GB2107953A - Supplying plural kinds of information over a television channel - Google Patents

Abstract

Plural kinds of television information are available to a user for display on a video display (44) from a central library of information stored in a video cassette recorder/reproducer (41) i.e., still frame pictures (3) of diverse subjects, initially compressed and subsequently decompressed, audio (2) that may accompany such pictures, and alpha-numeric text (1), with or without sound or pictures, as well as the usual television service. The desired kind and item of information is selected by the user from index presentations and the subsequent manipulation of a control in the form of a hand held keyboard (200) which is functionally connected to a local controller (43') by multiple wire cable (201). <IMAGE>

Description

SPECIFICATION Method and apparatus for supplying plural kinds of television information over a television channel The present invention relates to a picture, aural and text service selectively available in a video signal format.

The usual television presentation is well known.

A video signal continuously provides moving pictures and a separate sound channel provides accompanying sound.

Apparatus for exhibiting a single television frame as a still picture has been available in "stopmotion" practice; often utilized in televised sports coverage.

Recently, a small still picture and printed text combined in one television-like frame has been available in England, using the trade name of Picture Prestel. A known narrow-band telephone line data transmission channel carries datacompressed digital encoded picture information.

About 10 seconds is required to assemble a partial picture. The receiving apparatus must have digital memory for picture storage and processing logic for data decompression.

This system is described in 'The U.K. Prestel Service, Technical Developments Between March 1980 and March 1981", by Clarke8Fenn, Proceedings of Videotext '81, International Conference and Exhibition, May 20-22, Toronto, Canada, page 147.

Similar systems, worl-wide, are treated by J.

Roizen, in his paper, Teletext in the U.S.A.", SMPTE Journal, Vol. 90, No. 7, July 1981, pages 602-610.

Roizen discloses principally the operating characteristics of each system, and considerations of standardization. All his systems utilize one, or a few, television lines within the vertical blanking interval for carrying digital information, to reproduce printed text.

This invention provides plural services over one video channel at video speed on a selective basis.

According to one aspect of the present invention there is provided a method of supplying plural kinds of information over a television channel, which includes at least two of the forming method steps of: (a) forming and storing digital alpha-numeric information in video format; (b) forming and storing compressed audio information in video format; (c) forming still pictorial information in a frame of video format; (d) selectively displaying said frame of pictorial information in video format; (e) selectively simultaneously uncompressing and reproducing said compressed audio information; and (f) substitutionally displaying said alphanumeric information instead of said frame of pictorial information in video format.

According to a second aspect of the present invention there is provided apparatus for supplying plural kinds of information over a video channel, which includes at least two sources of different kinds of information, including: (a) a source of alpha-numeric information in video format; (b) means to store said alpha-numeric information; (c) a source of compressed audio information in video format; (d) means to store said compressed audio information; (e) a source of at least one video frame of pictorial information; (f) means to selectively display said pictorial and said alpha-numeric information; (g) means to decompress said compressed audio information; (h) means to reproduce said decompressed audio information; and (i) control means associated with the aboverecited elements to selectively cause display of said pictorial information, so as to selectively cause reproduction of said decompressed audio information, and to selectively cause display of said alpha-numeric information.

The method and apparatus for accomplishing usual television are well known. The method and apparatus for accomplishing still-picture "burst" video frames service is disclosed in our copending application, No. 82.01831 published under Serial No. (2095949). The method and apparatus for accomplishing "compressed audio" service is set forth in our co-pending application No.82.10817 published under Serial No.

(2100091). The method and apparatus for accomplishing "television digital data frame" service is set forth in our copending application, No.82.16217 published under Serial No.

A wide-band television channel is used, to deliver a full still picture in 1/30th second, or 10 seconds of compressed audio in another 1/30 second, or printed text in another 1/30 second.

A simple control panel includes push-buttons for selecting the kind of service desired, and control of the service selected; such as "next page", "previous page", "yes" (accepting a prompting), "no" (rejecting a prompt), "index" (of subjects), and "link" (more on the same subject).

These controls serve each of the plural services; such as to repeat a prior audio sequence when desired, rather than a previous page.

The control panel effects commands through a microprocessor having both ROM and RAM memories, and by interconnection to microprocessors of the plural available services.

Two services may be offered, rather than three or more; such as a picture and text, a picture and audio, text and audio, and so on.

