KR20040007730A - A reception unit for performing seamless switches between video signals - Google Patents

Abstract

A receiver receiving television programming can perform seamless switching between individual video signals. The receiver includes a microprocessor 564 that controls the selection of RF channels and two tuners 560A, 560B for tuning to individual RF channels. Each RF channel carries an analog signal or a digital signal. Two demodulators 568A, 568B are provided, which are connected to each tuner to demodulate digital signals in each RF channel. Similarly, two analog demodulators 569A, 569B are provided and connected to each tuner to demodulate the analog signal on each channel. A digital demultiplexer / decoder 572 is coupled to receive demodulated digital signals from the selected RF channel, demultiplex and decompress the received digital signals, and apply the resulting signals to the digital display processor 576. Analog display processor 580 formats any selected, demodulated analog signal for display. The vertical blanking interval switch is connected to the digital display processor 584 output and the analog display processor 580 output to perform seamless (no connection traces) switching between video signals.

Description

Receiving unit for performing seamless switching between video signals {A RECEPTION UNIT FOR PERFORMING SEAMLESS SWITCHES BETWEEN VIDEO SIGNALS}

The present invention relates to a unit for seamless switching between video signals.

US Pat. No. 5,724,091 provides a way to provide seamless switching between video signals while watching the first video signal even if the video signal being switched is on a different broadcast channel or on the same channel multiplexed with the currently viewed video signal. Doing.

The present invention seeks to provide a receiving unit for seamless switching between video signals using a less complex method.

According to one aspect of the invention, programming is received and seamlessly switches from a first analog signal to a second analog signal, or from an analog signal to a digital signal, or from a first digital video signal to a second digital video signal. As a receiving unit,

A microprocessor that selects one of the video signals and directs seamless switching with the selected video signal;

A pair of tuners coupled to the microprocessor to tune the RF channels, where the pair of tuners select the RF channels upon instruction from the microprocessor;

A pair of analog demodulators connected to each of said tuners and arranged to receive one analog signal;

A pair of digital demodulators connected to each of said tuners and arranged to receive a digital signal;

A digital demultiplexer / decoder coupled to the pair of digital demodulators for demultiplexing digital signals, decompressing digital signals, and performing seamless switching from one digital video signal to another;

A digital display processor coupled to the output of the digital demultiplexer / decoder to convert the decompressed output digital signal into an analog signal; And

A receiving unit is provided that includes a vertical blanking interval switch coupled to the output of the digital display processor and to the outputs of the digital analog demodulators to perform seamless switching between analog video signals.

In an embodiment, the receiving unit further comprises an analog display processor arranged to format the demodulated analog signal, the analog display processor being coupled to the outputs of the analog demodulators and the vertical blanking interval switch to vertically blank the analog modulator outputs. Connect to interval switch.

Preferably, the multiplexer combines the various digital signals into a reduced number of transmission data streams for transmission. Various NTSC television channels are allocated in a predetermined manner to maximize the number of signals transmitted simultaneously. The multiplexer, together with the television transmission system, multiplexes the required data streams onto the required channels and carries these signals over an NTSC channel. The number of video signals that can be multiplexed into a data stream on a single transport channel varies depending on the video signal being transmitted. Television channels comprising a data stream of multiplexed video signals may be transmitted on a standard cable television distributed network, or on a direct broadcast satellite transmission system.

After encoding, compression multiplexing, and modulation, program signals and interactive program signals are not limited, but transmissions include satellite, cable television, optical fiber, public switched telephone stations, terrestrial broadcast stations, closed circuits, etc., where modulation techniques are defined by means of transport. Distributed by means. The modulation scheme here is defined by the transmission means. Additionally, the distributed content may include signal conversion and retransmission prior to receipt by the end user.

The program is received at the end user location and is connected to the appropriate receiving device. Receivers include, but are not limited to, cable television receivers / converters, satellite receivers, terrestrial broadcast receivers, and personal computers, for example. The receiver receives one or more television channels that are part or all of the video signal of the multiplexed data stream or the non-multiplexed digital video signal, selects a particular data channel / data stream for playback with the signal selector and then of the data stream. A particular video signal from the multiplexed signal is selected and finally magnified to a video signal for playback on a television monitor if necessary.

The signal selector may comprise a controller and software, for example, in a digital set top box. Controllers and software in the digital set-top box operate to control the receiver and signal selector to select a particular digital video signal.

User input preferably responds via a standard remote device. The user can change from one digital channel to another, or provide a response to an interactive program.

The invention also receives programming and performs a seamless switching from a digital video signal multiplexed on a first program signal received on a first RF channel to an analog video signal multiplexed on a second program signal received on a second RF channel. As a no-defective switching unit,

A microprocessor instructing switching from a digital video signal to an analog video signal;

A first tuner coupled to the microprocessor to tune a first RF channel;

A digital demodulator connected to the first tuner for demodulating a first program signal;

A digital demultiplexer / decoder coupled to the digital demodulator and microprocessor to demultiplex a first program signal to decompress and decode the digital signal to obtain a digital video signal;

A digital display processor coupled to the digital demultiplexer / decoder to convert digital video signals to analog;

A second tuner coupled to the microprocessor to pretune to a second RF channel;

An analog demodulator connected to the second tuner to receive and demodulate an analog signal; And

And a vertical blanking interval switch coupled to an output of the digital display microprocessor and an analog demodulator output to perform a seamless blanking switch from the converted digital video signal to the analog video signal during the vertical blanking interval of the signals. .

Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an interactive television system of the present invention.

2 is a block diagram of an alternative interactive television in a two-way transmission configuration.

3 is a block diagram of an embodiment for switching a video signal without a trace of connection.

4 is a block diagram of an alternative embodiment for switching a video signal without a connection trace.

5 is a block diagram of an embodiment of a central programming relay station location.

6 is a block diagram illustrating video junction points and time gaps within a video programming stream.

7 is a block diagram of an alternative receive box.

8 is a block diagram of an alternative audio frame.

9 is a block diagram of a TV station switch.

10 is a block diagram of an embodiment for switching of a non-related program.

11 is a block diagram of an embodiment for switching in multiple event programs.

12 is a block diagram of an embodiment for picture in picture program switching without a connection trace.

13 is a block diagram of an embodiment for switching in multiple trading / shopping programs.

14 is a block diagram of an embodiment for digital program insertion-addressable advertisement.

15 is a block diagram of an embodiment for switching without a trace of connection from a signal group to another signal in a server.

16A and 16B are block diagrams of two alternative tuner environments.

17 is a block diagram of two alternative tuner environments.

The present invention relates, for example, to a receiver capable of performing a seamless switching between an analog video signal and a digital video signal. An embodiment of the present invention is shown in FIG. However, an interactive television system with full features is presented for clarity.

The present invention relates to an interactive television system that provides a plurality of viewers with a plurality of different program information message signals simultaneously. A plurality of video signals 1 are provided. The video signal 1 may be, for example, various fields of a sporting event or game show and / or audio synchronized camera angle with content and a host operating in response to the user's selection. Alternatively, the video signal 1 may be any video signal suitable for interaction as disclosed in US Pat. Nos. 4,847,700, 3,947,972, 4,264,925 or 4,264,924, which are incorporated herein by reference. There are various types of video signals related to time and content that are suitable for interaction.

In conventional systems, these various signals are transmitted to receivers on separate broadcast or cable channels, each requiring a 6 MHz NTSC channel. According to the invention, the video signal 1 is transmitted to an analog-to-digital (A / D) converter 2 which converts various video signals into a digital format for transmission. The A / D converter 2 is a conventional type of converter for converting an analog signal into a digital format. An A / D converter is not required for each video signal 1 but only one converter with the ability to digitize a smaller number of converters or even multiple video signals 1 may be required. Interactive video programs are also provided in pre-digitization and / or pre-compression formats on cable or other distribution networks.

