JPH0676413A - Intermusic detecting method for video tape and video tape recorder - Google Patents

Abstract

PURPOSE:To enable the detection of intermusic with high accuracy to be conducted regardless of recording modes by couting the control signal in the non change part of an audio signal and judging to be intermusic when a count value becomes a prescribed value. CONSTITUTION:A control circuit 4 generates a CTL signal from the control signal reproduced by an audio control erase head 3. The audio signal reproduced by the head 3 is processed by a normal audio circuit 5, a blank is detected in a sound presence or absence discimination circuit 6 and a mute detection signal is generated. A microcomputer 8 judges to be intermusic when the mute detection signal is generated and a prescribed number of CTL signals is inputted, controls a capstan motor 7 by a motor control signal and searches a detection location. Therefore, intermusic can be detected with high accuracy regardless of the recording modes of a video tape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape interval detection method and a video tape recorder for detecting a music interval based on information recorded on a video tape.

[0002]

2. Description of the Related Art In recent years, karaoke devices using video tape recorders have begun to spread overseas. In such a karaoke device, in order for the user to select a desired song from a plurality of songs, it is necessary to have a function of detecting the interval between songs and finding the beginning of the song.

In order to detect such a tune, a control signal (CTL signal) conventionally provided for synchronization with a control track of a video tape.
There is an INDEX system (VISS etc.) video tape recorder that records a binary code by changing the duty ratio of the.

Further, as another method for detecting the music interval, as shown in FIG. 12, a voiceless portion is detected from the voice signal recorded in the voice recording portion of the magnetic tape, and the voiceless portion is kept for a predetermined time t.
When one is continued, there is also one that is detected as a music interval and generates a signal having a pulse width t2, for example.

[0005]

However, in the above-mentioned INDEX type video tape recorder, the duty ratio of the control signal is changed to record the binary code indicating the inter-track. Therefore, the control signal is reproduced and the binary code is reproduced. Since it is necessary to detect a chord and recognize that this binary code is a chord for a song, there is a problem that the configuration of the video tape recorder becomes complicated.

Further, a video tape recorder which detects a non-voice portion and detects the non-voice portion as a music interval when the non-voice portion continues for a predetermined time t1 can be realized by a simpler structure than an INDEX system video tape recorder. In the scheme,
Since the inter-track detection is performed by the time detection of the non-voice part,
For example, when a video tape is searched for the beginning of a song, there is a problem that the beginning of a song cannot be accurately found due to a change in the search speed due to mechanical fluctuation. Furthermore, it supports video tape recording modes (eg, standard recording mode (SP) in NTSC system, low-speed recording mode (LP, EP), standard recording mode (SP) in PAL system, low-speed recording mode (LP)). There is also the problem that it cannot be done. Furthermore, there is a problem that the inter-track detection position is different between the forward search and the backward search with respect to the reproduction direction.

The present invention has been made in view of the above circumstances, and a method for detecting a track interval of a video tape capable of accurately detecting a track interval with a simple configuration regardless of the recording mode of the video tape, and The purpose is to provide a video tape recorder.

[0008]

According to a first aspect of the present invention, there is provided a method of detecting a gap between tracks of a video tape, wherein chattering is performed as an audio signal monitoring process for monitoring an audio signal from the video tape and detecting a unchanged portion of the audio signal. Return processing S10 and inter-track-CTL counting processing S11 as a non-change period measurement process for counting CTL signals from a video tape in a no-change portion of an audio signal.
And, when the count value of the CTL signal counted in the no-change period measurement process becomes n, a blank detection output process S12 as a music interval detection process for determining a music interval.

A video tape recorder according to a second aspect of the present invention includes an audio signal recorded on a video tape and a C signal.
ACE head 3 as a magnetic head for reproducing TL signals
And a sound presence / absence determining circuit 6 for detecting a silence portion from the reproduced audio signal to generate a silence detection signal, and a music interval when n CTL signals are input while the silence detection signal is generated. Microcomputer 8 as an arithmetic circuit for determining
And is provided.