Of course, apparatus for three services may be provided, with one or two services remaining inactive if only one or two services are desired at any particular time.

The present invention will now be described in greater detail by way of example with reference to the accompanying drawings, wherein:- Figure 1 is a diagrammatic representation of two sequences of a three service transmission; Figure 2 is a block diagram of the user control; Figure 3 is a diagram of the local (user) controller for three services; Figure 4 is a flow chart for the apparatus shown in Figure 3; Figure 5 is a further flow chart relating to the apparatus shown in Figure 3; and Figure 6 is a schematic diagram of the apparatus of block 51' shown in Figure 3.

Referring to the diagrammatic representation shown in Figure 1 , the successive events as a whole represented by the reference numeral 0 are shown relative to the whole system as a function of time T.

Two sequences are shown for a transmission of three services. These are illustrative; any combination of services can be called-for, including sequences of usual moving picture television.

Frame 1, of television format, as 1/30 second for two fields, interlaced, for the U.S. NTSC standard, is devoted to "digital". This carries text information, from which printed characters are formed and exhibited to the user screen, as disclosed in or copending Application No.

82.16217.

This digital frame is not exhibited for viewing by the user. If it were there would be random "snow" over the whole screen, created by the many digital bits.

A given sequence of information is repeated on the second field of a frame to assure that all data is correctly received by providing 100% redundancy. Each line of data is accompanied by a, check code to detect errors in the data and to cause the redundant data to be used.

Frame 2 of the television format in the example of Figure 1 is devoted to "compressed audio". This carries audio information, in which 10 seconds of sound (or more) is transmitted in 1/30 second, as disclosed in our copending Application No.

82.10817.

This information is also not visually exhibited to the user, but is converted from analog to digital form, stored in a memory, and then read-out at an audio rate for delivery to the loudspeaker, say of the user's television receiver. The audio rate readout accomplishes decompression.

Frame 3 of the television format, is devoted to still picture "burst" service. The term "burst" is used as a shorthand to identifying a video signal burst of one frame, as disclosed in our copending Application No.82.01831.

A full frame high-definition television image is made available, and this is exhibited upon the user's screen. It is reproduced for as long as the user desires by a still-frame technique utilizing a video cassette recorder (VCR), or the equivalent.

The aspects of these three services are given herein. For further details of each of these, reference should be made to the three above referred to copending Patent Applications.

The second sequence is shown as frames 1 2', and 3'. Typically, in the use of the system, these relate to new subject matter. In video frame 3' the illustration is a car, whilst in frame 3 the illustration was a person.

It is not required that the subject matter be new in each sequence. The subject matter may be a related continuation. Whatever the relation might be, the method and apparatus functions to handle each sequence de novo; i.e. from the beginning as a new matter.

A preferred form of user control is shown in Figure 2. This is a hand-held simplified keyboard 200, which is functionally connected to a local controller 43' by either a multiple wire cable 201, or an equivalent light beam or connection not using wires.

The local controller 43' is interconnected with a video cassette recorder-reproducer 41 and also to a video display 44, which latter may be a known type of television receiver. These elements are shown in greater detail in Figure 3.

For purposes of disclosing general structure and mode of operation of keyboard 200 and the apparatus with which it functions, a magnetic video tape already recorded with alpha-numeric data, compressed audio, "burst" (still) pictures, and/or segments of usual television (having moving pictures) is postulated as in the playing (reproducing) mode in video cassette recorder reproducer (VCR) 41. An indexting code, such as the SMPTE vertical interval time code (VITC) has also been included, thus allowing any frame upon the tape to be found.

The video tape is contained within a cassette 41 a, and becomes a source of information for the apparatus of the Figure 3.

The tape in the VCR is rewound to the beginning and the VCR is put into "reproduce" operation. TV display 44 is blank unless visual information is reproduced.

Should alpha-numeric frames be desired to be reproduced, this is arranged by pressing button 232. if the display is a picture, pressing button 232 will change the display to text, and vice versa.

One form of alpha-numeric display is a text of 1 6 lines of 32 characters each. This text can be superimposed upon a still picture or blank raster by means of circuits typified by integrated video display generator S68047, made by American Microsystems, Inc.

A whole page of alpha-numeric text, to reproduce a page in a book, is accomplished by several successive displays of 1 6 by 32 characters each.

