Abstract:
An audio-visual system includes a receiver and a remote control unit linked by a radio frequency wireless link. The receiver receives displays a primary television signal having a first format. The primary television signal is then transcoded to a secondary television signal having a second format compatible with the remote control unit. The remote control unit receives and displays the secondary television signal on a touch-sensitive display that can be used to operate the receiver.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to the field of audio-visual systems, and more particularly to remote control units used with audio-visual systems.  
         BACKGROUND OF THE INVENTION  
         [0002]    Audio-visual (AV) systems are fairly common and available in the market today. Some of these AV systems have interactive digital television capabilities. Interactive AV systems enable a user to interactively engage with the AV content. These interactive AV systems use a remote control unit (RCU) and menus displayed on a television screen to enable the user to interact with the content.  
           [0003]    [0003]FIG. 1 shows the components of a typical prior art AV system  100 . A digital AV receiver  300  receives a television signal  101  by satellite, terrestrial, or cable means. The digital AV receiver  300  decodes the television signal  101 , and renders the content on an output device, such as a television screen  120 . The television screen  120  can be a cathode ray tube, a projector, or a LCD. A remote control unit  200  can control the AV receiver  300  using remote control functions  201 , such as channel selection, volume adjustment, and receiver setup. The remote control unit  200  is also used to navigate the AV program by pressing buttons on the remote control unit. Typically, the RCU communicates with receiver via an infra-red (IR) transmitter  142  and an IR receiver  141 . FIG. 2 shows the remote control functions  200  in greater detail. The RCU includes a processor  210  to execute functions such as volume control  211 , channel selection  212 , and menu control  213 . Usually, a keypad  220  is used for entering commands. An encoder  230  encodes the commands for the IR transmitter  142 . The AV receiver  300  decodes and acts on the commands. Current program information such as the name and number of the selected channel, and current time and date information can be displayed on the television screen  120 . In addition, the television screen  120  is used to display menus and data entry fields for configuring the receiver  300 .  
           [0004]    [0004]FIG. 3 shows the prior art digital AV receiver  300  in greater detail. The digital AV receiver  300  receives the signals  101  by the cable, satellite, or terrestrial means. A tuner  310  is used to select a specific frequency that corresponds to a specific television channel. The tuner  310  is responsive to user commands decoded by a remote input processor  320 , e.g., selected channels. The selected channel is demodulated  330  to recover the digital AV program data that is transmitted by a means such as the MPEG-2 transport stream.  
           [0005]    An MPEG-2 demultiplexer  340  partitions the transport stream into audio and video signals, and any interactive TV commands. An audio decoder  351  provides an audio signal for an amplifier  361  connected to audio output means  371 , e.g., loudspeakers. Similarly, a video decoder  352  provides a signal for a display and graphics processor  362 . The processor  362  can combine the video output from the decoder  352  with any optional graphical elements, such as interactive TV menus, sub titles, and AV receiver setup menu obtained from the ITV command processor  353 . The composite video is then rendered to a display device, such as the television screen  120  of FIG. 1. The remote input processor  320  also processes other commands, such as volume control, and interactive TV commands.  
           [0006]    U.S. Pat. No. 6,351,270 issued to Nishikawa et al., on Feb. 26, 2002 describes an AV system for displaying a graphical menu and a “decimated” video on a television screen to that a user can navigate through available content.  
           [0007]    U.S. Pat. No. 5,767,919 issued to Lee et al., on Jun. 16, 1998 describes a remote control unit for displaying and processing graphical menus displayed on a television screen.  
           [0008]    To interact with content delivered to a television, most interfaces use of a graphical overlay on the television screen to allow users to interact with the content and to alert users to the presence of interactive content on the television. U.S. Pat. No. 6,335,736 issued to Wagner et al. on Jan. 1, 2002 describes one such system.  
           [0009]    Some systems allow dynamically changing the user interface based on certain characteristics, see U.S. Pat. No. 6,292,187 issued to Gibbs et al. on Sep. 18, 2001.  
           [0010]    U.S. Pat. No. 6,144,003 issued to Chor et al., on Oct. 31, 2000 describes a graphical user interface that includes a channel bar and icon for selecting available channels.  
           [0011]    Some digital AV systems combine audio with the visual user interface to prompt users when particular options are available. U.S. Pat. No. 6,388,715 issued to Eggen et al., on May 24, 2002 describes an electronic program guide that produces an audio signal that is characteristic of a particular program category when that program category is selected.  
           [0012]    U.S. Pat. No. 6,313,887 issued to Gudorf et al., on Nov. 6, 2001 describes a pager that can receive and display paging information, e.g., program schedules, broadcast by a pager service provider.  
