JPH0445909B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a magnetic recording recompression method, and more particularly to the construction of an identification signal when an information signal to be recorded and reproduced is comprised of a digitized audio signal and an identification signal.

2. Description of the Related Art Recently, a method of converting an analog audio signal into a digital signal and recording and reproducing the same has been widely used because it enables recording and reproducing of high quality audio signals. For example, in the 8mm VTR standard as shown in Figure 2, in addition to the conventional 180 degree wrapping of the tape around the cylinder with a built-in rotary head, the tape is wrapped around the cylinder with a built-in rotary head, and the audio signal converted into a digital signal (hereinafter referred to as PCT signal) is ) This is achieved by wrapping approximately 36 degrees more in order to record the angle.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 58-222402, one track is divided into a plurality of (six) sesterces as shown in Fig. 3, and by the same method as the PCM signal recording method shown in Fig. 2, A method of recording a signal in each sector, that is, a method of using a VTR as a multi-track PCYM device, has been proposed. To explain Figure 3 a little, the audio signal of one source is BL1−
Record A1, BL1−B1, BL1−A2, etc. sequentially,
The audio signals from another source are BL2−A1, BL2−B1,
BL2−A2, etc. are recorded sequentially. Further, in Japanese Patent Application Laid-Open No. 59-70230, as shown in Fig. 3, a device is provided that records each sector divided into six sectors in either the forward direction (FOW direction) or the reverse direction (REV direction). The BL1 sector is recorded in the FOW direction, and when it reaches the end of the tape, it continues to the BL2 sector without rewinding.
A device that records and plays in the REV direction has been proposed.
It is also possible to lengthen the recording time by reducing the tape speed to a fraction of the normal speed, as in VHS-VTR. Figure 4 shows the multi-channel PCM format shown in Figure 3, two recording directions (FOW, REV) and two recording speeds (SP,
An example of the tape format when LP) is standardized is shown. In devices that are capable of performing a wide variety of recordings, the user only has to manually select the recording mode appropriate for the purpose when recording, but when playing back, the content that was manually selected during recording is
The recording mode is detected by recording the information on the tape and reproducing the recorded information during playback.
It is desirable to automatically set the playback mode to the same mode as when recording. As a method for recording this recording information, in a device such as an 8mm VTR that can record an identification signal together with a digitized audio signal, the above-mentioned (FOW, REV), (LP, SP) information can be recorded. However, the information recorded in the identification signal section is the program number,
It is more convenient to record various information such as the elapsed time from the beginning of the tape, but it is impossible to record all of this information simultaneously in a limited identification signal section.

As a solution to these problems,
Publication No. 210502 discloses that the identification signal is divided into an inspection code section and a control data section as shown in Figures 5 and 6.
In the figure, a method is proposed for recording ^2M ways of control data.

In other words, in 8mm video, each track has a 6-byte identification signal, and each byte is given a name from ID0 to ID5.
ID5 is determined as a common ID as shown in Fig. 7. ID1 is also used as an inspection code, and up to now six codes have been determined, some of which are shown in Figures 8 and 9.

Problems to be Solved by the Invention As mentioned earlier, it is possible to set many types of data to ID1 to ID4 using the inspection code of ID1, but it is possible to play back the ID signal while running the tape at high speed. Moreover, as shown in Figure 10,
If ID0 to ID5 are recorded in a dispersed manner, it is extremely difficult to reproduce all six IDs at the same time (because during high-speed searches, the reproducing head scans across the recording track,
This is because the faster the tape feeding speed becomes, the more one track is divided into a larger number of areas. In other words, when ID1 and ID2 to ID5 are recorded at separate positions, such as the ID signal in PCM audio of 8mm video, the information of ID1 and the information of other IDs (ID2 to ID5) can be recorded simultaneously (on the same track). (above meaning), it becomes extremely difficult to correctly detect the identification signal, and it becomes impossible to determine what data is recorded in the identification signal.

Figure 10 shows the recording signal format for 8 mm video, and in an NTSC magnetic recording/reproducing device, it consists of 132 blocks, each block containing a synchronization signal, an address signal, P and Q parity signals, and an 8-word data signal. , consists of a 16-bit CRCC signal.

