JP2519528Y2 - Magnetic recording controller - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a digital audio tape recorder (DA
In T), the present invention relates to a magnetic recording control device for controlling whether digital copying is possible.

[Prior Art] Since a DAT can directly input and record and reproduce a digital signal, it has an excellent characteristic that there is no signal deterioration even if copying (dubbing) is repeated many times. However, this has led to copyright issues. In order to solve this copyright problem, the SCMS method (serial copy management method) has been proposed.

This SCMS method is to judge the category code and copy bit in the digital signal input according to the Digital Audio Interface Standard of Japan Electronic Machinery Manufacturers Association (EIAJ standard CP-340). Copying is possible even for generations, but copying is prohibited if copying is prohibited, or copying is allowed for only one generation.

FIG. 4 shows the format of a digital signal of the digital audio interface standard, and is composed of subframes, frames and blocks. In the case of two channels of stereo, a subframe includes audio data (sample word: 20 bits) of one channel, and a 4-bit synchronous preamble and an auxiliary code are transmitted prior to the audio data. 1 after audio data
The bit validity flag V, the user data U, the channel status C, and the parity bit P are transmitted. Two L / R subframes make up one frame, and 192 frames make up one block.

The channel status is from frame 0 to 191 (1
One word consists of 192 bits of (block).
FIG. 5 shows the format of the channel status 1 block. Controls (codes indicating the presence or absence of pre-emphasis) are assigned to bits 1 to 5. In this control, bit 2 is a copy code, "0" represents digital copy prohibition, and "1" represents digital copy permission (see FIG. 6). Bits 8 to 14 are category codes that indicate the type of digital signal source source. "10000000" is a compact disc (C
D) (see FIG. 6).

In the SCMS method, when the DAT inputs a digital signal given in such a format, the state of the copy bit is judged in the DAT. Basically, if it is "0", the input digital signal is not recorded and "1" is not recorded. Controls to record only when ". However, if the category code indicates a copyrighted medium such as a CD, even if the copy bit is "0" (prohibited), digital copying is allowed only once (one generation only). To control. In that case, ID6 in the main ID is recorded on the recorded DAT tape.
A code indicating that copying is prohibited is recorded on the tape so that digital copying using this tape as a master tape is prohibited.

FIG. 7 shows the track format of DAT, and among the main IDs included in the main area in which the PCM audio signal is recorded, the upper 8 bits W1 include ID1 to ID7.
Actually, ID6 is recorded at the sixth block address of W1 (see FIG. 8). This ID6 is 2 bits,
Copy permission when "00", copy prohibition when "10", "1"
When it is 0 ", it indicates the first generation copy permission. Therefore, when performing digital copy from a recording medium such as a CD that holds copyright to this DAT, record this ID6 as" 10 "
It prohibits digital copying using the tape as a master tape, and disables the creation of so-called grandchild tapes.

On the other hand, in recent years, writable CDs (read-write CDs,
RW-CD) is under development, but this RW-CD
In the case of a CD, the category code included in the subframe format in the digital audio interface (see Fig. 5 and 6) is "10000000" as in a normal CD.
Therefore, the copy bit (see FIG. 6) is changed at the transmitting side (RW-CD reproducing device side) at 101010 ... at a 4 to 10 Hz cycle so that the output signal is RW-CD. ing. When the DAT side detects this periodically changing copy bit, it is considered that the copy is prohibited and control is performed so as not to perform digital copy.

[Problems to be solved by the invention] Even in the case of RW-CD, in order to support the SCMS method, it is necessary for the DAT side to detect that the copy bit changes in a cycle of 4 to 10 Hz. is there. for that purpose,
It is necessary to specially provide a circuit for detecting the 4 to 10 Hz cycle in the DAT device, which causes an increase in the circuit configuration.

[Means for Solving the Problems] The present invention is directed to a pulse generating means for generating a pulse in accordance with the rotation of a rotary head, and a recording means for detecting the state of a control signal in a digital signal in synchronization with the generation of the pulse. It is mainly provided with a control means for controlling the recording or the recording stop.

[Operation] The pulse generating means is a pulse generator used for cylinder servo or signal processing timing in the DAT, and generates a pulse in synchronization with the rotation of the cylinder to which the rotary head is attached. The control means
Every time this pulse is output, the state of the copy bit is judged, and it is detected whether or not there is a predetermined cycle change, and whether or not DAT recording is possible is controlled.