Digital conversion causes very large amounts of data. It is therefore desirable to reduce the amount of data to be transmitted, which allows more signals to be transmitted over a single transmission channel. Thus, a two hour standard video is about 80 gigabytes. Since it is 30 frames / sec in such a video, the data rate is 22 megabytes / sec. This large amount of data is reduced by digital compression.

In order to reduce data transmission requirements, various digital video signals are preferably compressed prior to transmission. Video can be compressed by any prior art algorithm, the two most common types being " processor intensive " and " memory intensive " types.

A processor-intensive approach is to remove the invariant aspect of the image from processing the information to frame-to-frame transmission, and to inflate other pieces of image information with mathematical calculations that determine how much motion in the image can be perceived by the human eye. Compression is performed by manipulation. This approach depends on the high speed processing capability at the transmission point.

The memory scheme involves dividing an image frame into blocks of hundreds of very small pixels, each of which is given a code representing a change in chromaticity set and luminance. A code that is an increment of smaller information than all the information representing a given pixel block is sent to the receiver. This calls the same coded block from the library of blocks stored in the receiver's memory.

Thus, the bit stream represents a smaller portion of the picture information in this way. Such systems are generally limited by the various picture blocks that can be stored in the receiver, which is directly related to memory size and the ability of the microprocessor.

Examples of commonly known compression techniques that can be used in the present invention are JPEG, MPEG1 and MPEG2.

A data compressor 3 is provided to reduce the data for each video signal to be transmitted. The data compressor 3 is any general type of compressor generally known in the art for compressing video images as described above. Compression of the various video signals may be performed using a smaller number of data compressors than using one compressor per video signal. For example, in a conventional analog NTSC system, it is common to transmit one video signal per 6 MHz channel. By digitizing the video signal, it is possible to transmit a data stream comprising one or more video signals on one channel. Compressing the digitized signal allows more video signals to be transmitted over one transport channel. The number of signals that can be transmitted on one channel is generally related to, for example, a) the type of video to be transmitted b) the video compression scheme in use c) the processor and memory capabilities used and d) the bandwidth of the transmission channel. .

Compression techniques take advantage of the fact that there are very small changes in images moving from frame to frame. Eliminating redundancy and coding only changes between frames allows higher compression rates. Thus, video types that generally include a significant amount of high-speed movement, such as occur in live sports events, have a low compression rate. On the other hand, movies with a lower frame rate and a lower frame-to-frame change than a live sports event can achieve higher compression rates. Currently, generally known compression regimes have varying compression ratios from 2: 1 to 10: 1 for satellites and 2: 1 to 5: 1 for cable television systems, depending on the degree of movement.

Once the various video signals 1 are digitized and compressed, the multiplexer 4 combines the various digital signals into a reduced number of transmission data streams for transmission. For example, 68 NTSC channels are used, and each channel transmits four digitized and compressed slow-motion video signals (e.g. movies) or two digitized and compressed high-speed video signals (e.g. sports). If so, several NTSC channels can be allocated in a predetermined manner to maximize the location of the signal that can be transmitted simultaneously.

As an example, the broadcast frequency corresponding to the first NTSC channel includes a data stream of each digitally compressed non-interactive movie. For this frequency, the data stream contains video signals representing various movies. However, unlike in the case of interactive programs, the video signal is not related to time and content. The frequency corresponding to the second channel preferably comprises a digital data stream of an interactive sports program consisting of two multiplexed and compressed high speed video signals relating in time and content. The frequency corresponding to the third channel comprises a digital data stream of an interactive movie consisting of four multiplexed and compressed video signals relating to time and content. The frequency corresponding to the fourth channel includes analog NTSC signals related to the local program. Thus, using the present invention, four NTSC channels include channels of multiplexed movies, interactive sports programs, interactive movies and local programs.

The multiplexer 4 receives the incoming compressed digitized video signal, multiplexes the desired video signal to the desired channel with the transmitter 5 in a predetermined conventional manner and transmits this signal over the NTSC channel. A given NTSC channel may contain only one video or other signal in analog or digital form.

As described above, the number of video signals that can be multiplexed into a data stream on a single transport channel can vary. In addition, the number of channels using the data stream may vary. The transmission data stream is transmitted by the transmitter 4 via the transmission medium 6 to the receiver 7. The transmitter 4, the medium 6 and the receiver 7 may be any general means for transmitting digital video signals including broadcast television, cable television, direct broadcast satellite, optical fiber or other means of transmission. Alternatively, the present invention may be included in an independent system as described below.

The transmission means may also be a telephone system for transmitting digital video data signals. Thus, multiplexed data streams containing multiple broadcast channels or interactive programs with associated video signals can be delivered directly to the user via a single telephone line. The above-mentioned digital transmission device may comprise means for transmitting an analog signal.

In the first preferred embodiment, the digital transmission signal is transmitted using a cable television system. The receiver 7 receives various NTSC channels, and any or all channels comprise multiplexed or demultiplexed digital video signals. Typically, one or more channels are transmitted by the transmitter 5 and received by the receiver 7 as in a conventional cable television system. However, each different channel has a data stream containing several digitized video signals. Thus, the receiver 7 preferably operates in conjunction with the signal selector 8 to select a particular NTSC channel for playback, and then selects a particular video signal from the multiplexed signal of the data stream and finally plays back to the monitor. And if necessary for decompressing or extending the compressed video signal.

The multiple selection controller 9 operates to control the receiver 7 and the signal selector 8 to select a particular video signal for reproduction. In practice, the user does not need to know that multiple signals are used per channel. For example, if 68 channels with 4 signals per channel are used, the controller 9 together with the receiver 7 and the signal selector 8 are programmed to present these channels to the user as channels 1-2-72. For example, the monitor 10 is a general television. The signal selector 8 preferably comprises a general demultiplexer for selecting a particular video signal in the data stream on the channel currently being received by the receiver 7. The signal selector 8 also comprises an essential decompression or expansion device corresponding to the compression scheme used by the compressor 3.

In practice, an interactive sports event program uses a 6 MHz cable television signal using a compression-multiplexing scheme that allows two sports video signals (e.g. A and B) to be transmitted on a single NTSC channel (e.g. channel 34). Can be sent to. It may be desirable to have four video signals (eg A-D) for a particular interactive sports event. The first video signal (signal A) contains the standard broadcast signal of the game, the second video signal (signal B) contains the game action of the close-up screen, and the third video signal (signal C) is the game continuously updated. Playback of the highlight, and the fourth video signal (signal D) may comprise statistical information. These four video signals AD are, for example, next: video signals A and B are multiplexed into a data stream transmitted on cable channel 34 and video signals C and D are multiplexed into a data stream transmitted on cable channel 35. May be multiplexed as. Alternatively, all four video signals A-D may be multiplexed into one data stream carried on one frequency channel. However, when the viewer selects on multiple selection controllers and a switch without a connection trace occurs between them, these four signals are mapped by the controller 9 or the signal selector 8 to reproduce the individual channel display to the user. Each video signal in this interactive program may include a label that reads, for example, "Press full screen action-A: Press close-up action-B: Press play-C: Press stats-D". have.

As shown, if more signals are required for the interactive program than can be mapped to a data stream on a single channel, the signal selector 8 works with the receiver 7 in order to provide the required level of interaction. 1) can be programmed to switch between various broadcast channels as well. However, preferably all the various video signals related to a particular interactive program are multiplexed on one channel.

In addition, the signal selector 8 stores information related to current and previous user responses. For example, the viewer's personal profile or the viewer's previous response pattern may be stored in memory. This information may be used with instructions sent in the video signal, as disclosed in patent 4,602,279, which is incorporated herein by reference. The stored personal profile information and the received command can be used to switch between the data stream and the video signal interactively without any further response from the user.

