JP2005327336A - Input signal processing device, recording device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform recording without sound distortion at an appropriate level corresponding to the line-output level (2 Vrms) of stationary audio devices and the line-output level (approx. 0.775-1 Vrms) of portable audio devices. <P>SOLUTION: The user can select either one of the two line-input modes, the 1st mode corresponding to the line-out level of approx. 0.775-1 Vrms and the 2nd mode corresponding to the line-out level of 2 Vrms. When the 2nd mode is selected, the audio signal gain (level) is reduced by the variable gain amplifier composing the line-input circuits or the AGC circuit. Or a clearance is maintained between the AGC limit level and the maximum input level by lowering the limit level of the AGC. Alternatively, the distortions are hardly made even at steep attacks by shortening the attack time of the AGC processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an input signal processing apparatus, a recording apparatus, and a recording method for an audio signal as line input.

JP-A-9-93063

  Various recording devices that record line-input audio signals (audio signals) with respect to optical disc (magneto-optical disc) media, tape media, and the like are widely used. For example, MD recorders using MD (Mini Disc), which is a magneto-optical disc, as recording media are widely used as stationary and portable devices, but these MD recorders are provided with a line input terminal and are connected to external devices and lines. By being connected, an audio signal supplied from an external device can be recorded on the MD.

When recording the input audio signal is considered, the level of the input audio signal may fluctuate greatly, and distortion may occur in the recorded sound due to an excessive level input. For example, in a device that digitizes and processes an input audio signal, if there is an input that exceeds the upper limit (full bit value) of the conversion range of the A / D converter, it will be clipped and output with the full bit value. Distortion occurs.
For this reason, an AGC (auto gain control) circuit is generally mounted in a circuit system for line input and microphone input in a recording apparatus. As already well known, the AGC circuit controls the gain of the variable gain amplifier according to the input level, and when there is an excessive level input, the level of the audio signal is suppressed by suppressing the level. It prevents distortion. A large number of techniques related to the AGC circuit are known, and for example, they are also disclosed in Patent Document 1 described above.

  Similarly, in order to prevent an excessive input level, an input level adjustment volume is provided so that the user can manually adjust the input level. For example, an attenuation volume for an audio signal as a line input or a microphone input is provided, and the user adjusts the volume level to an appropriate level, thereby preventing an excessive input from occurring.

By the way, regarding the line input, since the audio signal level is based on the line output level of the source-side device, it can be said that there is little sudden level fluctuation compared to the microphone input.
However, there are roughly two types of line outputs of audio devices that are currently popular as their effective voltages. For example, in the case of a stationary audio device, the maximum effective value of the line output is often set to 2 Vrms, while in the low voltage output device such as a portable audio device, the maximum effective value is about 0.775 to about 1 Vrms. There are often.

  On the other hand, automatic gain adjustment (AGC) at the time of line input recording in a portable recording device is optimized for low voltage output devices (about 0.775 to about 1 Vrms) such as portable machines. Therefore, when recording is performed by connecting to the line output of 2Vrms output, which is often found in stationary devices and high-end portable devices, the gain of the input audio signal is too high, and there is little margin to the maximum input level of the A / D converter, making it steep There is a tendency that the AGC is not in time for an attack or the like and the sound is easily broken.

Here, considering the line input from a stationary device on the recording device side, for example, if attenuation processing is performed on the line input audio signal or the AGC characteristic is optimized, it can be improved that the sound breaks, In that case, in the case of a line input audio signal from a portable audio device, the level is suppressed more than necessary, the dynamic range is wasted, and the conversion range of the A / D converter cannot be used effectively.
The line input level may be manually changed by the user. However, manual input volume adjustment is relatively difficult and troublesome for the user.

  Therefore, the present invention is suitable for both the line output level (2 Vrms) often found in stationary audio devices and the line output level (about 0.775 to about 1 Vrms) often found in portable audio devices, with no sound cracking. The purpose is to be able to record at a reasonable level and not to be too difficult for the user.

  An input signal processing apparatus according to the present invention includes a line input unit for inputting an audio signal from an external device, and a selection for performing an operation of selecting a line input mode between the first mode and the second mode as a user operation. When the second mode is selected by the operation means and the selection operation means, the gain of the audio signal input by the line input means is lower than when the first mode is selected. Gain switching means, and auto gain control means for suppressing the excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level.

  The input signal processing apparatus of the present invention includes the same line input means, selection operation means, and auto gain control means as those described above, and when the second mode is selected by the selection operation means, There is provided limit level switching means for lowering the limit level of the auto gain control means than when the mode is selected.

  The input signal processing apparatus of the present invention includes the same line input means, selection operation means, and auto gain control means as those described above, and when the second mode is selected by the selection operation means, There is provided attack time switching means for shortening the attack time when the gain is reduced in the auto gain control means than when the mode is selected.

  In addition to the configuration of these input signal processing devices, the recording device of the present invention includes recording means for recording the audio signal output via the auto gain control means on a recording medium.

  The recording method of the present invention includes a mode determination step for determining a selection state of a first mode and a second mode as a line input mode selected by a user operation as a recording method of a line input audio signal, and the mode determination described above. A gain switching step for switching the gain so as to lower the gain of the audio signal when the step determines that the second mode is selected, compared to when the first mode is selected; An auto gain control step that suppresses an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level, and output through the auto gain control step. Recording step of recording the recorded audio signal on a recording medium Equipped with a.

  The recording method of the present invention also includes a mode determining step, an auto gain control step, and a recording step. When the mode determining step determines that the second mode is selected, A limit level switching step is provided for setting the limit level of the auto gain control process in the auto gain control step to be lower than when the first mode is selected.

  The recording method of the present invention also includes a mode determining step, an auto gain control step, and a recording step. When the mode determining step determines that the second mode is selected, There is provided an attack time switching step for setting the attack time when the gain is lowered in the auto gain control process in the auto gain control step to be shorter than when the first mode is selected.

That is, the present invention comprises two line input modes, a first mode corresponding to the line output level (about 0.775 to about 1 Vrms) and a second mode corresponding to the line output level (about 2 Vrms). To.
If the AGC circuit system (automatic gain control means) is optimized to the line output level (about 0.775 to about 1 Vrms) which is the first mode, for example, when the second mode is set, By using the three methods (1) to (3) or using them in combination, a line output level of 2 Vrms is supported.
(1) The gain (level) is lowered by a line input system circuit or a variable gain amplifier (PGA: programmable gain amplifier) constituting the AGC.
(2) The AGC limit level (AGC level: the level at which AGC starts gain reduction processing) is lowered to maintain the clearance from the maximum input level.
(3) The attack time of the AGC process is shortened so that even a steep attack is less likely to be distorted.