The magnetic tape in the VCR 41 has been recorded with initial data frames stating what is contained on that tape. The VCR is controlled by microprocessor 47 via machine l/O 51 ' according to a bootstrap program stored in a ROM 49. This initial program causes the VCR to play the information on these data frames into a RAM memory 50, as well as one compressed audio frame, if present.

Then the VCR stops and the descriptive alpha numeric text will be displayed on the TV display 44.

Keyboard 200 may be considered as a detached extension of control and status panel 52 in the local controller 43'. The keyboard is comprised of keyswitch contacts only, arranged in rows and columns for scanning. Key actuations by the operator are communicated to the controller via a cable 201 or an equivalent, such as an infrared link, to control panel 52 circuits, and from there to a panel l/O 53 to the microprocessor bus 48, and the microprocessor 47.

The panel i/O 53 is comprises of medium scale integration (MSI) digital circuits, organized in the conventional microprocessor manner, for address decoding, device selection, tri-state gating to insert selected data on the bus 48, and flip-flops to store selected data from the bus. These elements may be the Texas Instruments, Inc.

74LS240, 74LS30, 74LS1 38, 8 74LS259.

The tri-state gates have three states; a normal binary "hi", a binary "lo", and a completely opencircuited state. This allows a large number of these gates to be connected to the bus.

When a gate is in the open-circuit state it does not load the bus and so does not interfere with any other action upon the bus. When a gate is in the active state it does impress on the bus either a "hi" or a "lo" condition. The circuit structure is similar to the old telephone party line. Each tristate gate has an enable function pin connection.

An address decoder decodes the particular address for that tri-state gate. Whenever that address occurs only that tri-state gate is put in the active state and then communicates to the bus the condition that is associated with that gate input.

Additionally, in Figure 3, there are audio decompression circuits 203. The audio information is compressed in originating apparatus by digitizing at an audio rate, storing in a memory, and reading out at a video rate. The read-out is converted from digital to analog for transmission over the television channel. The high speed analog is converted to digital, stored in a memory, and read out at the same audio rate that was oriyinally utilized.

The apparatus is according to Figure 4 of the "compressed audio" system of our copending Application No. 82.10817. The flow chart for the whole receiving apparatus is Figure 5 thereof, and the flow chart for the microprocessor for decompression is Figure 8B. All of these are pertinent to the present Figure 3, as to the apparatus and with the flow charts as to how the apparatus functions.

The audio decompression circuits 203 are controlled by the microprocessor 47, via the bus 48. The video frequency information that is the compressed audio and which is to be decompressed enters the circuits 203 via a conductor 204 from the VCR 41 The desired audio frequency signals leave the circuits 203 via a conductor 205, which is connected to loudspeakers in TV display 44 of Figure 2, or is reproduced for the user to hear in any equivalent apparatus.

If decompressed audio service is not to be provided the audio decompression circuits 203 can be omitted. Another approach is to provide apparatus for all three services, and merely not energize one service if it is not desired at any particular time.

Proper control of the apparatus of Figure 3, is shown in Figures 4 and 5, herein which are flow charts. Overall control for handling plural kinds of television information requires certain modifications in the stand-alone apparatus and its functioning.

Referring to the flow chart shown in Figure 4, it will be noted that it is little modified from that required for the same equipment as shown in Figure 6 of the "burst" Application No.82.01831.

One modification is that the code match query 91 in both Patent Applications is now an offset match by a small number of frames, say sixteen, prior to the actual frame of interest. This accomplishes a slow-down of an otherwise rapidly moving video tape. An exact match is then made.

The second modification consists in substituting all of Figure 5, for the action item "playback selected video" 93 in Figure 4.

Figure 5 encompasses handling plural kinds of information rather than only one kind as previously proposed.

In Figure 5, the input to "playback video forward at normal speed" 210 is derived from the "yes" output of "does code match?" 91 of Figure 4. After step 210 comes function 211, "read vertical interval code, frame by frame". This is to come to the exact match with the frame selected by the user.

Decision point 212 asks, "frame = selection?".

