JP2001119301A - Digital recording system for recording sampling time - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital recording system where the precision of a sampling position in a time base direction is improved. SOLUTION: In the digital recording system, an analog signal is converted into a digital signal by quantizing and encoding an amplitude level in the sampling position of a scribed time interval and it is recorded in a medium. The time of the sampling position is quantized and encoded and it is recorded in the medium together with the quantized and encoded amplitude level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an analog signal,
The present invention relates to a digital recording method in which an amplitude level at a sampling position at a predetermined time interval is converted into a digital signal by quantizing and encoding, and recorded on a medium.In particular, an analog audio signal is sampled at a predetermined time interval. The present invention relates to a digital recording method in which an amplitude level at a quantization position is converted into a digital signal by quantizing and encoding, and is recorded on a medium.

[0002]

2. Description of the Related Art In a conventional digital recording system,
The accuracy of the recorded digital signal in the signal level direction, that is, the quantization error is important, and the accuracy in the time axis direction is
It was said that there was no problem if it was sampled by the sampling frequency determined by the sampling theorem. As long as the quantization error is within a predetermined range in the signal level direction, it has excellent physical properties,
The sound quality of the reproduced audio signal was also considered to be of high quality.

[0003]

However, in actuality, the human auditory characteristics in the time axis direction are extremely high, and in such a conventional digital recording system, when sampling an acoustic signal which is an analog signal, It has been found that the displacement of the sampling position in the time axis direction causes an effect that can be perceived by a human in the reproduced audio signal, and, for example, it has been found that the high sensitivity information (especially air feeling) of the reproduced sound is significantly impaired. Was. Such a displacement of the sampling position is
At an accuracy of about 10%, which has been conventionally considered to be acceptable, there is a possibility that the reproduced sound quality will be seriously affected.

In the conventional digital recording method, the clock accuracy is measured on the order of 1 ns despite the fact that the measuring instrument is measured by applying a PLL to the signal under test, despite the fact that it fluctuates at a low frequency. The value is displayed, but it is known that it is actually several hundred nsec.

[0005] The recorded signal is converted to a DSP (Digital Si).
Although signal processing with a general processor or the like is common practice at the recording site, if the digital signal generated by the conventional digital recording method is further processed by a DSP or the like, the inaccuracy of the sampling position is further increased. And the sound quality may be further deteriorated. In addition, such signal processing is often performed many times, and each time the sampling position may fluctuate.

[0006] In addition, CD, DAT,
And the like perform decoding and reproduction of digital data by rotating or running a recording medium. In the process, the decoded clock signal fluctuates due to various factors such as eccentricity of the disk, warpage, fluctuation of the rotation speed of the motor, mechanical vibration of the device, and electrical noise. The conventional apparatus stabilizes the fluctuation by a PLL circuit or the like, but does not faithfully reproduce the sampling position at the time of recording. That is, the sampling clock at the time of recording is
Instead of being reproduced with the fluctuation, it is reproduced with different fluctuations due to the above factors.

In view of the above, it is an object of the present invention to provide a digital recording system and a digital recording system as described above, in which the accuracy of the sampling position in the time axis direction is improved.

[0008]

A digital recording system and a digital recording system according to the present invention quantize and encode the time of the sampling position and record the quantized time on the medium together with the quantized and encoded amplitude level. It is characterized by the following.

[0009] Since the sampling time is recorded, the reproduction system can accurately reproduce the recording time.
(Digital Signal Processo
r) does not increase the inaccuracy of the sampling position, which is a conventional problem. As a result, high-quality reproduced sound quality can be obtained even with a large number of signal processing systems. However, since the time of the reference oscillator is recorded, it is necessary to reduce the jitter of the oscillator as much as possible.

[0010] In equal sampling at the present time, which is frequently used, recording of time is sequential unlike recording of signal level. Can be realized with a small code length.

[0011]

FIG. 1 is a block diagram showing an example of a digital signal generator used in a digital recording system according to the present invention. The digital signal generator 1 includes an analog-to-digital converter 3, a first clock 5, a counter 7, a second clock 9, a DPCM coder 11, and a formatter 13.

The analog-to-digital converter 3 which receives an analog audio input signal from an analog audio signal source (not shown) such as a microphone or an analog recording medium generates a first clock 5, for example, sampling at 44.1 kHz. According to the frequency f _s , the analog audio input signal is sampled, quantized and coded, for example, generates a 16-bit digital data signal, and supplies it to the formatter 13.

[0013] counter 7 receives the sampling frequency f _s from the first clock, the time of the sampling positions where the analog-to-digital converter 3 samples the said analog acoustic input signal,
Measurement is performed based on a higher precision than the first clock 5, for example, a reference clock f _{ref of} 1 GHz received from the second clock 9, and a 16-bit digital time signal is generated, for example, and supplied to the DPCM coder 11.

