JP2005210180A - Input signal processing apparatus, recording apparatus, and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize AGC processing capable of coping with both the conversation recording or the like and music recording or the like. <P>SOLUTION: A standard mode wherein the attack time / recovery time suitable for recording a conversation, a conference, and comparatively quiet music (chamber music or the like) or the like is selected, and a music mode, wherein the attack time / recovery time suitable for recording music such as rock is selected, can selectively be set as to the AGC processing. In the case of the music mode, the by making the recovery time longer, unnatural level variations in music is suppressed and first and succeeding intermittent peak tones are less likely to be distorted, and by making the attack time shorter, distortions in the peak tone in excess of an AGC level are improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

JP-A-8-297923 JP-A-9-93063

  Various recording apparatuses for recording an audio signal (audio signal) collected by a microphone with respect to an optical disk (magneto-optical disk) medium, a tape medium, and the like are widely used. For example, MD recorders using magneto-optical discs such as MD (Mini Disc) as recording media are widely used as stationary and portable devices. For example, recording by a microphone or recording of a live performance, musical instrument, etc. It is used for various recording applications such as recording in practice, recording as a memo of a conference / meeting, recording of environmental sound.

Considering recording of these microphone input sounds, the level of the input audio signal often fluctuates 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, in general recording apparatuses, an AGC (auto gain control) circuit is mounted in the microphone input system. 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 great number of techniques related to the AGC circuit are known, and for example, they are also disclosed in Patent Documents 1 and 2.

By the way, in the AGC process, it is necessary to appropriately set an attack time and a recovery time.
The attack time is the time lag until the gain for the input signal is sufficiently lowered when there is an excessive input, and the recovery time is the gain that is reduced to the original level after the gain is reduced by the excessive input. It is time to be done.
Referring to FIGS. 7A and 7B, when there is an input signal as indicated by a broken line in FIG. 7A, the gain G is lowered when the input signal exceeds the AGC level. The AGC level is a threshold at which the AGC function is activated. That is, when the input signal becomes an excessive level exceeding the AGC level, for example, the gain G given to the input signal is lowered with an attack time AT as shown in FIG. 7B. As a result, the input signal is output with the level suppressed as shown by the one-dot chain line in FIG.
If the input signal does not reach the AGC level after the gain is lowered, the gain G is gradually increased. When the recovery time RC elapses, the gain G becomes the original level.

  Normally, the level of the audio signal varies in various ways, and the attack time and recovery time cannot be said uniquely depending on the level change (whether it is a steep change, etc.), the change width, etc. The attack time and the recovery time are set based on the time lag measured when an input signal whose level rises and falls with a predetermined steepness is given. As an example, in an AGC circuit of a microphone input system for audio recording, the attack time is set to about 170 milliseconds and the recovery time is set to about 4 seconds.

For example, setting the attack time to about 170 milliseconds and the recovery time to about 4 seconds is a setting suitable mainly for recording of conversations, conferences, meetings, and the like.
Depending on the AGC processing, the attack time should be as short as possible in order to prevent distortion due to excessive input. However, when recording a conversation or the like, even if a loud voice is suddenly input, for example, the sudden increase in the voice signal level due to the voice is not so steep when considered in the order of milliseconds, and about 170 milliseconds is practically sufficient. is there.
Further, in the case of conversation recording, since it is necessary to consider a case where a person with a low voice speaks immediately after a person with a high voice, it is not preferable to make the recovery time too long. On the other hand, when the recovery time is about 1 second, the fluctuation of the recorded signal level is noticeable. For these reasons, a recovery time of about 4 seconds is appropriate.

However, such a setting is not very appropriate when recording music, especially band practice, live performance, and the like.
For example, in the case of a music genre such as rock and pop, an excessively high level input is periodically generated as a strong rhythm sound, for example, a drum sound. In such music recording, if AGC processing is performed with a short recovery time of about 4 seconds, for example, there is an input exceeding the AGC level immediately after the gain is recovered to the original level, and the gain suddenly decreases again. It happens frequently. As a result, the recorded audio signal level is noticeable with periodic fluctuations, which is unnatural and extremely difficult to hear.
Also, drum sounds, electronic rhythm sounds, and the like often increase considerably sharply compared to loud sounds as human voices. If the attack time is about 170 milliseconds, the level is reduced by reducing the gain. Often repression is not in time. That is, distortion is likely to occur. In addition, even if the level of the audio signal is lowered after the volume peak due to the rhythm, the gain returns early due to the short recovery time, so that the sound tends to be broken even at intermittent peaks such as the rhythm sound.

