JP3235109B2 - Digital audio signal recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital audio signal recording apparatus, and more particularly to a digital audio signal recording apparatus, which performs bit compression processing of an input digital audio signal and controls writing and reading to and from a memory so as to record data in a predetermined data unit. The present invention relates to a digital audio signal recording device that performs recording on a digital audio signal.

[0002]

2. Description of the Related Art The applicant of the present invention has previously described a technique of compressing an input digital audio signal into bits and recording the digital audio signal in bursts using a predetermined data amount as a recording unit, for example, as disclosed in Japanese Patent Application No. 2-221364. , Japanese Patent Application No. 22-22136
No. 5, Japanese Patent Application No. 2-222821, Japanese Patent Application No. 2-2228
No. 23 has been proposed in the specification and drawings.

This technique uses a magneto-optical disk as a recording medium and records and reproduces AD (adaptive difference) PCM audio data specified in the audio data format of a so-called CD-I (CD-interactive) or CD-ROM XA. The ADPCM data is recorded in a burst on the magneto-optical disk using, for example, 32 sectors of ADPCM data and several sectors for linking for interleave processing as a recording unit. Here, Table 1
The level of ADPCM audio in the CD-I format and CD-ROMXA format is
D (Compact Disc) Format (CD-DA
Format).

[Table 1]

In Table 1, for example, in a level B mode, digital audio data is compressed to approximately 1/4, and the playback time (play time) of a disk recorded in this level B mode is a standard CD. -4 times that of the DA format. Since a recording and reproducing time of the same order as a standard 12 cm can be obtained with a smaller disk, the size of the apparatus can be reduced.

However, as the original recording data according to the CD-I format, for example, in the case of the level B, the ADPCM data of four channels appears cyclically in a cycle of four sectors. When reproducing one channel, it is necessary to perform reproduction while periodically extracting data of one sector for every four sectors. However, one channel ADPC
When recording M data, there is a problem such as interleave including other channels, so that it is almost impossible.
The CM audio data is time-compressed in a predetermined unit (for example, for 32 sectors), and a connecting sector (linking sector) is added before and after in consideration of interleaving with data of an adjacent sector, and the sector is continuously burst-wise. To record.

[0006]

As described above, bit-compressed audio data (for example, AD
In a recording apparatus that records PCM data in a predetermined data amount (32 sectors + several sectors for linking) in units of bursts, for example, during recording of an audio signal, for example, a break between music tunes or talk during conversation. When a silence state such as that occurs and the time of the silence state is prolonged, the silence portion is recorded as it is on a recording medium such as a disc, and the medium is wasted, the battery is wasted, and the silence state is prolonged during reproduction. And the like.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has been made in consideration of the above-described circumstances. When recording bit-compressed digital audio data, it is possible to avoid a problem caused by recording a silent portion as it is. It is intended to provide an audio signal recording device.

[0008]

SUMMARY OF THE INVENTION A digital audio signal recording apparatus according to the present invention performs a predetermined compression process on an input audio signal, temporarily stores the compressed signal in a memory, and then records the signal on a recording medium. In, the silence detecting means for detecting a silence part of the input audio signal, and whether or not the silence part detected by the silence detection means has continued for a predetermined period or more, it has been determined that continuous for a predetermined period or more In some cases, the above-described problem is solved by providing a control unit that restricts the generation of a silent portion longer than the predetermined period in the memory.
The silence signal detection means detects a silence portion based on a silence level of the analog monitor signal. The silent signal detecting means detects a silent portion based on the level of the input digital audio signal. Here, the interruption of the signal recording operation can be realized by controlling the writing to the memory by the control means. For example, the silent part data is overwritten on the already written silent part data in the memory (overwrite). Alternatively, the reading may be stopped by stopping the write pointer so that the data amount does not reach the predetermined amount. Further, the digital audio signal recording apparatus according to the present invention is a digital audio signal recording apparatus which performs a predetermined compression process on an input audio signal, temporarily stores the input audio signal in a memory, and blocks and records the data in units of a predetermined data amount. A silence detecting means for detecting a silence part of the input audio signal, and judging whether or not the silence part detected by the silence detection means continues for a predetermined period over a predetermined block, and the silence part The above-mentioned problem is solved by providing a control unit that regulates, when it is determined that a continuous period extends over a predetermined block for a predetermined period or more, so that a silence portion for a predetermined period or more is not generated in the memory.

[0009]

Since the signal recording operation is interrupted in response to the detection of silence, it is possible to prevent the silence portion recorded on the recording medium from being lengthened, and to reduce waste of the medium, waste of the battery, and silence during reproduction. Problems such as prolongation can be effectively solved.

[0010]

FIG. 1 is a block circuit diagram showing a schematic configuration of a disk recording / reproducing apparatus as an embodiment of a digital audio signal recording apparatus according to the present invention. In FIG. 1, a digital audio signal from an A / D converter 12 is bit-compressed by an ADPCM encoder 13 and writing and reading to and from a memory 14 such as a RAM are controlled so that a predetermined data amount (for example, 32 sectors + FIG. 2 shows a disk recording / reproducing apparatus for performing recording on a magneto-optical disk 2 which is a recording medium in units of several sectors for linking), and further includes silence of an input audio signal supplied to an input terminal 10 by a silence detection circuit 18. Is detected, and the signal recording operation is interrupted in accordance with the detection output from the silence detection circuit 18 to prevent an increase in the silence recording portion on the magneto-optical disk 2.