[0010]

According to the method of detecting a music interval between video tapes having the structure of claim 1, the chattering processing S10 monitors an audio signal from the video tape to detect a music interval-CTL.
The unchanged portion of the audio signal is detected by the count processing S11, the CTL signal in the unchanged portion of the audio signal is counted, and the count value of the CTL signal counted by the blank detection output processing S12 in the unchanged period measurement process is When the number becomes n, it is determined that it is the music interval, so that the music interval can be accurately detected regardless of the recording mode of the video tape.

In the video tape recorder having the structure of claim 2, the ACE head 3 reproduces the audio signal and the CTL signal recorded on the video tape, and the sound presence / absence determining circuit 6 detects a non-voice portion from the audio signal. A silence detection signal is generated, and if n CTL signals are input while the silence detection signal is being generated by the microcomputer 8, it is determined that there is a music interval. Therefore, the configuration is simple regardless of the video tape recording mode. It is possible to accurately detect the interval between songs.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 11 relate to an embodiment of the present invention. FIG. 1 is a block diagram showing a configuration of a main part of a video tape recorder, and FIG. 2 is a configuration of a normal audio circuit and a sound presence / absence determining circuit. Configuration diagram, FIG. 3 is a flow chart showing the flow of the main processing of the video tape recorder, FIG. 4 is a flow chart showing the flow of blank detection processing, FIG. 5 is a flow chart showing the flow of chattering processing, and FIG. FIG. 7 is a flowchart showing the flow of processing, FIG. 7 is a timing chart showing the timing of signals at the time of detecting a track interval, FIG. 8 is a flowchart showing the flow of blank detection output processing, FIG. 9 is a flowchart showing the flow of search control processing, and FIG. Is a timing chart showing the signal timing during the forward search, and FIG. 11 shows the signal timing during the backward search. It is a timing diagram.

As shown in FIG. 1, the video tape recorder 1 of the present embodiment records and reproduces audio signals and control signals recorded on audio tracks and control tracks formed in the longitudinal direction of the video tape 2 (ACE ( An audio control erase) head 3 and a control circuit 4 for processing a control signal reproduced by the ACE head 3 and generating a CTL signal based on the control signal are provided. Further, the audio signal reproduced by the ACE head 3 is processed by the normal audio circuit 5, and from the output of the normal audio circuit 5, the sound presence / absence determining circuit 6 detects a blank which is a non-voice part, and a silence detection signal. Is designed to generate.

Microcomputer (hereinafter, microcomputer)
When the silence detection signal is generated and n CTL signals are input, 8 is determined to be a music interval, the capstan motor 7 is controlled by the motor control signal, and the detection position is searched. ing. Other configurations are
Since it is the same as a well-known video tape recorder, its explanation is omitted. The microcomputer 8 is controlled by an instruction means (not shown), for example, a control signal for searching, and displays the processing state on a display means (not shown).

As shown in FIG. 2, the normal audio circuit 5 includes an amplifier (AM) for amplifying an audio signal from the audio head unit 20 in the ACE head 3.
P) 21 and an equalizer (EQ) 22 that adjusts the frequency characteristic of the audio signal amplified by the amplifier 21 to generate a reproduced audio signal.

Further, the sound presence / absence determining circuit 6 receives the reproduced audio signal from the normal audio circuit 5 from an amplifier 23 and a band pass filter (FILTE).
R) 24, a comparator 25 for comparing with a predetermined reference voltage, a PNP transistor 26 driven by the output of the comparator 25, and a PNP transistor 26.
And the waveform shaping circuit 27 for shaping the output of the waveform output to the microcomputer 8 and detecting the case where the reproduced audio signal is below a predetermined level.

Incidentally, instead of the bandpass filter 24,
A bandpass filter and a half-wave (full-wave) rectifier circuit may be used. Further, the reproduced audio signal is transmitted to a reproduced audio signal processing circuit (not shown) and reproduced as an audio signal.

