JP2647903B2 - High-speed search method for magnetic recording / reproducing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for recording / reproducing an audio signal or the like in the form of a digital signal by using a rotary head, and particularly to record a table of contents information at a predetermined position on a magnetic tape. Thus, a desired program can be quickly searched. 2. Description of the Related Art Conventionally, as a digital tape recorder for recording an audio signal or the like on a tape in the form of a digital signal, a digital tape recorder using a rotating head is known. This is R-DAT (DAT)
The tape is wound around a cylinder of, for example, 30 mm in diameter by 90 ° and is provided at 180 ° intervals.
The heads are rotated at, for example, 2000 rpm, and are alternately scanned on the tape by 90 °. FIG. 7 shows the tape format of this DAT. In each recording track T, a PCM audio signal is recorded in an area PCM in the middle of the track T, and in two areas ATF on both sides of this area PCM. Is recorded with a servo signal for a tracking servo, a sub-code is recorded in an area SUB on that side, and a margin area is provided at the beginning and end of each track T. In each of the two subcode areas SUB, 8 blocks of subcode blocks are written, and in the upper and lower areas of one track, the same subcode is written. FIG. 8 shows the format of the subcode block. One block is composed of 288 bits and the first 8
Bits are block synchronization signal SYNC, data W ₁ are sub-code ID in the next 8 bits, the data W ₂ is sub-code ID and the address signal of the block of the next 8 bits, the following 8-bit data W ₁ W ₂ The parity P for error correction and the remaining 256 bits (8 bits form one symbol and consist of 32 symbols) are subcode data and its parity for error correction. The 8-bit data W ₁ W ₂ is recorded in more detail as shown in FIG. That, MSB data W ₂ is used for the block to identify whether PCM data block or subcode Bro arrive, when the subcode Bro poke is
It becomes [1] as shown in the figure. The lower 4 bits of data W ₂ has the LSB in Bro poke address

The content of the subcode ID differs depending on [0] or [1].

When [0], data W ₁
Consists control ID and 4-bit data ID of 4 bits, the upper three bits of data W ₂ is the the format ID. At this time, the control ID includes a program start identification signal (S-
ID) and a TOC-ID indicating whether or not the table of contents information is recorded in the program. LSB of block address
When There [1], the upper 3 bits of data W ₁ and the data W ₂ indicates the program number. Program number is represented by BCD code 3 Deijitsuto top three data W ₂ bits P
NO-1 is the most significant digit, the top four of the data W _1-bit PNO-2
Represents the middle digit and the lower 4 bits PNO-3 represents the least significant digit. PNO-1, PNO-2 and PNO-3 are combined to form a PNO.
-ID. The PNO-ID is represented from [001] to [799], and the program number [OBB] is the lead-in area,
[OEE] indicates a lead-out area, and [OAA] indicates invalid. Note that the LSB of the block address is

The subcode block of [0] and the subcode block of [1] are:
Four of the eight blocks in each subcode area SUB are recorded alternately, and the LSB of the normal block address is [1].

The two sub-code blocks of [0] are handled as one set. As shown in FIG. 10, the sub-code data consists of seven data blocks (PACK-1 to PA) called packet data.
CK-7) and parity (C ₁₎ have been made to allow recording, the number of the packed data recorded is indicated by the format ID represented in BCD code 3 Deijitsuto. That is, for example, when the format ID is [011], PACK1 to PACK3 and C1 are recorded, and all other areas are recorded.