According to the present invention, there are two line input modes, a first mode corresponding to a line output level (about 0.775 to about 1 Vrms) and a second mode corresponding to a line output level (about 2 Vrms). This can be selected by the user.
When the second mode is selected, there is provided gain switching means for lowering the gain of the audio signal input by the line input means than when the first mode is selected.
Alternatively, when the second mode is selected, a limit level switching unit that lowers the limit level of the auto gain control unit is provided compared to when the first mode is selected.
Or, when the second mode is selected, there is provided an attack time switching means for shortening the attack time when the gain is reduced in the auto gain control means than when the first mode is selected.
As a result, for example, even when a stationary audio device is connected in a line and an audio signal having a maximum effective value of 2 Vrms is recorded, the distortion is eliminated and recording at an appropriate level is possible. Of course, in the case of the first mode, it is possible to record at an appropriate level when recording an audio signal having a maximum effective value of about 0.775 to about 1 Vrms.
In such a line input mode, the user only has to select one, and the user's operation is much simpler than the input volume adjustment.
That is, according to the present invention, the input signal processing and AGC processing are optimized only by the user selecting the line input mode, and appropriate recording is possible regardless of the connected audio device.

Embodiments of the present invention will be described below. The recording / reproducing apparatus of the embodiment has a function as a recording apparatus capable of recording a line-input audio signal (music or the like) on a recording medium, and corresponds to the recording apparatus of the present invention. The recording method of the present invention is also executed. Further, the line input system has a configuration as the input signal processing device of the present invention.
The description will be given in the following order.
1. 1. Configuration of recording / reproducing apparatus and disc 2. Line input system for switching the gain. Line input system for limit level switching 4. Line input system for switching attack time 5. Line input system for complex switching Modified example

1. Configuration of recording / reproducing apparatus and disc

FIG. 1 is a block diagram showing an internal configuration example of a recording / reproducing apparatus 1 as an embodiment.
As an example, the recording / reproducing apparatus 1 according to this embodiment is a recording / reproducing apparatus for a mini-disc (MD) disc that is a magneto-optical disc on which data recording is performed by a magnetic field modulation method. However, not only music mini-discs that are already in widespread use, but also high-density recording that can be used for storage of various data for computer use (also called next-generation discs). It is a playback device.

Further, the recording / reproducing apparatus 1 of this example is a device capable of data communication with an external device such as a personal computer (or network) 50, for example.
For example, the recording / reproducing apparatus 1 can function as an external storage device for the personal computer 50 by being connected to the personal computer 50 via a transmission path 51 such as a USB cable. In addition, music or various data is downloaded via a personal computer 50 or connected to the network by providing a function that can be directly connected to the network, and the disc loaded in the storage unit 2 in the recording / playback apparatus 1 is downloaded. It can also be saved.

On the other hand, the recording / reproducing apparatus 1 functions as an audio device, for example, without being connected to the personal computer 50 or the like. For example, audio data such as music / speech input from other audio devices, etc., or audio data such as music / speech input from a connected microphone (or built-in microphone) can be recorded on a disk or recorded on a disk. Audio data can be played back and output.
That is, the recording / reproducing apparatus 1 of this example is an apparatus that can be used as a general-purpose data storage device by being connected to the personal computer 50 or the like, and can also be used as an audio recording / reproducing device by itself.

Here, prior to the description of the configuration of the recording / reproducing apparatus 1 of the present example, an outline of a next-generation disk by magneto-optical recording that the recording / reproducing apparatus 1 supports will be described.
First, such a next-generation disc uses a FAT (File Allocation Table) system as a file management system to record and reproduce content data such as audio data so that compatibility with current personal computers can be achieved. Is.
Further, by improving the current MD system, such as an error correction method and a modulation method, the data recording capacity is increased and the data reliability is increased.

Two types of specifications are currently being developed as recording and playback formats for next-generation discs. For the sake of explanation, these will be referred to as a first next generation MD and a second next generation MD.
The first next-generation MD is a specification that uses a disk that is exactly the same as the disk used in the current MD system, and the second next-generation MD is a disk that is used in the current MD system. The outer shape is the same, but by using magnetic super-resolution (MSR) technology, the recording density in the linear recording direction is increased and the recording capacity is further increased.

In the current MD system (audio MD or MD-DATA), a magneto-optical disk having a diameter of 64 mm housed in a cartridge is used as a recording medium. The disc has a thickness of 1.2 mm, and a center hole having a diameter of 11 mm is provided at the center thereof. The cartridge has a length of 68 mm, a width of 72 mm, and a thickness of 5 mm.
In the specifications of the first and second next generation MDs, the shape of the disc and the shape of the cartridge are all the same. Regarding the start position of the lead-in area, the first and second next-generation MD disks start from a radial position of 29 mm and are the same as the disks used in the current MD system.
That is, compatibility with the conventional MD system on the outer shape is ensured.

  Regarding the track pitch, in the second next generation MD, it is considered to be 1.2 μm to 1.3 μm (for example, 1.25 μm). On the other hand, the track pitch is set to 1.6 μm in the first next generation MD that uses the disk of the current MD system. The bit length of the first next generation MD is 0.44 μm / bit, and the second next generation MD is 0.16 μm / bit. The redundancy is 20.50% for both the first and second next generation MDs.

In the second generation MD specification disk, the recording capacity in the linear density direction is improved by using a magnetic super-resolution technique. In the magnetic super-resolution technology, when a predetermined temperature is reached, the cut layer becomes magnetically neutral, and the magnetic wall transferred to the recording layer is transferred, so that a minute mark can be seen in the beam spot. It is a thing using what becomes.
Specifically, in the second generation MD disc, a magnetic layer serving as a recording layer for recording information, a cutting layer, and a magnetic layer for reproducing information are stacked on a transparent substrate. The cutting layer is an exchange coupling force adjusting layer. When the temperature reaches a predetermined temperature, the cut layer becomes magnetically neutral, and the domain wall transferred to the recording layer is transferred to the reproducing magnetic layer. As a result, minute marks can be seen in the beam spot. At the time of recording, a minute mark can be generated by using a laser pulse magnetic field modulation technique.

In the second generation MD disc, the groove is deepened and the groove is sharpened to improve detrack margin, crosstalk from the land, crosstalk of the wobble signal, and focus leakage. Yes. That is, in the second next-generation MD specification disk, the groove depth is, for example, 160 nm to 180 nm, the groove inclination is, for example, 60 degrees to 70 degrees, and the groove width is, for example, 600 nm to 700 nm.
Regarding the optical specification, in the specification of the first next generation MD, the laser wavelength λ is 780 nm, and the numerical aperture NA of the objective lens of the optical head is 0.45. Similarly, in the specification of the second next generation MD, the laser wavelength λ is 780 nm, and the aperture ratio NA of the optical head is 0.45.
As the recording method, the groove recording method is adopted for both the first and second next generation MDs. That is, the groove (groove on the disk surface of the disk) is used as a track for recording and reproduction.

