JPH0884343A - System for transmitting digital data encoded in video signal - Google Patents

Abstract

PURPOSE: To provide a system for transmitting digital audio data and/or digital graphic data within a band width usable for transmitting television signals to the house or office of an end user. CONSTITUTION: This system is provided with a video tape player 13 for recording digital coded video signals, a cable television distribution system 15 for distributing the recorded digital coded video signals to end users, a decoding means 21 for decoding the video signals in order to generate output signals representing the channel selected by a user, and a means 22 for decoding the output signals in order to convert the digital coded video signals to digital data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable television system, and more particularly to a system for transmitting digital sound files, graphic files and real-time files via a cable.

[0002]

BACKGROUND OF THE INVENTION In the US cable television system, coaxial cable is commonly used which requires the use of a signal amplifier having a bandwidth of about 300 MHz, which is sufficient to carry information for about 50 television channels. Efforts are underway to reduce the number of signal amplifiers and to ensure 1 GHz bandwidth for cable television systems by replacing optical fibers. The bandwidth thus increased can carry about 150 television channels. But the community is 15
It is unlikely that it will need 0 separate channels, so it will use only half of the bandwidth available for television channels (half of which is 75 channels) and the remaining 1
It is advantageous to use a bandwidth of / 2 GHz for digital data.

[0003]

The present invention is directed to a method and apparatus for transmitting digital voice data and digital graphics data within the aforementioned 1/2 GHz (especially upper) usable bandwidth.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided a means for recording a digitally encoded video signal, a means for distributing the recorded digitally encoded video signal to an end user, and a video. Decoding means for decoding the signal to generate an output signal representative of the channel selected by a single user, and means for decoding the output signal and converting the digitally encoded signal into digital data. It is solved by the system that comprises The present invention is not limited to using the available bandwidth of the upper 1/2 GHz, but rather transmits digital voice and graphic data over the conventional television channels of various cable systems. It is possible to do. If the signal received at home is of sufficiently high quality, this system can be used for television signal broadcasting at normal broadcast frequencies.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a videotape 11 is constructed so that digital audio information, graphic information and data information to be sent to the cable subscriber's home over a cable or optical fiber are encoded into an image signal. It Suitable video tapes that can be used in the practice of the invention include 3/3 which is commonly used as a medium for storing digital data on a master tape for making compact discs.
It is a 4-inch video tape. The bits of digital data are represented by the light and dark areas of the video image. An industry standard tape for 3/4 inch for compact disc masters is called PCM 1630. However,
Digital audio standards also exist for inexpensive 1/2 inch video tapes in formats such as Beta or VHS®. The reference format for 1/2 inch video tape used for digital audio information is called F-1. The present invention is a beta, S
It can be implemented using any one of VHS, VHS or F-1 formatted videotapes.

The video tape 11 is a video tape
It is put in Ya 13. Video signals containing digital audio signals, graphic signals or data, as well as video channels (including audio) contained in cable television services, are provided to and processed by the cable television distribution system. .

There are several cable television distribution systems that include many companies that supply video for distribution to cable subscribers. Here, the cable television distribution system 15 includes, for example, a fiber optic cable (if available) that terminates in a coaxial cable 17 to the headend operation, subscriber home, for example. Other distribution systems including, for example, satellite-parabolic antennas and parabolic antenna-satellite will work as well.

Coaxial cable 17 carries a signal containing all of the television channel service to the subscriber. In the case of the present invention, the one or more television signals also contain information of the digital audio (along with the data and / or graphics, if any) encoded on the original videotape.

Although cable distribution may introduce noise, digital data can be decoded at home if the noise is low and the data content is not particularly important. If the broadcast television signal arrives at the home with sufficiently low noise, it is possible to provide digital audio and graphical information by broadcast television broadcasting. However, in the preferred embodiment, error detection / correction and synchronization signals are added to the television signal, as described below.

The cable 17 entering the home contains signals for all television services including digital voice, data and / or graphics. With or without the invention, this cable 17 is an input to a decoder box 21 at home, the output of which is used by the television / stereo system 22. FIG. 2 shows a decoder box modified to allow decoding of digital audio in addition to the decoding operation of the television channel selected by the subscriber.

In FIG. 2, the decoder box 21 includes a channel decoder 23 of the type commonly used in the home wired for cable television. The decoder 23 receives the coaxial cable 17 and decodes the single television channel selected by the subscriber. The decoder box produces a radio frequency signal that is available to almost all televisions in use today and is converted by the television into a display signal.

Television channels with digital audio signals, graphic signals or data require some additional processing. Although this additional processing is shown in FIG. 2 as being performed by separate boxes 25 and 27, all of the necessary processing can be done in a single physical box.