[0] is recorded. 4-bit data called an item is recorded at the head of each packet data, and is used to identify the contents of each packet data. That is, if the item is [0001], the pack data is the time from the start of the program, if [0010], the pack data is the absolute time from the beginning of the tape, and if the item is [0100], the time is from the start of the tape. Indicates that the pack data is table of contents information. In the table of contents information, a program number and its start time are recorded. The start identification signal of the subcode is recorded at the beginning of each program as follows. That is, at the time of recording, when the recording is started from the stop state or the pause state, the start identification signal is recorded, for example, for 9 seconds at the beginning. This start identification signal is also recorded at the beginning of the next program for 9 seconds when a no-signal period between programs continues for a predetermined time during recording. In addition, it can be recorded at an arbitrary position by a user's button operation. When recording the program number from the beginning of the tape, a serial number is recorded for each program together with a start identification signal, and when recording from the middle of the tape, [OAA] is recorded. Since the start identification signal is automatically recorded during the no-signal period between the programs as described above, there may be a case where the start identification signal is not accurately recorded at a position considered to be the start point of the program. That is, if the beginning of the song is at a very low level, a start identification signal is recorded from the middle of the song at which the volume level has reached a certain level, or if the no-signal period is very long, It could be recorded long ago. Furthermore, if the low volume level period continues for a predetermined time in the middle of a song, a start identification signal may be erroneously recorded. Therefore, conventionally, the start identification signal is configured to be re-recordable at a desired position on the tape. As a method for searching for a desired program on a tape recorded in a format as described above, Japanese Patent Application Laid-Open No.
There is a prior art as disclosed in Japanese Patent Application Laid-Open No. 62-188804 (G11B27 / 10). That is, in this prior art, when searching for a target program by performing high-speed reproduction, the value of the target program number is compared with the value of the target program number obtained each time the rotary head is scanned, and the comparison is performed. When the error value is large, the value determined from the program number obtained by a plurality of head scans is used, and when the comparison error value is small, the value obtained by the scan at that time is used for comparison with the target program number. When the target program number matches the reproduction program number, the tape is stopped or normal reproduction is performed. In this conventional search, quick search can be performed by controlling the tape speed so that the distance from the target program is high and the tape speed is gradually reduced as the target program is approached. However, the difference between the target program number and the reproduction program number is not proportional to the length of the tape up to the target program, and is merely a guide. Therefore, there is a disadvantage that the speed of the tape cannot be optimally controlled by the search based on the program number as in the above-described prior art. Therefore, as described above, the absolute time from the beginning of the tape is recorded as subcode data, and the absolute time at the start point of each program is recorded at a predetermined position on the tape as table of contents information. It is also considered to conduct a search. (C) Problems to be Solved by the Invention By using the table of contents information recorded on the tape, the tape is run at a high speed in a place away from the desired program, and gradually slows down as the program approaches the desired program. In addition, since the tape speed can be optimally controlled, the search can be performed accurately and quickly. However, the table of contents information is created based on the start identification signal, and as described above, when the user re-records the start identification signal at a position determined to be the start point of the actual program, Such a search based on the table of contents information has a disadvantage that the performance cannot be started from the start point of the actual program. Therefore, an object of the present invention is to solve the above-mentioned drawbacks and provide an apparatus capable of starting reproduction from an appropriate position. (D) Means for Solving the Problems In order to achieve the above object, in the high-speed search device of the present invention, the start identification signal exists within a predetermined range centered on the start point of the program indicated in the table of contents information. In this case, the reproduction is started from the start point of the start identification signal, and when there is no start identification signal, the reproduction is started from the start point of the program indicated in the table of contents information. (E) Function According to the above method, the reproduction is started from the position where the user determines that the program is the start point. (F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows the system configuration of the present invention, where (1) is a tape drive mechanism, and (2)
Is a rotary head cylinder having a pair of magnetic heads (3) and (3 ') separated by 180 °, (4) is a capstan, (5)
Is a pinch roller, (6) and (7) are supply reels and take-up reels, (8), (9), (10), and (11) are tape guides,
(12) (13) and (14) are FG detectors that detect rotation of cylinder (2) capstan (4) supply and take-up reels (6) and (7), (15) is magnetic tape, and (16) is magnetic A loading drive system for winding the tape (15) around the cylinder (2). Further, (17) is an input terminal to which an information signal such as an audio signal is input, (18) is a sample and hold circuit that samples an input analog signal, and (19) is an A / D that converts an analog signal into a digital signal. Conversion circuit, (20) interleave digital signal, add error correction code,
A digital signal processing circuit for performing time axis compression, etc., (21) a head amplifier, (22) a REC / PLAY switching circuit for switching between recording and reproduction, (23) a reproduction amplifier, and (24) a waveform of a reproduced digital signal. A waveform shaping circuit, (25) a D / A conversion circuit that converts the reproduced digital signal into an analog signal, (26) a low-pass filter, (27) an output terminal,
(28) a servo system for controlling the rotation of the cylinder (2) capstan (4) supply and take-up reels (6) (7);
9) is a system control microcomputer that controls the entire system, (30) is a subcode processing microcomputer that processes subcode signals such as program numbers and time information, and identification signals indicating the beginning of the program. (31) is a table of contents. A TOC memory for recording information, (32) a display unit for displaying various information such as time information and a program number, and (33) a key input unit. FIG. 2 shows the subcodes on the tape recorded by the above system configuration. .., N + 1 are recorded on the tape, as well as a program number (PNO), an identification signal (S-ID) indicating the start of the program, table of contents information (TOC), A subcode such as an absolute time (A-TIME) is recorded. The PNO and S-ID are the first 300 frames (9
