EP0205433A1

EP0205433A1 - Method for controlling a video-tape apparatus for the automatic spotting of recorded video-tape segments and video-tape apparatus for implementing such method

Info

Publication number: EP0205433A1
Application number: EP19850900978
Authority: EP
Inventors: Christian Ebeling
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-02-18
Filing date: 1985-02-16
Publication date: 1986-12-30
Also published as: DE3405910C1; WO1985003797A1

Abstract

Procédé de commande d'un appareil à bande vidéo pour la recherche automatique de segments de bande vidéo enrégistrés (13, 17), en particulier en cas de déroulement rapide de la bande, où une valeur de recherche introduisible et caractérisant le début du segment de bande vidéo (13, 17) est comparée avec la position d'un compteur (58) qui compte positivement ou négativement en fonction de la direction de déroulement de la bande. Afin d'améliorer la précision de la recherche des débuts des segments de bande vidéo (13, 17), on utilise les impulsions CTL servant à la synchronisation des têtes vidéo pour commander le compteur (58). Au début des segments de bande vidéo est inscrite sur la bande une modification des impulsions CTL, par exemple sous la forme d'un vide d'impulsions CTL (25), qui est lue et évaluée par la tête CTL (48) et qui sert à commander le déroulement de recherche de la bande.Method for controlling a video tape device for the automatic search for recorded video tape segments (13, 17), in particular in the case of rapid tape unwinding, where an enterable search value characterizing the start of the tape segment video tape (13, 17) is compared with the position of a counter (58) which counts positively or negatively depending on the direction of unwinding of the tape. In order to improve the accuracy of the search for the beginnings of the video tape segments (13, 17), the CTL pulses used for synchronizing the video heads are used to control the counter (58). At the beginning of the video tape segments, a modification of the CTL pulses is written on the tape, for example in the form of a vacuum of CTL pulses (25), which is read and evaluated by the CTL head (48) and which serves to control the band search sequence.

Description

Method for controlling a video tape device for the automatic detection of pre-recorded ones. Video tape sections and video tape device for performing the method

The invention relates to a method for controlling a video tape device according to the preamble of patent claim 1 and a video tape device for performing the method, as is known from DE-OS 28 1 721.

It is known to use a counter to find video tape sections of certain content. The counter - mechanical or electronic - is designed as a forward / reverse counter and is driven depending on the rotation of the tape winding axes or tape guide rollers interacting with them in accordance with the tape running direction. As a rule, a device for zeroing the counter is then also available. It is also already known to use input keyboards to specify a specific counter reading, upon reaching which the fast tape run is stopped by a comparison circuit. Such a procedure is cumbersome and also fraught with uncertainties, since the meter control does not take place directly from the belt, but rather from drive elements that interact only indirectly with it. Band slip and

Band elongation has an adverse effect on the count. 1 It is also known to imprint coded information on audio tracks of a magnetic tape, which characterizes the beginning of a tape section to be sought. Because of the not inconsiderable noise and the relatively small bandwidth of the sound track and the scanning elements interacting with it, this type of finding of a specific section of tape is also unsafe and fails at high forward and / or reverse speeds of the tape, in particular because _Q because of the Frequency response of the sound signal processing is limited. Further falsifications are caused by "drop-out's" and interference pulses. Also be provided in addition to the analog Tonsignalverarbeitungselementen di¬ gitale processing elements _ξ to processing methods. are able to process the coded digital information contained in the audio signal.

According to DE-OS 28 14721, a control device for magnetic recording and / or reproducing devices 0 is known, in which pulse sequences which can be tapped are stored in the magnetic recording medium. A counter, which registers the pulse sequences readable from the magnetic medium, provides a count value assigned to a specific position on the magnetic medium. 5 A value corresponding to a specific position on the recording medium is read into a programmable memory. A comparator compares the count value indicated by the counter against the value recorded in the memory. A specific position _Q on the magnetic recording medium is approached by a search device which selectively switches on a rapid drive of the magnetic tape device until there is a specific relationship between the two position values compared by the comparator and which then opens the magnetic tape device sets a different operating speed. In particular, the magnetic recording device is a cassette video tape recording device. For necessary control pulse sequences, the so-called CTL pulses are used, which actually deobandgerätes are used to synchronize ^'the heads of Vi¬. According to the known control device, the CTL pulses are counted during the tape pass and thus a specific value is assigned to each tape position. If a specific belt position is to be selected, the corresponding pulse count must be entered in a memory. If the current count of the counter reaches this value, the control device switches to normal belt travel. Since errors can occur during pulse counting, particularly during fast tape forward and reverse search, the desired tape position is not exactly achieved. In addition, the counter values caused by scanning errors and deviating from the real instantaneous position cannot be corrected during the entire search procedure.