The multiplexed interactive program can be transmitted over a single telephone line if required. In this embodiment, multiple selection controllers 9 are programmed to switch between various video signals on a single telephone line. If additional channels are required, the structure of the transmit / receive scheme may be used as described below.

The system of the present invention can be used in an educational environment. In this embodiment, the information is stored on each data stream in a number of replicable information segments, each of which is a video signal selection by the signal selector 8 in response to a user selection on the plurality of selection controllers 9. It contains a complete message that can be replicated by the receiver in direct response. Each information segment in the various data streams includes a query message associated with multiple selection responses, response messages, message information messages, or a combination thereof.

The various segments of information in the various data streams relate to real time and content such that the video signal is displayed and interaction occurs as the user answers the various questions contained in the video signal. As the user answers a particular question with multiple selection responses, information in the video signal related to the particular selection is displayed by the signal selector 7. Various information, response messages and information messages may generally be included in any one or more than one or all of the various video signals.

Using a data stream containing multiple video signals per broadcast channel can be used for many types of interactive programs such as those disclosed in the above-mentioned US patents. Other interactive programs can be deployed that fall within the scope of the present invention.

The invention can also be used as a standalone system without any necessary means of transmission. In this embodiment, the digitized video signal constituting the interactive program is stored in a local storage means such as a video tape, video disk, memory (e.g. RAM, ROM, EPROM, etc.) or a computer. Preferably, the digital video signal is multiplexed onto a standard NTSC signal. Specific storage means are connected to certain interactive boxes shown in FIGS. 3 to 5 and described below. The interactive box is connected to a television set. Alternatively, the circuits of FIGS. 3-5 may be implemented on a board and inserted into a standard personal computer (PC). Individual microprocessors on the interactive board are not necessary in this architecture because a standard PC processor performs the functions of the processor 108 shown in FIGS.

As shown in FIG. 2, the system of the present invention may operate in a transmit / receive structure. In this mode, the various video signals 1 are processed as described above, digitized by the A / D converter 2 and compressed by the video compressor 3. The signal is then sent to a central relay station 14. In this embodiment, switching between the various video signals is performed at the head end rather than at the receiver. The multiple selection controller unit 9 relays the user's multiple choices back to the relay station 14 located remotely via the relay box 17. Many of the options are relayed by relay box 17 to a relay station by general means such as transmit and receive cable television, telephone or FM transmission. The relay station 14 receives a number of choices of the user and sends them to the transmitter 5, which typically delivers the required video signal on the appropriate cable channel for the particular user. If desired, the transmitter also delivers the generic program on a cable channel that is not used for an interactive program. Alternatively, relay station 14 may include a multiplexing device as described above, thereby operating multiple interactive or non-interactive programs over a single television channel.

For example, if required to implement a program of an interactive football game, a single NTSC cable channel may be assigned to the program. However, in this example, the video signal can be provided for transmission. In response to the signal from the radio controller 9, a signal is applied by the relay box 7 to the cable TV relay station, which relays the requested signal to the user requesting it. Such systems require very fast switching equipment but can be implemented using digital video.

Alternatively, it is desirable to transmit an interactive sports event over a single telephone line. When the user enters a selection on the controller 9, the signal is transmitted via a telephone line to a central relay station, such that a single link handles both the interactive selection formed at the receiver from multiple selections from the head end and the transmission of the selection, The relay station transmits the required signal of the interactive program over the telephone line of the user, and at the head end, actual switching takes place in response to the interactive selection made at the receiver.

The transmit and receive link between the user and the relay station may be used for other purposes. Demographic data may be transferred from the user to the broadcast network for commercial or other commercial or non-commercial purposes, such as sending a winning number to win a prize to the winner of a targeted advertisement, billing, or game show. Can be.

As mentioned above, compression systems are generally less efficient when the frame-to-frame content involves many changes in the pixel content (e.g., fast motion or screen changes). The system of the present invention can be easily programmed to facilitate the processing added to the uncompressed program. When a key on the controller is pressed to select the desired signal, there is a slight unperceivable delay if required. This delay allows a short time in the decompression or extension algorithm to adjust for fast changes from one video signal to another, which in terms of the efficiency of the algorithm causing video glitches that may appear on the screen display. It usually causes deterioration.

3, 4, 7, 7, 16 and 17 show the receiver 7 and the signal selector of the present invention which enables switching without flicker without a flicker between digital video signals on the same or different channels of the present invention. The preferred embodiment for (8) is shown. This embodiment is simply connected to the output of any single storage medium for an interactive program that is connected to any transmission medium or digitized and multiplexed. Preferably, the receiver 7 and the signal selector 8 are both parts of an interactive program box 11 which connects to a television or other display monitor. Alternatively, the required functions of the RF receiver 7, the signal selector 8 and the monitor can all be combined in a single personal computer with the addition of a few components to the personal computer. To provide this capability, only RF demodulator boards, digital demultiplexers, decompressors, frame buffers and synchronization components are required to be added to the personal computer. These and some other components may be connected to a PC processor or storage element as shown in FIGS. 3, 4, 7, 16, and 17. In this embodiment, the user makes a selection via computer keyboards.

3 illustrates an embodiment using a single analog frame buffer. 4 includes a pair of RF demodulators, an error corrector and demultiplexer, and / or a digital video buffer as described below.

3 illustrates an embodiment that allows a video switch without a connection trace between two or more individual digital video signals. As shown in FIG. 3, microprocessor 108 is connected to RF demodulator 102 and digital demultiplexer 106. The microprocessor 108 directs the modulation and demultiplexing of the appropriate channel and data stream to obtain the correct video signal. The appropriate channel is determined by an example of a user's input from user interface 130 and / or some other information or criteria (such as personal profile information) stored in RAM / ROM 120. RAM / ROM 120, for example, stores instructions stored in a video signal such as disclosed in patent 4,602,279, which is incorporated herein by reference. The user interface 130 is an infrared, wireless or wired receiver that receives information from the plurality of selection control units 9.

The RF demodulator 102 is part of the receiver and modulates the data from the broadcast channel directed by the microprocessor 108. After the data stream is modulated, it is forwarded through the forward error correction circuit 104 to the digital demultiplexer 106. Demultiplexer 106 is controlled by microprocessor 108 to provide a particular video, audio and data signal from a number of video, audio and data signals located within the data stream, and transmits the signals to a suitable device for use in the system. Adjust In order to join from one video stream to another without a connection trace, it is desirable to perform switching in the digitally compressed region and thus eliminate the need to decode the two video audio and data streams at the same time.

When compressed digital video is applied to a video decoding operation, the video is first stored in memory 160 until enough information is buffered to ensure continuous playback of the video stream. Due to the compression nature of the video information, a relatively small buffer 160 (on average 5 to 6 frames) can store a significant amount of video information. This means that there is a significant delay from the time the compressed video is received to the time it is decompressed and output. Accordingly, a suitable method for switching on the set top is to continue playing the previous video on the monitor while selecting a new video into the video buffer 16. This can be easily accomplished since the incoming stream is generated by creating a concatenable syntactically correct MPEG segment. In this way, there is no need for any additional hardware in the receiver. Video is always provided to the viewer as a single video stream with no repeated or dropped frames.

MPEG allows reproduction of the video clock at the receiver 1 through the use of a data field called PCR (Program Clock Reference). This is necessary to ensure that the decoder can play the decoded video at the same rate as it is input in order to prevent repeating or falling frames. Information added further in the MPEG stream includes a Perstation Time Stamp (PTS) and a Display Time Stamp (DTS). These signals are used to maintain a silent fit with the audio and also to inform the receiver when video and audio are to be displayed.

4 shows an embodiment of an alternative dual tuner for switching without traces between individual video signals. In this embodiment, the microprocessor 108 controls the selection of the RF channel that is demodulated by the RF demodulators 102A, 102B. The demodulated data stream is applied to forward error correctors 104A, 104B. At the output of the forward error corrector, the data stream is passed to the digital demultiplexers 106A, 106B.