Also, the identification signal is sent to the first block (part a in Figure 10).
ID0, second block (part b in Figure 10), ID1,
The 45th block (Fig. 10 c part) has ID2, the 46th block (Fig. 10 d part) has ID3, and the 89th block (Fig. 10 d part) has ID2.
ID4 in the 90th block (Fig. 10 f)
ID5 is recorded in section). As you can see from this figure, two digits each of ID0 and ID1, ID2 and ID3, and ID4 and ID5 are recorded at temporally close positions, so
Even if the tape is run at high speed and the slope of the reproducing head scanning trajectory differs from the recording trajectory, there is a very high probability that two IDs can be played back at the same time.
The present invention focuses on this point and aims to provide a method for efficiently recording and reproducing identification signals under these conditions.

Means for Solving the Problems The technical means of the present invention for solving the above problems is to perform azimuth recording using two heads with different head gap angles, as in the case of PCM audio signal recording in 8 mm video. In such a device, the mode of the identification signal (consisting of 6 bytes) recorded by one head is limited to one type, and the 6-byte identification signal is recorded in at least two adjacent
Information that is completed within the byte identification signal,
The other head allows any mode of identification signal to be recorded.

By using azimuth recording, the present invention allows only identification signals recorded at one specific gap angle to be detected at the head at the same gap angle (at the head at the opposite gap angle, the identification signal is detected due to azimuth loss). (The output will attenuate and detection will no longer be possible.)
Taking advantage of this fact, only one type of identification signal is recorded in the head at a specific gap angle, and by making the information complete with the adjacent 2-byte identification signal, it is possible to perform a high-speed search. The identification signal can also be detected stably. In addition, by allowing the other head to record any identification signal mode intermittently, many identification signal modes can be recorded.

However, although the identification signal recorded by the other head is difficult to detect during high-speed search, it can be sufficiently detected during normal tape running.

Embodiment Before explaining the details of the present invention, an outline of PCM audio recording, which is the basis of the present invention, will be explained using FIG. 11 using an 8 mm video method as an example. In the figure, an audio signal input from a terminal 1 is converted into a 10-bit digital signal by an AD converter 2, and further compressed to 8 bits. The audio signal converted into a digital signal is guided to the signal processing circuit 3, and an identification signal generated by the identification signal processing circuit 16 is added thereto according to a command from the system control circuit 17. An error correction code is added to the audio signal to which this identification signal has been added, and it is temporarily stored in random access memories 4 and 5 alternately, for example, every 1/60 seconds, and the information stored in these memories 4 and 5 is alternately stored. After being read out at high speed and subjected to modulation suitable for recording, it is led to the switch circuit 7.
In the switch circuit 7, the video signal input from the terminal 6 and the FM audio signal are mixed together, and the PCM
The signal is temporally switched, mixed with a pilot signal led from a terminal 9, passed through a recording amplifier 8, and led to a magnetic head 10 via a recording/reproduction changeover switch (SW), where it is recorded on a magnetic tape. During reproduction, the signal reproduced from the head 10 is guided to the head switch circuit 12 through the preamplifier 11. One side of the output of the head switch circuit 12 is a video signal, an FM audio signal, and a pilot signal taken out from a terminal 13, and the other side is led to a PCM signal demodulation circuit 14 where it is returned to the original PCM signal. Then, the data is guided to the audio signal processing circuit 3 again to perform error correction, and then is stored alternately in the random access memories 4 and 5, and the stored data of 4 and 5 are read out using the reference clock.
A demodulated reproduced audio signal is obtained from a terminal 15 guided to the DA converter 2.

Similarly, the identification signal is also guided to the identification signal processing circuit 16, where the identification signal is decoded and the decoded control data is sent to the system control circuit 17 as necessary.
The system control circuit 17 performs necessary processing according to the data thus guided. In addition,
Here, 2 is shown assuming that the AD converter and DA converter switch between recording and playback, and the signal processing circuit also switches between recording and playback. Also,
In actual 8mm video, the audio signal is passed through a compression circuit before being input to the AD converter, and during playback
The DA output is led to an expansion circuit, but it is omitted here. As explained above, it is possible to record on the tape as shown in FIG. 2 using the circuit shown in FIG. It is determined based on the standard. Therefore, if you shift the phase of the rotation pulse by 36 degrees so that only the PCM audio signal is recorded without recording the video signal or FM audio signal, the recording position of the PCM signal can be shifted sequentially as shown in Figure 3. Can be recorded.