By this, without providing a cycle detection circuit,
RW-CD can also perform recording control compatible with the SCMS system.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a partial block diagram of a DAT device to which the present invention is applied, and FIG. 1 shows only a recording system circuit block in particular. In the figure, reference numeral 1 is a cylinder to which rotary heads 2a and 2b are attached. Magnetic bodies 3a and 3b having different polarities are arranged in opposition to each other in the cylinder 1. A pulse generator (PG) 4 detects contact and separation of the magnetic bodies 3a and 3b, and one pulse is generated for each rotation of the cylinder 1 ( PG pulse) is output. It is given to the PG pulse control unit 5 and is used for signal processing timing control, servo control, and copy bit state detection described later.

Also, in FIG. 1, 6 is an analog input terminal, and the analog input signal input from this terminal 6 is an A / D.
The conversion unit 7 converts the digital data. A / D converter 7
Is sent to the signal processing unit 8, the signal processing unit 8 generates a signal of the DAT format shown in FIG. 7, and the signal recording unit 9 performs magnetic modulation and recording amplification, and the rotary head
It is recorded on the magnetic tape 10 by 3a and 3b. Signal processing unit 8
Then, various processes such as addition of an error correction code, interleaving, and time axis compression are executed by writing / reading an input signal to / from the storage unit 11. The series of processes is performed by the control unit 5 according to the recording instruction operation on the operation unit 12.
It is executed under the control of.

Reference numeral 13 is a digital input terminal. When a digital input signal (see FIG. 4) conforming to the digital audio interface standard is applied through this terminal 13, the frame disassembly unit 14 disassembles it into subframe units based on the sync preamble. Then, the audio data in the sub-frame is extracted by the audio data extraction unit 15, and the channel status is extracted by the channel status extraction unit 16. The audio data extracted by the audio data extraction unit 15 is
The signal is supplied to the signal processing unit 8 and subjected to the signal processing as described above, and then recorded on the magnetic tape 10. Further, the channel status extracted by the channel status extraction unit 16 is given to the control unit 5, and recording permission / prohibition is controlled based on the copy bit included in the channel status.

FIG. 2 shows a partial internal structure of the control unit 5. In FIG. 2, reference numeral 51 is a format construction unit, which sequentially inputs the channel status contained in each frame of the digital input signal and constructs the block format shown in FIG. 5 for 192 frames. The category code of bits 8 to 15 is extracted by the category code extracting unit 52, and the copy bit, which is bit 2 in the control data of bits 1 to 5, is extracted by the copy bit extracting unit 53,
It is sent to the 54 digital recording judgment section. The digital recording determination unit 54, from the state of the category code and copy bit,
A recording control signal indicating whether recording is possible and an ID6 to be recorded on the DAT tape are generated and output. The control unit 5 controls the entire system according to the recording control signal, executes recording operation control or recording stop control, and during recording,
Various ID codes including ID6 and subcodes are sent to the signal processing unit 8.

Note that the digital recording determination section 54 of FIG. 2 is provided with various registers for detecting the state of the copy bit, particularly the copy bit changing in the 4-10 Hz cycle of the RW-CD. That is, the register TIM (8 (8) used as a subtraction timer for measuring the cycle of change of copy bits
Bit), the initial value “01100110” (100 in decimal) of TIM, the register INI that holds the copy bit inversion count, the register INI (4 bits), and the register C _n that holds the current value of the copy bit. , A register C _n-1 which also holds the previous value, and a register I which stores a recording enable / disable flag
D (2 bits) is provided.

Next, the operation of this embodiment having such a configuration will be described.

In a typical DAT system, cylinder 1 is driven at 2000 revolutions per minute. Pulse generator 4 is cylinder 1
Since one PG pulse is output per one rotation, the period of the PG pulse is 30 msec. In the case of RW-CD, the copy bit in the digital output signal is periodically changed at 4-10Hz.
Since digital copying of RW-CD is prohibited, it suffices to measure the reversal period of the copy bit to determine whether or not recording is possible. In the present invention, the PG pulse that is indispensable for DAT is used without adding a special circuit for this measurement.
That is, it is determined whether or not the number of times the copy bit is inverted is 16 or more during 100 counts of PG pulse (3 seconds). The number of reversals 16 times in 3 seconds is about 2.7 Hz in terms of frequency.
Is equivalent to If it is less than 16 times, it is determined to be a malfunction such as noise, and if it is more than 16 times, it is determined to be a copy bit indicating RW-CD.

