other BPFs (e.g., BPF 410b, 410c, etc.), the following IGC  420  may be duplicated to detect and generate an interrupt for virtually any desired number of VIS  204 .  
         [0034]    In one embodiment, the IGC  420  is a one-shot interrupt generator which comprises a resistor R 1   421  connected to the base of a bipolar Transistor  422 . The emitter of the Transistor  422  may be terminated by connecting a resistor R 2   423  in parallel with a capacitor C 1   424  to ground. The combination of these resistors, capacitor and transistor provides a signal of logical state level 1 (i.e., high) after a predetermined period from the occurrence of a signal activity on the output of the BPF 410a. The occurrence of signal activity is typically in response to detecting of a video signal VIS  204 .  
         [0035]    The voltage signal at the emitter of the Transistor  422  is connected into a first input of a NOR Gate  425 . The output of the NOR Gate  425  is connected to one end of a capacitor C2  426 . The voltage signal at the output or, in this case, collector of the Transistor is connected to the other end of C2  426  via a resistor R3  427 . The other end of C2  426  is fed into an inverter  428  whose output is fed back into a second input of the NOR Gate  425 . Examples of the inverter  428  include the SN7405 manufactured by TI. The output of the inverter  428  may be fed into a J input of a JK flip-flop (JKFF)  429 . As is well known in the art, the characteristics equation of a JKFF  429  is Q(t+1)=JQ&#39;+K&#39;Q. In a JKFF  429  the letter J is for “set” and the letter K is for “clear”. Examples of the JKFF  429  include the SN74F109 manufactured by TI. As noted above, in an ISA based video system, the JKFF  429  receives a clock pulse (CP) input from the ISA clock  432 . The output Q&#39; (Q-not) of the JKFF  429  is connected to another inverter  431  whose output is fed into the MPC  220  (FIG. 2). The inverter  431  drives an interrupt line with an open collector output in compliance with the ISA standard.  
         [0036]    The operation of the various components of the VDC  230  is described hereafter. When a VIS  204  is received by a BPF 410, the Transistor  422  is triggered and thereby charges C 1   424 . When the voltage signal across C 1  (i.e., emitter voltage) reaches a logical state of level 1, then R 1   421 , NOR Gate  425 , C2  426 , and inverter  428  are activated to generate an input into J of the JKFF  429 . The JKFF  429  receives the output of the inverter  428  and produces an interrupt over the ISA bus to the MPC  220  for action. Upon processing the interrupt by the MPC  220 , the GPIO  240  reads the status of each VIS  204  through its respective JKFF  424  and transistor  422  connection. Once it reads the status of each VIS  204 , the GPIO  240  resets the JKFF  424  through the K input. In case of more than one VIS  204 , the GPIO  240  may reset one or more JKFF  424  simultaneously.  
         [0037]    It is desirable to have the values of C 1   424  and R 2   423  be selected so that C 1   424  maintains the logical state 1 despite and through momentary lapses in activity of the VIS  204 . The duration of maintaining the logical state  1  across C 1   424  may be in the order of few seconds. This duration aids in preventing the generation of another independent interrupt from an invariant video source, i.e., which has an essentially constant VIS  204 . A typical value for C 1  may be in the range of about 90-100 picofarads, and for R 2  may be in the range of about 0.9-1 kOhms.  
         [0038]    It is desirable to select values for C2  426  and R3  427  so that the inverter  428  outputs a pulse signal having a period equal to at least twice the period of the CP of the JKFF  429 . The duration of at least twice the period of the CP ensures that the JKFF  429  captures a change in the logical state of the output signal of the inverter  428 . The one-shot aspect of the IGC  420  refers to the ability of the IGC  420  not to output another signal until the voltage level across C 1   424  falls below than and rises back to the logical state 1. Alternatively, a Schmitt trigger circuit (not shown in this figure) may be used to charge C 1   424  to generate this type of logical state output. The design and implementation of a Schmitt trigger circuit is well known in the art.  
         [0039]    If T is the duration of a one-shot pulse signal, C is a capacitance (i.e., C2  424 ), R is a resistor (i.e., R3  427 ), and Cf is the clock frequency of CP, then T=0.69*R*C and R*C=2/(0.69*Cf). Hence, for example, for a clock frequency of 33 MHz, then appropriate values are R3=910 Ohms, and C2=100 picofarads, thereby providing a pulse duration T =62.8 nanoseconds. It is desirable to have the clock pulse (i.e., CP) of the JKFF  429  be fast enough to ensure that the duration of the one-shot pulse signal terminates before the minimum interrupt response time of the video system. Having the one-shot pulse signal terminate in this manner avoids the generation of spurious interrupts when the JKFF  429  is reset.  
         [0040]    [0040]FIG. 5 is an exemplary screen display indicating the presence of one or more video signals in the video system of FIG. 2. As shown in FIG. 5, upon detecting the presence of a new VIS  204 , the MPC  220  prompts the user to select whether to view the new signal or maintain current viewing status. The MPC  220  also prompts the user to switch to a control panel whereby the user may set default information such as selection of a video source. In this embodiment, the user makes a selection by simply clicking an appropriate button on the screen.  
         [0041]    [0041]FIG. 6 is an exemplary screen display of a control panel of the video system  200 . As shown in FIG. 6, a control panel allows a user to select a default video input port (i.e., a video source). The number of input ports may be limited by the number of various video sources available to the video system  200 . In this embodiment, four video sources are shown: (1) Front S-Video; (2) Rear S-Video; (3) NTSC (RCA Jack); and (4) NTSC (BNC Jack). These video sources are provided to illustrate the kind and nature of video source selection and, hence, many other video sources may be selected. Moreover, the control panel may provide several other functions which a user may desire to control or set default values thereto.  
         [0042]    In view of the foregoing, it will be appreciated that the invention overcomes the long-standing need for a system and method for selecting a desired video input in accordance with the desire of a user. The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiment is to be considered in all aspects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which fall within the meaning and range of equivalency of the claims are to be embraced within their scope.