Next, an example of the identification signal of the present invention is shown in FIG.
This will be explained using FIGS. 13 and 14. Assume that the ID is intermittently recorded in 2-byte increments as shown in FIG. 10, such as in 8-mm video PCM, and is 6-byte data. ID0 is the test code named mode number (in the case of Figure 12, mode 7 is shown), and ID5 is the test code named mode number.
This control is called the control shown in the figure, and is designed to record whether the stereo signal is a monaural signal, an audio signal, or some other signal. Also, ID4 is designed to record the program number.

In ID1, as shown in Figure 13, BO indicates the recording direction of the tape, B1 and 2 indicate the tape speed, B3, 4 and 5 indicate the track to be played next, and B6 and 7 indicate the audio signal. Is it the recorded part?
Indicates the time between songs. ID2 and ID3 are information such as time code, and for example, in these 2 bytes,
Hour, minute, and second data from the beginning of the tape and hour, minute, and second data from the beginning of the program number are recorded. That is, the maximum value of minutes and seconds is 59, and it is sufficient to record the maximum value of time up to 59. This means that the tens digit can be displayed with 3 bits. That is, it becomes possible to use the BO of ID3 and the BO of ID2 as test bits. therefore
ID2 BO indicates the time from the beginning of the tape, or ID4
B0 of ID3 is set to B1 of ID2 as a check bit to check whether it indicates the time from the start of the program number shown by
It can be used as a check bit to determine whether B7 indicates hours or minutes. Figures 14a to 14d show the contents of each bit corresponding to the test bit. Correspondence tables for each bit indicating the tens digits 0 to 5 and the ones digits 0 to 9 of hours, minutes, and seconds are shown in FIGS. 15a and 15b.

Now, the identification signal shown in the examples from FIG. 12 to FIG. and record it on the other head B.
FIG. 1 shows an example of recording arbitrary modes M _x , My _y , etc. Figure 1 shows only the BL1 sector to make the explanation easier to understand. In Fig. 1, A ₁ , A ₂ . . . are recording tracks by the A head,
B ₁ , B ₂ , . . . are recording tracks by the B head, and audio PCM data is recorded on each track, and the identification signal mode 7 (M ₇ ) mixed therein is recorded on each track.
is recorded in the A head, and mode X (M _x ), mode y (M _y ), etc. are recorded in the B head. In addition,
v _H is the head scanning direction, and v _t is the tape running direction.

When performing a high-speed search for a tape on which identification signals have been recorded as shown in Fig. 1, the A head intermittently plays back the information of only tracks A ₁ , A ₂ , . . . recorded in the A head, and the B head The recorded track information is virtually unplayable due to azimuth loss.

Therefore, the identification signal M ₇ in the reproduction signal of the A head
Of the 6 bytes of
ID0, ID1; ID2, included in blocks a, b, c, d, e, f in the figure, respectively.
The combination of ID3; ID4 and ID5 has a high probability of being correctly played back on the same track. Therefore, for example, when the same track ID2 and ID3 in FIG. 12 are reproduced, there is a high probability that both ID2 and ID3 will be correctly reproduced, and if both are correctly reproduced, the identification signals a to d in FIG. 14 can be correctly detected. Also, since only the _M7 mode identification signal is recorded on the track recorded in the A head, if you try to search by specifying the program number during a high-speed search, for example, the track will be played back from the A head. Of the identification signals, it is only necessary to observe ID4 in FIG. 12. Also, when searching by specifying a time during a high-speed search, first check the hours (HOR.) and minutes (MIN.) from the beginning of the tape, and then slow down the search speed when you almost reach the specified point. seconds (SEC.)
By observing the , high-speed searches in seconds are possible. This can be achieved if both ID2 and ID3 in FIG. 12 are correctly detected when the same track is reproduced. In addition, when trying to detect a song interval during a high-speed search, bits 6 and 7 of ID1 in Figure 12 are used.
All you have to do is keep an eye on the information.