Furthermore, as an error correction coding system, convolutional codes based on ACIRC (Advanced Cross Interleave Reed-Solomon Code) are used in the current MD system, but in the specifications of the first and second next generation MDs, RS A block-complete code combining a Reed Solomon-Long Distance Code (LDC) and a Burst Indicator Subcode (BIS) is used.
By adopting a block completion type error correction code, a linking sector becomes unnecessary. In an error correction method combining LDC and BIS, an error location can be detected by BIS when a burst error occurs. Using this error location, erasure correction can be performed by the LDC code.

As an addressing method, a wobbled groove method is used in which a single spiral groove is formed and wobbles as address information are formed on both sides of the groove. Such an address system is called ADIP (Address in Pregroove).
The specification of ADIP is the same as that of the current MD system. However, in the current MD system, a sector of 2352 bytes is used as an access unit for recording and reproduction, whereas the first and second next generation MDs are used. In the specification, 64 Kbytes are used as a recording / reproducing access unit (recording block).
In the current MD system, a convolutional code called ACIRC is used as an error correction code, whereas in the specifications of the first and second next generation MDs, a block completion type combining LDC and BIS. Is used.
Therefore, in the specification of the first next generation MD that uses the disk of the current MD system, the handling of the ADIP signal is made different from that in the current MD system. In the second next-generation MD, the specification of the ADIP signal is changed so as to match the specification of the second next-generation MD.

  As for the modulation method, EFM (8 to 14 Modulation) is used in the current MD system, whereas RLL (1, 7) PP (RLL) is used in the specifications of the first and second next generation MDs. Run Length Limited, PP; Parity Preserve / Prohibit rmtr (repeated minimum transition run length)) (hereinafter referred to as 1-7pp modulation). Further, the data detection method is Viterbi using partial response PR (1, 2, 1) ML in the first next generation MD and using partial response PR (1, -1) ML in the second next generation MD. It is a decoding method.

  Further, the disk drive system is CLV (Constant Linear Verocity), and the linear velocity is 2.7 m / sec in the first next generation MD specification, and 1.98 m in the second next generation MD specification. Per second. In the specification of the current MD system, it is 1.2 m / second for a 60-minute disk and 1.4 m / second for a 74-minute disk.

In the specification of the first next-generation MD in which a disk used in the current MD system is used as it is, the total data recording capacity per disk is about 300 Mbytes (when an 80-minute disk is used). By changing the modulation method from EFM modulation to 1-7pp modulation, the window margin is changed from 0.5 to 0.666, and in this respect, a 1.33 times higher density can be realized.
Further, since the error correction method is a combination of BIS and LDC from the ACIRC method, the data efficiency is improved, and in this respect, 1.48 times higher density can be realized. Overall, a data capacity of about twice that of the current MD system was realized using exactly the same disk.
On the other hand, in the disc of the second next generation MD specification using magnetic super-resolution, the recording density is further increased in the linear density direction, and the total data recording capacity is about 1 Gbyte.
The data rate is 4.4 Mbit / sec in the first next generation MD, and 9.8 Mbit / sec in the second next generation MD.

FIG. 2A shows the configuration of the first next-generation MD disk.
The first next-generation MD disc is a diverted version of the current MD system disc. That is, a dielectric film, a magnetic film, a dielectric film, and a reflective film are laminated on a transparent polycarbonate substrate. Further, a protective film is laminated thereon.
In the first next-generation MD disk, as shown in FIG. 2A, a P-TOC (pre-mastered TOC (Table Of Contents)) area is provided in the lead-in area on the inner periphery of the disk. This is a pre-mastered area as a physical structure, and control information and the like are recorded as P-TOC information by embossed pits.

The outer periphery of the lead-in area in which the P-TOC area is provided in this way is a recordable area (a magneto-optical recording area), which is a recordable / reproducible area in which a groove is formed as a guide groove for a recording track. ing. A U-TOC (user TOC) is provided on the inner periphery of the recordable area.
The U-TOC in this case has the same configuration as the U-TOC used for recording disc management information in the current MD system. For confirmation, the U-TOC is management information that can be rewritten according to the order of tracks (audio tracks / data tracks), recording, erasing, etc. in the current MD system. The start position, end position, and mode are managed for the parts constituting the track.

  An alert track is provided on the outer periphery of the U-TOC. The alert track is a warning track on which a warning sound indicating that this disc is used in the first next generation MD system and cannot be reproduced by a player of the current MD system is recorded.

FIG. 2B shows the configuration of the recordable area of the disc of the first next generation MD specification.
As shown in FIG. 2B, a U-TOC and an alert track are provided at the beginning (inner circumference side) of the recordable area. In the area including the U-TOC and the alert track, the data is modulated by EFM and recorded so that it can be reproduced by a player of the current MD system.
An area where data is modulated and recorded by 1-7pp modulation of the next generation MD1 system is provided on the outer periphery of the area where the data is modulated and recorded by the EFM modulation. The area where data is modulated and recorded by EFM modulation and the area where data is modulated and recorded by 1-7pp modulation are separated by a predetermined distance, and a guard band is provided. .
Since such a guard band is provided, it is possible to prevent a malfunction from being caused by mounting the disc of the first next generation MD specification on the current MD player.

A DDT (Disc Description Table) area and a secure track are provided at the beginning (inner circumference side) of an area where data is modulated and recorded by 1-7pp modulation. The DDT area is provided for performing a replacement sector process for a physically defective sector (recording block).
A unique ID (UID) is further recorded in the DDT area. The UID is an identification code unique to each recording medium, and is based on a predetermined random number, for example.
The secure track stores information for protecting the content.

Furthermore, a FAT (File Allocation Table) area is provided in an area where data is modulated and recorded by 1-7pp modulation. This FAT area is an area for managing data in the FAT system.
The FAT system performs data management conforming to the FAT system used in general-purpose personal computers. The FAT system performs file management by a FAT chain using a directory indicating entry points of files and directories at the root and a FAT table in which FAT cluster connection information is described.
In such a first-generation MD specification disc, the U-TOC area has information on the start position of the alert track and the start position of the area where the data is modulated by 1-7pp modulation and recorded. This information is recorded.

Here, when the first next-generation MD disc having the above-described configuration is mounted on the player of the current MD system, the U-TOC area is read, and the position of the alert track is known from the U-TOC information. The alert track is accessed and the playback of the alert track is started. In the alert track, a warning sound is recorded indicating that this disc is used in the first next generation MD system and cannot be reproduced by a player of the current MD system.
This warning sound informs that this disc cannot be used with the current MD system player.
Note that the warning sound in this case may be a warning in a language such as “cannot be used with this player”. Of course, a buzzer sound may be used.