As with the RF demodulators 102A and 102B, the digital demultiplexers 106A and 106B are controlled by the microprocessor 108. This structure allows the microprocessor 108 to independently select two different time multiplexed video signals on different channels and data streams. If all the video signals of an interactive program are contained in a single channel or data stream, it is only necessary to have one RF modulator, forward error corrector and digital demultiplexer connected in series to two digital video buffers.

Two data streams are provided from the digital demultiplexers 106A and 106B. The output of the demultiplexer includes a number of video and audio data directed to the appropriate device under microprocessor 108 control. In this way, it is no longer necessary to take all the information contained within one RF channel. Instead, information can be found at different frequencies in the RF spectrum, and we can still join between streams. By placing a simple digital switch at the outputs of the two demultiplexers, we can avoid copying the entire decoding chain. Note that this is only a cost saving method, and that the copy of the rest of the chain is valid.

Standard MPEG streams contain different types of encoded frames. There are I (Intracoded) frames, P (Predicated) frames and Bi-directionally predicted (B) frames. The standard MPEG structure is known as the GOP (Group Of Picture). GOPs generally start with I frames and end with P or B frames. Generally there is one I frame per GOP, but there are many P and B frames. It is not necessary to have certain I frames, but for many reasons they are used.

GOPs ending with B frames are considered open. GOPs ending with P frames are considered closed. For the present invention, the preferred code is a closed GOP to ensure that there are no motion vectors pointing to frames that exist outside of the current GOP.

MPEG also rearranges video frames from their original display order during the encoding process to code the video more efficiently. This rearrangement must be unwound at the decoder so that the video is properly presented.

The conjugation occurs at the end of the B frame at the end of GOP1 before the I frame of GOP2. Using appropriate control, it is important to point out that the encoder can code using various GOP lengths and can position the joint frame correctly in order to obtain a suitable mutual effect. If the content is not relevant, the encoder can be spliced at the end of every GOP that allows multiple switching opportunities. Since the GOP ends in a P frame, a closed GOP is created.

Enhanced connection traceless switching in digital systems

The implementation of any of the above receiving units is used to handle the switching trace of the present invention. However, in the preferred embodiment, switching without connection traces in the receiving unit is enhanced through some new modifications to the encoding process.

As mentioned above, whether representing an independent television program or representing a different related signal in one interactive program, switching without a connection trace between the digital video signals is important for the viewing experience. Switching without connection traces is defined as video stream switching that does not form visible artifacts. The effect of this encoding process is to simplify and enhance the switching process without a trace of connection.

The encoding process is performed at the central relay station location, the elements of which are shown in FIG. As shown in FIG. 5, a number of video signals 300 are shown that include live or previously recorded video streams. The original video signal is formed from live video, video servers, video tape decks, DVDs, and cameras for satellite feeds. The video signal is a signal of MPEG format, HDTV, PAL or the like. Multiple audio signals 308 come from CDs, tapes, microphones, and the like.

The data code shown as originating from the data code computer 316 of FIG. 5 is an interactive command for interactive processing used by the set top converter as described above. Preferably, the data code is part of an interactive original language, such as an ACTV original language derived from coding computer 316. The data code is also passed to encoder 312. This data code facilitates multiple interactive program selection at the receiving unit. This embodiment requires a data channel to enable simultaneous switching between the first video stream and the second video stream. This data channel contains code that links different program elements and information segments on different video signals to each other.

With reference to video signal 300, multiple video signals 300 are genlocked at video genlocking device 304 and are thus time synchronized. The time synchronized video signal is passed to the video and audio encoder 312. In a preferred embodiment, compatible encoder 312 is required at the cable head end to cooperate with the digital receiving unit at the remote site. The interactive application of the present invention is facilitated, preferably by synchronizing the command at the head end to a particular video frame and a particular audio frame. This level of synchronization can be achieved with the syntax of the MPEG-2, MPEG 4 and MPEG 7 specifications.

In order to facilitate switching without a trace of connection at the receiving site, the video encoder 312 is preferably time synchronized. This synchronized start is essential to ensure that the junction point located within the video content occurs at the correct frame number. It is not necessary to achieve this level of accuracy for all program types but this can be achieved. This gives the content producer the ability to schedule video switch generation at frame boundaries within the resolution of the GOP. SMPTE time code and vertical time code (VTC) information may be used to synchronize encoder 312. In addition, the junction can be positioned exactly in a given frame by using GOPs of various lengths. Based on instructions from an external control device, such as ACTV command code computer 316, encoder 312 may be instructed to insert the joint into the frame number. Positioning the encoder modifications at the head end ensures more efficient traceless switching in the set-top converter.

As shown in FIG. 5, multiple video signals 300, data codes 316 and audio signals 308 are input to encoder 312. In the preferred embodiment, four video channels are input to encoder 312. However, some video streams may be input based on the content to be delivered. In this environment, the practical limit on the number of videos is based on picture quality. Ultimately, however, there is no limit to the number of video and audio that can be included in a single channel. In addition, all existing limitations may be removed through the use of alternative embodiments describing implementations comprising two tuners.

Preferably, encoder 312 uses a standard MPEG-2 compression format. However, other compression formats such as wavelets and fractles as well as MPEG-4 and MPEG 7 can be used for compression. This technology is compatible with existing ATSC and DVB standards for digital video systems. However, in order to facilitate switching without a desired connection trace in the set top box, the MPEG stream is modified to some degree. This modification to the encoding stream is described below with reference to the video frame structure 332 shown in FIG.

The switch at the power receiving site occurs at the video junction point 336. Program switching is facilitated through the supply of junction points. This junction point is identified in the program stream via adaptive field data. Program switching occurs at this point based on user input, personal profile information stored in the memory of the set top converter, or instructions from the program source.

With reference to the generation of the video junction point 336, the video encoder inserts the junction point into all GOPs as shown in FIG. A GOP is generally composed of one I frame and a series of P and B frames based on a parameter set in the MPEG regime. Preferably, the GOP is encoded as a "closed" GOP structure, meaning that the GOP ends in a P frame. Accordingly, no motion vector exists until the next GOP. If the motion vector crosses from one GOP to the next, the artifact is created and visible when the screen is switched. Thus, the closed GOP structure follows the MPEG syntax and is essential to ensure no visible artifacts after the conjugation run.

The GOP length is programmable and can range from 1 to infinite frames of video. However, the GHP preferably contains 10-15 video frames. Referring to Fig. 6, four video signals are shown. It is desirable that switching without any video signal be connected to another video signal.

As shown in FIG. 6, video switching without a connection trace occurs at the GOP video frame boundary. For previously recorded components, a junction point is required to be identified for the switching point. For programs (eg sports) where "free" channel selection is required, all GOP boundaries are encoded as junction points. The switch should be shown without a trace of the connection, but this does not have to happen immediately. As an example, a command or key input requires a limited time for processing. As a result, the video switch may be delayed up to 1.5 GOPs.

As shown in FIG. 6, the conjugation takes advantage of the non-real-time nature of MPEG data during transmission over a digital channel forming a time gap 340, during which time a decoder can take one stream. You can switch from decoding to decoding another stream. Thus, the gap 340 shown in FIG. 6 represents the switching time. The key is that most complex video is completed and the first packet of the next GOP passes through the channel before passing through the channel. By encoding at a bit rate lower than the channel capacity, some extra time is generated at the end of the GOP for switching. In this way, two MPEG streams can be mixed to produce a single syntactically correct MPEG data stream. As shown in FIG. 5, this gap can be created at encoder 312 using any compression scheme.

Preferably the audio signal is encoded using the AC format. However, the present invention covers certain general audio encoding schemes.