The invention is based on the object of initially specifying a method which, in a simple and reliable manner, permits the exact finding of recorded video tape sections, in particular in the case of fast tape advance and rewind. This object is achieved in that the information characterizing the beginning of the respective video tape section is imprinted on the tape as a change in the CTL pulses, which are evaluated by the CTL head and a processor which interacts with the CTL head to control the tape run (faster or slower, forward or reverse tape search). At the same time, this creates the possibility of setting quasi reference marks along the CTL pulse track of a video tape can be used in the search mode to correct the "current count for the compensation of counting errors. The method advantageously makes use of signals that are present on every video tape anyway ^* and whose purpose can be seen in the synchronization of the video head. Necessary However, the synchronous or CTL pulses are only in those areas of the tape in which video information is actually stored on the video tape and thus field synchronization of the video heads is necessary depending on the CTL pulses. Since the synchronization of the video heads is not necessary, a new task is assigned to the CTL track or the CTL head within this gap, namely to serve as a carrier or detector for the initial information of subsequent video tape areas.

Claims 2-6 describe advantageous types of changes in the CTL pulses which can be easily generated and decoded by simple electronic components. If, for example, the change in the CTL pulses is present as a pulse gap, this gap represents, as it were, digital switching information that can thus be evaluated without analog-digital conversion, e.g. can be used to advance an up-down counter or can be used as a stop pulse for fast tape travel.

In order to obtain current information about the current position of the tape, it may be advantageous to continuously count the CTL pulses impressed on the tape into a forward-backward counter which increases the counting reliability when pulse changes occur (e.g. from CTL pulse gaps) is corrected to an assigned target value via a memory. This corrects counting errors that can occur with very fast forward / reverse. This also compensates for counting errors caused by scattered interference pulses.

According to claim 8, CTL start pulses are used to supply a "reset pulse" to the first up / down counter at the beginning of the tape. Claim 9 makes it possible to assign several changes in the CTL pulses to a specific counter reading of the first up-down counter and thereby to correct the counter reading at a plurality of tape positions, which further improves error suppression.

Claim 10 not only uses the number of changes in the CTL pulses to correct the first up-down counter, but also the number of CTL pulses within the video tape sections, i.e. between the changes in the CTL pulses. As a result, a second measure is taken to correct counting errors. With this double security system, video tape sections are correctly determined and found with a high degree of security.

Claim 11 teaches a particularly advantageous way of transferring the changes in the CTL pulses from a mother tape to the video tape to be coded during a copying process.

In a device according to claim 12, the

Changes in CTL pulses pulse conduit in a simple manner either by interruption of the ^'signal processing unit with the CTL-head connecting I (producing a pulse gap) or by connecting a frequency ^* or modulation generator to the pulse line (generating a frequency or modulation change) of the CTL pulses. The (preferably electronic) switches can easily be opened and closed by a corresponding audio signal, so that the components required for carrying out the method can be easily retrofitted to conventional video recorders of all systems, provided that care is taken that in the latter the CTL head remains on the belt during fast forward and rewind. Claims 13-18 describe the device design which is advantageous for carrying out the above-mentioned method. In particular, it should also be noted that the device, in conjunction with the method according to the invention, can solve both the counting problems that arise from the fact that, in most commercially available video recorders, the tape often lifts something off the heads when the tape stops (so that a simple incremental or decremental counting often fails due to the swallowing of CTL pulses per se on the tape), as well as the counting errors resulting from tape slip or tape stretching are compensated and corrected.

