CA2064111C - Video communication system - Google Patents

Abstract

A system and method for transferring video programs from a first location to a remote location provides for communication of the programs over selected commercial telephone networks. The program signals are digitized, compressed, and stored at the first location, and transferred to the remote location on request of a viewer. Due to the compression of the program, the time required for electronically transferring the program to the remote location is much less than the viewing time for such program. The compressed program is reconstructed at the remote location for viewing on available video display devices.

Description

1 ~ACKG~OU1~~ ~F'TH~ ii~'V~1~9~'i~DN

2

3 i. Field of the Invention:

4 The present invention relates generally to 6 video systems and more specifically to a system and 7 method for transferring a video program for display at 8 a remote location.

2. . Description of the Prior Art:

12 Viewing of various types of video programs 13 has become increasingly popular. These programs are 14 generally viewed on standard television sets. Typical video programs include motion pictures, entertainment 16 produced for television, and educational and training 17 programs. An extremely wide variety of programs have 18 been designed or adapted for television viewing.

In order to transfer the video programs to a 21 remote location where they can be viewed, programs can 22 be broadcast using radio waves, transferred to the 23 remote location by means of a specially installed 24 dedicated cable, or transfer of a physical copy on video tape or video disk can be made. Each method of 26 distributing video programs has drawbacks fox certain 27 applications.

29 When video programs are transferred using radio waves, there is little or no control over who 31 receives and views the program. This method of 32 transferring video programs is not suitable for limited 33 distribution of pay programs. In addition, the number 1 of channels for transferring programs is not unlimited, 2 and picture quality of the program can be degraded by 3 atmospheric conditions.

Barring technical problems, programs ~6 transferred to a remote location along a specially 7 installed, dedicated cable generally have a reliably 8 good picture quality. However, the cable must be 9 installed at each remote location, and controlled through a centralized facility. Although many video 11 channels can be carried over some cable systems, the 12 number of channels is, again, not unlimited. As is the 13 case with broadcast systems, transmitting equipment 14 must be made available at the time any particular program is to be viewed. The selection of programs and 16 times for viewing are made centrally, as is the case 17 with broadcast systems, and are not under the control 18 of a viewer at a remote location.

Physical transport of video tapes to a remote 21 location allows the viewer to select the program to be 22 viewed and the time for viewing. However, such tapes 23 must be physically transported to the remote location.
24 This takes time, and is often not convenient tar the viewer. In addition, the physical video tape or disk 26 containing the programming is subaect to loss, theft, 27 and deterioration.

29 It would be desirable to provide a system and method for transmitting video programs to remote 31 locations which overcomes various drawbacks as 32 described above.

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1 sun~nn~,RV o~ -~H~ ir~vE~~aonr 3 It is therefore an object of the present invention _ 4 to provide a system and method for transferring video programs from a first location to a remote location.

7 It is another object of the present invention to 8 provide such a system and method wherein the programs 9 are electronically transferred in a short period of time relative to the viewing time of the programs.

12 It is a further object of the present invention to 13 provide such system and method which does not require 14 that special, dedicated cables be connected to the remote location.

17 Therefore, according to the present invention, a 18 system and method for transferring video programs from 19 a first location to a remote location provides for communication of the programs over selected commercial 21 telephone networks. The program signals are digitized, 22 compressed, and stored at the first location, and 23 transferred to the remote location on request of a 24 viewer. Due to the compression of the progr~, the time required for electronically ~transferring'~ the 26 program to the remote location is much less than ~~the 27 viewing time for such program. The compressed program 28 is reconstructed at the remote location for viewing on 29 available video display devices.

