JP3527758B2 - Information 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 an information recording apparatus for efficiently recording information such as voice on a recording medium such as a semiconductor memory.

[0002]

2. Description of the Related Art Conventionally, as a method of recording information when compressing and encoding information such as voice and recording it on a recording medium such as a magneto-optical disk, in consideration of recording time and sound quality,
There is known a method in which several modes such as a standard mode and a long time mode are provided for the compression rate and recording is performed at a compression rate corresponding to each mode. Here, in the long time mode, it is possible to record information on the recording medium for a long time, but in this case, by increasing the compression rate of the information as compared with the standard mode, it is possible to record on the recording medium. Since the time recording is realized, the sound quality after being reproduced is lower than that of the standard mode.

FIG. 7 shows a specific example of such an information recording apparatus according to the prior art. In FIG. 7, the input terminal 3
An audio signal AS is supplied to 02, and this audio signal AS is sent to the common terminal of the switching means 310. The switched terminal a of the switching means 310 is connected to the input terminal of the standard mode encoding means 312, and the switched terminal b is connected to the input terminal of the long time mode encoding means 313. The standard mode encoding means 312 encodes the supplied audio signal AS in the standard mode, and the long time mode encoding means 313 encodes the supplied audio signal AS in the long time mode. The output terminal of the standard mode coding means 312 is connected to the switched terminal a of the switching means 315, and the output terminal of the long time mode coding means 313 is the switching means 31.
5 is connected to the switched terminal b. The common terminal of the switching means 315 is connected to the input terminal of the recording medium writing means 314. The recording medium writing means 31
Reference numeral 4 records an audio signal encoded on the magneto-optical disk or the like in either the standard mode or the long time mode.

Here, when the user selects the standard mode or the long time mode, the recording mode selection means 311 determines whether the standard mode recording or the long time mode recording is performed. select. That is, the recording mode selection means 3 according to the user's selection
The selection information WS from 11 is the switching means 310 and 3
15 and the switching means 310 and 315 are switched according to the selection information WS to select the output of the standard mode coding means 312 or the long time mode coding means 313. Specifically, when the selection information WS is information indicating the standard mode, the switched terminals a of the switching means 310 and 315 are selected,
When the selection information WS is information indicating the long time mode, the switched terminals b of the switching means 310 and 315 are selected. The audio signal as encoded by any one of these modes is sent to the recording medium writing means 314. At this time, the selection information WS is also supplied to the recording medium writing unit 314, so that the writing unit 314 executes recording on the recording medium at the writing speed according to the standard mode or the long time mode. Become.

Next, FIG. 8 shows a concrete example of a conventional reproducing apparatus corresponding to the recording apparatus of FIG. In FIG. 8, the recording medium reading means 412 reads the encoded audio signal as from the recording medium. The audio signal as from the recording medium reading means 412 is sent to the common terminal of the switching means 403. The switching means 403 is switched to the switched terminal a or b according to the selection information RS from the reproduction mode selection means 411. Also,
The switched terminal a of the switching means 403 is connected to the input terminal of the standard mode decoding means 413, and the switched terminal b is connected to the input terminal of the long time mode decoding means 414.

Here, the user of this apparatus selects, by the reproduction mode selection means 411, whether to perform the reproduction in the standard mode or the reproduction in the long time mode. The selection information RS from the reproduction mode selection means 411 indicates whether the reproduction is in the standard mode or the long-time mode.
The switching means 403 and the recording medium reading means 41
Sent to 2. Therefore, the encoded audio signal as read from the recording medium by the recording medium reading means 412 is switched terminal a or b of any one of the switching means 403 switched according to the selection information RS. Via the standard mode decoding means 41
3 or long time mode decoding means 414.

The output terminal of the standard mode decoding means 413 is connected to the switched terminal a of the switching means 405, and the output terminal of the long time mode decoding means 414 is connected to the switched terminal b of the switching means 405. ing. The switching means 405 is also switched based on the selection information RS from the reproduction mode selection means 411, like the switching means 403.

As described above, the audio signal A decoded by the long-time mode decoding means 414 or the standard mode decoding means 413 selected based on the selection information RS.
S is output via the output terminal 404. The recording medium reading means 412 reads from the recording medium, but also controls the reading speed from the recording medium according to the selected mode.