Considering these points, it is sufficient to set the attack time to be short and the recovery time to be long when designing the AGC circuit, but this makes it impossible to perform appropriate processing for the above-described conversation recording.
For these reasons, it has been considered inappropriate to use the AGC function in recording relatively intense music. When recording music, it was recommended to turn off the AGC function and adjust the input level manually.
That is, the input level can be manually changed by the user, and the user can adjust it according to the situation (volume etc.) at the time of recording.

  However, it is not easy to set an optimal input level by manual input adjustment. Also, in situations where the input level fluctuates greatly or a loud volume is predicted, such as when recording live performances, it must be adjusted to a low level with a margin to prevent sound distortion. In that case, the dynamic range of the audio signal is sacrificed. For example, in the case of a recording apparatus that digitizes and processes an input audio signal with an A / D converter, the conversion range of the A / D converter cannot be used effectively. From these things, it took considerable skill to leave a good recording after adjusting the input level manually.

  SUMMARY OF THE INVENTION The present invention has an object to enable not only conversation recording and the like, but also to appropriately adjust the input level by AGC processing appropriately for relatively intense music such as rock and pop, and to easily perform good recording. To do.

An input signal processing device according to the present invention includes an auto gain control unit that suppresses an excessive level of signal input by performing gain control processing corresponding to a signal level on an audio signal obtained by a microphone, and the above auto gain. Selection means capable of selecting the operation mode of the control means, and mode control means for variably setting the attack time and / or recovery time of the gain control processing in the auto gain control means in accordance with the mode selected by the selection means With.
The recording apparatus of the present invention further includes recording means for recording the audio signal output via the auto gain control means on a recording medium, in addition to the input signal processing apparatus having the above configuration.
In these input signal processing devices or recording devices, the selection means can select a standard mode and a music mode, and the mode control means determines the attack time when the standard mode is selected. 1 attack time and / or when the recovery time is set as the first recovery time and the music mode is selected, the attack time is set to a second attack time shorter than the first attack time. And / or the recovery time is set to a second recovery time longer than the first recovery time.

  The recording method of the present invention includes a selection detection step for detecting a selection state between the standard mode and the music mode, a first attack time longer than that in the music mode when the standard mode is selected, and / or When the first recovery time shorter than that in the music mode is set and the music mode is selected, the second attack time shorter than that in the standard mode and / or in the case of the standard mode. A mode control step for setting a long second recovery time and an input audio signal obtained by a microphone in a state of an attack time and / or a recovery time set in the mode control step according to the signal level Auto gain control step that suppresses excessive level signal input And a recording step of recording an audio signal output through the automatic gain control step in the recording medium.

That is, the present invention relates to an AGC (automatic gain control) process, a standard mode with an attack time / recovery time suitable for recording of conversations, conferences, relatively quiet music (chamber music, etc.), and music such as rock. It is possible to selectively set a music mode as an attack time / recovery time suitable for recording.
Especially in the music mode, the recovery time is lengthened to suppress unnatural fluctuations in the music level, make it difficult to distort the first and subsequent intermittent peak sounds, and shorten the attack time to reduce the AGC level. Improves distortion during peak sound exceeding.

  According to the present invention, a plurality of modes having different attack time / recovery time can be selected as the operation mode of the AGC process. That is, the user can select an optimal AGC operation mode according to the recording situation. Thus, there is an effect that appropriate recording can be easily performed according to various recording situations (recording targets).

For example, a standard mode, which is an attack time / recovery time suitable for recording conversations, conferences and relatively quiet music, and a music mode, which is an attack time / recovery time suitable for recording music such as rock, etc. Two modes can be set selectively.
In standard mode, by shortening the recovery time, you can input and record conversation voices properly.
Also, in the music mode, the recovery time is lengthened to suppress unnatural level fluctuations in the music, making it difficult to distort the first and subsequent intermittent peak sounds, and shortening the attack time to reduce the AGC level. Distortion at the time of peak sound can be improved.
As a result, appropriate AGC processing is performed for both recording of conversations and recordings of relatively rhythmic music and the like, and it is possible to easily record a good audio signal.

  Embodiments of the present invention will be described below. The recording / reproducing apparatus according to the embodiment has a function as a recording apparatus capable of recording an audio signal (sound, music, etc.) input to a microphone 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 microphone input system has a configuration as the input signal processing device of the present invention.