The invention is explained using an exemplary embodiment in the drawing. Show it:

1 is a schematic representation of a video tape coded according to the method,

2 shows a first type of change in the CTL pulses,

3 shows a second type of change in the CTL pulses,

4 shows a third type of change in the CTL pulses,

5 shows a fourth type of change in the CTL pulses, FIG. 6 shows a fifth type of change in the CTL pulses, FIG. 7 shows a visual representation of the essential components of a video tape device for carrying out the method.

5 The video tape designated 1 in FIG. 1 has a video track 2, a sound track 3 and a CTL pulse track 4. The latter are impressed when the tape CTL-Tmpulse 5 is recorded on. At the beginning of the tape 6, a first tape section 7 is described with initial CTL pulses 8, which are followed in the tape scanning direction 9 in a second tape section 10 by a first pulse change 11 in the form of a pulse gap 12, which is used for the initial identification of a first video tape section 13 , whose signals are recorded in a third band section 14.

Another pulse gap 15 follows in a fourth tape section 16 and serves to identify a second video tape section 17 in a fifth tape section 18.

2-6, a band section is shown at 20, on which five different types of changes in the CTL pulses 5 are indicated in a schematic representation one above the other in the drawing. 21 shows a pulse change in the form of a CTL frequency change, 22 a change in the CTL pulses in the form of an amplitude reduction or change, 23 a modulation change in the CTL pulse envelope 24, 25 a CTL pulse θ gap (see pulse gaps 12 and 15) and 26 a frequency modulation change of the CTL pulses. - It is of course possible to mix amplitude modulation, frequency modulation or envelope modulation of the CTL pulses with one another, so that - depending on whether _j - frequency- or amplitude-selective evaluation - different information is included in the pulse changes can be registered. It is also possible to provide the pulse change in the form of a so-called pulse telegram, which is then evaluated, as in the case of a bar code reader. Of fundamental importance for the _. However, the invention is primarily the necessity that the tape-scanning video recorder recognizes the changes in the CTL pulses as such and - depending on the occurrence of a change in the CTL pulses - the corresponding tape control steps are initiated.

In the exemplary embodiment shown in FIG. 7, a demodulator is shown at 40, at whose input 41 there are, for example, the output signals of a further video recorder on which a mother tape is played for copying purposes. The demodulator 40 is followed by a signal processing unit 42, in which the audio and video signals are separated and, depending on the video signal, the CTL pulses required to control the video heads are generated. The signal processing unit 42 is connected via an audio head line 43 to a sound head 44, via a video head line 45 to the video heads 46 and a CTL pulse line 47 to a CTL head 48. In order to be able to impress the changes in the CTL pulses on the tape during recording, a first switch 49 is provided (for generating pulse gaps), which is switched into the CTL pulse line and can interrupt it if necessary to generate gaps ( or to "zero potential"). This switch is opened and closed as a function of a sound signal detection unit 50, which responds when a sound signal, for example a very specific frequency, is output from the mother tape. For this reason, the audio signal detection unit 50 is also connected to the audio header 43. If the changes in the CTL pulses are not to be pulse gaps, but rather, as described above, modulation or frequency changes, a modulation or frequency generator 51 is provided for this purpose, which is connected to the CTL pulse line via a second switch 52. device can be activated. The second switch is also opened and closed depending on the sound signal detection unit 50. The arrangement of the switches shown is a simplified arrangement, it is conceivable, for example, that the switch 49 must be opened and the switch 52 closed in order to connect the modulation or frequency generator, or - if the "normal" CTL pulses are superimposed with such a frequency generator 51 for generating a pulse change that both switches 49 and 52 must be closed. The switches 49 and 52 will also not be mechanical but electronic switches.

For reasons of clarity, the audio head 44, the video heads 46 and the CTL head 48 are again shown under the designations 44 ', 46' and 48 'for the following description of the processes when playing a coded tape and with the essentials for evaluation the elements provided for the changes in the CTL pulses.

To control the. Video heads 46 ', the output 53 of the CTL head 48' is connected to a device for controlling the video heads 46 ', which is referred to as head servo 54 for short.