Therefore, in the DAT system of FIG. 1, when recording a predetermined source on a DAT tape, a signal is applied to either the analog input terminal 6 or the digital input terminal 13 depending on the form of the source. When a signal is given to the analog input terminal 6, it is converted into a digital signal by the A / D conversion unit 7, and then, via the signal processing unit 8 and the signal recording unit 9, by the rotary heads 3a and 3b, the magnetic tape. Recorded on 10. In this case, "00" indicating the copy permission is recorded as the ID6.

When a digital input signal (a signal conforming to the digital audio interface standard of FIG. 4) is given to the digital input terminal 13, the audio data extracted by the frame decomposing unit 14 and the audio data extracting unit 15 is processed by the signal processing. Although it is sent to the section 8 to be recorded, whether or not recording is possible is controlled according to the category code and copy bit state of the digital input signal at this time. That is, the channel status in the digital input signal is detected by the channel status extraction unit 16 and given to the control unit 5. Inside the control unit 5, the category code is detected by the format construction unit 51 and the category code extraction unit 52 shown in FIG.
It is given to the digital recording determination unit 54. The copy bits extracted by the copy bit extraction unit 53 are also sent to the digital recording determination unit 54.

The digital recording determination section 54 executes the control operation shown in FIG. 3 every time a PG pulse is input.

First, as an initial state, the initial value 100 ₍₁₀₎ held in the register IMI is set in the register TIM for the subtraction timer for measuring the change period of the copy bit. In addition, the register CNT and the register ID are cleared. In this state, the copy bit being sent from the copy bit extraction unit 53, it is stored and held as a current value by PG pulse in the register C _n, also the contents held in the register C _n up to now, this PG pulse It is shifted and transferred to the register C _n-1 . This allows register C
The copy bit of the previous value is held in _n-1 as viewed from the PG pulse.

In such a state, every time a PG pulse is input, the digital recording determination unit 54 determines whether or not the content of the register TIM is “0”, and unless it is “0”, the register TIM indicates “−1”. Subtraction is performed (steps S1 and S2 in FIG. 3). Next, the previous value C _{n-1 of the} copy bit is compared with the current value C _n (step S3), and if they match, that is, if the copy bit does not change, the content of the register TIM is "0". It is determined whether or not (step S4). In this way, the contents of TIM are sequentially subtracted from the initial value each time a PG pulse is input, unless the copy bit changes. With the exception of RW-CD, the copy bit does not change regardless of copy prohibition / permission.
The content of M is subtracted, and during that time, it is determined whether or not the register ID is "10" after the process of step S4 (step S
6). In this case, the register ID remains "00" as it is initialized.
Therefore, in the next step S13, the ID6 to be recorded on the tape is set from the contents of the copy bit and the category code, and the control for executing the digital recording is performed.
Also, when it is determined that TIM = 0 in step S4, the register CNT for counting the number of times of inversion of the copy bit is set to "0" (step S5), and then the process proceeds to step S13.

As described above, in the normal case where the copy bit does not change, whether or not the digital recording is possible is determined according to the content of the copy bit and the content of the category code, and the corresponding control operation is executed. In the case of SCMS method, the category code is DA
If the copy bit is "1" indicating the permission when T is indicated, the digital copy permission is unlimited regardless of the generation, and the ID6 recorded on the tape is "00" indicating the permission. When the copy bit is "0" indicating prohibition, digital copy is not performed. In the case of the category code of pre-recorded DAT tape (DAT soft tape), even if the copy bit is "0" indicating prohibition, only one generation of digital copy is permitted and the digital copy is recorded on the tape at that time. ID6 is "10" indicating that digital copying is prohibited,
Digital copying using the tape is prohibited. Furthermore, when the category code indicates CD, a normal CD is also RW-C.
D has the same category code, but if the copy bit does not change, it can be specified as a normal CD instead of RW-CD. When the processing route of S1 to S6 or S1 to S5 described above has passed, it can be specified that the CD is a normal CD with no change in the copy bit, and therefore, as the process of step S13 in this case, the copy bit is In the case of "1" indicating permission, ID6 is set to "00" indicating unlimited permission and the digital copy execution process is performed. When the copy bit is "0" indicating prohibition, set ID6 to "10" indicating prohibition of copying,
Performs a process to perform digital copy of only one generation.