To interrupt the signal recording operation, the silence detection signal is sent to the system controller 7 and the memory 1
4 can be realized by, for example, overwriting (overwriting) the already written silent part data in the memory 14 with the ADPCM data of the silent part, or stopping the write pointer, and The data amount (for example, 32 sectors) may not be reached, and the reading may not be performed. When silence is no longer detected, a normal write operation is performed on the memory 14, and when the written data reaches the predetermined data amount (32 sectors), the data is read out in a burst, and before and after the linking number. Sectors are added and data is recorded on the magneto-optical disk 2 in a burst of sectors.

Hereinafter, a specific configuration of FIG. 1 will be described in detail. In the disc recording / reproducing apparatus shown in FIG.
First, a magneto-optical disk 2 driven to rotate by a spindle motor 1 is used as a recording medium. When recording data on the magneto-optical disk 2, for example, a so-called magnetic field modulation recording is performed by applying a modulation magnetic field corresponding to the recording data by the magnetic head 4 in a state where the optical head 3 irradiates the laser light. Data is recorded along the second recording track. At the time of reproduction, the recording track of the magneto-optical disk 2 is traced by a laser beam by the optical head 3 to perform magneto-optical reproduction.

The optical head 3 is composed of, for example, a laser light source such as a laser diode, an optical component such as a collimator lens, an objective lens, a polarizing beam splitter, a cylindrical lens, and a photodetector having a light receiving portion having a predetermined pattern. The optical head 3 is provided at a position facing the magnetic head 4 via the magneto-optical disk 2. When data is recorded on the magneto-optical disk 2, the magnetic head 4 is driven by a recording-system head drive circuit 16, which will be described later, to apply a modulation magnetic field according to the recorded data. By irradiating the track with laser light, thermomagnetic recording is performed by a magnetic field modulation method. The optical head 3 detects reflected light of the laser beam applied to the target track, detects a focus error by, for example, a so-called astigmatism method, and detects a tracking error by, for example, a so-called push-pull method. When reproducing data from the magneto-optical disk 2, the optical head 3 detects the focus error and the tracking error, and at the same time, detects the difference in the polarization angle (Kerr rotation angle) of the reflected light of the laser light from the target track and reproduces the data. Generate a signal.

The output of the optical head 3 is supplied to an RF circuit 5. The RF circuit 5 extracts the focus error signal and the tracking error signal from the output of the optical head 3 and supplies the focus error signal and the tracking error signal to the servo control circuit 6 and binarizes the reproduction signal and supplies it to a reproduction system decoder 21 described later. .

The servo control circuit 6 comprises, for example, a focus servo control circuit, a tracking servo control circuit, a spindle motor servo control circuit, a thread servo control circuit and the like. The focus servo control circuit performs focus control of the optical system of the optical head 3 so that the focus error signal becomes zero. Further, the tracking servo control circuit performs tracking control of the optical system of the optical head 3 so that the tracking error signal becomes zero. Further, the spindle motor servo control circuit controls the spindle motor 1 so as to rotate the magneto-optical disk 2 at a predetermined rotation speed (for example, a constant linear speed). Further, the thread servo control circuit moves the optical head 3 and the magnetic head 4 to target track positions of the magneto-optical disk 2 designated by the system controller 7. The servo control circuit 6 that performs such various control operations supplies information indicating the operation state of each unit controlled by the servo control circuit 6 to the system controller 7.

A key input operation unit 8 and a display unit 9 are connected to the system controller 7. The system controller 7 controls a recording system and a reproduction system in an operation mode specified by operation input information from the key input operation unit 8. The system controller 7 controls the magneto-optical disk 2
The recording position and the reproduction position on the recording track traced by the optical head 3 and the magnetic head 4 are managed on the basis of the address information of the sector unit reproduced from the recording track by the header time, the data of the sub-Q code and the like. I do. Further, the system controller 7 performs bit compression mode information in the ADPCM encoder 13 described later, which is switched and selected by the key input operation unit 8, and bit compression mode information in playback data obtained from the RF circuit 5 via a playback system described later. On the display unit 9 based on the data compression ratio in the bit compression mode and the reproduction position information on the recording track. Do.

This reproduction time display is based on address information (absolute time information) in sector units reproduced from a recording track of the magneto-optical disk 2 by a so-called header time or so-called subcode Q data, etc. The actual time information is obtained by multiplying the reciprocal of the compression ratio (for example, 4 in the case of 、 compression), and this is displayed on the display unit 9. At the time of recording, if absolute time information is recorded in advance on a recording track of a magneto-optical disk or the like (preformatted), the preformatted absolute time information is read and the data compression ratio is adjusted. By multiplying the reciprocal, the current position can be displayed by the actual recording time.