If the answer is "no", then the activity returns to the input of step 211 and the apparatus advances another frame. If the answer is "yes", then the activity goes on to another decision point 213, is this a "data frame?". If the answer is "yes", then the activity is to "store data in RAM memory" at step 214. This is RAM 50 in Figure 3. If the answer is "no" then the activity goes on to another decision point 215, is this an "audio frame?". There is an output from step 214 to the junction between decision points 21 3 and 215, to continue the operational flow when the step 214 is involved.

If the decision at point 215 is "yes", then the activity goes to step 216, "digitize and store compressed audio". This is accomplished by "analog to digital converter" 41 and "memory" 44 of Figure 4 of the "compressed audio" Application No. 82.10817. As above, there is an output from step 21 6 to the "no" output from decision point 215, to continue the operation.

If the decision at point 21 5 is "no", then the activity goes on to the third possibility of kind of data; i.e. the reproduction of a "still frame on picture", step 217. This is the functioning of video cassette recorder reproducer 41 of Figure 3.

The next activity is "playback decompressed audio", step 218. This can advantageously occur while the still frame of picture is being exhibited, at step 21 7. After one playback, decision point 219 is encountered, with the question, "repeat audio?". If the answer is "yes", then step 218 is reactivated and the audio is repeated.

If the answer is "no", then the activity goes on to "display text pages" 220. This is a third kind of information, and originates at video character generator 56, of Fig. 3, which is supplied with digital data from RAM 50. These data were loaded into the RAM 50 at step 214 in this flow chart, as described above.

An output from step 220 passes on to decision point 221, "repeat text?". If the answer is "yes", then step 220 is reactivated.

If the answer is "no", the activity on flow chart Fig. 5, is completed, and the activity returns to Fig.

4, at the input to decision point 94, "is playback complete?". Normally the playback would be complete, and so the activity goes back to the "start" of Fig.4.

The several decisions that are made in these flow charts, other than the ones that are concerned with matching a selected frame, are made by the user, utilising control panel 52, or the equivalent panel 200.

The video code reader 54, functions to extract digital information carried by the video signal at 55, which is derived from the VCR 41. This is described in detail in the 'TV digital data frame" Application No. 82.16217.

Each television field contains two lines of vertical interval time code. These provide a unique identifying address for each television frame, and also a numerical sequence of addresses for search control to move the video tape in the correct direction and to stop it when the desired address is reached.

In addition to the time code the user-bit portions of the SMPTE code are used to identify each frame as either a data frame, a compressed audio frame, or a picture frame. The detailed block diagram for the reader 54 is given in Fig. 4 of 'TV digital data frame" Application No. 82.16217 and the flow chart for the operation thereof is given in Fig. 6 of that specification.

Fig. 6 shows the schematic diagram of the apparatus of the "machine l/O" 51 ' of Fig. 3, which is now considered in greater detail.

In Fig. 6 the connections at the left are made to the bus 48 of Fig. 3, which bus has 28 conductors.

The connections at the right are made to the VCR 41 of Fig.3.

Fig. 6 shows the hardware utilised to carry out instructions between the microprocessor 47, which is connected to the bus 48, and the VCR 41. This apparatus implements the flow charts of Figs. 4 and 5.

The bus 48 has three kinds of conductors; address, data and control. These relate to the microprocessor 47 and the elements of Fig. 6 in a manner indicated in the following instructions.

IN (port) The port address (0 to 255) is placed on the high order address lines A9 to A15 of Fig. 6. A READ pulse is generated and the lO/bf line is held "high" (true = 10 mode). External logic places data on the data bus, which in turn is loaded into the microprocessor internal accumulator register.

OUT (port) The data in the accumulator are placed on the data bus and the port address on the eight high-order bits of the address bus while a WRITE clock output occurs with the IO/M output "high" (true).

The microprocessor 47 may be an Intel 8085.

The input READ pulse is inverted by inverting amplifier 280 and logically combined with I0/M true ("high") in NAND gate 281, to produce an IN pulse, which occurs when an "in" instruction occurs and only then.

Similarly, the input WRITE pulse passes through inverting amplifier 282 and is logically combined with IO/ true in NAND gate 283, to produce an OUT pulse, which occurs when an "out" instruction occurs and only then.

Concurrent with these instructions and the respective pulses, the specific port address appears on the address outputs A8 to Al 5, as given in the program involved. If the program instruction calls for input from port 254, address 254 appears on A8 to A15. That is, A8 is "low" and A9 to Al 5 are "high". (Al 5 is interpreted as a value of "128", A14 as "64", A13 as "32", etc.) The combined "high" states of A9 to Al 5 cause the output NAND gate 284 to go "low".