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 external 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 / second 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 second-generation MD specification disk 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 MD1 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 disc, and partial response and Viterbi decoding during playback of the first and second next generation MD system discs. 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, as operations related to AGC processing to be described later, operators for AGC mode selection operations and AGC function on / off operations (auto / manual selection) are provided in 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 a microphone input in the input / output processing unit 5 is provided. As the AGC processing in the AGC circuit system, a standard mode and a music mode can be selected.
Hereinafter, AGC processing corresponding to microphone input 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 microphone input and its control system are shown.
The input terminal 60 is an input terminal to which an external microphone is connected, and an analog audio signal input by the microphone connected to the input terminal 60 is supplied to the microphone amplifier 61 in the input / output processing unit 5. The microphone amplifier 61 amplifies and equalizes the analog audio signal input from the microphone and supplies the amplified analog audio signal to a PGA (programmable gain amplifier) 62 at the next stage.
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 AGC level (threshold value for operating the AGC function) has been exceeded.
When a level exceeding the AGC 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, AGC mode control and AGC function on / off control are performed on the AGC control unit 65 by the system controller 8.
As shown in the figure, the operation unit 7 is provided with an operation element 7b for the user to select auto / manual. By operating this operation element 7b, the user selects whether or not to activate the AGC function during recording. it can. When auto is selected by the operator 7b, the system controller 8 instructs the AGC control unit 65 to execute the AGC operation.
On the other hand, when the manual is selected by the operator 7b, the system controller 8 instructs the AGC control unit 65 not to execute the AGC operation. In this case, the gain in the PGA 62 is set by the user using an operator (not shown). That is, the user performs the recording operation after adjusting the input level.

When the user selects auto with the operation element 7b in order to validate the AGC function, the user can further select an AGC operation mode with the operation element 7a. In this case, an AGC standard mode and an AGC music mode can be selected.
The AGC standard mode is an AGC mode suitable for, for example, conversation, conference, or quiet music. As shown in FIG. 6, the AGC operation attack time is set to 170 ms and the recovery time is set to 4 seconds. It is.
On the other hand, the AGC music mode is an AGC mode suitable for music with relatively intense rhythm such as rock and pop, and as shown in FIG. 6, the attack time in the AGC operation is set to 80 ms and the recovery time is set to 20 seconds. Mode.
When the AGC standard mode is selected, the system controller 8 instructs the AGC control unit 65 to execute the gain control of the PGA 62 with the attack time set to 170 milliseconds and the recovery time set to 4 seconds. When the AGC music mode is selected, the AGC control unit 65 is instructed to execute gain control of the PGA 62 with the attack time set to 80 milliseconds and the recovery time set to 20 seconds.
The AGC control unit 65 performs the AGC process described above with the attack time / recovery time specified by the system controller 8.

FIG. 7 shows the input / output waveform of the audio signal of the PGA 62 and the gain of the PGA 62 in each mode. A broken line indicates an audio signal input to the PGA 62, an alternate long and short dash line indicates an output audio signal waveform and gain G from the PGA 62 in the AGC standard mode, and a solid line indicates an output audio signal waveform and gain G from the PGA 62 in the AGC music mode, respectively. Show.
First, in the AGC standard mode, when the input signal level exceeds the AGC level, the gain G of the PGA 62 is lowered with the time lag of the attack time AT set to 170 milliseconds as shown in FIG. After that, the gain G is increased at the recovery time RC set to 4 seconds, and if there is no input exceeding the AGC level during that time, the gain G is recovered to the original value with the recovery time RC. By such gain control, the audio signal output from the PGA 62 becomes as indicated by a one-dot chain line in FIG. That is, the excessive level is suppressed compared to the input audio signal, and the level is the same as the audio signal input at a relatively early time.
For example, when AGC processing is performed in such an AGC standard mode, an audio signal in a state suitable for recording such as conversation can be obtained. In other words, distortion is reduced or prevented by reducing the gain in response to sudden loud voices and sounds, and by recovering the gain relatively quickly, a small voice immediately after a loud voice can also be at an appropriate level. It can be recorded.

On the other hand, in the AGC music mode, when the input signal level exceeds the AGC level, the gain G of the PGA 62 is lowered with a time lag of the attack time AT set to 80 milliseconds as shown in FIG. Thereafter, the gain G is slowly increased at the recovery time RC set to 20 seconds, and if there is no input exceeding the AGC level during that time, the gain G is recovered to the original value with the recovery time RC.
By such gain control, the audio signal output from the PGA 62 becomes as shown by the solid line in FIG. 7A, that is, the excessive level is suppressed more quickly than the input audio signal, and thereafter the recovery time is increased. This is because the low gain state continues for a relatively long time.
When AGC processing is performed in such an AGC music mode, an audio signal in a state suitable for recording relatively intense music having a large rhythm sound such as drums can be obtained. In other words, the long recovery time suppresses unnatural music level fluctuations, makes it difficult to distort the first and subsequent intermittent peak sounds, and the short attack time reduces the steep peak sound exceeding the AGC level. Distortion is improved.