Second), a program number and S-ID = "1" are recorded. A-TIME records the absolute time from the beginning of the tape over the entire recording length of the tape. In the TOC, the absolute time at the beginning of each program is recorded in the first 300 frames of the program 1 as shown in FIG. Next, a search operation of a desired program on a tape recorded in such a format will be described with reference to FIGS. In the apparatus of the present invention, when a tape is mounted, the tape is first rewound to the beginning of the tape, and the TOC is reproduced. Therefore, it is assumed that the TOC is stored in the TOC memory (31) next time the search operation starts. FIG. 4 shows a case where the program N in which the S-ID position is rewritten after searching in the format as shown in FIG. 2 is searched, (A) shows the recording position of the S-ID, B) shows the movement of the tape during the search operation, (C) shows the tape speed during the search, and (D) shows A-TIME recorded on the tape. First, when the search for the program N is instructed, the program N stored in the TOC memory (31) is read.
A-TIME (T _N ) at the start position of
After determining the running direction by comparing with -TIME (T), A-TIME
Run at high speed while reading (T). During high-speed running, T and T _N are successively compared, and the tape speed is reduced at a point (A ₁ ) at which the difference becomes a predetermined value (for example, 60 seconds). Furthermore, with T
When the S-ID is detected at the time (A ₂ ) when the difference in T _N falls within a predetermined range (for example, 20 seconds before and after T _N ), the tape running is stopped.
At this time, since it usually exceeds the beginning of the S-ID, it returns to the beginning (A ₃ ) of the S-ID and performs normal reproduction from there, or enters a pause state, and completes the search operation. FIG. 5 shows a search operation when the S-ID is erased by an erroneous operation and the S-ID does not exist near the head position of the desired program. Also in this case, as in the case of FIG. 4, the difference between T and T _N to decelerate the tape speed at A ₁ point has reached a predetermined value. In this case, since the S-ID does not exist within the predetermined range of the difference between T and T _N , the point (A ₄ ) is outside the predetermined range.
To stop the tape running and return to the position of T _N (A ₅ ), from which the normal reproduction or the pause state is performed, and the search operation is completed. FIG. 6 is a flowchart of the above search operation.
First, when the tape is loaded, it is determined whether or not the tape is at the beginning (step 34). If not, the tape is rewound to the beginning of the tape (step 35). Thereafter, the tape is reproduced and the recorded TOC is stored in the TOC memory (31). (Step 36), and waits in this state. In this state, when a search for the program N is instructed (step 37), the TOC memory (3) is read in (step 36).
From the information stored in 1), the absolute time (T _N ) at the beginning of the program N is known (step 38). After that, play the tape and find out the absolute time (T) of the current position (Step 39),
The running direction of the tape is determined by comparing the magnitudes of T and T _N (step 40), and the tape is played at approximately 200 times the normal playback speed.
The vehicle is driven while reproducing the subcode at twice the speed (step 41). At this time, the absolute time (T) in the reproduced sub-code is compared with T _{N. If} the difference is smaller than a first predetermined time (for example, 60 seconds), the tape speed is reduced (step 42). ) (Step 43). Then, it is determined whether or not the difference between T _N and T has become smaller than a second predetermined time (for example, 20 seconds) (step 44), and if the S-ID is detected within the range of less than 20 seconds (step 44). 45) The tape is stopped (step 46), the tape is fed to the beginning of the S-ID (step 47), and the tape is played from there or the tape is paused (step 48) to complete the search. When the S-ID cannot be detected in (Step 45) (Step 49)
When it is detected that the difference between T _N and T exceeds 20 seconds, the tape is stopped (step 50), the tape is fed to the position of T _N (step 51), and the tape is played or paused from there (step 50). Step 48) Complete the search. The desired program is searched as described above, and TO
If the S-ID exists within a predetermined range before and after the head position of the program recorded in C, the S-ID starts from the starting point of the S-ID,
If the ID does not exist, the program is reproduced from the beginning of the program recorded in the TOC. (G) Effects of the Invention Since the present invention is configured as described above, even if the user re-records the start identification signal at the position determined to be the actual program start point, the start position can be determined from the appropriate position. Reproduction becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing the system configuration of the present invention, FIG. 2 is a diagram showing subcodes recorded on a tape, FIG. 3 is a diagram showing the structure of table of contents information, FIG. 4 and FIG. FIG. 6 is a flowchart showing a search operation, FIG. 6 is a flowchart for explaining the operation of the present invention, FIG. 7 is a diagram showing a tape format of DAT, FIG. 8, FIG. 9 and FIG. FIG. 5 is a diagram showing a format of a subcode recorded in a sub-code. (1)… tape drive mechanism, (20)… signal processing circuit, (29)… system control microcomputer, (3
0) Subcode processing microcomputer, (31) TOC memory.

Claims (1)

(57) [Claims] A plurality of programs to which a program number which changes for each data which is completely completed on a magnetic tape are added, and information indicating an absolute time from a start end of the magnetic tape are recorded. A start identification signal indicating that the start point of the program is recorded at the start position, and a high-speed search method for a magnetic tape in which table of contents information including the program number and the absolute time at the start position of each program is recorded. The magnetic tape travels while reading the information indicating the absolute time from the start of the magnetic tape, and compares the absolute time indicated in the table of contents information with the absolute time from the start of the magnetic tape. When the start identification signal is detected, the running speed of the magnetic tape is reduced. After stopping, the tape is fed to the start position of the start identification signal. If the start identification signal is not detected and the difference is smaller than the second predetermined value, the tape corresponds to the absolute time indicated in the table of contents information. A high-speed search method for a magnetic recording / reproducing apparatus, wherein a search operation is completed at a position where the search is performed.