This gate may be a 74LS30. This "low" and the "low" input from A8 and the IN pulse combine in NAND gate 285 (a 74LS27) to produce a "high" pulse, "input clock port 254". This pulse is inverted by amplifier 286, and is applied to enable tri-state octal line receiver 287 (a 74LS244) to place VCR status signals on the data bus.

Whenever the instruction "IN (254)" occurs in the program, the VCR status signals will be loaded into the microprocessor accumulator. The "power on" status will reside in bit 0, the "humidity switch" status in bit 1 , the "end of tape switch" status in bit 2, the "cassette in place switch" status in bit 3, the "record mode' status in bit 4, the "pause mode" status in bit 5, the "play mode" status in bit 6, and the "stop mode" status in bit 7.

These status bits can be examined individually by further program steps. The indicated amplifier elements within tri-state receiver 287 each include a Schmidt trigger.

Similarly, whenever "OUT (254)" occurs in the microprocessor program "output clock port 254" occurs, and the contents of the microprocessor accumulator is placed on the data bus. The "output clock" is inverted by inverting amplifier 289, and the negative-going pulse is applied to octal D flip4lop 290, which may be a 74LS273.

The positive-going trailing edge of this pulse causes the data bus signals to be clocked into the flip-flops.

If the accumulator contained a 1 , the VCR "stop" command results; if a 2, the "play" command; if a 4, the "forward search" command; if an 8, the "reverse search" command; if a 16, the "pause" command; if a 32, the "frame advance" command; if a 64, the "rewind" command; if a 128, the "record" command.

If the program specifies port 255, NAND gate 291, inverting amplifier 292, and octal D flip-flop 293 are actuated. If the accumulator contains a data 1, the "forward wind" command is given; if a 2, the "variable play" command; if a 4, the "1/3 play speed" command; if an 8, the "1/10 play speed" command.

In this implementation 1 6, 32, 64 and 128 accumulator values have no assigned function at port 255. The port 255 output clock is selected when A8 is "high", causing the output of inverter 292 to be "low" and enabling the output of flipflop 293 when all A9 to Al 5 are also "high" and the OUT pulse occurs as a result of an "out" instruction in the program.

The control program then uses "out" instructions with appropriate initial values in the accumulator and appropriate port number to cause the VCR to change modes as required.

The program also examines the VCR status by invoking the "IN (254)" command and subsequently testing the status of the respective bits in the accumulator. Program branching occurs depending on the status detected. if the power to the VCR is not "on", no attempt is made to proceed with VCR alogorithms. Instead, an error indication is given to the operator.

When the power situation is corrected, normal operation may continue.

Examples of how a user manipulates the apparatus of this invention to obtain desired information follow.

At the start of the manipulation, the VCR 41 plays through data frames located at the beginning end of the tape, loading information into the memory 50.

Thereafter, descriptive alpha-numeric text describing the information to be found on that tape is displayed on the TV display 44. This may, or may not, be superimposed on a stop-motion picture relating to the contents of the cassette. In some cases the still picture may be the only display.

The highest level index is first displayed by the user pressing "Index" button 230. Typically, following the title and a brief description would be three lines: ? -Alphabetical index Categorical index Sequential index The first line in the above example is preceded by a cursor (?-), indicating this to be the question at hand.

Pressing the "No" button 225 on keyboard 200 in Fig. 2 causes the microprocessor 47 program control to advance to the next possible selection, and the cursor to move down one line; i.e., to "Categorical index". Holding the "No" button down causes the cursor to continually step after a short delay. When the cursor reaches the last question on the page it automatically jumps to the first question on the page.

This is accomplished by program instructions measure the duration of the "No" button closure, and which initiates an automatic advance when the duration exceeds a threshold of one half second, for example. The control program moves the cursor display in a repeating cycle until the "No" button is released and a "Yes" answer is received at some point.

If "Yes" button 226 is pressed while the cursor is on the first line, VCR 41 is moved to exhibit the first page of the alphabetical arrangement of all of the titles in the cassette on video display 44. This is accomplished by a branch instruction in the control program that was reached as a result of a "Yes" answer. The branch causes the control program to replace the previous display with a new display that is another part of the data stored in the memory 50.