The various video, audio and data signals are all digitized and combined at encoder 312 in FIG. Preferably, the compressed and encoded signal is output in DS3, Digital High Speed Expansion Interface (DHEI) or any other conventional format. The data type doesn't matter, it's just data. The encoding process outputs the digital data stream at the appropriate bit rate for the target channel.

Modulator 32 uses one of several different modulation schemes possible. Preferably 64-QAM was chosen as the modulation scheme. In this case, the data rate at the output of modulator 320 is about 29.26 Mbps. However, any of the following modulation schemes having separate approximate data rates, or a general modulation scheme (such as FSK, n-PSK, etc.) may be used with the present invention.

Modulation set-up ratio

64-QAM 29.96 Mbps

256-QAM 40 Mbps

8 VSB 19.3Mbps

64 QAM PAL 42 Mbps

256 QAM PAL 56 Mbps

Each NTSC channel is combined in a common combiner, preferably a combiner using frequency modulation. Thus, switching traceless in a set-top converter can occur from one signal to another within one NTSC channel or from one NTSC channel to another, as described below.

In summary, as described below, the encoder time-synchronizes the signal to the GOP, time-locks the encoder and creates a time gap 340 in each digital video stream (indicating the difference between the encoding rate and the channel capacity). This facilitates switching without a trace of connection at the decoder.

After encoding, modulation and multiplexing, the signal can be delivered to the receiving site via satellite, wireless, terrestrial, broadcast and any other common transmission system. In a preferred embodiment, the signal can be distributed to a remote site via a cable or other transmission medium.

Receiving site

At the receiving site consisting of the elements shown in FIG. 7, a signal is received via the tutor device 344. Tuner 344 may be a wideband tuner for satellite deployments, a narrowband tuner for standard MPEG signals, or two or more tuners for linkless switching between different signals located within different frequency channels, as described below. have. In the case of an MPEG signal, the tuner 344 is tuned to the particular NTSC channel indicated from the instruction by the host processor 360. The host processor 360 is preferably a Motorola 68331 processor but is one of the processors including PowerPC, Intel Pentium, and the like.

The signal is then passed to a demodulator 364. Demodulator 364 demodulates the combined signal, strips off the FEC and sends the digital signal to video and audio decoder 372. In digital decoder 372, the signal is separated and decompressed. Decoder 372 separates the program identification number (PID) and passes this PID to the appropriate decoder depending on whether it is video, data, audio or graphics. Audio is preferably delivered to Dolby Digital Processing IC 380. The selected video and audio are decoded as described below and the video is passed to a video digital-to-analog converter 388 that prepares the selected video for display.

The phase locked loop (PLL) reproduces the encoded clock encoded in the PCR portion of the MPEG adaptation field. The ROM is preferably backed up to maintain the drive system for the receiving unit 342 and to allow downloadable code using flash-ROM. In addition, there are memory devices connected to the decoder 372 and 380 and the graphics chip 376 which are used for storing, for example, graphic overlays. Moreover, profile data for various users at home may be stored in non-volatile RAM or ROM 352.

Backchannel encoders and demodulators 368 are provided to carry data to the headend. Such data includes personal profile information, interactive choices, statistical data for targeted advertising purposes, game show scores, and the like.

In addition, the receiving unit 342 allows a new software application to be downloaded to the unit. This application controls the unit, limiting the unit's function within the limitations of the hardware. The control here is fairly broad, including control of the mapping of front-panel displays, on-screens, all input and output ports, MPEG decoders, RF tuners, graphics chips and IR remote functions.

Preferably, the interactive program technology of the present invention, including providing multiple camera angles, individual advertisements, and the like, is implemented as software in the receiving unit 342. This technique is preferably located in the ROM or flash ROM 352 of the receiving unit as shown. However, interactive techniques may alternatively be located in other types of memory devices, including RAM, EPROM, EEPROM, PROM, and the like. As such, the software can access and control the hardware elements of the device. In the preferred embodiment, no additional hardware is required for the full use of the interactive programming technique in the receiving unit 342 to achieve the functions described above.

Any type of general remote control device 348 can be used with the present invention. However, it is preferred that the remote control autonomous 348 is an infrared (IR) device and include at least four select buttons and associated IR codes.

Switching without a trace of connection at the receiving unit 342 is described in the paragraph below. The receiving unit 342 shown in FIG. 7 is preferably capable of real time MPEG-2, MPEG-4 or MPEG-7 decoding. Receiving unit 342 monitors the switching of the information and video and audio streams transmitted from the user dialogue and program sources as appropriate, without traces of connectivity.

Based on the viewer's response and request, the receiving unit automatically switches without a trace of connection between video, graphic and audio programming sequences that reflect the viewer's previous response. The interactive technique of the present invention allows for a high level of conversation and at the same time does not require the set top unit 342 to send any information back to the program source.

In the video decoder 372 shown in FIG. 7, the header data is separated from the MPEG stream. The particular video is selected based on the instructions from the host processor 360. The selected video is buffered in a standard video buffer and output for decoding. The physical buffer size is defined by the MPEG standard, which is implemented by reference. Sufficient time is allowed to fully fill the buffer with I frames and other data at the initial start of decoding.

After buffering, the selected video is subjected to various stages of MPEG decoding processing, which preferably uses variable length decoding (VLD). In general, variable length decoding converts to a run-length encoded data stream and converts it to its longer bit stream format. The bit stream is decoded into components, such as motion vectors, dct coefficients, etc., so that the video can be reconstructed. As a result, the data stream is transformed into information in the frequency domain using an inverse discrete coding transform (DCT) filter. If the frames are intercoded, pixel data is generated and stored in a buffer.

With reference to FIG. 7, the switching trace of one MPEG video stream to another MPEG video stream will be described. As shown in Figure 6, the switch occurs at the video junction point. When the demultiplexer / decoder 372 of Figure 7 finds a junction point, it switches to the selected video signal to be sent to the buffer. Thus, prior to switching, the first video signal frame is still buffered. The PID of the next signal is loaded from the host processor 36 to the decoder 372. In order to achieve switching to one of the four video streams, the video decoder 372 shown in FIG. 7 must identify the PID number of the new video stream. In addition, each incoming video and audio signal has its own PID known to the interactive application stored in the memory of the set-top converter 342 to facilitate switching traceless between independent video and audio streams. desirable. The routine to perform the switching must be called. The next PID identifying the next selected video signal is based on a user selected or interactive control code or both. When the next PID is loaded, the decoder 372 starts looking for the selected video stream, and because of the gap 340 formed in the video stream, the decoder 372 always looks for the header information of the next video. When the junction point indicator of the first video is found by the decoder 372 and the second video signal is identified by the decoder 372, the first video signal is continuously played and the second compressed video signal is transferred to the buffer. Starts to load. The new video signal is selected based on user selection or based on interactive control code.

The junction point counter and the junction point flag are one of the necessary items for switching without a trace of connection. These two indicators are located in the adaptation field of the MPEG video stream. The junction point counter indicates the number of video packets prior to the junction point. The junction point flag indicates that there is a junction counter in the stream. Once the decoder 372 determines the junction point, it begins to buffer the next video stream and successively decompresses the signal as if it were one MPEG stream.

Audio switching

As in the video stream, each of the four AC-3 audio streams is preferably identified by a unique PID, one per service. The PID number is obtained from an MPEG-2 conversion table such as SI, PG and PM in the call of the interactive service. One of these PIDs is selected as the default audio channel and selected for acquisition of service. The remaining three channels are selectable and may be selected by the control program based on the control message and / or user input. While the audio channels are generally switched with the associated video channel, they can also be switched independently.