The DPCM coder 11 differentially quantizes the digital time signal received from the counter 7 and outputs, for example, 8
A bit digital difference time signal is generated and supplied to the formatter 13.

The formatter 13 converts the digital data signal received from the analog-to-digital converter 3 into a DPCM signal.
The digital difference time signal received from the coder 11 is associated with and formatted to generate a digital output signal. This digital output signal can be transmitted, for example, via a network, a broadcast medium or the like (not shown), and can be recorded on a recording medium (not shown) such as a DAT or CD. Further, signal processing may be performed by a DSP or the like. FIG. 2 shows an example of the data format of such a digital output signal.

FIG. 3 is a diagram showing an example of an analog signal reproducer for reproducing an analog signal from a digital signal obtained by the method of the present invention. Analog signal regenerator 15
Is a PLL 17, a decoder 19, a DPCM decoder 2
1. A time adjustment circuit 23, a third clock 25, and a digital-to-analog converter 27 are provided.

For example, the PLL 17 receiving a digital input signal in the format shown in FIG. 2 from a network, a broadcast medium or the like (not shown) or a recording medium such as a DAT or CD (not shown), The signal is supplied to the decoder 19, and the sampling frequency f _s ′ is reproduced and supplied to the time adjustment circuit 23. The sampling frequency f _s ′ is caused by the fluctuation of the sampling position when the digital input signal is generated, and is increased by signal processing by a DSP or the like later, or the fluctuation generated when reading from a recording medium. Contains.

The decoder 19 decodes the digital input signal received from the PLL 17, generates the digital data signal and the digital difference time signal, supplies the digital data signal to the digital / analog converter 27, and The signal is supplied to the DPCM decoder 21.

The DPCM decoder 21 inversely quantizes the digital difference time signal received from the decoder 19, generates the digital time signal, and generates a digital time signal.
Supply 3 This digital time signal represents the exact time of the sampling position when the digital input signal was generated.

The time adjustment circuit 23 includes a DPCM decoder 2
1 and the digital time signal received from
The reference clock used to generate the
A third reference clock having the same accuracy as the second reference clock 9)
25, eg 1 GHz reference clock f_ref
And the sample containing the fluctuation received from PLL17 based on
Activation frequency f_s′ And correct the actual sampling time
Clock signal f _s″ To generate a digital analog
To the converter 27.

The digital-to-analog converter 27 converts the digital data signal received from the decoder 19 into an analog signal according to the clock signal f _s ″ received from the time adjustment circuit 23, and supplies an analog audio output signal.

In the above-described embodiment, only the digital recording system for an audio signal has been described. However, the digital recording system according to the present invention can be applied to any signal having a time axis.

[0023]

According to the present invention, it is possible to provide a digital recording system and a digital recording system in which the accuracy of the sampling position in the time axis direction is improved. A digital recording method capable of solving the above-described problems in the sound quality of the conventional digital recording (sound quality deterioration due to sampling position distortion) and providing high-quality sound quality, and contributing to the development of digital recording equipment. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a digital signal generator used for a digital recording system according to the present invention.

FIG. 2 is a diagram showing an example of a data format of a digital signal generated by a digital recording method according to the present invention.

FIG. 3 is a block diagram showing an example of an analog signal reproducer for reproducing a digital signal generated by a digital recording method according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 digital signal generator 3 analog-to-digital converter 5 first clock 7 counter 9 second block 11 DPCM coder 13 formatter 15 analog signal regenerator 17 PLL 19 decoder 21 DPCM decoder 23 time adjustment circuit 25 third clock 27 digital-to-analog converter

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D044 AB05 DE32 DE44 DE52 EF05 FG02 FG12 GK14 GM14 GM15 5D045 DA02 5J064 AA01 BA04 BB01 BC02 BC05 BC06 BD03

Claims (4)

[Claims] 1. A digital recording system for converting an analog signal into a digital signal by quantizing and encoding an amplitude level at a sampling position at a predetermined time interval and recording the digital signal on a medium, wherein a time at the sampling position is recorded. A digital recording method which quantizes and encodes, and records the quantized and encoded amplitude levels on the medium together with the amplitude levels. 2. The digital recording method according to claim 1, wherein the time at the sampling position is recorded as a difference time. 3. A digital recording system for converting an analog audio signal into a digital signal by quantizing and encoding an amplitude level at a sampling position at a predetermined time interval and recording the digital signal on a medium. A digital recording method, wherein time is quantized and encoded, and the time is recorded on the medium together with the quantized and encoded amplitude level. 4. The digital recording method according to claim 3, wherein the time at the sampling position is quantized and recorded.