A portion of memory 50 is allocated to provide a stack memory, in which the control program stores the previous page number each time it jumps to a new page. Pushing "Previous page" button 227 moves the stack pointer back one location, recalling the number of the old page and automatically causing the previous page to be displayed on display 44.

Following a step backward, the next step forward overwrites the next number.

If the alphabetic index page on display does not contain a subject of interest, "Next page" button 228 is pushed by the user. This gives sequential stepping to the next "page" of, say 1 6 entries in an alphabetic sequence of titles. This button can also be held down to scan pages, in the same manner as previously described for lines.

When a page containing a subject of interest is reached the "No" button is used as required to move the cursor to the desired line having the subject of interest title, and then the "Yes" button is used to branch to that subject.

All lines except the one selected are blanked from display 44 during the search period by VCR 41 by the mechanism of time code search. The initial data frames on the tape contain not only an alphabetical index of subjects recorded on the tape, but also a time code cross-reference address at which the subject may be found. Although these time codes are not displayed with the subject index they are available to the control program to direct it to search the tape to locate the selected subject.

When the selected page is located any associated digital data frame is read and stored in RAM memory 50. Then any associated compressed audio frame is read and stored in the RAM memory 15 in Fig. 2 of the "compressed audio" Application No. 82.10817. The VCR is then still-framed on the selected picture frame, and the 10 second audio message (if any) begins to play shortly after the picture appears.

When the message is completed it can be repeated by pushing "Audio" button 231, as many times as desired. The message can be aborted and stopped by pushing the "No" button. This causes the control program to branch to a waiting condition, which is the same as that reached when the audio is complete.

Text associated with the picture may be summoned by pressing "T/P"button 232. The picture disappears and the text appears on a blank raster. If more than one screen of text is associated with the picture, the bottom line on the screen will read ".7NEXT SCREEN".

When the user has read all of the text on one screen he presses the "Yes" button to view the next screen of text. This process is repeated until all of the associated screens have been displayed, at which time the next screen is the first screen. If button 232 is pressed again the picture will appear.

When the information on a page has been comprehended by the user and he is ready for the next page, "Next page" button 228 is pressed. The VCR 41 then moves to the next picture frame and also plays back any digital data frame and compressed audio frame that are associated with that picture frame. During the movement of the tape the alpha-numeric text name of the next picture to be displayed can be shown in TV display 44. This is accomplished by means of the control program, which has a cross-index of time code addresses and subject names. The next page has a known time code address, which is used to recover from RAM memory 50 the alpha-numeric text giving the subject title of the next picture.

The user continues to press the "Next page" button for as long as the pictures are of interest.

Thereafter, several choices are possible.

One is "Link" button 229. This causes VCR 41 to move the tape to another segment that has a previously identified relation with the subject matter just viewed. This is arranged by another cross-index of linked time code addresses originally read from the start of the tape and stored in RAM memory 50. The present time code is used by the control program to recover a linked time code from memory (if any) and automatically initiate a time code search on tape to that linked time code address.

Another choice is the "Index" button 230. This causes the apparatus to go back to the highest level index and work down again.

Another choice is to actuate "Previous page" button 227 and also "Link" button 229. This will move the tape back to the beginning of the segment.

Another choice is to actuate the "Link" button 229 during the first of an associated group of pictures. This causes the present group to be bypassed and the next link group to be displayed.

Another choice is to actuate "Next page" button 228 and start viewing the group of pictures (segment) on the next subject.

When the picture segment is motional, the user bits of the time code address identify it as such to the control program and it is played at normal VCR television speed. If the segment is long, a few minutes or more, then the usual audio track recorded on the tape car, be used. Often, however, compressed audio is to be used because a short distance of tape motion according to this invention will not give a useful interval of audio on the usual audio track.

The make-up of the VCR tape preferably includes digital data in the SMPTE vertical interval code format with 64 useful bits per television line.

In addition to the 64 data bits, each line has a cyclic redundancy check (CRC) code, with which the integrity of the date can be verified.

Each television frame has a unique code, specifying its sequentiai address in hours, minutes, seconds and frames. The code is nondrop-frame. The code for each frame specifies its absolute address (the user bit code), in a library &num; using 6 bits, a voluke FS 6 bits, and a book 6 bits; giving 67 million numbers. it is further identified as to type of information.