  On the other hand, when the disc of the first next generation MD is mounted on the player compliant with the first next generation MD, the U-TOC area is read, and the data is 1-7pp modulated from the U-TOC information. The start position of the recorded area is known, and the above-mentioned DDT, secure track, and FAT area are read. As described above, in the 1-7pp modulation data area, data management is performed by the FAT system, not by the U-TOC.

Next, FIG. 3A shows a configuration of a second next-generation MD disk.
Also in this case, the disk is formed by laminating a dielectric film, a magnetic film, a dielectric film, a reflective film on a transparent polycarbonate substrate, and a protective film on the upper layer.
In the case of the second next-generation MD disc, as shown in the figure, control information is recorded in the lead-in area on the inner periphery of the disc by an ADIP signal.
In the second next-generation MD disc, the lead-in area is not provided with a P-TOC by embossed pits, and instead, control information by an ADIP signal is used. The recordable area starts from the outer periphery of the lead-in area, and is a recordable / reproducible area in which a groove is formed as a guide groove for a recording track. In this recordable area, data is modulated and recorded by the 1-7 pp modulation method.

Whether a certain disk is the first next generation MD or the second next generation MD can be determined from, for example, lead-in information.
That is, if a P-TOC due to an embossed pit is detected in the lead-in, it can be determined that the disc is the current MD or the first next-generation MD. If control information based on the ADIP signal is detected in the lead-in and the P-TOC due to the embossed pit is not detected, it can be determined that the second next-generation MD.
Note that the determination of the first and second next-generation MDs is not limited to such a method. It is also possible to discriminate from the phase of the tracking error signal between on-track and off-track. Of course, a detection hole for disc identification may be provided in the cartridge or the like.

As the configuration of the recordable area of the disc of the second next generation MD specification, as shown in FIG. 3B, an area where data is modulated and recorded by the 1-7pp modulation method is formed. A DDT area and a secure track are provided at the beginning (inner circumference side) of an area where data is modulated and recorded by the 1-7pp modulation method.
Also in this case, the DDT area is an area for performing a replacement sector process on a physically defective sector (recording block). The UID described above is recorded in the DDT area. Further, in this case, information for protecting the content is stored in the secure track.
A FAT area is provided in an area where data is modulated and recorded by 1-7pp modulation. The FAT area is an area for managing data in the FAT system. The FAT system performs data management conforming to the FAT system used in general-purpose personal computers.

In the second next-generation MD disc, no U-TOC area is provided as can be seen from the figure. That is, the second next-generation MD disc is assumed to be used only by a player compliant with the next-generation MD.
In a player compliant with the next-generation MD, when a second next-generation MD disc is loaded, the DDT, secure track, and FAT area at a predetermined position are read, and data management is performed using the FAT system. It will be.

In order to cope with the next generation disc as described above, the recording / reproducing apparatus 1 of this example shown in FIG. 1 includes a storage unit configured as shown in FIG. Recording / playback is assumed.
In FIG. 4, in the storage unit 2, the loaded disk 40 is rotationally driven by the spindle motor 29 by the CLV method. The disc 40 is irradiated with laser light from the optical head 19 during recording / reproduction.
In this case, as the disk 40, there is a possibility that the current MD specification disk, the first next generation MD specification disk, and the second next generation MD specification disk may be mounted. Therefore, the linear velocity differs depending on these discs.
For this reason, the spindle motor 29 is rotated in accordance with different linear velocities corresponding to the loaded disks 40.

  The optical head 19 performs a high level laser output for heating the recording track to the Curie temperature during recording, and a relatively low level laser output for detecting data from reflected light by the magnetic Kerr effect during reproduction. . For this reason, although not shown, the optical head 19 is equipped with a laser diode as laser output means, an optical system including a polarizing beam splitter, an objective lens, and the like, and a detector for detecting reflected light. The objective lens provided in the optical head 19 is held so as to be displaceable in the radial direction of the disk and in the direction of contacting and separating from the disk, for example, by a biaxial mechanism.

A magnetic head 18 is disposed at a position facing the optical head 19 with the disk 40 interposed therebetween. The magnetic head 18 performs an operation of applying a magnetic field modulated by the recording data to the disk 40.
Although not shown, a sled motor and a sled mechanism are provided to move the entire optical head 19 and the magnetic head 18 in the radial direction of the disk.

  In the case of the second next-generation MD disk, the optical head 19 and the magnetic head 18 can form minute marks by performing pulse drive magnetic field modulation. In the case of the current MD disc or the first next-generation MD disc, the magnetic field modulation method is used.

  In addition to the recording / reproducing head system using the optical head 19 and the magnetic head 18 and the disk rotation driving system using the spindle motor 29, the storage unit 2 includes a recording processing system, a reproducing processing system, a servo system, and the like.

In the recording processing system, in the case of the disc of the current MD system, at the time of recording an audio track, error correction coding is performed by ACIRC, data is recorded by being modulated by EFM, and the first and second next generations. In the case of MD, there is provided a portion for performing error correction coding by a system combining BIS and LDC, and modulating and recording by 1-7pp modulation.
The playback processing system uses EFM demodulation and error correction processing by ACIRC during playback of the current MD system disk, and partial response and Viterbi decoding during playback of the first and second next-generation MD system disks. A portion for performing 1-7pp demodulation based on data detection and error correction processing by BIS and LDC is provided.
Further, a part for decoding an address based on an ADIP signal of the current MD system or the first next generation MD and a part for decoding an ADIP signal of the second next generation MD are provided.

Information detected as reflected light by laser irradiation of the optical head 19 on the disk 40 (photocurrent obtained by detecting the laser reflected light with a photodetector) is supplied to the RF amplifier 21.
The RF amplifier 21 performs current-voltage conversion, amplification, matrix calculation, and the like on the input detection information, and reproduces a reproduction RF signal, a tracking error signal TE, a focus error signal FE, and groove information (track on the disk 40) as reproduction information. ADIP information recorded by wobbling) is extracted.

When reproducing the disc of the current MD system, the reproduced RF signal obtained by the RF amplifier is processed by the EFM demodulator 24 and the ACIRC decoder 25.
That is, the reproduced RF signal is binarized by the EFM demodulator 24 to be converted into an EFM signal sequence, EFM demodulated, and further subjected to error correction and deinterleave processing by the ACIRC decoder 25. That is, at this time, the ATRAC compressed data state is entered.
At the time of reproducing the disk of the current MD system, the selector 26 is selected on the B contact side, and the demodulated ATRAC compressed data is output as reproduced data from the disk 40.