In addition, the output 53 of the CTL head is provided with a CTL recognition device 55. And with the counting inputs 56 and 57 of a first and third forward.

Down counter 58.59 connected. Occur CTL pulses at the output 53 of the CTL head 48, the first and third up-down counters will count up or down, depending on a strip travel direction discriminator (not shown) for detecting the strip travel direction.

A first output 60 of the CTL detection device 55 emits a signal whenever a change in the CTL pulses occurs at the output 53 of the CTL head 48 '. The change of state of the output 60 is used via a line 61, to count a ^'second forward Rück¬ Windwärts counter 62 up or down (abhän¬ gig from Richtungsdiskriminato), to which the line 61 to a count input 63 of the second forward Back counter 62 is connected. In addition _^ is placed the CTL pulses over a zeroing input 64 of the third forward-Rück¬ Windwärts counter to zero upon the occurrence of a change, so that this only the Tenden occurring between the changes of the CTL pulses CTL pulses, so the belongs to the videotape sections.

To detect the initial CTL pulses, the output 53 of the CTL head 48 'is also connected to an initial pulse detection device 65, the output 66 of which is connected to further zeroing inputs 67, 68 of the first and second up-down counters 58 and 62 is connected so that the latter are set to zero at the beginning of the tape.

In order to be able to use the counting information stored in the second and third up-down counters 62 and 59 to correct the first up-down counter 58, the outputs 69, 70 are assigned to the second and third up-down counters Storage 71,72 downstream, in which either a transfer device 73, one or more setpoints will stored can ^"n or Sollwertabspeicherung 'is automatically stored via a pulse line 74, for example, at a first lang¬ seed passage of the coded tape depends on the number of the CTL pulses at the output 53 of the CTL head 48th For example, the second up / down counter 62 will activate the memory 71 when the first CTL pulse occurs, and store the associated setpoint (for example 150) via the set input 75 in the first up / down counter when the second pulse change occurs (Counter reading 2 in the second up-down counter) store the associated setpoint (for example 1520) in the first counter, etc. The third up-down counter 59 and the downstream memory 72 act accordingly, whereby however, not due to the changes in the CTL pulses but depending on the number of CTL pulses / video tape cuts a setpoint assigned to this is taken over the set input 75 in the first up-down counter. The changes in the CTL pulses and the length of the video tape sections thus serve in the same way as "reference marks" for correcting the counter reading of the first up-down counter, the counter reading of which is used to locate a video tape section. For this purpose, a search value can be entered via the input device 73 which corresponds to the beginning of a video tape section. This search value is compared in a comparator 76 with the present counter reading of the first up-down counter, and if differences in the values to be compared occur, a tape drive control for driving the video tape forwards or backwards is influenced. The audio head 44 'and the video head 46' are followed by a signal processing device 42 ', in which the audio and video signals are processed in such a way that they can be made visible on a monitor 78.

Claims

1. A method for controlling a video tape device for the automatic detection of recorded video tape sections, in particular in the case of fast tape running, whereby an inputable search value which characterizes the beginning of the video tape section is compared with the status of a counter which depends on the tape running direction upwards or below counts, and for its operation the synchronization of the video heads of the video tape recorder is used. The CTL pulses recorded on the video tape and scanned by a CTL head are used, characterized in that at the beginning of the video tape sections (7, 14, 18) a change in the CTL pulses (5) is impressed on the video tape (1), which is recognized and evaluated by the CTL head (48) and is used to control the tape search.

2. The method according to claim 1, characterized in that the change in the CTL pulses (5) is a change in the pulse frequency.

3. The method according to claim 1, characterized in that the change in the CTL pulses (5) is a change in the CTL pulse amplitude.

4. The method according to claim 1, characterized in that the change in the CTL pulses (5) is a Modula¬ tion change of the envelope of the CTL pulses.

5. The method according to claim 1, characterized in that the change in the CTL pulses (5) "is a CTL pulse gap.

6. The method according to claim 1, characterized in that the change in the CTL pulses (5) is a Modula¬ tion change in the CTL pulse frequency.