[0009]

By the way, in the conventional recording / reproducing apparatus as described above, for example, 60 minutes of recording is possible in the standard mode, and 120 minutes in the long time mode.
For example, when a signal of 70 minutes is to be recorded on a recording medium capable of recording minutes, the recording time is short in the standard mode, so recording is performed only in the long-time mode in which the sound quality is significantly lower than in the standard mode. Can't do.

Therefore, an object of the present invention is to provide an information recording apparatus capable of obtaining high quality sound quality while effectively utilizing the recording medium.

[0011]

The information recording apparatus of the present invention has been proposed in order to achieve the above-mentioned object, and a recording time designating means for designating a recording time of the input information, and the input information. recording time based on the information indicating the capacity of the recording medium available for recording, the input information of the
Assigned to each of the predetermined time frames when encoding the information
Calculator for calculating the number of bits in a frame
And stage, based on the number of bits calculated by the frame bit number calculating means, and allocation means for performing adaptive bit allocation within the predetermined time frame, based on the number of bits allocated by the allocating means And a recording medium writing unit for recording the input information encoded by the encoding unit on the recording medium, the encoding unit encoding the input information for each predetermined time frame. is there.

When the remaining capacity of the recording medium available for recording becomes smaller than the amount of information determined based on the remaining recording time, the in-frame bit number calculating means The number of bits is calculated so that the remaining capacity allows recording for the remaining recording time.

The information recording apparatus of the present invention constantly records the free space of the recording medium, compares the free space with the amount of information to be recorded in the future, and records the amount of information to be recorded. The recording medium may be further provided with a remaining bit number recording means.

As the recording medium of the present invention, a recording medium composed of a semiconductor memory can be mentioned.

[0015]

According to the present invention, when the input information is recorded on the recording medium, the recording time is selected instead of the recording mode, and the encoding is performed according to the recording time (compression according to the recording time). By compressing information at a rate) and recording the obtained information, information recording of optimum quality for the recording time is performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the information recording apparatus of this embodiment when an audio signal is recorded as a recording medium in, for example, a semiconductor memory.

As shown in FIG. 1, the information recording apparatus of this embodiment is an information recording apparatus which encodes input information such as an audio signal supplied to a terminal 513 and records it on a recording medium such as a semiconductor memory. Then, the input information is encoded based on the input recording time information (the time designated by the recording time designating means 501) and the information indicating the capacity of the recording medium (semiconductor memory) available for recording. When
Number of bits allocated to each of the given time frames of
And an encoding means 503 for encoding the input information on the basis of the bit number obtained by the in-frame bit number calculating means 502.

As the audio signal supplied to the input terminal 513, for example, a waveform signal obtained by using a microphone is used by an A / D (analog / digital) converter (not shown). A digitized one can be used.

In this embodiment, the input terminal 513 is used.
The digital audio signal via the
03. The encoding in the encoding means 503 is performed every certain fixed time frame.

Further, the user of the apparatus of this embodiment designates the time for recording on the recording medium (semiconductor memory) by the recording time designating means 501, and the designated time information is the bit number in frame calculating means 502. Sent to. The in-frame bit number calculating means 502 calculates each time from the recording time designated by the recording time designating means 501 and information indicating the free space of the recording medium (semiconductor memory) arranged in the recording medium writing means 504. Information on the number of bits assigned to the frame is obtained, and the information on the number of bits is sent to the encoding means 503.

As a result, the input audio signal supplied through the input terminal 503 is compressed by the encoding means 503 by a method to be described later so that the number of bits allocated to each time frame can be accommodated. After
It is sent to the recording medium writing means 504. The recording medium writing unit 504 records the data from the encoding unit 503 in the semiconductor memory which is the recording medium.

As described above, when a recording medium composed of a semiconductor memory is used, the recording medium writing means 504 writes the coded data at the time when the coding of each time frame is completed. The address of the semiconductor memory may be designated and recorded.

Here, a concrete method of encoding the audio signal in the encoding means 503 will be described below.

There are various techniques for high-efficiency coding of signals such as audio or voice. For example, non-blocking in which audio signals on the time axis are not divided into blocks but are divided into a plurality of frequency bands for coding Band division coding (sub-band coding: SB
C) or a block frequency band division method for converting a signal on the time axis into a signal on the frequency axis (spectral conversion), dividing into a plurality of frequency bands, and encoding for each band, so-called conversion encoding. Can be mentioned. Further, a method of high efficiency coding in which the above band division coding and transform coding are combined is also considered, and in this case, for example, after performing band division by the above band division coding, A signal for each band is spectrum-converted into a signal on the frequency axis, and each spectrum-converted band is encoded.