Next, in the recording system of the disk recording / reproducing apparatus, an analog audio input signal A _IN is input from an input terminal 10 through an A / D converter 12 through a low-pass filter 11.
The A / D converter 12 quantizes the analog audio input signal A _IN . Digital audio data obtained from the A / D converter 12 is supplied to an AD (adaptive difference) PCM encoder 13. ADPCM
The encoder 13 converts the input signal AIN into digital audio PCM data at a predetermined transfer rate obtained by quantizing the input signal _AIN by the A / D converter 12 as shown in Table 1 above.
It performs bit compression (data compression) processing corresponding to various modes in the I system, and an operation mode is designated by the system controller 7. For example, in the level B mode in Table 1, the sampling frequency is 37.8 kHz and the number of bits per sample is 4
Bit-compressed data (ADPCM data) is supplied to the memory 14. The data transfer rate in the level B stereo mode is 1/4 (1) of the data transfer rate (75 sectors / second) of the standard CD-DA format.
8.75 sectors / sec).

Here, in the embodiment of FIG. 1, the sampling frequency of the A / D converter 12 is, for example, the standard C
4 which is the sampling frequency of the D-DA format
It is fixed to 4.1 kHz, and ADPCM encoder 1
3, sampling rate conversion according to the compression mode (for example, 44.1 kHz to 37.
After conversion to 8 kHz, bit compression processing from 16 bits to 4 bits is performed. As another configuration example, the sampling frequency of the A / D converter 12 may be switched and controlled in accordance with the compression mode. In this case, the switching frequency of the A / D converter 12 that has been switched is controlled. The cutoff frequency of the low-pass filter 11 is also switched and controlled according to the sampling frequency.
That is, the sampling frequency of the A / D converter 12 and the cutoff frequency of the low-pass filter 11 may be simultaneously switched in accordance with the compression mode.

Next, writing and reading of data in the memory 14 are controlled by the system controller 7, and A
The ADPCM data supplied from the DPCM encoder 13 is temporarily stored, and is used as a buffer memory for recording on a disk as needed.
That is, in the level B stereo mode, for example, the compressed audio data supplied from the ADPCM encoder 13 has a data transfer rate of a standard C
Data transfer rate of D-DA format (75 sectors /
Second), that is, 18.75 sectors / second, and the compressed data is continuously written to the memory 14. As described above, it is sufficient for the compressed data (ADPCM data) to record one sector for every four sectors. However, such recording every four sectors is practically impossible. I try to keep a record. This recording is performed at intervals of the same data transfer rate (75 sectors / second) as a standard CD-DA format by using a cluster consisting of a plurality of predetermined sectors (for example, 32 sectors + several sectors) as a recording unit through a pause period. It is done on a regular basis. That is, in the memory 14, ADPCM audio data in the level B stereo mode, which is continuously written at a low transfer rate of 18.75 (= 75/4) sectors / second according to the bit compression rate,
The recording data is read out in bursts at the transfer rate of 75 sectors / second. The overall data transfer rate of the read and recorded data, including the recording pause period, is as low as 18.75 sectors / sec, but within the time of the recording operation performed in bursts. The instantaneous data transfer rate at the above is the standard 75 sectors / second. Therefore, when the disk rotation speed is a standard CD
-At the same speed (constant linear speed) as the DA format,
Recording of the same recording density and storage pattern as in the CD-DA format is performed.

ADPC read from the memory 14 in a burst at the above-mentioned (instantaneous) transfer rate of 75 sectors / second.
The M audio data, that is, the recording data, is supplied to the encoder 15. Here, in the data string supplied from the memory 14 to the encoder 15, a unit continuously recorded in one recording is a cluster composed of a plurality of sectors (for example, 32 sectors) and a cluster connection arranged before and after the cluster. For several sectors. The cluster connection sector is set to be longer than the interleave length in the encoder 15 so that even if interleaved, data in other clusters is not affected. Details of the recording in cluster units will be described later with reference to FIG.

The encoder 15 converts the recording data supplied from the memory 14 in a burst
Encoding processing for error correction (parity addition and interleaving processing), EFM encoding processing, and the like are performed. The recording data that has been subjected to the encoding process by the encoder 15 is supplied to the magnetic head drive circuit 16. The magnetic head drive circuit 16 is connected to the magnetic head 4,
The magnetic head 4 is driven so that a modulation magnetic field corresponding to the recording data is applied to the magneto-optical disk 2.

The system controller 7 performs the above-described memory control on the memory 14 and continuously records the recording data read out from the memory 14 by the memory control on the recording track of the magneto-optical disk 2. The recording position is controlled so that The recording position is controlled by controlling the recording position of the recording data read out from the memory 14 in a burst manner by the system controller 7 and transmitting a control signal designating the recording position on the recording track of the magneto-optical disk 2 to a servo control circuit. 6
Is performed by supplying the

Next, a reproducing system in the disk recording / reproducing apparatus will be described. This reproducing system is for reproducing the recorded data continuously recorded on the recording tracks of the magneto-optical disk 2 by the above-mentioned recording system. The reproduced output obtained by tracing with
A decoder 21 is provided which is supplied by being binarized by the F circuit 5.