The operation of the video tape recorder 1 thus constructed will be described. The microcomputer 8 is a built-in counter that performs the counting process of the CTL signal and performs job as shown in FIG. That is, in step (hereinafter referred to as S) 1, a blank which is a silent portion is detected from the silence detection signal and the CTL signal (blank detection processing), and search control is performed based on the blank detection in S2. The processing time for 1 Loop of this main processing is, for example, 2 ms.

As shown in FIG. 4, the blank detection process in S1 is composed of a plurality of subroutines, and in S10, the chattering of the audio signal is monitored to detect a state (inter-track state) in which the audio signal is not chattering. The chattering process is performed as an audio signal monitoring process, and the song-to-CTL count process is performed as a no-change period measurement process of counting the CTL signal in the song interval state detected by the chattering process in S11. When the count value in the interval-CTL count process becomes n, a blank detection output process is performed as a song interval detection process for determining a blank.

The details of the chattering returning process in S10 are shown in FIG. First, in S21,
By inputting the silence detection signal from the sound presence / absence determining circuit 6 into the port, the value of the previous job stored in the buffer (not shown) in the microcomputer 8 (the output of the previous sound presence / absence determining circuit 6) and the port input It is measured whether the value (the output of the present sound presence / absence determining circuit 6) has changed.

That is, the signal reproduced from the audio track of the video tape 2 by the audio head unit 20 of the ACE head 3 is amplified by the amplifier 21 of the normal audio circuit 5, equalized by the equalizer 22, and then the sound presence / absence determination circuit 6 is provided. Entered in. Sound presence / absence determination circuit 6
In, the input audio signal is amplified by the amplifier 23, and a predetermined frequency band component is separated from the input audio signal by the bandpass filter 24. The comparator 25 compares the level of this component with a reference level, and when the level is higher than the reference level, outputs a logical L, for example, to output PN.
The P-transistor 26 is turned on, and when it is small, a logic H is output to turn off the PNP transistor 26. The output signal of the PNP transistor 26 is further waveform-shaped by the waveform shaping circuit 27 and supplied to the microcomputer 8. That is, the waveform shaping circuit 27 outputs a logic L when there is an audio signal, and outputs a silence detection signal of a logic H when there is no audio signal (between songs).

The microcomputer 8 checks the change in the state of the detection signal input from the sound presence / absence determining circuit 6 in S21. This change in state is, for example, an exclusive OR (exc
It can be easily checked by performing the operation of "plus OR".

Next, it is determined in S22 whether or not there is a change. If it does not change, the process proceeds to S23, and if it changes,
Proceed to S24. In S23, the value of the buffer is copied to the chattering output and the process ends. In S24, the value of the buffer is inverted for the next job, and the process ends. As a result, the chattering return output is output when the silence detection signal has not changed from the previous state. That is, this eliminates chattering.

Next, the inter-track-CTL counting process will be described. As shown in FIG. 6, in S30, the increment of the CTL signal from the previous job is saved, and in S31, the output of the sound presence / absence determination circuit 6 is masked except during the transition and during the search. In other words, if the mechanism for FF or REW of the video tape 2 is in transition due to its operation, or immediately after that, when the running of the video tape 2 is unstable, the inter-track detection is performed. Therefore, the inter-track detection is not performed during this period. In S32, it is determined by the chattering return output when the silence detection signal does not change whether it is in the inter-track state (logic H). If YES (intersection), proceed to S33, and if NO (non-intersection), S.
Proceed to 34.

In S33, the increment of the CTL of the previous job and the increment of the CTL of the current job are added, and the sum is saved. As a result, this sum corresponds to the number of CTL signals during the music. In S35, it is determined whether or not this sum is greater than or equal to an arbitrarily set value (reference value) n. If YES, the process proceeds to S36, and if NO, the process ends. CTL
Since the sum of the number of signals becomes n or more, the inter-track detection flag is set in S36, the counter of the sum of CTL increments is reset in S37, and the process is ended. On the other hand, in S34, since it is not between songs, the song interval detection flag is cleared, and the process ends.