           [0013]    The prior art systems primarily use the keypad on the remote control unit to make content selections and navigate the graphical menu displayed on the television screen. User input is typically provided by selecting highlighted portions on the television screen followed by clicking the appropriate buttons on the remote control unit. The user cannot randomly select an option. Navigation among available options is done by sequentially “scanning” through the options. The disadvantage is that the user has to rely on the graphical menu on the television in order to activate a selection button on the remote control unit. Another disadvantage is that the user has to be near the television to see the display and operate the remote control unit due to the limited line-of-sight range of IR transceivers.  
           [0014]    Therefore, there is a need for an audio-visual system that overcomes the problems of prior-art systems.  
         SUMMARY OF THE INVENTION  
         [0015]    The present invention provides a remote control unit (RCU) for an audiovisual (AV) receiver, with a secondary display, which is based on the primary display seen on a television screen. The secondary display includes a touch-sensitive surface for entering commands corresponding to interactive display elements. In addition, communication between the AV receiver and the RCU uses radio signals which do not need to be line-of-sight.  
           [0016]    The digital AV receiver is equipped with an encoder to generate a secondary television signal from the primary television signal. The RCU decodes the secondary television signal and renders the decoded signal on a touch-sensitive display screen. The AV receiver and the RCU are equipped with a wireless communication means with sufficient bandwidth to carry the transcoded signals from the AV receiver to the RCU, as well as, user commands the RCU to the AV receiver. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0017]    [0017]FIG. 1 is a block diagram of a prior art digital AV receiver and remote control unit;  
         [0018]    [0018]FIG. 2 is a block diagram of a prior art remote control unit;  
         [0019]    [0019]FIG. 3 is a block diagram of a prior art AV receiver;  
         [0020]    [0020]FIG. 4 is a block diagram of an AV receiver and remote control unit according to the invention;  
         [0021]    [0021]FIG. 5 is a block diagram of the remote control unit according to the invention;  
         [0022]    [0022]FIG. 6 is a block diagram of the AV receiver according to the invention; and  
         [0023]    [0023]FIG. 7 a - c  depict application scenarios according to the invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0024]    System Overview  
         [0025]    [0025]FIG. 4 shows an AV system  400  according to the invention. The system  400  receives a television (TV) signal  101  by cable, satellite, or terrestrial means. An AV receiver  600  decodes the TV signal for display on a television screen  120 .  
         [0026]    Primary to Secondary TV Signal Transcoding  
         [0027]    The receiver  600  also provides input to an audio/video/ITV encoder  420 . We call this the primary TV signal  401 . The format of the primary TV signal is essentially as is seen on the television screen  120 . The encoder  420  encodes the primary TV signal  401  to a secondary TV signal  402  having a format suitable for decoding and display on a RCU  500 , as described in greater detail below. We call the conversion of the primary to the secondary TV signal “transcoding.” 
         [0028]    A first wireless transceiver  441  has sufficient bandwidth to transmit the encoded secondary TV signal  402  to a second wireless transceiver  442  of the RCU  500 . The wireless transceivers  441 - 442  are also used to transfer commands, such as channel selection, volume control and interactive commands, from the RCU  500  to the AV receiver  600 . The commands are generated by a remote control function  510  of the RCU  500 . The RCU  500  also includes a decoder  520 , and a touch sensitive display  530 . The user response decoding block  430  decodes the RCU commands for further processing by the receiver  600 . The commands are encoded  540  in the RCU  500  before transmitted to the receiver  600 .  
         [0029]    Remote Control Unit  
         [0030]    [0030]FIG. 5 shows the RCU  500  according to the invention. In addition to the traditional RCU functions  510 , the RCU is equipped with a touch-sensitive display  530 , a wireless transceiver  442  based on the technology such as Bluetooth, a demultiplexer  550 , an audio decoder  561 , a video decoder  562 , an ITV command decoder  563 , an audio output port  570 , such as head phone plug, a graphics overlay mixer  580 , and a processor  590 .  
         [0031]    The RCU  500  receives encoded visual, audio, and ITV data via the wireless data transceivers  441 - 442  transcoded as the secondary TV signal  402 . The demultiplexer  550  de-multiplexes and passes the encoded data of the secondary TV signal to the appropriate decoders  561 - 563 . Depending on the configuration of the system and the capabilities of the digital AV receiver  600  and the RCU  500 , the RCU can just receive transcoded video with instructions to capture the user interaction in the form of the display coordinates.  