On the other hand, when reproducing the first and second next-generation MD discs, the reproduction RF signal obtained by the RF amplifier 21 is processed by the RLL (1-7) PP demodulator 22 and the RS-LDC decoder 25. . That is, the reproduced RF signal is detected by the RLL (1-7) PP demodulator 22 by means of data detection using PR (1, 2, 1) ML or PR (1, -1) ML and Viterbi decoding. ) Reproduced data as a code string is obtained, and RLL (1-7) demodulation processing is performed on this RLL (1-7) code string. Further, the RS-LDC decoder 23 performs error correction and deinterleave processing.
When the first and second next-generation MD discs are reproduced, the selector 26 is selected on the A contact side, and the demodulated data is output as reproduced data from the disc 40.

The tracking error signal and focus error signal output from the RF amplifier 21 are supplied to the servo circuit 27, and the groove information is supplied to the ADIP demodulator 30.
The ADIP demodulator 30 performs band limitation on the groove information by a bandpass filter to extract a wobble component, and then performs FM demodulation and biphase demodulation to demodulate the ADIP signal.
The thus-demodulated ADIP address, which is absolute address information on the disk, is supplied to the system controller 8 shown in FIG. The system controller 8 executes necessary control processing based on the ADIP address.
The groove information is supplied to the servo circuit 27 for spindle servo control.

The servo circuit 27 generates a spindle error signal for CLV servo control, for example, based on an error signal obtained by integrating the phase error with the reproduction clock (PLL clock at the time of decoding) with respect to the groove information.
Further, the servo circuit 27 performs various servo control signals (tracking control signals) based on a spindle error signal, a tracking error signal supplied from the RF amplifier 21, a focus error signal, a track jump command, an access command, or the like from the system controller 8. , A focus control signal, a thread control signal, a spindle control signal, etc.) are generated and output to the motor driver 28. That is, various servo control signals are generated by performing necessary processing such as phase compensation processing, gain processing, and target value setting processing on the servo error signal and command.

The motor driver 28 generates a required servo drive signal based on the servo control signal supplied from the servo circuit 27. The servo drive signal here includes a biaxial drive signal for driving the biaxial mechanism (two types of focus direction and tracking direction), a sled motor drive signal for driving the sled mechanism, and a spindle motor drive signal for driving the spindle motor 29. It becomes.
With such a servo drive signal, focus control and tracking control for the disk 40 and CLV control for the spindle motor 29 are performed.

When recording audio data on the disc of the current MD system, the selector 16 is connected to the B contact, so that the ACIRC encoder 14 and the EFM modulator 15 function.
In this case, the compressed data supplied from the cache memory 3 shown in FIG. 1 as recording data is subjected to interleaving and error correction code addition by the ACIRC encoder 14 and then EFM modulation by the EFM modulation unit 15.
The EFM modulation data is supplied to the magnetic head driver 17 via the selector 16, and the magnetic head 18 applies a magnetic field to the disk 40 based on the EFM modulation data, thereby recording an audio track.

On the other hand, when data is recorded in the first next generation MD or the second next generation MD, the selector 16 is connected to the A contact, and the RS-LDC encoder 12 and the RLL (1-7) PP modulation unit 13 Will work. In this case, high-density data from the cache memory 3 is subjected to interleaving and RS-LDC error correction code addition by the RS-LDC encoder 12, and then RLL (1-7) PP modulation unit 13 performs RLL (1 -7) Modulation is performed.
Then, the recording data as the RLL (1-7) code string is supplied to the magnetic head driver 17 via the selector 16, and the magnetic head 18 applies a magnetic field based on the modulation data to the disk 40, thereby data tracks. Is recorded.

The laser driver / APC 20 causes the laser diode to perform a laser emission operation during reproduction and recording as described above, but also performs a so-called APC (Automatic Laser Power Control) operation.
That is, although not shown, a detector for laser power monitoring is provided in the optical head 19, and the monitor signal is fed back to the laser driver / APC 20. The laser driver / APC 20 compares the current laser power obtained as the monitor signal with the set laser power and reflects the error in the laser drive signal, so that the laser power output from the laser diode is , It is controlled to stabilize at the set value.
As the laser power, values as reproduction laser power and recording laser power are set by the system controller 8 in a register in the laser driver / APC 20.

  Each of the above operations (access, various servo, data write, and data read operations) is executed based on an instruction from the system controller 8 shown in FIG.

Returning to FIG. 1, the overall configuration of the recording / reproducing apparatus 1 of this example will be described.
In FIG. 1, a cache memory 3 is a cache memory that buffers data recorded on the disk 40 by the storage unit 2 having the above configuration or data read from the disk 40 by the storage unit 2, for example, D- It consists of RAM.
Writing / reading data to / from the cache memory 3 is controlled by a task activated in the system controller (CPU) 8.

  The USB interface 4 performs processing for data transmission when connected to the personal computer 50 through a transmission path 51 as a USB cable, for example.

The input / output processing unit 5 performs processing for input / output of recording / playback data, for example, when the recording / playback apparatus 1 functions alone as an audio device.
The input / output processing unit 5 includes, for example, an analog audio signal input unit such as a line input circuit / microphone input circuit, an A / D converter, and a digital audio data input unit as an input system. It also includes an ATRAC compression encoder / decoder. The ATRAC compression encoder / decoder is a circuit for executing compression / decompression processing of audio data by the ATRAC system. Of course, the recording / reproducing apparatus of the present embodiment may adopt a configuration capable of recording / reproducing compressed audio data in other formats such as MP3. In this case, these compressed audio data An encoder / decoder corresponding to the format may be provided.
In this embodiment, video data is not limited to a format that can be recorded / reproduced. For example, MPEG4 can be considered. The input / output processing unit 5 may be provided with an encoder / decoder corresponding to such a format.
Further, the input / output processing unit 5 includes an analog audio signal output unit such as a digital audio data output unit and a D / A converter and a line output circuit / headphone output circuit as an output system.

  In this case, the input / output processing unit 5 includes an encryption processing unit (not shown). In the encryption processing unit, for example, the AV data to be recorded on the disk is encrypted by a predetermined algorithm. For example, when the AV data read from the disk is encrypted, a decryption process for decryption is executed as necessary.

Audio data is recorded on the disc as processing via the input / output processing unit 5 when, for example, digital audio data (or an analog audio signal) is input to the input / output processing unit 5 as an input TIN.
The input TIN collectively represents various inputs such as digital audio data input using an optical cable, analog audio signal input as a line input, and analog audio signal input using a connected external microphone. Although not shown, for example, a microphone may be built in the recording / reproducing apparatus 1, and an analog audio signal obtained by the built-in microphone may be used as the input TIN.