1 BRIEF DESCRIPT1~~8 ~F THE DRAWfNGS

3 The novel features believed characteristic of the 4 invention axe set forth in the appended claims. The invention itself however, as well as a preferred mode 6 of use, and further objects and advantages thereof, 7 will best be understood by reference to the following 8 detailed description of an illustrative embodiment when 9 read in conjunction with the accompanying drawings, wherein:

12 Figure 1 is a high level block diagram of a system 13 for transferring video programs to a remote location;

Figure 2 is a block diagram of a central data 16 facility;

18 Figure 3 is a block diagram of a system for 19 digitizing and compressing video programs;
21 Figure 4 is a block diagram of a distribution 22 interface for use with the jystem of Figure 1; ' 24 Figure 5 is a block diagram of a receiver for use at a remote location;

2~ Figure 6 is a flowchart describing a method for 28 making video programs available for transfer to a z9 remote location; and 31 Figure 7 is a flowchart illustrating a method for 32 requesting, receiving, and displaying video programs at 33 a remote location.

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1 DES~I~IPTiON OF THE PREFERRED ENtBODIMENT

3 Referring to Figure 1, a system for transferring 4 video programs to a remote location includes a central data facility 10 connected to a commercial telephone ~ 6 network _ 1?.. The central data facility 10 will be 7 described in further detail in connection with the 8 following figures. Telephone network 12 preferably 9 includes optical fiber connections capable of transferring digital data at very high rates, such 11 optical fiber systems are currently being installed in 12 selected locations in the United States, and are 13 expected to be widely available in the future.

At a remote location, a telephone 14 and receiving 16 unit 16 are connected to the telephone network 12. A
17 video display device 18, such as a television 18 conforming to the NTSC standard, is connected to the 19 receiving unit 16 for displaying video programs which have been transferred from the central data facility 10 21 to the receiving unit 16. A viewer who wishes to~down 22 load a program from the central data facility 10 into 23 his receiving unit 16 calls the central data facility 24 10 using the nox-mal telephone 14. After the program has been ordered, the user places the telephone 14 on-26 hook and switches the receiving unit 16 to standby.
27 The central data facility 10 then returns the call and 28 down loads the requested program into the receiving 29 unit 16 for viewing at a time selected by the viewer.
31 A keybaard or other input device is preferably 32 provided on the receiving unit 16 for the viewer to 33 identify the requested program. Identifying 1 information far the receiving unit, used for billing 2 and call-back, can be stored in the receiving unit.

4 A block diagram of the central data facility 10 is shown in Figure 2. The central data facility to °6 includes a central processor 20 connected to one or 7 more mass storage devices 22. Mass storage devices 22 8 are preferably high density devices such as optical 9 disks. Programs which are to be handled by the central data facility 10 are originally provided from one or 11 several different types of video source 22 as known in 12 the art. The video programs are digitized and 13 compressed in a digitizing processor 26, and 14 transferred to the central processor 20 for retention in mass storage devices 22.

17 Incoming requests for programs are connected to a 18 request interface 28, which is in turn connected to the 19 central processor 20. outgoing programs being transmitted to remote receiving units are routed 21 through a distribution interface 30.

23 In a preferred embodiment, a user connects to the 24 central data facility 10 through the request interface 28 by means of a standard touch-tone telephone. Once a 26 connection has been made, the viewer can identify 27 himself and request any available program by entering a 28 proper set of codes. The DTMF tones transferred to the 29 request interface 28 are converted to characters and transmitted to the central processor 20. Central 31 processor 20 identifies the caller and determines 32 whether the requested selection is available. Desired 33 information, such as the availability of a selection, I
1 any delay which may be incurred prior to down loading 2 the selected program, or an indication of the charges 3 incurred in the transaction, can be returned to the 4 viewer through a request interface 28 by means of DTMF
tones or recorded or synthesized spoken messages.
'6 7 Once a request has been made and acknowledged, 8 central processor 20 selects an available output 9 channel to distribution interface 30, and requests a telephone switching network connection. Since each 11 viewer must identify himself when the request is made, 12 central processor 20 is able to call an authorized 13 number at a known location corresponding to such user.
14 Once the connection is established, the requested program can be transferred from mass storage 22 through 16 the distribution interface 30 to the remote location.
17 Accounting data regarding the transaction is logged by 18 the central processor 20 for administrative purposes.