Therefore, as shown in FIG. 7, the microcomputer 8
Monitors the silence detection signal input from the sound presence / absence determination circuit 6, starts the CTL counter at its rising edge, and when the CTL counter reaches n or more,
When the inter-track detection flag is set and the silence detection signal is turned off, the inter-track detection signal is cleared.

Details of the blank detection output process in S12 of FIG. 4 will be described with reference to FIG.
In S40, the state of the inter-track detection flag (S36) from the previous inter-track-CTL counting process is determined. If the inter-track detection flag changes, the process proceeds to S41, and if not, S42.
Proceed to. In S41, it is determined whether the command by the search control signal from the instruction means (not shown) is a forward search or a backward search. If the command is a forward search, the process proceeds to S43.
In the case of reverse search, the process proceeds to S44. In S43, the down edge of the inter-track detection flag is detected, in S44, the up edge of the inter-track detection flag is detected, and the process proceeds to S45.
In step S45, a blank detection flag that is chattering output is set, and the process ends. On the other hand, since the inter-track detection flag has not changed in S42, the blank detection flag set in S45 is cleared and the process ends.

When the blank detection process is completed in this way, the search control process starts. In the search control process, as shown in FIG. 9, it is determined in S50 whether there is a search trigger signal which is a search control signal from an instruction means (not shown). If yes, the process proceeds to S51, and if no, to S52. move on. In step S51, the search mode is set on the basis of the search control signal from the instruction means (not shown). Is set to # 1, and the process proceeds to S52. S
At 52, it is determined whether or not the search mode is currently set (when the search control process is executed again after the search mode is cleared at S54 described later, S5
If it is determined that there is no search trigger signal at 0, S5
1 is skipped, search mode is not set), N
If it is O, the process is terminated, and if YES, the process proceeds to S53, and the process NO. Check. In S53, process N
O. If is # 0, go to S54, if it is # 1, go to S55, # 2
If so, the process proceeds to S56, and if # 3, the process proceeds to S57.

In step S54, the search mode is cleared and the process ends. The process of S54 is the process of S64, which will be described later. Is set to # 0 (when the search operation is completed).

In step S55 (in step S51, the process NO.
When 1 is set and the search operation is performed), the tape drive servo system (hereinafter, mechanical) is FF or RWD in the search direction, and the process proceeds to S58. In S58, the state of the blank detection flag is checked. If the blank detection flag is set (set in S45), a blank is detected and the purpose of the search is achieved.
59, the FF or REW stop command is issued, the search CTL counter is cleared, the blank detection flag is cleared in S60, and the process NO. Is set to # 2, and the process ends.

When the search is completed and a blank is detected, S
61 in process NO. In S56 executed when # 2 is set to, the mechanism is returned in the direction opposite to the search direction (rewinding the excess amount). In this case, when the search direction is the reverse direction, the value n is added to the CTL counter (the meaning will be described later). Next, in S62, it is determined whether or not the search CTL counter is 0 (whether the excess amount by FF or REW is rewound), and if 0, S6.
If it is not 0, the process ends. In S63, the process NO. Is set to # 3, and the process ends.

In S57, the mechanism is set to the reproduction mode (or stop), the process proceeds to S64, and the process NO. Is set to # 0, and the process ends.

Through the series of processes described above, in the inter-track detection in the forward search, as shown in FIG. 10, first, in order to find the beginning of the music, a silence detection signal of logic H is detected. The number of CTL signals is counted. Then, when the number reaches n, FF or REW is stopped and a logical H inter-track detection flag is set. After that, in order to accurately detect the beginning of the music, the trailing edge of the silence detection signal is detected while the inter-track detection flag is set. Then, the blank detection flag is set at this detection position. When this blank detection flag is set, the search CTL is cleared. After that,
After the FF or REW stop is commanded to the cleared position, the excessive portion is returned.