  Linear PCM digital audio data as input TIN, or linear PCM audio data obtained by analog audio signal input and converted by an A / D converter is ATRAC compression encoded as necessary and stored in the cache memory 3. The Then, the data is read from the cache memory 3 and transferred to the storage unit 2 at a predetermined timing (data unit corresponding to an ADIP cluster). In the storage unit 2, the transferred compressed data is modulated by a predetermined modulation method and recorded on the disk.

  When mini-disc audio data is reproduced from the disc, the storage unit 2 demodulates the reproduced data into the ATRAC compressed data state and transfers the data to the cache memory 3. Then, it is read from the cache memory 3 and transferred to the input / output processing unit 5. The input / output processing unit 5 performs ATRAC compression decoding on the supplied compressed audio data to obtain linear PCM audio data, which is output from the digital audio data output unit as an output TOUT. Alternatively, an analog audio signal is obtained by a D / A converter, and line output / headphone output is performed as an output TOUT.

The system controller 8 performs overall control in the recording / reproducing apparatus 1 and communication control with the connected personal computer 50.
The ROM 8a shown in the figure stores an operation program for the system controller 8, fixed parameters, and the like.
The RAM 8b is used as a work area by the system controller 8 and is a storage area for various necessary information.
For example, various management information and special information read from the disk 40 by the storage unit 2, for example, the management information of the music track such as the above-described P-TOC data, U-TOC data, FAT data, etc. are taken into the cache memory 3. However, the system controller 8 takes necessary information out of the management information into the RAM 8b for processing.
The cache management memory 9 is composed of, for example, an S-RAM, and stores information for managing the state of the cache memory 3. The system controller 8 controls data cache processing while referring to the cache management memory 9.

The display unit 6 displays various information to be presented to the user based on the control of the system controller 8. For example, character data such as operation state, mode state, name of music, track number, time information, and other information are displayed.
In this example, when the disk 40 is a next-generation disk, for example, it is assumed that image data is stored in association with music data on the disk 40. It is also conceivable to display the image data associated in this way based on the control of the system controller 8 when the disk 40 is loaded or played back.

In the operation unit 7, various operation buttons, a jog dial, and the like are formed as various operators for user operations. The user gives a required operation instruction to the recording / reproducing apparatus 1 by operating the operation unit 7. The system controller 8 performs a predetermined control process based on the operation information input by the operation unit 7.
In this example, an operator for selecting a line input mode, which will be described later, is provided on the operation unit 7.

Note that the configuration of the recording / reproducing apparatus 1 described so far is merely an example. For example, the input / output processing unit 5 may include not only audio data but also an input / output processing system corresponding to video data.
Further, the connection with the personal computer 50 is not USB, but another external interface such as IEEE 1394 may be used.
Further, as the operation unit 7, it is possible to provide an operation element similar to that illustrated above on the remote controller.

In the recording / reproducing apparatus 1 having the above configuration, an AGC circuit system corresponding to the line input in the input / output processing unit 5 is provided.
Hereinafter, each example of the line input circuit system having the AGC processing system will be described.
The line input circuit system according to the present embodiment includes an example in which the gain of the audio signal is switched according to the line input mode, an example in which the limiter level of the AGC circuit is switched according to the line input mode, and the line input mode. Thus, there is an example in which the attack time of the AGC circuit is switched, and an example in which these switchings are performed in combination is conceivable.

2. Line input system for gain switching

First, a line input circuit system for switching the gain of an audio signal according to the line input mode will be described.
FIG. 5 shows the input / output processing unit 5, the system controller 8, and the operation unit 7 in the recording / reproducing apparatus 1. In particular, only the input signal processing circuit system corresponding to the line input and its control system are shown.

The input terminal 60 is a line input terminal, and an analog audio signal is input from the external device by connecting the line output of the external device to the input terminal 60.
The input analog audio signal is input to the attenuators 61A and 61B and attenuated by a predetermined level. Then, it is selected by a switch 66 and supplied to a PGA (programmable gain amplifier) 62.
The PGA 62 is a variable gain amplifier, and in particular, a gain value given to an analog audio signal is controlled by an AGC control unit 65 described later.
An analog audio signal to which a certain gain is given by the PGA 62 is converted into digital data by the A / D converter 63. The digital audio signal output from the A / D converter 63 is supplied to the encoder 64 and subjected to, for example, the above-described ATRAC compression encoding. The audio data that has been subjected to a predetermined encoding process in the encoder 64 is supplied to the cache memory 3 shown in FIG. After that, the data is transferred to the storage unit 2 having the configuration shown in FIG. 4, subjected to recording encoding processing, and recorded (recorded) on the disk 40.

The output of the A / D converter 63 is also supplied to the AGC control unit 65. The AGC control unit 65 monitors the level of the audio data output from the A / D converter 63 and detects whether or not a predetermined limit level (AGC level: a threshold value for operating the AGC function) has been exceeded.
When a level exceeding the limit level is detected, control is performed so that the gain of the PGA 62 is lowered at a predetermined attack time. Further, after the gain is lowered, the gain of the PGA 62 is recovered at a predetermined recovery time.

Here, switching control is performed on the switch 66 by the system controller 8.
As shown in the figure, the operation unit 7 is provided with an operation element 7a for the user to select a line input mode. By operating the operation element 7a, the user selects mode A or mode B as the line input mode. it can.
Mode A is a mode corresponding to an effective value of about 0.775 to about 1 Vrms of the line output level, and Mode B is a mode corresponding to an effective value of 2 Vrms of the line output level. That is, the user can select mode A when a portable audio device is connected as a device on the line output side to the recording / reproducing apparatus of this example, and mode B when a stationary audio device is connected. Good.

The system controller 8 determines the mode selection state of the user by the operation element 7a.
When it is determined that the mode A is selected by the operation element 7a, the system controller 8 controls the switch 66 to the terminal TA side. When it is determined that the mode B is selected, the system controller 8 sets the switch 66 to the terminal TB side. To control.
Accordingly, in the case of mode A, the input audio signal is supplied to the PGA 62 via the attenuator 61A, and in the case of mode B, the input audio signal is supplied to the PGA 62 via the attenuator 61B.
Here, the attenuators 61A and 61B are set to have different attenuation amounts.
That is, the attenuation amount (resistance division value) of each attenuator 61A, 61B is set so that the audio signal via the attenuator 61B becomes a signal attenuated by 6 to 8 dB as compared with the audio signal via the attenuator 61A. Settings have been made.

In this example, the attenuators 61A and 61B in each of the modes A and B are shown, but the input audio signal passes through the attenuator 61B only in the mode B without providing the attenuator 61A. It is good also as a structure. In that case, the attenuator 61B is set to attenuate the input audio signal by 6 to 8 dB.
In any case, in the case of mode B, the voltage level of the input audio signal is about ½ that of mode A.