7. The method according to any one of the preceding claims, characterized in that the CTL pulses (5) are counted into a first up / down counter (58), the counter reading when a change in the CTL pulse occurs (5 ) is set to a setpoint stored in a memory (72).

8. The method according to any one of the preceding claims, characterized in that the video tape (1) at the beginning of the tape (6) CTL initial impulses (8) are impressed, which are recognized as such by the CTL head (48) and when they occur the up-down counter (58) is set to zero.

9. The method according to any one of the preceding claims, characterized in that the changes in the CTL pulses (5) by a second up-down counter (62) are recorded numerically and the counter reading of the first pre up-down counter (58) is set depending on the counter state of the second up-down counter (62).

10. The method according to any one of the preceding claims, characterized in that the CTL pulses (5) between the changes between the CTL pulses (5) recorded video tape sections in a third forward ^' backward counter ( 59) can be counted in, which is set to zero when each change in the CTL pulses (5) occurs, and the first up-down counter (58) is set as a function of its counter reading.

11. The method according to any one of the preceding claims, characterized in that for coding the video tape provided for the operation of the Videobandge¬ device (1) an audio signal impressed on a mother tape switches off the CTL head (48) of the video tape device (generation of a CTL pulse gap 25th ) or the CTL head (48) of the video tape device with a modulation generator or frequency generator (51) (generating a modulation or frequency change of the CTL pulses 5).

12. Video tape device for performing the method according to one or more of claims 1 to 11 with a signal processing unit (42), as well as this electronically connected, with the video tape (1) cooperating recording and playback heads (video heads 46, sound head 44, CTL head 48) and a first electronic forward / reverse counter (58) and an input device (73) for entering the counter reading to be searched, characterized in that

- The CTL head (48) acts on the video tape (1) when the tape runs fast, and

- The CTL pulse line (47) connecting the signal processing unit (42) with the CTL head (48) is provided with a switch (49) for generating a CTL pulse gap or for generating CTL pulse frequency or modulation changes a modulation or frequency generator (51) can be connected to the CTL pulse line (47).

13. Video tape recorder according to claim 12, characterized in that the counting input (56) of the first electronic up-down counter (58) for numerical detection of the CTL-Impul¬ se scanned from the video tape (5) with the output (53) of the CTL Head (48 ') is provided.

14. A video tape recorder according to claim 12 or 13, characterized in that a CTL pulse detection device (55) for detecting changes in the CTL pulses (5), the output of which is connected to the output (53) of the CTL head (48 ') (60) is connected to the counter input (63) of a second up-down counter (62) for numerical detection of the changes in the CTL pulses (5), the output (69) of which is connected to a first assignable memory (71). is connected, the output of which in turn is connected to a set input (75) of the first up-down counter.

15. Video tape device according to one of claims 12 to 14, c characterized in that the output (60) of the CTL detection device 1 (55) is connected to the zeroing input (64) of a third up-down counter (59), whose counting input (57) ^' for numerical detection of the CTL pulses occurring between the changes in the CTL pulses (5) 5 (5) is connected to the output (53) of the CTL head (48 ') and its output (70) is connected to a second assignable memory (72), the output of which is connected to the set input (75) of the first Up-back-0 counter (58) is connected.

16. Video tape recorder according to one of claims 12 to 15, characterized in that the mutual association of the count values present on the outputs 5 of the second and third forward-backward counters (62, 59) with those in the memories (71, 72) existing setpoints of the first up / down counter (58) are carried out by a microprocessor connected to the up / down counters and memories 0.

17. Video tape device according to one of claims 12 to 16, characterized in 5 that the first and second allocating memory (71, 72) are connected to a manual input device (73).

18. Coded video tape for use in a video tape device according to one of the preceding claims 12-17 or according to the method according to one of the preceding claims 1-11, characterized in that at the beginning of the tape (6) over a tape duration of approximately 1-60 seconds of initial CTL pulses (8) are embossed, which are followed in the tape scanning direction (9) immediately afterwards and between the recorded sections of the video tape (video tape sections 13) over a tape running time of approx. 1-20 seconds changed CTL pulses or a pulse gap (12).