Referring to Figure 3, a block diagram of the 21 digitizing and compression processor 26 is shown.
22 Source 24 provides separate video and audio signals to 23 processor 26. The video signal is applied to a sync 24 and blanking stripper circuit 32. The various sync signals and blanking intervals contained in the video 26 signal are necessary only for display of the program, 27 and can be recreated in the receiving unit 16. The 28 output from sync and blanking stripper 32 is connected 29 to a signal separator 34, which breaks the video signal into its various basic elements. The number of 31 separate channels into which the video signal is 32 separated at this point will depend upon system 33 implementation, with signals such as luminance and g ~~~~~11~.
1 chromanence being likely candidates for separate 2 handling.

4 The separated signals are then converted to digital signals in analog to digital converters 36, and "6 stored in a buffer 38. As shown in Figure 3, three 7 separate video signals axe digitized, but one, two, or 8 more than three signals may be used. If the video 9 signal is not split into two or more parts, t1-~e output of the sync and blanking stripper 32 can be input 11 directly to an analog to digital converter 36.

13 Since the audio signal is frequency modulated 14 instead of amplitude modulated, it is preferably handled separately from the video signal. The audio 16 signal is demodulated and filtered in filter 40, and 17 digitized in analag to digital converter 42. The audio 18 signal is also stored in buffer 38.

pigital data from buffer 38 is input to a data 21 compression circuit 44. Compressed data is input to an 22 encoder 46, which encrypts the data in order to 23 preserve privacy. From the encoder 46, the digital 24 data representing the program originally provided by the source 24 is transferred to the central processor 26 20.

28 Buffer 38 can be a relatively small buffer, which 29 requires that data be extracted therefrom and compressed in data compression circuit 44 as it is 31 being generated by the source 24. In the alternative, 32 buffer 38 can include mass storage capable of holding 33 an entire program. In this event, the compression and g 1 encoding of the data can be performed after the entire 2 program has been digitized, if desired.

4 Referring to Figure 4, a block diagram of a preferred embodiment for the distribution interface 30 ''6 is shown. Central processor 20 is connected to a high 7 speed bus 48, which is in turn connected to several 8 gateways 50. Although two gateways 50 are shown in 9 Figure 4, the number actually used depends upon details of the system implementation, especially with reference 11 to the data throughput capabilities of the central 12 processor 20 and the gateways 50.

14 Each gateway 50 is connected to a low speed bus 52. Each low speed bus 52 is preferably a commercially 16 available local area network. A plurality of optical 17 converters 54 are connected to each low speed bus 52.
18 In Figure 4, only two converters 54 are shown connected 19 to each low speed bus 52, but more are preferably connected in an actual implementation. The number of 21 converters 54 connected each low speed bus 52 depends 22 on the data transfer rate of the converters 54 and data 23 handling capability of the buses 52.

Data transferred to a converter 54 is placed into 26 an internal buffer 56. Control circuitry 58 controls 27 operation of the converter 54 and communicates with the 28 gateway 50 over low speed bus 52. Control circuitry 58 29 also controls operation of optical drivers 60, 62.
Each optical driver 60, 62 transmits the data from 31 buffer 56 via a modulated light signal as known.in the 32 art. Each optical driver 60, 62 is connected to an 33 optical coupler 64, which combines the different light .

1 signals onto a single optical fiber. In a preferred 2 embodiment, optical drivers 60, 62 generate light 3 having different wavelengths, which is multiplexed onto 4 a single optical fiber by coupler 64. Particular system designs can utilize only a single optical driver '6 60, or more than the two optical drivers 60, 62 shown 7 in Figure 4.

The distribution interface 30 shown in Figure 4 allows a single central processor 20 to drive a 11 relatively large number of converters 54 at one time.
12 Various alternative designs to that shown in Figure 4 13 can, of course, be utilized if desired.