In a preferred embodiment, as shown in the digital frame representation 392 of the four audio streams of FIG. 8, switching occurs at the frame boundary. When switching from one channel to another occurs, one frame is dropped (in case of frame 5) and the audio resumes at frame 6 of the new channel. The audio decoder 380 may perform audio switching by providing an insertion of an audio junction point to the encoder 312 shown in FIG. 5. Preferably, encoder 312 inserts the appropriate value into the joint countdown slot of the adaptation field of the current audio frame.

When the audio decoder 380 detects this junction point, the decoder switches the audio channel. Although the audio junction is not without a trace of the connection, switching is hardly recognized by the user.

Data command

In the digital embodiment, since the data command is time sensitive, the data command is sent from the head end via the command data PID (Packet IDentification). The command should be synchronized with the video GOP at the end of the encoder. To accomplish this, the data code computer shown in FIG. 5 must send individual instructions in complete packets. Each instruction is made up of two small bytes. Therefore, the generator must fill the rest of the packet with code FF (hexadecimal). When this complete packet is sent to encoder 312, encoder 312 sends it at its earliest convenient time. When a partial packet is sent to encoder 312, encoder 312 does not send a command until a subsequent command fills the rest of the packet.

Instructions identified as (1) ACTV Coding Language, Educational Instruction Set Version 1.1 and (2) ACTV Coding Language, Amusement Instruction Extension Version 2.0, which are implemented by reference in the present invention, are arranged by stringing two to six byte long instructions together. As such, it may be formed. The command data is provided in filled packets to ensure timely transmission of the encoder's ISO interface and command data.

The control program is preferably stored in the RAM 352. The processor 360 receives a command from the control program. In addition, keystrokes such as user response, personal profile information as well as control messages may be used by processor 360 to determine switching.

Preferably, the control program operates in five modes determined by the received interactive command message. The five modes are as follows.

. Audio and / or video switching based on user input

. Audio switching based on user input and stored data

. Audio and / or video switching based on user input and stored data

. Audio and / or video switching based on control messages

. Audio and / or video switching based on control messages and stored previous inputs

Multiple modes may be used simultaneously by a program.

The switching mode of the audio and video channels of the first mode described above is the simplest mode of operation. The control program is commanded by the microprocessor 360 to access one of the four remote input key codes to switch the corresponding audio / video channel. The program performs this switching at the video frame boundary at the end of the current GOP. Once a new channel is displayed, the program has the ability to update the on-screen display with new text and / or graphical messages stored or locally stored in the data stream from the head end.

The second mode described above, namely, displaying one video channel and switching the audio channel, continuously displays one video channel. When the remote input key code is received, video continues but the audio channel is switched at the appropriate audio frame boundary. As mentioned above, the appropriate audio frame boundary is determined by examining the junction point counter in the adaptation field. The selection made by the user is stored in the RAM register. At the time the selection was made by the user, the key code and the previously stored selection are reviewed by the program to determine the next audio channel.

The third mode described above, ie the audio / video channel switching mode based on the user and the previous selection, displays the initial audio / video channel. When commanded by the command message stream, text is displayed on the on-screen display. The program waits for user input. When a user input is received, it is stored in the RAM register with the previous user selection. The register is checked by the program and then, based on the stored logic, determines the next audio / video channel to be displayed.

The fourth mode, ie the audio / video channel switching mode based on the control message, also displays the initial audio / video channel. The program then waits for control input from the control message stream. Based on this input, the program switches the channel at the boundary of the video frame at the end of the current GOP.

The fifth mode described above, ie the switching mode based on the control message and the previous selection, displays the initial audio / video channel. The program then waits for control input from the control message stream. When a control message input is received, it is stored in the RAM register along with the previous user input and control message selection. The register is checked by the program to determine the next audio / video channel to be displayed.

Digital video system and application

The following paragraph discloses several applications using the digital embodiment disclosed in FIGS. 1-8 and the two tuner embodiments described below in FIGS. 16 and 17.

TV station switching

In this embodiment 412, switching from one signal to another signal without a trace is processed at the TV broadcast control center and sent to the user's digital receive set 408 of FIG. In the headend 396 several digital programs are combined according to one of the methods described above.

When the broadcast station receives the program, the signal is input to the digital stream selector 400. The selector includes the aforementioned elements of certain alternative implementation circuits for performing switchless traces except that such units are located at remote sites. The unit operates in the same manner as described above. All such switching, whether or not the digital stream selector 400 selects between multiplexed signals in one data stream on one channel or between signals of a different stream or from a locally inserted received signal, is illustrated in FIG. 9. In the embodiment shown there is no trace of connection. As mentioned above, the selection may be formed as a function of the privileged base station, remote user selection and / or personal profile information or target advertisement (sent to the TV station via the back channel).

Once a selection is made, the program signal is transmitted to the remote site 408 for presentation by any other general means 404.

Non-Related Program Switching

10 shows an embodiment 430 for switching between non-related programs. In other words, it is a simple switching from one TV channel to the next. Currently, switching from one signal to another has not been achieved without flicker in a digital environment.

In the present invention, the viewer can switch from one program to another, which is related or unrelated, and the transition is made without a trace of connection. In other words, no visible artifacts are seen in switching from one program to another.

If the program is compressed and multiplexed into one MPEG stream, any embodiment disclosed herein can perform switching without connection traces. Although the program is on a separate NTSC channel, an embodiment of one digital "two tuners" should be used to allow frequency shifting.

A system 430 of high level elements for non-related program switching is shown in FIG. The unrelated program is preferably compressed and multiplexed into one data stream using an MPEG stream using one NTSC channel in the video encoder chassis 416. Unrelated programs may be combined into one MPEG stream or transmitted on different NTSC channels. For example, programming may consist of a sports, news, sitcom or children's program. This program is modulated at the modulator / up counter 420 and transmitted via any suitable transmission means 429 as described above.

The end-user can watch the digital program via an external transducer 428 connected to a digital monitor / tuner, personal computer or analog television set, in which case a switchless connection is performed in the transducer. One of these various components allows a user to "surf" a channel depending on the viewer's preferences. Again, the receiving unit may be selected from one of the alternative embodiments described in FIGS. 1 to 4, 7 and 15 to 17.

Switching without traces between programs of different games

In the present embodiment shown in FIG. 11, system 450 is provided to allow a user to switch between multiple games within a single program. For example, Olympic broadcasts include several programs corresponding to different races, such as skiing, skating, figure skating, ski jumping, and the like. Preferably, these various competition programs are compressed and multiplexed on one MPEG digital stream in video encoder chassis 434, passed through modulator / upcounter 438 and transmitted via a transmitting means a single NTSC signal. However, such a game program may also be encoded at a broadcast station on various NTSC channels.

After modulation and subsequent transmission, the program is received at the remote site 446. Remote site 446 includes a receiving unit, which includes a digital monitor / tuner, a personal computer or an external digital converter connected to the monitor. The user can select a match using his remote control between different programs. If the user wants a different game program, the switching may be performed according to any of the methods and systems described above (Figs. 1-4 and 15-17).

Picture-in-picture program switching without connection traces

12 illustrates an embodiment 470 for switching between unrelated programs, preferably using "picture-in-picture". Regardless of whether the user switches between a program in a small framed display or a large framed display, all such switching is done using the present invention without a trace of connection.

In the present invention, the viewer can switch from one program of two displayed windows to another. In other words, no artifacts are provided in the switching of one program to another.

The high level element of the system for picture-in-picture program switching 470 is shown in FIG. Preferably, four to seven programs are compressed and multiplexed into MPEG streams in one data stream on one NTSC channel in video encoder chassis 454. Different programs are combined within other MPEG data streams in the video encoder chassis 454. For example, programs include sports, news, sitcoms, or children's programs. This program is modulated and delivered via any suitable transmission means 464, as described above.