         [0032]    The overlay mixer  580  mixes the decoded secondary TV signal, and any text or graphics produced by the ITV decoder  563 . The output of the overlay mixer  580  is displayed on the touch sensitive display  530  concurrent with the display of the primary TV signal. If audio data are present in the received data, the audio decoder  561  decodes that data and outputs the audio signal to the headphone output  570 . Any user interaction is appropriately encoded by the user response encoding function  540  and communicated to the digital AV receiver  600  over the wireless connection  403 .  
         [0033]    In one embodiment of the invention, the secondary TV signal  402  received by the RCU  500  is in the MPEG-4 “simple profile” format, the audio uses a low bit rate advanced audio coding (AAC), and the ITV commands are in MPEG-4 systems binary format for scenes (BIFS) format. ITV commands can include instructions to report coordinates of the point on the display with which the user interacts by touching the screen  530 .  
         [0034]    AV Receiver  
         [0035]    [0035]FIG. 6 shows the AV receiver  600  to support the remote control user interface according to the invention. In addition to the traditional digital AV receiver functions, the AV receiver is equipped with an audio transcoder  611 , video transcoder  612 , an ITV transcoder  613 , a multiplexer  620 , the wireless transceiver  441 , and the user response decoding function  430 .  
         [0036]    The transcoders  611 - 613  receive input from the corresponding decoders  351 - 353 . The audio decoder receives the decoded data and the audio transcoder re-encodes the decoded audio at, e.g., a lower bit rate.  
         [0037]    The video transcoder receives a partially decoded bitstream and transcodes the video bitstream into a video with different format, e.g., a lower spatial resolution, lower temporal rate and/or lower bit-rate. See for example, “Architectures for MPEG compressed bitstream scaling,” IEEE Transactions on Circuits and Systems for Video Technology, April 1996 by Sun et al. for rate reduction, and U.S. patent application Ser. No. 09/853,394, “Video Transcoder with Spatial Resolution Reduction,” filed on May 11, 2001 by Vetro et al., incorporated herein by reference.  
         [0038]    The ITV application uses the MPEG-4 Systems BIFS format and is transcoded appropriately to a smaller subset of the BIFS. The transcoded data are multiplexed  620  and communicated to the RCU  500  via the wireless data transceivers. The AV receiver, by means of the wireless data transceivers receives the user response entered on the RCU  500 . The user response decoding function  430  processes the user responses received from the RCU  500  and forwards the response to the remote input processor  320  to act on the RCU functions, or to the ITV command decoder  353  to act on the user response to the interactive application.  
         [0039]    The transcoded secondary content delivered to the RCU does not have to include all the three components audio, video, and ITV application. In the simplest form, using only video, the video along with the overlaid graphics are encoded into MPEG-4 video format and the ITV commands are set to receive the coordinates of the point the user interacts with (taps) on the RCU touch sensitive display. The user response decoding function and the ITV command decoder on the digital AV receiver translate the interaction point into an interactive event if the point lies on any of the interactive elements displayed on the television.  
         [0040]    Applications  
         [0041]    [0041]FIG. 7 a - c  depict an example application scenario making use of the invention. FIG. 7 a  shows the example, as seen on television, of a television game show with interactive TV application for users to play along with the game show. The users can select one of the answers A, B, C, or D and can also select a link to purchase a T-shirt with the game show logo.  
         [0042]    With the RCU  500  according to the invention, the transcoded game show application can be transmitted and then displayed on the RCU  500 . FIG. 7( b ) shows a reduced scale video and application displayed on the RCU. The digital AV receiver can transcode the content into the reduced scale application in one of the two ways.  
         [0043]    The video output of the graphics and overlay mixer is encoded into the MPEG-4 video format by the video transcoder and the ITV application component is not used. In this case, the RCU does not use its ITV decoder to process user response and just retransmits the coordinates of the interaction points back to the receiver.  
         [0044]    Alternatively, video and ITV application are transcoded separately and composed after the decoding process on the RCU. In this case the RCU can process the user response and communicate back the complete user response to the receiver. The visual displayed on the RCU is the same in both cases.  
         [0045]    [0045]FIG. 7 c  shows the content as seen on the RCU display. The composed visual on the RCU does not contain the scaled down video. In this case, the video and audio are not transcoded by the digital AV receiver; just the interactive elements of the content are transcoded and communicated to the RCU. The ITV decoder on the RCU decodes the ITV commands and renders the text and graphics on the RCU display.  
         [0046]    Although the invention has been described by way of examples of preferred embodiments, it is to be understood that various other adaptations and modifications may be made within the spirit and scope of the invention. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the invention.