Figure 5 shows a preferred embodiment of receiving 16 unit 16. The receiving unit 16 shown in Figure 5 is 17 used only as a stand alone receiver, and does not 18 incorporate the automatic program request facilities 19 described in connection with Figure 1.
21 The incoming optical signals are filtered by 22 wavelength and split, in optical splitter 64,' and 23 converted to digital electrical signals. In the 24 embodiment shown in Figure 5, two different wavelengths of light were used to transmit information over the 26 optical fiber connection, so two separate channels of 27 digital information are generated by splitter 64. The 28 number of optical drivers 60, 62 as described in 29 connection with Figure 4 determines the number of channels into which the incoming data is split by 31 splitter 64.

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1 Each channel of digital data is connected from 2 splitter 64 to a serial to parallel converter 66, which 3 converts the serial data to byte-wide data. As is 4 known in the art, the serial transmission of the program data preferably includes redundant error '~6 correcting code (ECC), allowing for correction of 7 errors within the receiving unit 16. Errmr correction 8 is performed in error correction units 68, and the data 9 is temporarily stored in buffer 70.
11 Under control of control unit 72, data is removed 12 from buffer 70 and transferred to decoder 74. Decoder 13 74 decrypts the compressed data, undoing t:.ne encryption 14 effects of encoder 46 described in cons~ection with Figure 3. Decoded data is then transferred through 16 storage interface 76 and stored into amass storage 17 device 78. Mass storage device 78 is preferably an 18 erasable optical disk, or other similar relatively low 19 cost, high density storage medium.
21 Data is stored onto mass storage device 78 until 22 the entire requested program has been down loaded from 23 the central data facility 10. Due to the removal of 24 unnecessary information, compression of the remaining data, and high speed transfer, this down loading can be 26 accomplished in much less time than is reqr.~ired to view 27 , the program in real time. Once transfer has been 28 completed, control unit 72 communicates such fact to 29 user interface 80, which indicates through visual or audible means to a viewer that the down loaded program 31 is now available for viewing. User interface 80 32 provides basic functions for the viewer, such as setup -- la _ 1 for down loading a program, play a program, and pause 2 during play of a down loaded program.

4 Once a viewer selects the play mode, control unit 72 causes the data stored in mass storage device 78 to f6 be transferred through storage interface 76 to a data 7 decompression unit 82. Data decompression unit 82 8 restores. the compressed data to its raw, uncompressed ,9 form, and transfers it to buffer 84. D_ata_is. extra_c_ted .from buffer 84 in real time as needed for viewing, and 11 converted to analog form in digital to analog converter 12 86. The original video and audio signals are then 13 restored in signal reconstruction circuit 88, which 14 restores blanking intervals, sync signals, and the like which were removed in the digitizing and compression 16 processor 26. The output of signal reconstruction 17 circuitry 88 is a composite video signal or a modulated 18 RF signal suitable for input to a standard television 19 set. If desired, the program signal can alternatively be recreated as a digital signal suitable for display 21 on a digital monitor as known in the art.

23 Referring to Figure 6, a preferred method for 24 making a video program available for transmission to a remote location is shown. The program is first 26 digitized 90 and compressed 92 as described in 27 connection with Figure 3. The program is also 28 preferably encoded 94, and stored 96 in a non-volatile 29 mass storage device. If desired, the encoding step 94 may be left out.

32 At this point, the program is compressed and 33 stored in condition to be transferred. The number of s:
1 programs which can be stored at one time is limited 2 only by the capabilities of the central processor 20, 3 and the storage available in mass storage devices 22.
4 When a request is received for a particular program 98, a check is made to see whether that program is 6 available 100. If the requested program is not 7 available, perhaps because the viewer made a mistake 8 when entering his selection, such fact is indicated to 9 the viewer 102. If the program is available for down loading, that fact is confirmed to the viewer 104 and 11 the central data facility 10 sets up a telephone 12 connection with the remote location 106. Transfer of 13 the program 108 is then performed as described above.

Referring to Figure 7, a preferred method is shown 16 by which the receiving unit 16 at the remote location 17 receives and displays a requested program. First, a 18 connection is made to the central data facility 110.
19 As described above in connection with Figure 1, this is preferably done by utilizing a standard touch-tone 21 telephone handset to dial the central facility and 22 enter a selection.