The decoder 21 corresponds to the encoder 15 in the above-described recording system, and performs the above-described decoding processing for error correction and EFM decoding on the reproduced output binarized by the RF circuit 5. Processing such as processing is performed to reproduce the level B, stereo mode ADPCM audio data at a transfer rate of 75 sectors / sec, which is higher than the normal transfer rate in the level B, stereo mode. The reproduction data obtained by the decoder 21 is supplied to the memory 22.

In the memory 22, the writing and reading of data are controlled by the system controller 7, and reproduced data supplied from the decoder 21 at a transfer rate of 75 sectors / second is written in a burst at the transfer rate of 75 sectors / second. It is. In the memory 22, the reproduction data written in a burst at the transfer rate of 75 sectors / sec is a level B, stereo mode normal 18.75.
It is read continuously at a transfer rate of sectors / second.

The system controller 7 writes the reproduced data to the memory 22 at a transfer rate of 75 sectors / second, and writes the reproduced data from the memory 22 to the above-mentioned 18.75.
Memory control for continuously reading data at a transfer rate of sector / second is performed. Further, the system controller 7 performs the above-described memory control for the memory 22, and reproduces the reproduction data written in a burst from the memory 22 by the memory control continuously from the recording tracks of the magneto-optical disk 2. Control the playback position.
The reproduction position is controlled by controlling the reproduction position of the reproduction data read in a burst from the memory 22 by the system controller 7 and transmitting a control signal designating the reproduction position on the recording track of the magneto-optical disk 2 to a servo control circuit. 6.

ADPCM audio data in level B, stereo mode, which is obtained as reproduced data continuously read from the memory 22 at a transfer rate of 18.75 sectors / second, is supplied to an ADPCM decoder 23. This A
The DPCM decoder 23 corresponds to the ADPCM encoder 13 of the above recording system, and
The operation mode is designated by, for example, the level B,
The 16-bit digital audio data is reproduced by expanding (bit expanding) the ADPCM data in the stereo mode four times. This ADPCM decoder 23
Digital audio data from the D / A converter 2
4 is supplied.

The D / A converter 24 converts the digital audio data supplied from the ADPCM decoder 23 into an analog signal and outputs the analog audio output signal A
Form _OUT . The analog audio signal A _OUT obtained by the D / A converter 24 is _supplied to a low-pass filter 2
5 through the output terminal 26.

The reproducing system of the disk recording / reproducing apparatus of this embodiment also has a digital output function.
Digital audio data from the PCM decoder 23 is taken out from a digital output terminal 28 as a digital audio output signal D _OUT via a digital output interface circuit 27.

Further, the analog audio signal from the input terminal 10 is also sent to a silence detection circuit 18 which performs level discrimination as to whether the input signal level has fallen below a predetermined level, for example. Detects a silent state. The detection output signal from the silence detection circuit 18 is sent to the system controller 7.

The magneto-optical disk 2 used in such a disk recording / reproducing apparatus desirably has a capacity capable of recording a stereo audio signal for about 60 minutes to about 74 minutes. 1 /
When a data compression ratio of 4 is adopted, about 130 Mbytes are required. In addition, in order to configure a portable or pocket-sized recording and / or reproducing apparatus, it is desirable to use a disk having an outer diameter of 8 cm or smaller. Further, regarding the track pitch and the linear velocity, the same track pitch of 1.6 μm as that of the CD was used.
m and a linear velocity of 1.2 to 1.4 m / s. As a disk satisfying these conditions, for example, the outer diameter of the disk is 64 mm, and the outer diameter of the data recording area is 6 mm.
1 mm, the inner diameter of the data recording area is 32 mm, the inner diameter of the lead-in area is 30 mm, and the center hole diameter is 10 mm. If this disc is stored in a disc caddy measuring 70 mm × 74 mm in length and width and supplied to the market, recording and reproduction on the disc can be performed by a recording / reproducing apparatus having a pocket size. Note that the range of the inner diameter and outer diameter of the data recording area of the disk for enabling recording and reproduction for about 72 to 76 minutes in the 1/4 data compression mode is the outer diameter when the inner diameter is 32 mm. Diameter 60mm ~
Outer diameter 71mm-7 when inner diameter is 50mm from 62mm
What is necessary is just to set suitably within the range of 3 mm.

Next, the basic recording / reproducing operation by the disk recording / reproducing apparatus as described above will be described in more detail.

First, recording data (data read from the memory 14) is clustered into a fixed number (for example, 32) of sectors (or blocks), and some of these clusters are connected for cluster connection. Are arranged. Specifically, as shown in FIG.
The cluster C is composed of 32 sectors (blocks) B0 to B31, and five connecting (linking) sectors L1 to L5 are arranged between these clusters C and connected to the adjacent cluster. I have. Here, when recording one cluster, for example, the k-th cluster C _k , not only the 32 sectors B 0 to B 31 of this cluster C _k but also three connecting sectors before and after, ie, the cluster C _k The three sectors L3 to L5 on the _-1 side (run-in block) and the three sectors L1 to L3 on the cluster C _{k + 1} side
(Run-out block), and recording is performed in units of a total of 38 sectors. At this time, the recording data for these 32 sectors is sent from the memory 14 to the encoder 15, and six sectors for linking are generated and added in the encoder 15. On the other hand, by interleave processing at the encoder 15 are performed, but reordering of distances up to 108 frames (equivalent to about 1.1 sector) is performed, the data in the cluster C _k are the run - in block It is well within the range from L3 to L5 to the run-out blocks L1 to L3, and does not affect other clusters Ck _-1 and Ck _{+ 1} . The linking sectors L1 to L5 are provided with dummy data such as 0, for example, so that an adverse effect on the original data due to the interleave processing can be avoided.
Further, when recording the next cluster C _{k + 1,} the three sectors L3~L5 of the five linking for sector L1~L5 between cluster C _k is a run - because used as an in-block, sector L3 Will be recorded twice, but there is no problem. Further, as the cluster, for example, 38 sectors including the linking sector may be defined as one cluster.