Here, as a filter for band-dividing an audio signal or the like on the time axis, for example, a so-called QMF filter can be cited. As this QMF filter, for example, 1976 RECrochiere Digital co
ding of speech in subbands Bell Syst.Tech. J. Vol.5
5, No. 8 1976. Also, for example, ICASSP83,
BOSTON Polyphase Quadrature filters-A new subband
Coding technique Joseph H. Rothweiler describes a technique of equal bandwidth filter partitioning.

As the spectrum conversion, for example, the input audio signal is divided into blocks in a predetermined unit time, and fast Fourier transform (FFT), cosine transform (DCT), modified DCT transform (M
There is spectrum conversion in which the time axis is converted to the frequency axis by performing DCT) or the like. Regarding the above MDCT,
For example, ICASSP 1987 Subband / Transform Coding Using
Filter Bank DesignsBased on Time Domain Aliasing
CancellationJ.P.Princen ABBradley Univ.of Surre
y Royal Melbourne Inst. of Tech.

As described above, by quantizing the signal divided for each band by the filter and the spectrum conversion,
It is possible to control the band in which the quantization noise is generated, and moreover, it is possible to perceptually perform highly efficient coding by utilizing properties such as a so-called masking effect. Also,
Here, if the normalization is performed for each band, for example, by the maximum absolute value of the signal component in that band before the quantization is performed, more efficient coding can be performed.

As the frequency division width for quantizing each frequency component obtained by frequency band division, for example, band division is performed in consideration of human auditory characteristics. That is, the audio signal is divided into a plurality of bands (for example, 25 bands) with a bandwidth which is generally called a critical band and which becomes wider in a higher band. In addition, when encoding the data for each band at this time, encoding may be performed by predetermined bit allocation for each band or adaptive bit allocation (bit allocation) for each band. it can. For example, when the coefficient data obtained by the MDCT processing is coded by the bit allocation, it is adaptive to the MDCT coefficient data for each band obtained by the MDCT processing for each block. Encoding will be performed with the allocated number of bits.

The following two methods are known as the bit allocation method. Ie, for example, IEEE Transactions
of Accoustics, Speech, and Signal Processing, vol.ASS
In P-25, No. 4, August 1977, bit allocation is performed based on the signal size of each band. With this method,
The quantization noise spectrum becomes flat and the noise energy becomes the minimum, but the actual noise feeling is not optimal because the masking effect is not used auditorily. Also, for example, ICASSP 1980 The critical band coder--digital
encoding of the perceptual requirements of the au
In the ditory system MAKransner MIT, a method is described in which auditory masking is used to obtain a necessary signal-to-noise ratio for each band and perform fixed bit allocation.
However, in this method, even when the characteristic is measured with a sine wave input, the characteristic value is not so good because the bit allocation is fixed.

In order to solve these problems, all bits that can be used for bit allocation are assigned a fixed bit allocation pattern predetermined for each small block and bit allocation depending on the signal size of each block. It is divided into parts to be used, and the division ratio depends on the signal related to the input signal,
A high-efficiency coding apparatus has been proposed in which the smoother the spectrum of the signal, the greater the division ratio into the fixed bit allocation pattern.

According to this method, when the energy is concentrated on a specific spectrum such as a sine wave input, a large number of bits are allocated to a block including the spectrum, thereby significantly improving the overall signal-to-noise characteristic. can do. In general, human hearing is extremely sensitive to a signal having a steep spectral component, so improving the signal-to-noise characteristic by using such a method not only improves the numerical value in measurement. It is effective for improving the sound quality in the sense of hearing. Many other methods have been proposed for the bit allocation method, and the model relating to hearing is further refined, and if the ability of the coding device is improved, more efficient coding can be performed in terms of hearing. .

Here, in the bit allocation as described above, it is possible to control the total amount of bits used therein for each certain time frame, but of course, a larger total bit amount is allocated to each time frame. Can reduce the level of quantization noise, and can further improve the sound quality.

FIG. 2 shows a concrete configuration example of the encoding means 503 of FIG. 1 for compressing an audio signal by the above method. In this configuration example, the entire band is decomposed into four, Normalization and quantization are performed.

In FIG. 2, an audio signal is supplied to the terminal 100 through the input terminal 513 of FIG. 1, and this signal is sent to the band dividing means 101. As the band dividing means 101, the band dividing filter as described above can be used, but of course, spectrum conversion may be used.