The end user can watch the digital program on a digital monitor / tuner, personal computer, or via an external converter 446 connected to an analog television set, in which case switching without connection traces is performed at the converter. The embodiment and flow shown in FIG. 12 allows a user to call picture-in-picture characteristics and switching without traces of connection of different programs in one MPEG stream. If switching from one MPEG multiplexed stream to another is required, the converter, PC, or digital monitor / tuner 466 may require multiple tuners / decoders, as in the examples shown in FIGS. 4, 16, and 17. will be.

Switching between multiple trade-shopping programs

The application of the present invention involves a transaction based on a system having a return path as shown in FIG. As in the other embodiments described above, video encoder 474 compresses and multiplexes several different programs onto one or more NTSC channels for transmission to the power site.

Preferably, several different types of shopping programs are compressed and multiplexed on a single NTSC channel. For example, many programs can relate to clothes, jewelry, household items, and so on. If more programs are required than are allowed in one, more than one NTSC channel may be used in the present invention.

The program is transmitted to the receiving unit 486 of the end user via any suitable transmitting means 482. In the receiving unit 486, the user can switch seamlessly between different product genres. Alternatively, remote unit 486 may switch to a given product program based on personal profile or statistical information. In this way, only products that most closely meet and match a particular individual's tastes and needs can be provided to the user. Such data may be stored in a storage device or headend within the receiving unit 486.

If the user decides to receive or purchase additional information related to the product, a back channel 490 such as that shown in FIG. 10 can be used to send this request back to the central relay station location.

Digital Program Insertion-Addressable Advertising

14 illustrates an embodiment 526 for providing digital program insertion. At some predetermined time during programming, a given advertisement is provided to the viewer. In a preferred embodiment, the advertisement may be personalized to a particular viewer based on personal profile information or statistical information. This targeted advertisement is illustrated in the following paragraph.

At the location of the central relay station, a number of advertisements are inserted into the program stream. Preferably, the central relay station uses a hybrid digital insertion system to insert the advertisement into the program. Hybrid digital devices replace the tape decks of analog systems with computers, digit drives and decoder cards, as deployed in the cable wrap cable advertising white paper cited herein by reference. The advertisement content 506 is derived from any one of several possible sources, including, but not limited to, servers, tape deck satellite feeds. For storage, the sport is preferably digitally encoded and compressed in off-line processing using MPEG1, MPEG1.5, MPEG2, or a suitable method. Distribution from encoders to servers and playback systems can be performed over the network by disk or tape.

After encoding, the sport is distributed to the server for storage until playback is required. Preferably, the sport can be played back directly from the server to the decoder card for conversion back to analog. The sport is converted to analog and transmitted through the insert switch means in the usual way. The output video and audio are passed to the cucumber and video encoders shown at the central relay station location in FIG. 5, after which the sport is digitally encoded and compressed as described in the paragraph described above with reference to FIG. 5.

Although digital advertisement insertion is not efficient, the actual switching of advertisements into the program can be achieved using conventional advertisement insertion systems using analog or tape based systems.

The location and display of advertisements into the program stream is controlled through the use of signaling and addressing capability command insertion 498. Personalized advertisements can be made effective by addressing certain advertisements for a particular viewer. Some car companies, for example, want to personalize their transactions to best meet the needs and needs of their viewers. Knowing that a particular user is male and enjoys nightlife, the programmer may want to watch an advertisement that corresponds to a sports car of an automobile company rather than a small economical car. The advertisement is pushed to the end user based on the data stored in the stream addressed to the end user device via a set top controller in the remote end user unit or provider's headend.

Preferably, several advertisement selections are encoded according to the manner described with reference to FIG. 5. Since the advertising sports video is genlocked and synchronized at encoder 510, switching to one of the advertisements in the main program may be seen as a link up to the viewer.

Switching without trace of group signal to other group signal in server

In another embodiment of the invention, the switching process between live broadcast and provided video content is described. In contrast to the switching from a single digital signal to another digital signal in a remote receiving unit, this embodiment allows for transition without a trace from one signal group to another. The transition is necessary to occur in such a way that the output bit stream is continuous and corrected with MPEG syntax. Proper switching ensures that any standard MPEG decoder plays the resulting bit stream as if it were a stream without any errors.

A preferred embodiment 530 for performing this switching is shown in FIG. The element of FIG. 15 is located at the cable head end, alternatively at a centralized op center for a satellite distribution network. For the sake of explanation, the live broadcast signal of the group is represented by the group A signal, and the group B signal is assumed to be a signal recorded in advance and stored in the server 550. For example, the group A signal may include several videos representing angles of different cameras in a sporting event. Group B signals can represent a series of transactions. However, it will also be appreciated that both Group A and / or Group B signals may represent pre-recorded or live broadcast signals.

In this embodiment, switching from group A signal to group B signal is required. The group A signal is received at server 550 from a real time encoder 546 located at a local or remote site. A defined MPEG digital packet is inserted into a group A content stream on a particular channel. Command and control terminal 534 provides an analog tone to the video signal prior to analog-to-digital conversion. When the signal reaches the real time encoder 546 from the command and control terminal 534, the real time encoder 546 inserts the digital tone at the appropriate point in the group A digital stream upon detection of the analog tone. Once the tone is inserted, the group A digital stream is output from the real time encoder 546 and delivered to the server 550 of the headend. When received at the server, the group A stream is delivered to the MPEG transport switch device in server 550. The control terminal 538 sends a command to the MPEG transport server switch device to start the switch looking for the inserted digital tone.

To reproduce the Group B content, the server switch device decodes the timing information from the Group A digital stream and subsequently re-stamps the Group B content with the appropriate timing signal from Group A. Preferably, with the video stream of the PCR, the encoding clock of the original Group A content is preferably generated by genlocking the same stream using a digital tone mounted therein and detaching the program clock reference (PCR) from the video stream. Regenerate At this point, the switch device has the ability to reinsert the timing information into the Group B contents to prepare for playback.

Upon detecting the digital tom, the server switch device initiates the transition to the group B digital stream consisting of the group B prerecorded signals. Preferably, the server switch device has prior knowledge of the length of the group B content, so that when the server switch device detects the end of the group B content, the device switches back to the group A content. Transmitter 554 delivers the digital data stream to the remote receiving site as previously described.

In this way, at a given time during the provision of a sporting event represented via a plurality of live digital video signals, for example, a video stream received at the receiving converter unit is automatically subjected to operation by, for example, a server switch device. On the basis of this, the transition to the prerecorded contents of the group B is performed. The decoder at the receiving site then selects an advertisement of group B content. At the end of the advertisement, the decoder automatically restarts the Group A content and selects one of the live signals as described above. In this way, switching without a trace of connection from live encoded video content to pre-recorded content is achieved at the server.

Example using two tuners for switchless connection

An embodiment 558 using two tuners for switching without a trace from a digital signal located in one frequency channel (channel A) to another digital signal located in another frequency channel (channel B) is shown in FIGS. 16A and 16. Shown in 16b.

As shown in Figs. 16A and 16B, this embodiment includes two tuners 560A, 560B (for tuning different frequency channels), a micro (for selecting frequency channels and digital signals mounted within the channels). Processor 564, demodulators 568A and 568B (to demodulate signals from carriers), digital demultiplexer / decoder 572 (to separate the selection of selected audio, video, and data from the composite digital stream) and ( Display processor 576) for formatting the video signal for display.

This embodiment operates to switch from one digital data stream in channel A to another digital data stream in channel B as follows. The first tuner 560A is tuned to channel A and preferably receives a composite digital stream in an associated frequency channel consisting of a plurality of digital video, audio and / or data signals. The composite digital stream is passed from the first tuner 560A to the digital demodulator 568A. The demodulation type can be one of those generally known in the art as shown below.

A composite digital stream is provided at the input of the digital demodulator / decoder 572, where the selected audio and video signals are separated from the composite digital stream in the demodulator 573, and separately audio and video decoders. 575, 574. This signal is then decompressed and decoded based on one of the signal encoding scheme, preferably the MPEG scheme. Once decoded, audio and video (and / or data) are passed to the display processor 576 and subsequently delivered to the monitor.