By performing such cluster unit recording, it is not necessary to consider mutual interference due to interleaving with other clusters, and data processing is greatly simplified. Also, if the recording data cannot be recorded normally at the time of recording due to defocus, tracking deviation, other malfunction, etc., re-recording can be performed in cluster units, and if effective data reading cannot be performed during reproduction, Re-reading can be performed in cluster units.

One sector (block) is 235.
23 bytes consisting of 2 bytes, 12 bytes for synchronization, 4 bytes for header, and data D0001 to D2336 from the beginning.
36 bytes are arranged in this order. Of the 12 bytes for synchronization in the sector structure (block structure), the first 1 byte is 00H (H indicates a hexadecimal number), followed by 10 bytes of FFH, and the last 1 byte is 00H. The next 4-byte header is composed of one byte for mode information, following the minute, second, and block address portions of one byte each. This mode information is mainly for indicating the mode of the CD-ROM, and the internal structure of the sector shown in FIG. 2 corresponds to the mode 2 of the CD-ROM format. CD-I is a standard using this mode 2.

The specific example of FIG. 2 further shows a format for recording compressed audio data. From the beginning of the 2336-byte area, an 8-byte sub-header, 128 bytes each, and 18 groups of sound groups SG01 to SG01 to SG18, a 20-byte space area, and a 4-byte reserved area are arranged in this order. 8 above
The byte subheader has a file number, a channel number, a submode, and a data type of 1 byte, which are arranged twice.

When such sector-structured data is recorded on a disk, the encoder 15 performs an encoding process including a parity addition and an interleave process, and performs an EFM (8-14 modulation) process. FIG. 3
Recording is performed in a recording format as shown in FIG.

In FIG. 3, one block (one sector) is composed of 98 frames from the first frame to the 98th frame, and one frame has a channel clock period T
588 times (588T) of the frame synchronization pattern part of 24T (+3 connection bits) in one frame, 14T
A (+ connection bit 3T) subcode portion and a 544T data (audio data and parity data) portion are provided. The data portion of 544T is so-called EFM-modulated 12-byte (12-symbol) audio data, 4-byte parity data, 12-byte audio data, and 4-byte parity data, and audio data in one frame. Is 24 bytes (that is, one word of audio sample data is 16 bytes).
12 words). The sub-code part is obtained by subjecting 8-bit sub-code data to EFM modulation, and is divided into blocks of 98 frames, and each bit forms eight sub-code channels P to W. However, the subcode portions of the first and second frames are block synchronization patterns S _{0 and} S ₁ outside the rules of the EFM modulation (out-of-rule), and the subcode channels P to W are shifted from the third frame to the third frame. It is 96 bits each for up to 98 frames.

The above-mentioned audio data is recorded after being subjected to an interleaving process. At the time of reproduction, the audio data is subjected to a de-interleaving process so as to be audio data having a data arrangement according to a time order. Instead of this audio data,
General CD-I data and the like can be recorded.

In the disk recording / reproducing apparatus shown in FIG. 1, as the digital data obtained from the A / D converter 12, for example, data similar to the above-mentioned CD-DA format, that is, a sampling frequency of 44.1 k is used.
It is possible to use audio PCM data with Hz, a quantization bit number of 16 bits, and a data transfer rate of 75 sectors / second. When this data is sent to the ADPCM encoder 13 and bit-compressed into, for example, the level B stereo mode, the data is first rate-converted to a sampling frequency of 37.8 kHz, and then the number of quantization bits is reduced to 4 bits. Due to the compression, the transfer rate of the compressed ADPCM data is output as 18.75 sectors / sec, which is 1/4 of the transfer rate of the input data. This ADP
Level B continuously output from the CM encoder 13 at a transfer rate of 18.75 sectors / second, A in stereo mode
DPCM audio data is supplied to the memory 14.

As shown in FIG. 4, the system controller 7 sets the write pointer W of the memory 14 to 18.
ADPCM audio data is continuously written to the memory 14 at a transfer rate of 18.75 sectors / second by continuously incrementing at a transfer rate of 75 sectors / second, and the ADP stored in the memory 14 is stored in the memory 14.
When the amount of the CM audio data exceeds a predetermined amount K, the read pointer R of the memory 14 is set to 75 sectors /
Memory control is performed such that the ADPCM audio data is read out from the memory 14 as recording data in a burst at a transfer rate of 75 sectors / second by the predetermined amount K at a transfer rate of 75 sec / sec.