The least significant 3 type I.D. bits are interpreted for differing purposes within each type of frame; as to usual sequential television exhibition, still-frame pictures, compressed audio messages, and the digital data frame.

These digital codes are associated with each television frame and are recorded redundantly in the vertical interval on lines 13 and 15 in a preferred embodiment.

The frames that carry text are composed of 460 iimes of digital data in the same basic SMPTE lineformat. This includes the horizontal synchronising pulse, 64 useable bits, and CRC, on each line. The lines are dual redundant, having 230 lines on one field and the same subject matter on the 230 lines of the companion field. The frames may be repeated twice. Each two frames thus nets 64 x 230 = 14,720 bits in quad redundancy, with CRC.

During the reading of these data text frames the CRC check is used to accept packets of 64 "good" bits. Each of these packets is assigned an 8-bit line number by counting within microprocessor 2 of Fig. 3 of the "teivision digital data frame", Application No.82.16217.

The line number is placed in video RAM memory 20 of Fig. 3 of that specification and is so positioned within that RAM along with the text that when the contents of the RAM are placed serially on horizontal lines in a television frame, the first 8 bits on each line make up the line number. Since the lines are numbered within the digital data recorded on them, each line can be identified when played back.

When a line CRC is in error the data from that line are conditionally accepted, and when not in error are unconditionally accepted. On reading the second 256 lines those not tagged as accepted are reread and checked as before. On the second redundant frame the process is repeated, if necessary, until all lines have been unconditionally accepted. All CRC errors are counted for each pair of frames and a status message is displayed on the display 44, following the playing of the initial data frames on the cassette. The message is held on the screen for 5 seconds and then operation proceeds.The status message gives an indication of the number of CRC errors relative to several thresholds; i.e., for 0 to 5 CRC errors the status message may be "Low error rate"; for 6 to 20 CRC errors, "Moderate error rate, check tape and head"; and for 21 or more CRC errors, "High error rate, check tape and head".

The data frames serve for alpha-numeric text and for other purposes, such as initialising the operating program and providing cross-index tables. The ROM program contains only enough instructions to read the initial few data frames and place them in the RAM memory 50 at addresses which will be interpreted as instructions constituting the main program. At the completion of reading and storing these first frames the control program jumps to the starting address of the main program which has just been loaded.

This provides great functional flexibility, since new main control programs can be provided as data frames at the beginning of each tape.

Some frames are useful to cross-index a specific list of classifications and sub classifications with code numbers. For example, 10 bit classifications (1024) and 6 bit sub classifications (64), or vice versa, with text identifying each. The codified classifications can then be used with still picture data, to provide greater efficiency than repeated text. A 1 6 bit "token" can be used to extract and print out on display 44 complete classification and sub classification text data, which may take 1 60 bits if stored in literal alpha-numeric form. By storing the literal information in one cross-reference table with the tokens, and then storing only tokens in the many text frames substantial savings in memory and recorded data bits can be achieved.

Other frequently used words can be codified with additional tokens for efficient utilisation of memory; i.e., for "the" = 87 HEXIDECIMAL rather than D4, C8, C5 HEX. saves two bytes every time "the" is used.

Another class of digital data frames would then be included to cross-identify time code frame numbers with a 32 byte text name; 32 bits for codified classification and sub-ciassifications, and 32 bits for a link time code address to a related picture item.

Compressed audio frames have a time code frame number one frame less than the still picture frame they support and hence have no specific title other than that associated with the picture.

Similarly, text frames supporting pictures have a frame number two frames less than the number of the picture frame.

An alternative mode of operating the system enhances its flexibility. The ROM memory 49 (Fig.

3) is provided with only a minimum operating program. This is supplemented by further operating program information provided in digital frame format either over a television channel, or prerecorded on the cassette tape at the header preceding the specific frames of the cassette involved. An operating program can thus be provided that is most appropriate for the subject matter involved.

In this mode the minimum operating program in the ROM has sufficient instructions to read and store the digital information in the television frame format. It may also have minimal function capabilities to locate and display subject matter information. In addition, it has program steps that recognise the specific category of data frames as program frames, and subsequently not only loads these instructions into RAM memory 50, but links the flow of control to these newly loaded instructions after they have been successfully loaded.