For example, FIG. 8 shows that the processing in the AGC music mode is suitable for an input signal in which a peak level appears periodically due to a rhythm sound due to drums, in comparison with the case of the AGC standard mode. explain.
The input signal (broken line) shown in FIG. 8 is, for example, a signal having a large level peak periodically. The AD full bit level in the figure indicates the upper limit of the conversion range of the A / D converter 63. That is, the signal level exceeding the AD full bit is clipped by the A / D conversion process, and distortion occurs.
The AGC level, which is the threshold for AGC processing, is naturally set to a level lower than the AD full bit.

  FIG. 8B shows a change in gain in the AGC standard mode (dashed line) and a change in gain in the AGC music mode for an input that periodically exceeds the AGC level as indicated by the broken line in FIG. (Solid line). By such gain control, the output waveforms from the respective PGAs 62 in the AGC standard mode and the AGC music mode are shown by a one-dot chain line and a solid line in FIG.

As can be seen from the figure, in the AGC standard mode, the recovery time is fast, so that the gain is recovered earlier after the gain is reduced by the input exceeding the AGC level, so the output waveform is at the same level as the input waveform earlier. To recover. For this reason, every time the peak level exceeding the periodic AD full bit is input, the output waveform also exceeds the AD full bit. At this time, since the AGC level is exceeded, the gain is controlled to be lowered. As a result, the difference in waveform shape between the input waveform and the output waveform becomes large when viewed as a waveform. This results in a sound in which the gain fluctuation is frequently performed and the volume feels unnatural in terms of hearing.
In addition, although the gain is lowered by a large level input exceeding the AGC level, it is indicated as X1 to X4 in the figure because the gain decrease cannot catch up with the steep large level input and the gain is recovered quickly. In the portion, the output waveform is distorted. Normally, when the voice of a person in conversation recording is used as an input signal, the rise in level is not as steep as compared to the rhythm peak in music, so the gain is reduced with an attack time of about 170 ms in the AGC standard mode. Therefore, in practice, the distortion is not a problem, or the gain can be appropriately lowered before the distortion exceeds the AD full bit. However, in the case of a rhythm sound of music, prevention of distortion cannot catch up because the peak input is steep. In addition, since the gain recovery is fast, periodic peaks cannot be suppressed and distortion occurs periodically. This tends to cause distortion in the sense of hearing.

On the other hand, in the AGC music mode, since the recovery time is as long as 20 seconds, the gain is gradually recovered after the gain is lowered by the input exceeding the AGC level. In other words, the gain fluctuation is moderate. For this reason, even if there is an input having a peak level exceeding the periodic AD full bit, a low gain that has not yet been restored to the original level is provided, so the output waveform does not exceed the AD full bit. Further, if the peak level of the output waveform exceeds the AGC level, the gain is lowered each time, but since the gain is lowered from a state that is hardly recovered, the reduction width is small.
That is, once the gain is lowered beyond the AGC level, the gain fluctuation is very gradual as shown by the solid line in FIG. 8B. As a result, the waveform of the input waveform and the output waveform can be seen in terms of the waveform. The shape is almost similar. This means that an output signal waveform that is quite faithful to the input signal waveform can be obtained after the peak level is within the AD full bit, and there is no unnatural volume fluctuation in the sense of hearing and it can be felt naturally. It becomes.
In addition, since the attack time is shorter than that in the AGC standard mode, it is possible to improve distortion caused by a steep large level input exceeding the AGC level. For example, Fig. 8 (c) shows an enlarged X1 in the figure, but the output in the AGC music mode (solid line) is higher than the AGC standard mode (dashed line) for inputs exceeding AD full bits. Since the waveform is quickly suppressed, distortion in hearing can be improved.
Furthermore, since the recovery time is long as described above, the second and subsequent periodic peak levels do not exceed the AD full bit. That is, in the case of the AGC standard mode, distortion occurs as indicated by X2 to X4. However, in the case of the AGC music mode, the level of the output waveform does not exceed the AD full bit at the timing of X2 to X4, and the distortion does not occur. It will not occur.
In this way, distortion is improved with respect to the first peak, and distortion is prevented for the second and subsequent peaks, thereby enabling music recording with almost no distortion in terms of hearing.