In the integrated box, the process of converting a radio frequency signal with a digitally encoded signal into a composite video signal may not be required as the composite video signal is obtained during decoding of the channel. However, when using an existing cable decode box, in a preferred example, the radio frequency signal-composite video signal function block 25 is used to provide the composite video signal required as an input to the digital signal decoder 27. . The radio frequency signal-composite video signal function block 25 is implemented using a video cassette recorder such as the Sony SLV-585HF.

The digital audio format used on the original video tape determines the type of digital signal decoder 27 required for this system. The cheapest set-up uses an F-1 format, with a Sony 60 as the digital signal decoder 27.
An F-1 decoder such as 1 ESD will be used.
This decoder takes in a composite video signal encoded in F-1 format and outputs a stereo audio signal to be supplied to a professional or home stereo amplifier 31 and a speaker 33. Radio frequency signal −
The output from the composite video signal function block 25 is simply sent to a conventional home television 35. PCM 16
A suitable decoder 27 for 30 formatted tapes would be a PCM 1630 decoder.

In addition to the transmission of digital audio signals, there is a lot of unused space in the video channel so that there is sufficient bandwidth to contain digital graphic information for displaying lyrics or song album information. The place where the digital graphic information may be included includes a portion of the video image signal which does not include the digital audio information (in particular, there is a lot of space in the F-1 format) or a portion of the video vertical blanking area. It is even possible to encode the digital graphic information as an FSK audio signal in the signal space normally used for audio information with video information.

If digital graphics information is to be provided, the format of the digital graphics information in one embodiment is that of a compact disc + graphics (known as the "red book" standard). , Or the same format used in Digital Compact Cassettes (DCC). Chip circuits or discrete circuits, the details of which are well known to those skilled in the art, can be used to process those formats in a video RAM into graphic signals from which the video RAM
The synchronized graphics program is sent to the same television set 35 that is hooked into the decoder box 21 to receive video on other television channels.

This digital output to digital recorder 37 represents a technique for delivering "records" to homes. There are several recording media for high quality digital recording. A number of very high quality recording digital audio tapes (DAT), lower quality but higher quality recording digital compact cassettes (DCC) or mini discs (Sony mini discs). There is a recording medium.

The home decoder device 21 can be connected to the recording device 37 if equipped with a standard digital output (eg SDIF). The resulting recording is better than most recorded cassette tapes available today. If the recording device is a DAT device,
Recording quality is as good as a compact disc. For this reason, in the preferred embodiment, the digital output is switched on only if the subscriber has paid a special fee to cover the program to cover the copyright fee.

The above system is a technique for delivering graphical voice information to cable subscribers. The system described above is easily adapted to deliver digital data as well as voice and graphic data. The process of distribution is the same as described above, except that it is not necessary to encode the information into audio and video or to decode the information from audio and video. Furthermore, in most cases digital data cannot tolerate data loss, so proper error correction / detection and synchronization are required.

In this regard, FIG. 3 is a block diagram outlining the components required to provide error detection / correction and synchronization to transmitted digital data.
However, it should be understood that the specific detection / correction and synchronization mechanisms described are provided merely as an illustration. FIG. 3 shows the AIFF or Audio Interchange File Format.
And a mechanism for encoding and decoding formatted audio data known as.

First, a digital information source in the form of graphics, text, real-time files, binary or other digital data source 61 can be a scanner, analog / digital
It is generated by a digital converter or a generation means by the operation of a computer program. The generation by manipulation of a computer program includes a word processor, a real-time file builder or paint program as disclosed in pending US patent application Ser. No. 906,712 filed July 1, 1992, assigned to the applicant. It is formed by a suitable mechanism such as. A real-time file is a file that contains multiple simultaneous video, audio or image sequences, or a combination thereof, each sequence being dynamically selectable for playback by the user. Digital information is stored on magnetic media such as hard disk 62 of personal computer system 63. Then the stored data is read out,
Parity bits are added to provide a mechanism for error detection and correction. In a relatively simple scheme, for example, the data is divided into data groups of 30 bytes (each byte is 8 bits). The 30-byte data is arranged in two columns of 15 bytes as shown in FIG. Then, four parity bytes are formed as follows. Parity byte 65 is formed by ANDing the bits in column 67 from the most significant bit to the least significant bit (or vice versa). The result of the AND operation of the bits in each column is stored in the corresponding bit position of parity byte 65. In a similar manner, parity byte 69 is determined by ANDing the bit positions of the bytes in column 71. Then, two more parity bytes 73 and 75 are added to row 7
It is calculated by ANDing the corresponding bit positions of 7 and 79. (A Visual Basic program for computing parity bytes for error detection / correction is shown in Appendix 1). Also, C for the DLL called by the program.
Contains the source code and globals used in the program.