Further, in the inter-track detection in the reverse search, as shown in FIG. 11, when the silence detection signal of logic H is detected, the number of CTL signals is counted. And
When the number reaches n, FF or REW is stopped and a logically high inter-track detection flag is set. In this case, the blank detection flag is set in synchronization with the rising edge of the inter-track detection flag. When this blank detection flag is set, the search CTL
The counter is cleared. As in the case of the forward search, even if the video tape 2 is instructed to stop the FF or REW, it is not actually stopped immediately but slightly overshoots. The excess amount is returned to the position where the CTL counter becomes 0. However, in the case of the backward search, since n is added to the CTL counter, the amount of overshoot and C
Only n TL signals are returned. As a result, the beginning of the music piece is accurately detected.

As described above, according to the video tape recorder 1 of the present embodiment, chattering of the audio signal is suppressed to detect the inter-track state, and the CTL in the detected inter-track state.
The signals are counted, and when the count value is n or more, it is determined that it is a song interval. Therefore, the song interval can be accurately detected with a simple configuration regardless of the recording mode and tape speed of the video tape. In addition to being able to perform, it is possible to perform the optimum music start according to the search mode.

In the above-mentioned embodiment, the case of searching at the beginning of the music is described, but the present invention is not limited to this, and the search position is CT.
It can be changed by correcting L.

[0038]

As described above, according to the method of detecting the inter-track distance of the video tape according to the first aspect, the CTL signal in the unchanged portion of the audio signal is counted, and the count value of the CTL signal is n. In this case, since it is determined that it is the music interval, there is an effect that the music interval can be detected accurately regardless of the recording mode of the video tape.

According to the video tape recorder having the structure described in claim 2, the CTL signal is reproduced while the audio signal and the CTL signal recorded on the video tape are reproduced by the magnetic head and the silence circuit is generated by the arithmetic circuit. Since it is determined that there is a music piece when n signals are input, there is an effect that the music piece can be accurately detected with a simple configuration regardless of the recording mode of the video tape.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of an embodiment of a video tape recorder of the present invention.

FIG. 2 is a block diagram showing a configuration example of a normal audio circuit 5 and a sound presence / absence determination circuit 6 of FIG.

FIG. 3 is a flowchart showing a flow of main processing in the embodiment of FIG.

FIG. 4 is a flowchart showing a more detailed flow of blank detection processing S1 of FIG.

FIG. 5 is a flowchart showing a more detailed flow of chattering return processing S10 of FIG.

FIG. 6 is a flowchart showing a more detailed flow of a music piece-CTL count processing S11 of FIG.

FIG. 7 is a timing chart showing the timing of signals at the time of detecting a track interval corresponding to the processing of FIG.

FIG. 8 is a flowchart showing a more detailed flow of blank detection output processing S12 of FIG.

9 is a flowchart showing a more detailed flow of search control processing S2 of FIG.

FIG. 10 is a timing chart showing the timing of signals during a forward search according to an embodiment.

FIG. 11 is a timing chart showing the timing of signals in the backward search according to the embodiment.

FIG. 12 is a timing chart showing the timing of signals at the time of detecting a track interval according to a conventional example.

[Explanation of reference numerals] 1 video tape recorder 3 ACE head 4 CTL circuit 5 normal audio circuit 6 sound presence / absence determination circuit 7 capstan motor 8 microcomputer

Claims (2)

[Claims] 1. An audio signal monitoring process for monitoring an audio signal from a video tape and detecting the unchanged portion of the audio signal, and counting the CTL signal from the video tape at the unchanged portion of the audio signal. No-change-period measurement process, and the CT counted in the no-change-period measurement process
A method for detecting a music interval between video tapes, which comprises a music interval detecting process for determining a music interval when the count value of the L signal becomes n. 2. A magnetic head for reproducing an audio signal and a CTL signal recorded on a video tape, a sound presence / absence determining circuit for detecting a silent portion from the reproduced audio signal, and generating a silence detection signal, A video tape recorder, comprising: an arithmetic circuit that determines that the interval is between songs when n CTL signals are input while a silence detection signal is being generated.