That is, in the recording system of the disk recording / reproducing apparatus shown in FIG. 1, the ADPCM encoder 1 is controlled by the memory control by the system controller 7.
The ADPCM audio data output continuously from 3., for example, at a transfer rate of 18.75 sectors / sec.
When the data amount of the ADPCM audio data stored in the memory 14 becomes equal to or more than a predetermined amount K at a transfer rate of 75 sectors / sec. Since K is read out in bursts at a transfer rate of 75 sectors / second, input data can be continuously written to the memory 14 while always securing a data write area of a predetermined amount or more in the memory 14. Here, the recording data read in a burst from the memory 14 is transmitted to the magneto-optical disk 2 by the system controller 7.
By controlling the recording position on the recording track of
Recording can be performed continuously on the recording tracks of the magneto-optical disk 2. Further, as described above, since a data write area of a predetermined amount or more is always secured in the memory 14, the system controller 2 detects that a track jump or the like has occurred due to disturbance or the like, and performs a recording operation on the magneto-optical disk 2. Even in the case of interruption, the input data is continuously written in the data write area of the predetermined amount or more,
In the meantime, the return processing operation can be performed, and the input data can be recorded on the recording tracks of the magneto-optical disk 2 in a continuous state.

The magneto-optical disk 2 is recorded with header time data corresponding to the physical address of the sector added to the ADPCM audio data for each sector. Also, catalog data indicating the recording area and the recording mode is recorded in the catalog area.

Next, in the reproducing system in the disk recording / reproducing apparatus shown in FIG. 1, the system controller 7 sets the write pointer W of the memory 22 to 75 sectors / byte as shown in FIG.
The transfer data is incremented at a transfer rate of second, and the reproduced data is written to the memory 22 at a transfer rate of 75 sectors / second, and the read pointer R of the memory 22 is continuously incremented at a transfer rate of 18.75 sectors / second. The reproduction data is continuously read from the memory 22 at the transfer rate of 18.75 sectors / second. When the write pointer W catches up with the read pointer R, the writing is stopped, and the reproduction stored in the memory 22 is stopped. When the data amount of the data becomes equal to or less than the predetermined amount L, the write pointer W of the memory 22 is burst-incremented at a transfer rate of 75 sectors / second so that writing is performed, and memory control is performed.

Therefore, in the reproducing system of such a disk recording / reproducing apparatus, the level B reproduced from the recording track of the magneto-optical disk 2 and the AD in the stereo mode are controlled by the memory control by the system controller 7.
The PCM audio data is written to the memory 22 in bursts at a transfer rate of 75 sectors / second, and the ADPCM audio data is read from the memory 22 as reproduction data.
Since the data is continuously read at a transfer rate of sectors / second, the reproduced data can be continuously read from the memory 22 while always securing a data read area of a predetermined amount L or more in the memory 22. The reproduction data read in bursts from the memory 22 is reproduced in a continuous state from the recording tracks of the magneto-optical disk 2 by controlling the reproduction position on the recording tracks of the magneto-optical disk 2 by the system controller 7. Can be.
In addition, as described above, since a data read area of a predetermined amount L or more is always secured in the memory 22, the system controller 7 detects that a track jump or the like has occurred due to disturbance or the like, and reproduces data from the magneto-optical disk 2. Even when the operation is interrupted, the reproduction data can be read from the data read area of the predetermined amount L or more and the output of the analog audio signal can be continued, and the return processing operation can be performed during that time.

Next, a specific example of the interruption of the signal recording operation in response to the silence detection will be described. First, the silence detection circuit 18 in FIG. 1 can be configured as shown in FIG. 6, for example. In FIG. 6, an analog audio signal from the input terminal 10 is sent to a peak hold circuit 18a of a silence detection circuit 18 to hold a peak voltage, and is sent to a comparator (comparator, level discriminator) 18b. It is compared with a predetermined reference voltage from the reference voltage source 18c. The time constant of the peak hold circuit 18a is, for example, about 0.1 second / full scale. The reference voltage source 18c is variable, and the silence detection level can be adjusted by changing the voltage. Comparator 18
The output signal from b is sent to the system controller 7 in FIG. 1 as a silence detection signal.

The system controller 7 controls the writing of the ADPCM data to the memory 14 in accordance with the silence detection signal from the silence detection circuit 18. That is,
The system controller 7 has a function of determining whether or not the silent portion detected by the silent detection circuit 18 has continued for a predetermined period or more. And a function of restricting the generation of the gas in the apparatus. This memory 14
For example, as shown in FIG. 7, one having a data storage capacity of 64 sectors of two clusters is prepared. In FIG. 7, the storage unit M1 of the memory corresponds to the storage capacity of one sector, and the first cluster is represented by M1 to M32.
M64 forms the second cluster. The ADPCM data input to the memory 14 is a so-called ring buffer which is written in order from M1 in the memory unit, is written in M33 after M32, is written to M64, and is written in order again from M1. ing. The data stored in M1 to M32 or M33 to M64 in this memory corresponds to the data of the 32 sectors (blocks) B0 to B31 in FIG.