FIG. 8 shows AGC input / output when the mode is switched in this way. The horizontal axis indicates the line input level at the time of input to the RPG 62, and the vertical axis indicates the output level of the PGA 62. L1 is a limit level (AGC level), and the full bit is a conversion upper limit (full bit) level of the A / D converter 63.
As described above, since the AGC control unit 65 performs the AGC process for suppressing the input level exceeding the limit level L1, the upper limit of the output level becomes the limit level L1.
Here, the case of mode A is indicated by a broken line, and the case of mode B is indicated by a solid line.
As described above, in the case of mode B, the level of the line input audio signal is attenuated by 6 to 8 dB compared to mode A. As a result, in the case of mode B, the input / output characteristics are shifted to the right in the drawing as compared to the case of mode A as shown in the figure.
Mode B is assumed to be input from a stationary audio device having a maximum effective value of about 2 Vrms. However, since it is a solid line characteristic, the AGC operation is not seen from the dynamic range of the input audio signal. The ratio of the level range XB to be performed is substantially equal to the level range XA in the case of input from a portable audio device having a maximum effective value of about 1 Vrms.

In other words, when AGC processing is performed assuming input from a portable audio device having a maximum effective value of about 0.775 to 1 Vrms, the line input mode is set to mode B when a stationary audio device is connected. Thus, the AGC function works within an appropriate range even for an audio signal having a maximum effective value of about 2 Vrms.
In addition, when an audio signal having a maximum effective value of about 2 Vrms is input, the margin to the maximum input level of the A / D converter 63 is an audio signal input having a maximum effective value of about 0.775 to 1 Vrms. Therefore, sound cracking is less likely to occur.
As described above, modes A and B are switched, and gain switching (switching of attenuation) according to the difference in effective value of the line input audio signal is performed, so that either a stationary audio device or a portable audio device can be connected to the line. Even when connected, audio signals can be recorded appropriately.

By the way, for gain switching, a configuration in which the attenuators 61A and 61B are not used is also conceivable. As shown in FIG. 6, the audio signal from the input terminal 60 is supplied to the PGA 62 as it is. Here, the system controller 8 supplies the gain setting signal CG of the PGA 62 in accordance with the operation of the operation element 7a, and switches the gain setting of the PGA 62.
That is, in the mode B, the gain setting of the PGA 62 may be halved compared to the mode A.
Even in the case of such a configuration, the input / output characteristics can be switched as shown in FIG.

3. Line input system for limit level switching

Next, a case where limit level switching of AGC processing is performed will be described.
FIG. 7 shows a configuration example. An input audio signal from the input terminal 60 is AGC processed by the PGA 62 and the AGC control unit 65, converted into digital data by the A / D converter 63, and supplied to the encoder 64.
In this case, the system controller 8 supplies the limit level setting signal CAGC of the AGC controller 65 according to the operation of the operation element 7a, and switches the limit level setting of the AGC controller 65 according to the mode.
That is, when the operation element 7a is operated in the mode A, the level L1 in FIG. 9 is set as the limit level, and when the operation element 7a is operated in the mode B, the level L2 is controlled as the limit level. The level L2 is a level 6 to 8 dB lower than the level L1.

Then, in the case of mode A, the input / output characteristics by AGC processing are as indicated by the broken line in FIG. 9, and in the case of mode B, the input / output characteristics by AGC processing are as indicated by the solid line.
When an audio signal having a maximum effective value of about 2 Vrms is input, by operating the AGC function at the limit level L2 as mode B, the AGC function can be applied even to an intermediate level input where the signal level does not reach 2 Vrms. The gain is lowered, so that a sufficient margin up to the clip level is secured. For this reason, even when there is a steep large input in the vicinity of 2 Vrms, the distortion can be prevented.

4). Line input system that switches attack time

Next, the case where the attack time of the AGC process is switched will be described.
The configuration example is the same as that in FIG. 7, but in this case, the system controller 8 supplies the attack time setting signal CAT of the AGC control unit 65 in accordance with the operation of the operation element 7a, and the AGC control unit 65 in accordance with the mode. Change the attack time setting.

The attack time is the time from when the input exceeds the limit level until the gain is lowered. For example, in the case of mode A, the attack time is the attack time ATa shown in FIG. It is switched to be ATb.
FIG. 10 shows a case where a level exceeding the full bit of the A / D converter 63 is generated as an input, as shown by a one-dot chain line.
Although not shown, the limit level of AGC processing is set to a level slightly lower than the full bit level.
In the mode A having a long attack time with respect to the input indicated by the alternate long and short dash line, the AGC responsiveness is moderate accordingly, so that the output waveform at the portion indicated by Z in the figure is indicated by the broken line. That is, due to the gradual response, the output is likely to exceed the full bit level with respect to the steep rise in the input waveform.
On the other hand, when the attack time ATb is set in mode B, the AGC response from the time when the limit level is exceeded to the time when the gain is lowered is rapid, so the output is a solid line even when the input waveform has a steep increase in level. As shown, it is often suppressed within the full bit level.

That is, by shortening the attack time, distortion is less likely in the case of a large level input.
For this reason, when it is difficult to achieve a large input level exceeding full bits, that is, when an audio signal having a maximum effective value of about 0.775 to 1 Vrms is input, the normal attack time ATa is set as mode A, while the large input level is set. In the case where an audio signal having a maximum effective value of about 2 Vrms is input, an input process that is less likely to cause sound cracking is possible by setting the attack time ATb in mode B.

5). Line input system for complex switching

Up to here, an example in which the gain of the input audio signal is reduced in the mode B in the attenuator 61B or the PGA 62, an example in which the limit level of the AGC process is reduced in the mode B, and the attack time of the AGC process in the mode B Although the example which shortens was shown, using these collectively is also considered.

For example, FIG. 11 shows input / output characteristics when all the three methods are executed.
First, by the gain setting of the attenuator 61B or the PGA 62, in the mode B, the gain of the input audio signal is decreased by less than 6 to 8 dB, for example, 3 dB.
Further, the limit level of the AGC processing is set to level L for mode A and L2 for mode B. The level L2 is, for example, 3 dB lower than the level L1.
Although not shown in FIG. 11, the attack time of AGC processing is set to ATa in FIG. 10 for mode A and ATb in mode B.
As can be seen from the characteristics in the modes A and B indicated by the broken line and the solid line in FIG. 11, the full bit of the A / D converter 63 is input in the mode B, that is, when an audio signal having a maximum effective value of about 2 Vrms is input. A sufficient margin up to the level can be secured, and input processing that does not easily cause sound cracking is realized.