Once the switching to one digital signal of frequency channel B is determined, microprocessor 564 sends a command to second tuner 560B to pretune to the frequency of channel B. The composite digital signal of channel B passes through a digital demodulator 568B and is passed to a digital demultiplexer / decoder 572. At this point, the digital demultiplexer 572 receives the digital streams on both sides located on channels A and B. Thus, when channel A and channel B carry four digital signals, demultiplexer 572 receives eight digital signals. The digital demultiplexer 572 receives instructions from the microprocessor 564 instructing to separate the digital signal from the composite digital stream from channel B. Respectively, the digital demultiplexer 572 separates selected video and audio (and / or data) from the composite digital streams from channels A and B. The selected signal is passed to the video and audio decoders 574 and 575. The video decoder 574 switches from the currently displayed video signal to the newly selected video signal as described with reference to FIGS. 6 and 7. Decoder 574 thus recognizes the junction point in the current stream. When decoder 574 detects the junction point, the decoder determines whether the switching time to the second stream is appropriate. Decoder 574 starts loading the second stream into the buffer and performs switching without connection traces because of the time gap in the first stream. When the second stream is output from the decoder, the stream is passed to processor 576, where the video signal is formatted for display display.

As described with reference to FIG. 11, the audio decoder 575 performs switching from the current audio stream to the second audio stream. When switching is complete, the second audio stream is delivered to the display processor 576.

Switching from analog signal to digital signal or digital signal to analog signal

An embodiment 590 is shown in FIG. 17 where two tuners are used for switching from an analog signal located in a first RF channel to a digitally compressed signal in a second RF channel, or vice versa. In this embodiment, the viewer watches a particular channel, whether it is an analog signal or a digital signal within one particular RF frequency, and switching to another channel within another RF frequency, whether analog or digital, is determined. Two tuners 560A, 560B are used for the transition from one RF frequency to another.

Assuming the viewer has watched one channel (channel A) using an analog signal and decided to switch to a digitally compressed signal in a different channel (channel B), the embodiment of FIG. 17 operates as follows. . Because the channel transmits an analog signal, tuner 560A passes the signal to analog demodulator 569A and VBI decoder 570A. Using any common analog demodulation scheme known in the art, analog demodulator 569A demodulates an analog signal. The VBI decoder 570A separates any information mounted in the vertical blanking interval (VBI) (eg, interactive command, caption closure). The demodulated analog signal is then passed to an analog display processor 580, which formats the analog signal and outputs it to the VBI switch 588, followed by a display device.

Once the switching to the channel containing the multiplexed and compressed digital signal is determined, the microprocessor 564 determines the RF channel location of this channel and, in command, conveys the information to the second tuner 560B. Upon receiving the command, the second tuner 560B pretunes to the indicated second RF frequency (channel B). The output of channel B is passed to an input of a digital demodulator 568B, which demodulates the signal using any digital demodulation scheme known in the art. The digital signal stream is output from demodulator 568B and received by digital demultiplexer / decoder 572. Microprocessor 564 sends instructions to digital demultiplexer / decoder 572 representing the selected digital signal. Digital demultiplexer / decoder 572 demultiplexes multiple digital signals and decompresses such signals. The components of the selected result (audio, video and data) are passed to the appropriate decoders 574, 575 as described with reference to FIG. 16 (see FIG. 16B), and the video decoder 574 starts to decode the video information. The signal is then passed to a microprocessor 564 that indicates whether the stream is properly decoded and the audio is squeezed.

Video and audio signals are passed to a digital display processor 584 where the signals are converted from digital to analog. The resulting analog signal corresponding to channel B is input to VBI switch 588. By instructions from microprocessor 564 to switch two videos, VBI switch 588 switches at the appropriate time during the vertical blanking interval, causing a switch from analog to digital channel.

If switching from a digital channel to an analog channel is desired, the process is simply reversed and the second tuner 560B pretunes to the analog channel. In addition, the embodiment shown in FIG. 17 may switch from analog to analog channels.

Although the invention has been described with reference to the preferred embodiments, it is understood by those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention as defined by the appended claims.

The present invention enables seamless switching between video signals using less complex methods.

Claims (12)

A receiving unit capable of receiving programming and performing a seamless switching from a first analog signal to a second analog signal, or from an analog signal to a digital signal, or from a first digital video signal to a second digital video signal, A microprocessor that selects one of the video signals and directs seamless switching with the selected video signal; A pair of tuners coupled to the microprocessor to tune the RF channels, where the pair of tuners select the RF channels upon instruction from the microprocessor; A pair of analog demodulators connected to each of said tuners and arranged to receive one analog signal; A pair of digital demodulators connected to each of said tuners and arranged to receive a digital signal; A digital demultiplexer / decoder coupled to the pair of digital demodulators for demultiplexing digital signals, decompressing digital signals, and performing seamless switching from one digital video signal to another; A digital display processor coupled to the output of the digital demultiplexer / decoder to convert the decompressed output digital signal into an analog signal; And And a vertical blanking interval switch coupled to the output of the digital display processor and the outputs of the digital analog demodulators to perform seamless switching between analog video signals. The method of claim 1, And an analog display processor arranged to format the demodulated analog signal, the analog display processor being coupled to the outputs of the analog demodulators and the vertical blanking interval switch to connect the analog modulator outputs to the vertical blanking interval switch. The method according to claim 1 or 2, The switching unit to the digital video signal comprises two video programs of picture in picture format. The method according to claim 1 or 2, The receiving unit is located at a broadcast station and further comprises means for transmitting signals to remote sites. The method according to claim 1 or 2, At least one of the two video programs of switching to the digital video signal corresponds to a main program feed, and the other digital video signal consists of replays, certain camera angles, advertisements, individual focus, slow motion video, and player statistics. Receiving unit corresponding to one selected from the group. The method according to claim 1 or 2, Switching to an analog video signal comprises two video programs of picture in picture format. The method of claim 6, At least one of the two video programs of switching to an analog video signal corresponds to a main program feed, and the other video signal is a group consisting of replays, predetermined camera angles, advertisements, individual focus, slow motion video, and player statistics. Receiving unit corresponding to the one selected from. A flawless switching receiving programming and performing seamless switching from a digital video signal multiplexed on a first program signal received on a first RF channel to an analog video signal multiplexed on a second program signal received on a second RF channel. As a unit, A microprocessor instructing switching from a digital video signal to an analog video signal; A first tuner coupled to the microprocessor to tune a first RF channel; A digital demodulator connected to the first tuner for demodulating a first program signal; A digital demultiplexer / decoder coupled to the digital demodulator and microprocessor to demultiplex a first program signal to decompress and decode the digital signal to obtain a digital video signal; A digital display processor coupled to the digital demultiplexer / decoder to convert digital video signals to analog; A second tuner coupled to the microprocessor to pretune to a second RF channel; An analog demodulator connected to the second tuner to receive and demodulate an analog signal; And And a vertical blanking interval switch connected to an output of the digital display microprocessor and an analog demodulator output to perform a seamless switching from the converted digital video signal to the analog video signal during the vertical blanking interval of the signals. The method of claim 8, And the vertical blanking interval switch is connected to the analog demodulator output via an analog display processor and is arranged to format the demodulated analog signal. The method according to claim 8 or 9, The analog video signal includes two video programs to be displayed simultaneously in a picture in picture format, wherein the switching unit is And a display device for simultaneously displaying two video programs included in an analog video signal in either side by side or picture in picture format. The method according to claim 8 or 9, And a digital video signal and an analog video signal comprise non-related programs. The method according to claim 8 or 9, At least one of the two programs of switching to an analog video signal corresponds to a main program feed.