After the parity bytes are calculated and added to the data file, sync fields are added to the beginning and end of the data file. One example of one suitable synchronization scheme would be to add a 16-byte long synchronization field at the beginning and end of a parity-coded data file that contains a repeating recognizable pattern unlikely to occur in the data. One suitable pattern is a byte containing a hexadecimal DB, 11011011 _2, which is repeated 16 times.

The digital data with the parity information and the sync field is then converted into the AIFF or Audio Interchange File Format (the specification of which is "Audio Interchange File Fpo" published by Apple Computer, Inc.).
rmat: AIFF Version 1.2 "), which is converted to a digital audio format. The data stored on the hard disk 62 is the Digidesign Sound Designer board 71 and Sound Design II software (see Both are Digi Design
(available from ign, Inc.) to an Apple Macintosh II computer 69. Next, this file is transmitted from the output port of the Digidesign board to the Digidesign DAT I / O box 73 (manufactured by Digidesign). Box 73 is Digidesign
A / F output from the sound designer board is suitable for input to Sony 601-ESD 75 S /
Convert to PDIF signal. Next, this Sony 601
-The ESD converts this signal into a signal suitable for broadcasting or transmitting over a cable network as described above. This converted signal can be recorded on a SVHS, VHS, beta or F-1 formatted videotape for use in the videotape player 13 of FIG.

At the receiving end, these processes are reversed by the digital signal decoder 27 as shown in FIG. The digital signal decoder 27 includes a device such as a Sony 601-ESD and outputs the signal to the SD.
Convert to a standard signal such as IF. This standard signal is then processed by a digital data processor 28, such as a DigiDesign Sound Designer II board on an Apple Macintosh computer, and a digital file suitable for other computer processing such as magnetic storage or AIFF. Is obtained. This file is
The sync field is removed and processed to perform error detection / correction as required. To process the received data, the sync field is removed to determine if the received data is in error and the signal processor 28
It is necessary to correct the errors detected during the digital signal processing performed by (see FIG. 2).

The results of this process may be displayed (including sound) by a television / stereo or other device connected to the decoder box 21 or stored in storage 29 for later use. . An inexpensive way to store would be an optical read / write minidisk from Sony. This disc is for television /
Used to receive in stereo or to be removed, displayed and listened to on various Sony handheld players. One application is digitally transmitted magazines and newspapers.
Home subscribers can receive this type of publication and view it using handheld players or televisions, as well as "paging" with data as well as print media.

Some of the aspects of the present invention will be described below. (A) The transmission system according to claim 1, wherein the digital data is voice information. (B) The transmission system according to claim 1, wherein the digital data is video information. (C) A system characterized in that the recording means is a video tape recorder capable of recording a video signal in a predetermined standard format. (D) The distributing means comprises at least a parabolic antenna-satellite, a satellite-parabolic antenna and a headend system, a fiber optic cable terminating in a coaxial cable of the cable subscriber's home. Transmission system. (D) A circuit in which the decoding means for decoding a video signal decodes a predetermined signal of a plurality of signals, which represents one piece of information of a plurality of channels, into a radio frequency signal so as to be suitable for use in a television receiver The transmission system according to claim 1, wherein

[Brief description of drawings]

FIG. 1 is a schematic block diagram of the system of the present invention.

FIG. 2 shows the components of a decoder box according to the invention and the connections to the components of a home audio / video system.

FIG. 3 illustrates an embodiment of the invention in which digital voice data, digital graphic data, digital text data or other digital data is converted for broadcasting or transmission over a cable.

FIG. 4 is a diagram showing a technique for adding parity information for data detection and correction.

[Explanation of symbols]

11 ... Video tape, 13 ... Video tape player, 15 ... Cable television distribution system, 17 ... Coaxial cable, 21 ... Decoder box, 22 ... Television stereo system, 23 ... Channel decoder, 25 ... Radio frequency-composite video function block 27 ... Digital signal decoder, 28 ... Sound processor, 29 ... Storage device, 31 ...
Stereo amplifier, 33 ... Speaker, 3
5 ... Television, 37 ... Digital recorder.

Front Page Continuation (72) Inventor Michael El Rajo USA 90291 Venice 1/2 California Palms Boulevard 709

Claims (1)

[Claims] 1. A system for transmitting digital data encoded in a video signal, comprising: (a) means for recording the digitally encoded video signal; and (b) said recorded digitally encoded video signal. And (c) a decoding means for decoding the video signal to generate an output signal representative of a channel selected by a single user, and (d) a decoding means for decoding the output signal. And a means for converting the digitally encoded signal into digital data, the system for transmitting encoded digital data in a video signal.