24 The viewer then requests the desired program 112, and waits to see if it is available 114. If not, the 26 process is complete. If the requested selection is 27 available, the viewer hangs up the telephone handset 28 and switches the receiving unit 16 to standby. The 29 program is then received by the receiving unit 118, decoded, and stored into mass storage 122. When the 31 viewer is ready to view the program, it is decompressed 32 124 and played back 126 for viewing on a video display.
33 The viewer may preferably pause display of the program 1~
1 at any time by entering a command at the user interface 2 80, and may view the program multiple times. r 4 The convenience and usefulness of the system described above depends in large part on the ability to '6 be able to quickly down load a video program to the 7 receiving unit 16. In order to illustrate the 8 convenience of the system described above, an example 9 illustrating the numbers involved will now be described.

12 A single television channel has a 6 megahertz 13 bandwidth. By stripping unnecessary signals as 14 described above, a video signal can be sampled at a rate of 16 megahertz and retain a good signal quality.
16 Samples having a resolution of 8 bits provide 17 sufficient video fidelity for television purposes.
18 This results in a raw data rate of 16 megabytes per 19 second of video data.
21 Assuming a desired program, such as a motion 22 picture, to have a length of two hours, 7200 seconds of 23 data must be digitized and stored. At a rate of 16 24 megabytes per second, this results in 115.2 gigabytes of raw data. As is known in the art, video information 26 is highly redundant, so that large compression factors 27 are obtainable. This means that a total data storage 2.8 requirement of approximately 2-4 gigabytes is expected 29 to be sufficient for a two hour video program. This is the storage requirement for a single program both in 31 the central data facility 10 and the receiving unit 16.
32 This amount of data is well within the capability of 33 optical disks which are presently becoming available.

J

2 Assuming 2.3 gigabytes are required for a 3 compressed program, and that a 50% overhead is required 4 for serial transmission of the program data, for error correcting code, blocking, and the like, 3.45 gigabytes 6 of serial data must be transmitted between the central 7 data facility 10 and the receiving unit 16. At eight 8 bits per byte, this results in 27.6 gigabits to be 9 transferred. Optical fiber connections currently 0 planned for installation to residential customers will 1 have a maximum data transfer rate of 144 megabits per 12 second. At this rate, the required 27.6 gigabits can 13 be transferred to the receiving unit 16 in 192 seconds, l4 which is just over three minutes. Thus, approximately

5 three minutes is required to transfer a typical video 16 program to the receiving unit 16.

18 Note that the numbers described above do not 19 require the use of more than one wavelength of light on 20 a single optical fiber. If it is necessary to increase 21 the sampling rate, or the magnitude of each sample, two 22 or more wavelengths of light can be multiplexed 'on a 23 single cable as described in connection with Figures 4 24 and 5. This would allow better resolution of the video 25 signal with no increase in. transmission time.

27 Tf a video camera and compression circuitry is 28 available at a remote location, it is possible to use 29 the system described above to transfer video 30 information between two remote locations. A call to 31 the central data facility can be used to initialize the 32 connection between two remote locations, and the 33 central data facility is no longer involved once the 1 connection is setup. Near.. real-time_ video..signals 2 obtained at one location are compressed and transferred to the second remote location over the phone lines.
4 Instead of storing the signals onto the mass storage device 78, they are transferred directly to the data

6 decompression circuitry 82 and displayed at the second

7 remote location. Near real-time video communication

8 can be accomplished by providing cameras and

9 compression circuitry at each end of a conversation.
1o 11 While the invention has been particularly shown 12 and described with reference to a preferred embodiment, Z3 it will be understood by those skilled in the art that 14 various changes in form and detail may be made therein without departing from the spirit and scope of the 16 invention.