Here, let us consider recording monaural 8-fold compressed ADPCM data on a disk in the B mode of the CD-I audio format. Assuming that the maximum allowable recording time as a silent portion is, for example, 1 second, the data of one second in real time is 0.125 seconds when the above-mentioned 8 times compression is performed, and one sector is equivalent to 1/75 second. .125 ÷ 1/75 ≒ 9.37, equivalent to about 9 or 10 sectors. Therefore, the recording operation is interrupted when the time of the silent part becomes 9 or 10 sectors or more.

FIG. 8 is a flowchart showing an example of a specific memory control operation. In step S1 of FIG. 8, a pointer indicating a sector address of the storage unit M1, M2 or the like of the memory 14 is set to an initial value 1, and a counter indicating the number of sectors of the silent portion is set to an initial value 0. In the next step S2, the input A is input to the sector address indicated by the pointer.
Write one sector of DPCM data. In the next step S3, when the silence detection flag MUTE is "H", that is, when silence is detected, the counter is incremented (+1). In the next step S4, it is determined whether or not the value of the counter has reached a predetermined value, for example, 9, and
If it has not reached (No), the process proceeds to step S5, and if it has reached (Yes), the process proceeds to step S6.

Here, the silence detection flag MUTE is
When the silence is detected by the silence detection circuit 18, an interrupt (interrupt 1) is applied to the system controller 7 so that MUTE is determined in step S12.
= “H”. In step S12, the counter is initialized to zero. Further, when the silence ends, MUTE =
It is set to “L”. However, this silence detection flag MUTE
The switching timing of the LPF 11, the A / D converter 12,
The signal delay is corrected by the ADPCM encoder 13 or the like, and the timing is adjusted with the memory input ADPCM data.

If the silence duration has not reached the predetermined number of sectors (for example, 9 sectors) at the time of the determination in step S4, the process proceeds to step S5. In this step S5, when the pointer becomes 32 or 64, the ADPCM for one cluster (32 sectors)
The data is read from the memory 14, encoded by the encoder 15, the linking sector is added before and after, and recorded on the magneto-optical disk 2 in a burst. In the next step S10, when the value of the pointer is 64 or more, 64 is subtracted (pointer-64). In the next step S11, the pointer is incremented (+1).
Then, the process returns to step S2.

If it is determined in step S4 that the silent state duration has reached nine sectors, the process proceeds to step S6. In step S6, the address obtained by adding 1 to the numerical value of the pointer, that is, (pointer + 1)
, Input ADPCM data for two sectors is written. In the next step S7, the silence detection flag MUT
It is determined whether or not E is "H", that is, whether or not the silent state is maintained. If Yes, the process returns to step S6,
The operation of writing two sectors from the same (pointer + 1) address is repeated. This means that, when the input ADPCM data is data in a silent state, data writing is repeated at the same position in the memory 14 without incrementing the pointer. At this time, the previously written silence data for two sectors is rewritten (overwritten) to data for the next two sectors.

In the next step S8, the pointer is increased by 2 (+2), and the flow advances to step S9. This step S
In 9, the pointer value is 32, 33, 34 or 6
When the number is 4, 65, 66, one cluster (32 sectors) is read out, encoded as described above, a linking sector is added, and the magneto-optical disk 2 is bursty.
To record. Next, the process proceeds to step S10.

The memory input ADP in operation as described above
9 and 10 show the relationship between CM data and memory contents
Shown in FIG. 9 shows a case where a silent portion indicated by a hatched portion in the figure is continuous for at least a predetermined n sectors (for example, n = 9).
Indicates a case where the silence portion indicated by the hatched portion in the figure is less than the above-mentioned n sectors (9 sectors). D1 and D2 indicate ADPCM data following the silent section.
By performing the above-described memory control, it is possible to perform recording without causing a silent portion to continue for a predetermined time (for example, about 1 second, about 9 sectors), and without loss of a signal in a rising portion from a silent state. Understand.

Next, FIG. 11 shows a case where the above-mentioned silence portion occurs from the first cluster to the second cluster. In this case, the end portion of the first cluster and the second
Is controlled so that the duration of the silence portion that is continuous with the leading end portion of the cluster does not exceed the predetermined time. Note that the memory is used as a ring buffer, and it goes without saying that the same control is performed even when a silent portion occurs from the second cluster to the first cluster.

Here, there are two types of servo control when recording signals on the magneto-optical disk 2. One is to read the absolute time information of the Q channel of the subcode and the time information (block address) from the header in the sector format during the waiting time until the data to be recorded is sent, The jump is repeated, and the recording head always waits at a position immediately before the next recording start point. The other is to perform recording while reading the time information and waiting for the next recording start point when data to be recorded is sent.

According to the embodiment as described above, the length of the silent portion recorded on the magneto-optical disk 2 can be suppressed to 9 sectors or less, and the silent portion is recorded for a long time. Waste of the medium can be prevented. Here, signal recording requires approximately twice as much power as during reproduction, but since the actual recording time can be shortened, especially in the case of a battery-driven type device, the battery life can be maintained long. In addition, when the recorded audio signal is reproduced, a silent portion does not last for one second or more, and thus, for example, when a silent portion is long, a trouble of performing a skip operation or the like can be omitted. Further, since the rising portion from the silent state is completely stored in the memory, no trouble such as interruption occurs.