As can be understood from the above, when recording music such as rock by microphone input, the AGC music mode can be suitably recorded. That is, since the recovery time is long, the unnatural level fluctuation of the music is suppressed, and the second and subsequent times of the intermittent and periodic peak levels are difficult to be distorted.
In addition, since the attack time is short, distortion at the peak level exceeding the AD full bit can be improved.
The AGC music mode and the AGC standard mode can be selected, so that the user can change the AGC characteristics according to the recording target, and can record the conference / conversation. It is possible to easily perform both appropriate recording and appropriate recording as music recording.

Although the embodiments have been described above, various modifications can be considered as the present invention.
First, in the configuration of FIG. 5, the PGA 62 is arranged in front of the A / D converter 63 and is controlled by AGC processing so that the input signal conforms to the conversion range of the A / D converter. In addition to this, for example, a variable gain amplifier such as a PGA 62 may be provided at the front stage of the microphone amplifier 61 so that AGC processing is performed, and control is performed so that waveform clipping at the microphone amplifier 61 does not occur.

Further, although the attack time in the AGC music mode is 80 milliseconds, there is no practical problem even if it is about 140 milliseconds, for example. In other words, in the AGC music mode, it is preferable to set the attack time as short as possible to suppress distortion with respect to the steep peak level. However, if the time is shorter than about 140 milliseconds, the above-described effect can be obtained.
It is an example of setting the recovery time in the AGC music mode to 20 seconds. For example, it is confirmed that the recovery time is appropriate for music recording even if the recovery time is about 10 to 40 seconds or longer. .

In the above example, both the attack time / recovery time are different values in the AGC music mode and the AGC standard mode. For example, it is possible to set a plurality of modes so that the attack time is the same and only the recovery time is different. The present invention also includes setting a plurality of modes so that the recovery time is the same and only the attack time is different.
Of course, the AGC mode is not limited to two modes, and three or more modes having different attack times and / or recovery times may be set and selectable.
Furthermore, it is conceivable that the user can variably set the attack time / recovery time in each AGC mode.

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. For example, appropriate AGC processing is realized for each audio signal recorded by switching the AGC mode between normal shooting and band performance shooting.
Furthermore, the present invention can also be applied to devices that transmit and output microphone input sound without recording (sound recording), for example.
That is, the present invention can be applied to any device that inputs a microphone sound signal or a device that inputs a microphone sound 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 microphone input system of embodiment. It is explanatory drawing of the AGC mode of embodiment. It is explanatory drawing of the gain change in the AGC mode of embodiment. It is explanatory drawing of the signal waveform by the AGC process for every AGC mode 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, 61 Microphone amplifier, 62 Programmable gain amplifier (PGA), 63 A / D converter, 64 encoder, 65 AGC controller

Claims (5)

Auto gain control means for suppressing an excessive level of signal input by performing gain control processing corresponding to the signal level on the audio signal obtained by the microphone;
Selection means capable of selecting an operation mode of the auto gain control means;
Mode control means for variably setting the attack time and / or recovery time of gain control processing in the auto gain control means according to the mode selected by the selection means;
An input signal processing apparatus comprising: In the above selection means, standard mode and music mode can be selected,
When the standard mode is selected, the mode control means sets the attack time to the first attack time and / or the recovery time to the first recovery time, and the music mode is selected. The attack time is set to a second attack time shorter than the first attack time and / or the recovery time is set to a second recovery time longer than the first recovery time. The input signal processing apparatus according to claim 1. Auto gain control means for suppressing an excessive level of signal input by performing gain control processing corresponding to the signal level on the audio signal obtained by the microphone;
Recording means for recording the audio signal output through the auto gain control means on a recording medium;
Selection means capable of selecting an operation mode of the auto gain control means;
Mode control means for variably setting the attack time and / or recovery time of gain control processing in the auto gain control means according to the mode selected by the selection means;
A recording apparatus characterized by comprising: In the above selection means, standard mode and music mode can be selected,
When the standard mode is selected, the mode control means sets the attack time to the first attack time and / or the recovery time to the first recovery time, and the music mode is selected. The attack time is set to a second attack time shorter than the first attack time and / or the recovery time is set to a second recovery time longer than the first recovery time. The recording device according to claim 3. A selection detecting step for detecting a selection state of the standard mode and the music mode;
When the standard mode is selected, a first attack time longer than that in the case of the music mode and / or a first recovery time shorter than that in the case of the music mode is set, and the music mode is selected. A mode control step for setting a second attack time that is shorter than that in the case of the standard mode and / or a second recovery time that is longer than that in the case of the standard mode;
In the attack time and / or recovery time set in the above mode control step, the input audio signal obtained by the microphone is subjected to gain control processing according to the signal level to suppress excessive level signal input. Auto gain control step to
A recording step of recording the audio signal output through the auto gain control step on a recording medium;
A recording method comprising:

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