Note that the combined method may be a combination of the above three methods or a combination of the two methods. That is,
An example in which the gain switching of the input audio signal and the limit level switching of AGC processing are performed according to modes A and B,
An example in which the gain switching of the input audio signal and the attack time switching of AGC processing are performed according to modes A and B.
An example of performing AGC processing limit level switching and attack time switching according to modes A and B,
Can be considered.

6). Modified example

Although the embodiments have been described above, various modifications can be considered as the present invention.

5 to 7, the AGC control unit 65 is configured to perform gain control on the PGA 62 by monitoring the output level of the A / D converter 63. However, the output stage (analog audio signal stage) of the PGA 62 is used. AGC configuration in which level detection is performed in step (3) is also conceivable.

In the above example, the recording apparatus, the input signal processing apparatus, and the recording method of the present invention have been described by taking the recording / reproducing apparatus corresponding to the MD as an example. However, the present invention can be applied to various devices.
For example, CD (Compact Disc), DVD (Digital Versatile Disc), and Blu-Ray discs are known as disc media other than MD, and audio signals can be recorded on those discs. Although systems are also known, the present invention can be applied as a recording apparatus or a signal input apparatus as those systems.
The present invention can also be applied to an audio recording device using a hard disk, a recording device using a magnetic tape, etc., and a recording device that records an audio signal using a semiconductor memory card or a built-in solid memory as a recording medium. .
For example, it is also preferable to employ the present invention in an audio input system in a video imaging device (video camera) that performs recording using a magnetic tape, a disk, or the like as a recording medium.
Furthermore, the present invention can also be applied to devices that transmit and output line input audio signals without recording (recording), for example.
That is, the present invention can be applied to any device that inputs a line input audio signal or a device that inputs a line input audio signal and records it on a recording medium.

It is a block diagram of the recording / reproducing apparatus of embodiment of this invention. It is explanatory drawing of the disk with which the recording / reproducing apparatus of embodiment respond | corresponds. It is explanatory drawing of the disk with which the recording / reproducing apparatus of embodiment respond | corresponds. It is a block diagram of the storage part of the recording / reproducing apparatus of embodiment. It is a block diagram of the structure of the line input system of embodiment which performs gain switching. It is a block diagram of the structure of the other line input system of embodiment which performs gain switching. It is a block diagram of the structure of the line input system of embodiment which performs limit level switching or attack time switching. It is explanatory drawing of the gain switching of embodiment. It is explanatory drawing of the limit level switching of embodiment. It is explanatory drawing of attack time switching of embodiment. It is explanatory drawing of the composite switching of embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Recording / reproducing apparatus, 2 Storage part, 3 Cache memory, 4 USB interface, 5 Input / output processing part, 6 Display part, 7 Operation part, 8 System controller, 8a ROM, 8b RAM, 9 Cache management memory, 61A, 61B Attenuator 62 Programmable gain amplifier (PGA), 63 A / D converter, 64 encoder, 65 AGC control unit

Claims (9)

Line input means for inputting an audio signal from an external device;
As a user operation, a selection operation means for performing an operation of selecting the line input mode in the first mode and the second mode,
When the second mode is selected by the selection operation means, gain switching means for lowering the gain of the audio signal input by the line input means than when the first mode is selected; ,
Auto gain control means for suppressing an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level;
An input signal processing apparatus comprising: Line input means for inputting an audio signal from an external device;
As a user operation, a selection operation means for performing an operation of selecting the line input mode in the first mode and the second mode,
Auto gain control means for suppressing an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level;
When the second mode is selected by the selection operation means, limit level switching means for lowering the limit level of the auto gain control means than when the first mode is selected;
An input signal processing apparatus comprising: Line input means for inputting an audio signal from an external device;
As a user operation, a selection operation means for performing an operation of selecting the line input mode in the first mode and the second mode,
Auto gain control means for suppressing an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level;
When the second mode is selected by the selection operation means, the attack time for shortening the attack time when the gain is reduced in the auto gain control means is greater than when the first mode is selected. Switching means;
An input signal processing apparatus comprising: Line input means for inputting an audio signal from an external device;
As a user operation, a selection operation means for performing an operation of selecting the line input mode in the first mode and the second mode,
When the second mode is selected by the selection operation means, gain switching means for lowering the gain of the audio signal input by the line input means than when the first mode is selected; ,
Auto gain control means for suppressing an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level;
Recording means for recording the audio signal output through the auto gain control means on a recording medium;
A recording apparatus characterized by comprising: Line input means for inputting an audio signal from an external device;
As a user operation, a selection operation means for performing an operation of selecting the line input mode in the first mode and the second mode,
Auto gain control means for suppressing an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level;
When the second mode is selected by the selection operation means, limit level switching means for lowering the limit level of the auto gain control means than when the first mode is selected;
Recording means for recording the audio signal output through the auto gain control means on a recording medium;
A recording apparatus characterized by comprising: Line input means for inputting an audio signal from an external device;
As a user operation, a selection operation means for performing an operation of selecting the line input mode in the first mode and the second mode,
Auto gain control means for suppressing an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level;
When the second mode is selected by the selection operation means, the attack time for shortening the attack time when the gain is reduced in the auto gain control means is greater than when the first mode is selected. Switching means;
Recording means for recording the audio signal output through the auto gain control means on a recording medium;
A recording apparatus characterized by comprising: As a recording method of line input audio signal,
A mode determination step for determining a selection state of the first mode and the second mode as a line input mode selected by a user operation;
When it is determined in the mode determination step that the second mode is selected, the gain switching is performed so that the gain of the audio signal is lowered compared to when the first mode is selected. Steps,
An auto gain control step for suppressing an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level;
A recording step of recording the audio signal output through the auto gain control step on a recording medium;
A recording method characterized by comprising: As a recording method of line input audio signal,
A mode determination step for determining a selection state of the first mode and the second mode as a line input mode selected by a user operation;
When it is determined in the mode determination step that the second mode is selected, the limit level of the automatic gain control process is set to be lower than that in the case where the first mode is selected. Limit level switching step;
As the auto gain control processing, an auto gain control step for suppressing an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level; ,
A recording step of recording the audio signal output through the auto gain control step on a recording medium;
A recording method characterized by comprising: As a recording method of line input audio signal,
A mode determination step for determining a selection state of the first mode and the second mode as a line input mode selected by a user operation;
When it is determined that the second mode is selected in the mode determination step, the attack time for reducing the gain in the automatic gain control process is shorter than when the first mode is selected. An attack time switching step that is set to
As the auto gain control process, an auto gain control step for suppressing an excessive level of the audio signal by reducing the gain of the variable gain amplifier in response to the signal level of the audio signal exceeding the limit level;
A recording step of recording the audio signal output through the auto gain control step on a recording medium;
A recording method characterized by comprising:

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