The signal for each band from the band dividing means 101 is sent to the normalizing means 111-114. As described above, these normalizing means 111 to 114 perform normalization for each band, for example, with the maximum absolute value of the signal component in that band before performing the quantization. This allows
Highly efficient encoding can be realized.

The outputs from these normalizing means 111 to 114 are sent to the corresponding quantizing means 121 to 124, respectively.

Here, the quantization precision determining means 141 is
The output from the band dividing means 101 is supplied, and the bit number information from the in-frame bit number calculating means 502 of FIG. The quantization precision determining means 141 allocates bits to each band within the range based on the above-mentioned number-of-bits information allocated to each time frame. The bit allocation information from the quantizing precision determining means 141 is sent to the quantizing means 123 to 124 via the quantizing means 121 and terminals 152 to 154.

The quantizing means 121 to 124 quantize the outputs from the normalizing means 111 to 114 based on the bit allocation information from the quantizing precision determining means 141. The outputs of these quantizing means 121 to 124,
The normalization information related to the normalization by the normalizing means 111 to 114 is sent to the multiplexer 131.

The signals multiplexed by the multiplexer 131 are sent to the recording medium writing means 504 of FIG. 1 via the terminal 103.

FIG. 3 shows the contents of information compressed by the encoding means 503. In FIG. 3, N bits of information are assigned to each time frame. The information of each time frame is the quantization accuracy information (quantization bit number information) q ₁ in each band.
To q ₄ , normalization information n _{1 to} n _4, and the normalizing means 1 described above.
11 to 114, and each quantizing means 121 to
The signal information s _{1 to} s ₄ quantized in 124.
These pieces of information are recorded in the recording medium (semiconductor memory).

In the above embodiment, the number of bits assigned to each time frame is fixed, but the number of bits assigned to each time frame does not have to be constant. For example, if the number of bits actually used for encoding in each time frame is less than N bits, a given recording medium can record the time specified by the user of the recording device, In this case, no problem occurs.

Furthermore, in the apparatus of the present embodiment, as another encoding method, for example, a pattern of 0 and 1 of signal information, for example, 1952 DAHuffman, A Method for Construct.
ion ofMinimum Redundancy Codes, Proc.IRE, 40, p.
The encoding method described in 1098 may be used to record the data so that it is statistically compressed.

In this case, N bits or more may be allocated in a certain time frame, but since the compression rate increases on average over a long time, in this case, the recording of the time specified by the user is performed. It can be performed. However, in case of emergency, first the information of the time frame is compressed to (N-1) bits by normalization and quantization, and then it is further compressed by the above-mentioned encoding. It is also possible to perform recording by the encoding only and to add 1-bit flag information as to which encoding was performed in that time frame.

As a method of ensuring the recording time designated by the user, as shown in FIG. 4, the remaining bit number recording means 525 is provided to constantly record the free space of the recording medium, and the free space of this recording medium is recorded. Is below a certain value,
The encoding unit 523 may be controlled by the in-frame bit number calculation unit 522 so that the recording of the remaining time designated by the user of the recording apparatus is completely performed. In addition,
In FIG. 4, the information sent from the in-frame bit number calculation means 522 to the encoding means 523 is absolutely index information of the total number of bits in the time frame and whether or not the index is strictly adhered to as the total number of bits in the time frame. Information transmitted from the encoding means 523 to the intra-frame bit number calculation means 522 represents the number of bits actually used for the time frame. Also,
In the configuration of FIG. 4, the input signal is divided at regular intervals, and a certain capacity of the recording medium is assigned in advance for each division.
You may make it perform the above-mentioned process by comparing the remaining capacity and the information to be recorded in each section. In this way, it is possible to prevent a sudden change in sound quality at the end of recording.

Although the embodiment of the recording apparatus has been described above, FIG. 5 is a block circuit diagram showing an embodiment of the reproducing apparatus corresponding to the recording apparatus of FIG.

In this reproducing apparatus, first, the recording medium reading means 601 reads the encoded information from the recording medium, sends it to the decoding means 602, and decodes it.
The audio signal is output from the terminal 603. Here, when a recording medium constituted by a semiconductor memory is used, the recording medium reading means 601 reads the coded data by designating an address of the semiconductor memory every time when decoding each time frame. Just put it out. In this reproducing apparatus, since it is possible to completely decode only the recorded information, it is not necessary to input the recording time or the like from the outside for reproduction.

Further, FIG. 6 shows the decoding means 6 of FIG.
02 shows a specific configuration.