Claims (9)

Claims:

1. A system for transmitting video programs to remote locations over a switched telephone network, comprising:
a central data facility having means for storing digital compressed versions of video programs;
a request interface connected to said central data facility and to the telephone network, wherein said request interface receives requests for video programs made over the telephone network and communicates them to said central data facility;
a distribution interface connected to said central data facility and to the telephone network, wherein said distribution interface initiates connections over the telephone network with remote locations in response to requests received by said request interface, and transmits thereto compressed versions of video programs previously requested through said request interface, such compressed versions being transmitted in less time than is required to view the programs in real time; and a receiver at each remote location for connecting to the telephone network and receiving compressed video programs transmitted from said distribution interface, for storing the received programs, and for subsequently playing the video programs at a real time rate on a video display.

2. The system of claim 1, wherein requests are made to said request interface through preselected sequences of DTMF
transmissions made from a telephone transceiver.

3. The system of claim 1, wherein said distribution interface comprises:
a plurality of converters for converting digital video programs to a format suitable for transmission over a telephone line; and a controller for simultaneously providing data representative of digital compressed video programs to each of said converters, wherein a plurality of the remote receivers can be simultaneously receiving such programs.

4. The system of claim 3, wherein said controller comprises:
a high speed central processor for providing processing and data transfer functions;
at least one gateway connected to said central processor by a high speed communications bus; and a communications network having a lower data carrying capacity than the high speed communications bus connected to each of said gateways, wherein a plurality of converters are connected to each communications network, and wherein said central processor controls the transfer of data to said converters through said gateways over the high speed communications bus and said communications network.

5. The system of claim 2, further comprising:
means for inputting video programs; and conversion means connected to said inputting means and to said central data facility for digitizing and compressing video programs read into said inputting means, and for transmitting such compressed video programs to said central data facility for storage and subsequent transmission to remote locations.

6. A method for viewing video programs at a location remote from a central data facility, comprising the steps of:
receiving at the central data facility a request for a selected program over a switched telephone network, such request identifying a preregistered requester;
determining whether the selected program is available;
if the selected program is available, initiating a connection over the telephone network to a remote receiving unit previously associated with the preregistered requester;

transmitting a previously stored compressed version of the selected program over the initiated connection in less time than is required to view the program in real time;
receiving the selected program at the remote receiving unit and storing it on a mass storage device; and after all of the selected program has been stored on the mass storage device, decompressing the selected program and playing it back in real time on a video display.

7. The method of claim 6, wherein the request received at the central data facility comprises a sequence of tones generated by a DTMF telephone.

8. The method of claim 6, wherein, if the selected program is available, such availability is confirmed during a connection in which such request is made, followed by terminating such connection prior to said step of initiating a connection.

9. A system for transmission of video programs over a switched telephone network, comprising:
a central data facility for storing a plurality of video programs in a digital, compressed format;
means connected to said central data facility for digitizing and compressing video programs, and communicating them to said central data facility for storage;
a request interface connected to the telephone network and to said central data facility for receiving requests for desired video programs over the telephone network, such requests being communicated to said request interface by sequences of tones generated by a DTMF telephone in response to a user pressing buttons thereon in selected patterns, such patterns identifying the user and the desired video program, wherein said request interface communicates to the user a confirmation of availability if a desired video program is available for the communication to the user;

a distribution interface connected to said central data facility and to the telephone network, said distribution interface containing a plurality of converters for converting compressed digital data to a form suitable for transmission over the telephone network, wherein said distribution interface initiates a connection with a receiving unit at a preselected remote location in response to the user's request and transmits the digitized, compressed video program to such remote unit over such connection in less time than is required to view the program in real time;
a plurality of receiving units at a plurality of remote locations, each of said receiving units connected to the telephone network and being capable of completing a connection initiated by said distribution interface and receiving digitized, compressed video programs over such connections, wherein each of said receiving units includes a mass storage subsystem for storing a received video program in compressed format, and a decompression subsystem for reading a stored video program from the mass storage subsystem at the user's convenience and converting it to a decompressed form suitable for display in real time; and a video display device connected to each receiving unit for displaying the converted video program.