Next, the RW-C in which the copy bit shows a periodic change of 4 to 10 Hz
The case of D will be described. In this case, as described above, the category code cannot specify the normal CD or the RW-CD. In this case, instead of the processing route of the above steps, the route is changed to another route. That is,
Each time a PG pulse is input, the processing of steps S1 to S3 in FIG. 3 is executed, but in this step S3, it may be determined that the current value and the previous value of the copy bit are different. PG pulse is 3 because the cylinder rotation of DAT is 2000 rpm
It is input every 0 msec. In RW-CD, the copy bit is periodically changed at 4 to 10 Hz.
If it is 50%, it will change in 50 to 125 msec. Therefore, in step S3, there are cases where it is determined that the current value and the previous value of the copy bit are the same, and where it is determined that they are different. When the input point of the PG pulse corresponds to the change point, the process proceeds from step S3 to step S7.
The process of step S7 is a process of determining whether or not the register CNT for counting the number of times of inversion of the copy bit is "0". Since it is “0” at the first time, the initial value of INI is set again in the register TIM as the process of step S8, and then the register CNT
Is incremented by "+1" (step S9). In this way, CNT is sequentially added by the processing of S7 to S9 each time a change in the copy bit is detected. And step S
After the addition process of 9, it is determined whether the content of the register CNT is "0" (step S10), and if it is not "0", the process proceeds to the ID determination process of step S6 described above. ID in this S6 process
Remains at the initial value, the process proceeds to step S13, and the process proceeds to the digital recording execution process. That is, digital recording is performed until the register CNT (4 bits) for counting the number of inversions overflows due to addition.

Then, when the register CNT overflows to the 16th count and becomes “0”, the process proceeds from step S10 to step S11. In the process of step S11, the initial value INI is set again in TIM, and thereafter, in step S12, the ID is set to "10" and the next PG pulse waits. Therefore,
From the next time onward, CNT is counted from "1", so that CNT ≠ 0 is determined in step S10, and the process proceeds to the ID determination process of step S6. However, the last time CNT overflowed and the ID
Is set to "10", so after this step S
14 digital recording stop processing will be executed.

In this way, the overflow in the 4-bit register CNT, that is, 16 counts, means that the change of the copy bit of 4 to 10 Hz is detected 16 times at the input of the copy bit of 30 msec. Although it depends on the duty of the copy bit change, this is equivalent to detecting a periodic change of at least 2.7 Hz or higher.

When the copy bit temporarily changes due to the influence of nozzles, etc., a change in the copy bit is detected in step S3, and the register CNT for inversion counting is added in step S9. Change,
The CNT overflow does not occur, so that the digital recording process (step S13) according to the category code and the copy bit content is executed as usual.

In the above embodiment, a register for copy bit inversion counting
With CNT as 4 bits, it was determined that the copy bit changed the regulation of RW-CD by its 16 count (overflow). In this case, the count number and the bit number are the initial value of the register TIM for the subtraction timer. It can be appropriately changed by considering the value, the change duty of the copy bit, the margin, and the like. Besides using a general-purpose register as shown in FIG. 2, it is also possible to configure a dedicated circuit using a logic gate such as a counter.
Furthermore, the PG pulse for copy bit determination is the DAT to be used.
Any pulse having a cycle set according to the system configuration may be used.

[Advantage of Invention] According to the present invention, it is possible to reliably detect the change of the copy bit period of the RW-CD by using the pulse generated in accordance with the rotation of the rotary head (cylinder rotation). A magnetic recording control device compatible with the SCMS system can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing only the recording system of a DAT which is an embodiment of the present invention, FIG. 2 is a diagram showing a partial internal configuration of a control section, and FIG. 3 is a control operation of a digital recording determination section. FIG. 4 is a diagram for explaining a digital signal format of the digital audio interface standard, FIG. 5 is a diagram showing a format of a channel status included in the digital signal of the standard, and FIG. Shows the contents of the copy bit and category code included in the digital signal of the same standard.
FIG. 8 is a diagram showing a DAT track format, and FIG. 8 is a diagram for explaining the ID6 included in the main ID of the DAT. 1 ... Cylinder, 2a, 2b ... Rotating head, 4 ... Pulse generator, 5 ... Control section, 16 ... Channel status extraction section, 52 ... Category code extraction section, 53 ...
Copy bit extraction unit, 54 ... Digital recording judgment unit

Claims (1)

(57) [Scope of utility model registration request] 1. A digital input terminal to which a digital signal in the form including a digital audio signal and a control signal indicating whether or not digital copying is possible is input, and a digital audio signal in the digital signal input from the digital input terminal. Recording means for recording on a magnetic tape by a rotary head, pulse generating means for generating a pulse with the rotation of the rotary head, and detecting the state of the control signal in the digital signal in synchronization with the generation of the pulse, A magnetic recording control device comprising: a control unit that controls recording or recording stop in the recording unit.