In FIG. 6, the signal from the recording medium reading means 601 of FIG. 5 is the encoding means 602.
It is sent to the demultiplexer 202 via the terminal 201 of. Quantization accuracy information (quantization bit number information) in each band for each time frame, obtained by demultiplexing in the demultiplexer 202, normalization information, and quantized signal information are respectively It is sent to the corresponding signal component constructing means 211-214, where it is reconstructed into signal components. The signal components for each of these bands are converted into band combining means 221.
Is output to the output terminal 251 as an audio signal that has been subjected to band synthesis by the band synthesis means 221 and has been decoded.

In the above embodiments, the audio signal is recorded on the recording medium composed of the semiconductor memory, but the signal to be recorded is not limited to the audio signal but is, for example, a video signal. However, the method of the present invention can be applied to the recording of this video signal.

The present invention can be applied even if the recording medium is not necessarily composed of a semiconductor memory, but the writing and reading speeds can be easily controlled as in this embodiment. If a semiconductor memory that can be used is used, the device can be simplified and convenient.

[0052]

As is apparent from the above description, according to the present invention, when the input information is recorded on the recording medium, the recording time is selected instead of the recording mode and the recording time is changed. By performing encoding (compressing information at a compression rate according to the recording time) and recording the obtained information, information such as audio signals is recorded with the optimum quality for the recording time required by the user. Will be able to. That is, according to the information recording apparatus of the present invention, it is possible to obtain high-quality sound quality while effectively utilizing the recording medium.

Therefore, at the time of the subsequent reproduction, the correct reproduction can be performed without designating how much time information is recorded on the recording medium.
Also, the reproduction operation becomes easy.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of a recording apparatus according to an embodiment of the present invention.

FIG. 2 is a block circuit diagram showing a specific configuration of an encoding means according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining the contents of recorded information according to the embodiment of the present invention.

FIG. 4 is a block circuit diagram showing a schematic configuration of another specific example of the recording apparatus according to the embodiment of the present invention.

FIG. 5 is a block circuit diagram showing a schematic configuration of a reproducing apparatus according to an embodiment of the present invention.

FIG. 6 is a block circuit diagram showing a specific configuration of a decoding means according to an embodiment of the present invention.

FIG. 7 is a block circuit diagram showing a specific configuration of a recording apparatus according to a conventional technique.

FIG. 8 is a block circuit diagram showing a specific configuration of a reproducing device according to a conventional technique.

[Explanation of symbols]

Recording time designating means 502, 522 ... In-frame bit number calculating means 503, 523 ... Encoding means 504, 524 ... Recording Medium writing means 525 ... Remaining bit number recording means 101 ... Band division means 111-114 ... Normalization means 121-124・ ・ ・ Quantization means 131 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Multiplexer 141 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Quantization accuracy determination means 601 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Recording medium reading means 602 ... Decoding means 202 ... Demultiplexers 211-214 ... Signal component constructing means 221 ... .Band synthesis means

   ─────────────────────────────────────────────────── ─── Continued front page       (56) References JP-A-59-100500 (JP, A)                 JP-A-4-145781 (JP, A)                 JP-A-5-35295 (JP, A)                 JP-A-5-122655 (JP, A)                 JP-A-3-112221 (JP, A)

Claims (3)

(57) [Claims] 1. An information recording device for encoding input information and recording it on a recording medium, which is usable for recording time designating means for designating a recording time of the input information and for recording the recording time of the input information. The above input information is encoded based on the information indicating the capacity of the recording medium.
Assigned to each of the predetermined time frames for
A frame bit number calculation means for calculating the that number of bits, and assigning means for, based on the number of bits calculated by the frame bit number calculating means carries out adaptive bit allocation within the predetermined time frame, Encoding means for encoding the input information for each predetermined time frame based on the number of bits assigned by the assigning means, and recording the input information encoded by the encoding means on the recording medium. An information recording apparatus comprising: 2. The in- frame bit number calculation means , when the remaining capacity of the recording medium available for recording becomes smaller than the information amount determined based on the remaining recording time,
2. The information recording apparatus according to claim 1, wherein the number of bits is calculated so that the remaining capacity can be recorded for the remaining recording time. 3. The free space of the recording medium is constantly recorded,
2. The remaining bit number recording means for comparing the free space with the amount of information to be recorded in the future to secure a capacity in the recording medium capable of recording the amount of information to be recorded. Information recording device.