In addition, since identification signals representing the year, month, day, etc. as shown in Fig. 8 are generally not needed during high-speed searches, they can be recorded mixed with the information recorded by head B in Fig. 1 ( For example, M _x in Figure 1)
The identification signal recorded on the B track can be correctly reproduced during normal reproduction. As shown in Fig. 1, the identification signal and specific detection signal necessary for high-speed search are recorded as one mode on the track recorded by the A head, and the identification signal that does not require high-speed search (for example, year, month, day, or Character data, etc.) can be recorded intermittently in a very large number of identification signal modes by recording them on the recording track by the B head, and a specified point can be searched stably even during high-speed searches. I can do it.

In Fig. 1, an example is shown in which mode 7 (M ₇ ) is recorded on all A tracks, but it is recorded on A ₁ , A ₃ , and A ₅ of A tracks intermittently, and on A ₂ and A ₄ . Of course, it is also possible to record data with all bits of ID0 to ID5 set to 0. This is because, as is clear from FIGS. 12 to 15, all 8 bits of ID0 to ID5 do not become 0. Therefore, if the IDs reproduced by the A head are all 0,
If you ignore and use data with at least one 1 in the ID as invalid data, it is possible to search in the same way as in the case of FIG. Of course, as the number of tracks recorded in mode 7 decreases, the ability to detect a search point during a search decreases.

Effects of the Invention As described above, in a two-head azimuth recording device, the mode of the identification signal recorded in one head is changed to one specific mode containing the identification signal necessary for high-speed search, and the mode of the identification signal recorded in the other head is By intermittently recording identification signals of various modes that do not necessarily require high-speed search, (1) By utilizing azimuth loss, only the identification signal of the A-head recording track is recorded during A-head playback. is played back correctly, so you can search for the specified point stably even during high-speed searches.

(2) It is possible to intermittently record identification signals in various modes, and it is possible to meet various requests for identification signals.

It becomes possible to record an identification signal that satisfies the above two points at the same time, which has great industrial value.

[Brief explanation of the drawing]

Fig. 1 is a tape recording pattern diagram for explaining the present invention, Fig. 2 is a diagram showing an 8 mm video tape pattern, and Fig. 3 is a tape pattern diagram when 8 mm video is used as a multi-channel PCM. Figure 4 is a diagram showing the tape pattern of multi-channel PCM when two types of recording directions and recording speeds are allowed for each sector of multi-channel PCM, and Figure 5 is a conventional diagram showing the configuration of the inspection code in the identification signal. An example diagram, Figure 6 is a diagram of a conventional example showing another configuration of Figure 5, and Figure 7 is an 8mm video ID
Diagram showing the data recorded in ID5 of the code, No. 8
Figure 9 shows an example of ID data determined for 8mm video, and Figure 10 shows an example of ID data determined for 8mm video.
A diagram showing the recording position of ID data in PCM, FIG. 11 is an electrical block diagram explaining a method of digitizing and recording an audio signal in 8 mm video, and FIG. 12 shows the case where the present invention is expanded to 8 mm video. Figure 13 showing an example of the contents of the ID signal of
The figure shows an example of the contents of ID1 in Figure 12.
Figure 4 shows an example of the contents of ID2 and ID3.
The figure is an auxiliary diagram of FIG. 14.

Claims (1)

[Claims] 1 A magnetic tape is wound diagonally around a rotating head cylinder containing two magnetic heads with different gap angles, and information signals are alternately recorded as a group of discontinuous recording tracks by the two heads, and one scanning track is recorded. In a magnetic recording and reproducing method in which a field is divided into a plurality of sectors and an information signal is recorded and reproduced in each sector, the information signal recorded in each sector is composed of a digital data signal and an identification signal (digital signal), and the above two 1st of the heads
The second head records an identification signal of one specific mode that includes at least the identification signal necessary for a high-speed search, and the second head records identification signals of arbitrary various modes intermittently. A magnetic device characterized in that a specified recording position on a tape is detected by using an identification signal of at least two adjacent bytes of a track recorded by the first head that is reproduced from the first head. Recording and playback method.