Since these instructions are essential to the correct operation of the controller 43', the data frames may be recorded in quad redundancy, or more often as might be practical, to insure accuracy.

This altnerate mode of operation does not suffer from reduction of over-all capacity of the system, since the set of program data frames occupies only a fraction of a second at the start of the cassette tape.

Herein, the term "cassette" is to be interpreted broadly. It is merely a present-day example of means to store video information. Video disks are an alternate. Also, what is normally recorded on the cassette may be transmitted directly over any kind of television channel without the recording step.

Claims (12)

1. The method of supplying plural kinds of information over a television channel, which includes at least two of the forming method steps of: (a) forming and storing digital alphanumeric information in video format; (b) forming and storing compressed audio information in video format; (c) forming still pictorial information in a frame of video format; (d) selectively displaying said frame of pictorial information in video format; (e) selectively simultaneously uncompressing and reproducing said compressed audio information; and (f) substitutionally displaying said alphanumeric information instead of said frame of pictorial information of video format.

2. The method according to claim 1 , which includes the additional method step of; (g) selectively manually controlling what kind of information will be presented to the user as to: (1) presenting the next video frame, (2) presenting the previous video frame, (3) presenting an index, (4) accepting an index entry to thereby be presented with further information thereon, (5) rejecting an index entry to thereby be presented with the next index entry, and (6) request further information related to the information presented.

3. The method according to claim 1 or claim 2, which includes for accomplishing viewing selection, the additional method step of: (h) reproducing video format information; (i) reading the vertical interval code on each frame of the video information; (j) comparing that code with the code of the selected frame; (k) storing the data in a RAM memory when the selected frame is a data frame; (I) digitizing and storing the audio frame in the compressed audio format when the selected frame is an audio frame; (m) playing the picture frame back for visual presentation when the selected frame is a picture frame; and (n) selectively playing back decompressed audio related to the visual presentation.

4. The method according to any one of the preceding claims, in which the kind of information to be reproduced includes the additional method steps of; (o) inserting code bits at the beginning of the formation of a kind of information identifying that kind of information; and (p) energising appropriate apparatus upon the reproduction of said information to present that information to a user.

5. The method according to any one of the preceding claims, which includes the additional method steps of; (q) providing microprocessor instructions for handling information at the beginning of a cassette tape that pertain to the kinds of information in that cassette, and (r! entering said microprocessor instructions in the RAM memory that is coactive with the microprocessor for the operational control of the reproduction of the information that is in the cassette.

6. Apparatus for supplying plural kinds of information over a video channel, which includes at least two sources of different kinds of information, including: (a) a source of alpha-numeric information in video format; (b) means to store said alpha-numeric information; (c) a source of compressed audio information in video format; (d) means to store said compressed audio information; (e) a source of at least one video frame of pictorial information; (f) means to selectively display said pictorial and said alpha-numeric information; (g) means to decompress said compressed audio information; (h) means to reproduce said decompressed audio information; and (i) control means associated with the aboverecited elements to selectively cause display of said pictorial information, so as to selectively cause reproduction of said decompressed audio information, and to selectively cause display of said alpha-numeric information.

7. Apparatus according to claim 6, in which said control means comprises; (j) a microprocessor having memory means; and (k) a video code reader to identify each frame, and to actuate at least one of the following elements according to the identity of the frame; (1) an alpha-numeric character generator, (2) decompression audio apparatus, and (3) video image reproducer.

8. Apparatus according to claim 6 or claim 7, which additionally includes; (I) a cassette having code bits in the user bit sequence of the vertical interval time code, coded to identify the kinds of information the cassette contains; and (m) means to selectively energise means to display visual information and audio information as activated by said code bits.

9. Apparatus according to any one of the preceding claims 6 to 8, wherein: (n) said source and said means to store alphanumeric information are both digital; and (o) said source produces alpha-numeric information substantially continuously throughout each said frame.

10. Apparatus according to any one of the preceding claims 6 to 9, additionally including: (p) means to reproduce data and television synchronising pulses in each of the said, alpha-numeric information, said compressed audio information, and said video frame.

11. The method of supplying plural kinds of information over a television channel substantially as herein described with reference to the accompanying drawings.

12. Apparatus for supplying plural kinds of information over a video channel, constructed and arranged to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.