As another recording method, it is considered that the silent recording portion is rewritten (overwritten) on the magneto-optical disk 2 as a recording medium to prevent the silent recording portion from increasing on the recording medium. Can be This is rewriting in cluster units, and when silence data is recorded over one cluster on the recording medium, the data of the next cluster is overwritten at this cluster position to erase the silence recorded data. Will do. In this case, there is no need to control the writing to the memory, but
The maximum duration of the recorded silent part is determined by the data amount of the cluster, and is slightly longer. However, this can be easily dealt with by reducing the number of sectors in the cluster.

The present invention is not limited to the above-described embodiment. For example, the above-mentioned silence detection is performed on an input analog audio signal. In
Silence detection may be performed on an analog monitor signal, or silence detection may be performed by directly performing level detection processing on a digital audio signal. Further, in the disk recording / reproducing apparatus of the above embodiment, the so-called CD-I system or CD-R
The recording and reproduction of compressed data in level B stereo or monaural mode in the ADPCM audio format of the OM XA method has been described, but recording and reproduction of bit-compressed audio data in other modes and other methods is similarly performed. It can be carried out. The number of sectors constituting the cluster is not limited to 32. For example, an arbitrary number of sectors such as 64 sectors may constitute one cluster. Furthermore, the recordable disc is not limited to a magneto-optical disc, but may be a phase change optical disc, an organic dye-based optical disc, a PHB (photochemical
(Hole Burning) The present invention can be applied not only to an optical disk or the like, but also to a card-like medium, a sheet-like medium, or a tape-like medium other than the disk-like medium.

[0061]

As is apparent from the above description, according to the digital audio signal recording apparatus of the present invention,
When a predetermined compression process is performed on an input audio signal and the data is temporarily stored in a memory and then recorded on a recording medium, the recording operation is interrupted in accordance with a silent detection signal of the input audio signal, and the recording operation is performed on the recording medium. Since the silence recording portion is prevented from increasing, problems such as waste of recording media, waste of batteries for driving the device, and prolonged silence during reproduction can be prevented.
Can be effectively resolved.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a configuration example of a disk recording / reproducing apparatus as one embodiment of a digital audio signal recording apparatus according to the present invention.

FIG. 2 is a diagram showing a format of a cluster structure which is a unit of recording on a recording medium.

FIG. 3 is a diagram showing a format of a frame and a sector (block) in the standard of a so-called CD (compact disk).

FIG. 4 is a diagram showing a state of a memory whose memory is controlled in a recording system of the disk recording / reproducing apparatus of the embodiment.

FIG. 5 is a diagram showing a state of a memory whose memory is controlled in a reproducing system of the disk recording / reproducing apparatus of the embodiment.

FIG. 6 is a block circuit diagram showing a specific example of a silence detection circuit 18.

FIG. 7 is a diagram showing a specific example of the internal structure of a memory 14;

FIG. 8 is a flowchart illustrating a specific example of a memory control operation associated with silence detection.

FIG. 9 is a diagram showing memory contents for memory input data upon detection of silence for a predetermined time or more.

FIG. 10 is a diagram showing memory contents for memory input data when silence is detected for less than a predetermined time.

FIG. 11 is a diagram showing memory contents for memory input data when silence is detected across two clusters.

[Explanation of symbols]

 2 ... Magneto-optical disk 3 ... Optical head 4 ... Magnetic head 6 ... Servo control circuit 7 ... System controller 10 ... Analog audio Signal input terminal 12 A / D converter 13 ADPCM encoder 14 Memory 15 Encoder 16 Magnetic head drive circuit 18 ..Silence detection circuit 21... Decoder 22... Memory 23... ADPCM decoder 24... D / A converter 26... Analog audio signal output terminal

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ryo Ando 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Hoasaaki Maeda 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo No. Sony Corporation (72) Inventor Hideo Obata 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 20/12 G11B 19/00 G11B 27/00

Claims (4)

(57) [Claims] An audio signal to be inputted is compressed in a predetermined manner.
Apply processing, temporarily store in memory, and record on recording medium
A digital audio signal recording device for detecting a silent portion of the input audio signal.
The detecting means and the silent part detected by the silent detecting means are linked for a predetermined period or more.
It is determined whether or not it has continued, and
If there is no sound in the memory for more than the predetermined period
A digital audio signal recording device, comprising: control means for suppressing generation of a section . 2. The method according to claim 1, wherein said silent signal detecting means includes an analog monitor.
Detecting silence based on the silence level of the
2. The digital audio signal according to claim 1, wherein
Recording device. 3. The apparatus according to claim 1, wherein said silence signal detecting means includes an
Silence is detected based on the level of the digital audio signal.
2. The digital audio device according to claim 1,
Dio signal recording device. 4. An input audio signal having a predetermined compression
After processing, once stored in the memory
Digital audio signal recorded in units of blocks
In the signal recording device, the silence detecting the silence portion of the input audio signal is performed.
The detection means and the silence part detected by the silence detection means are in a predetermined block.
It is determined whether or not it has continued for a predetermined period
Silence continues for more than a specified period over a specified block.
The predetermined period in the memory
Comprising a control means for suppressing the generation of more silent portion
A digital audio signal recording device characterized by the above-mentioned.