JPH10269702A - Digital sound recording machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a digital sound recording machine which adjusts time of sound program material in a writing side of a recording medium. SOLUTION: CPU 1 finds a ratio of broadcasting hours to standard reproducing time of input sound program material. A sampling clock generator 5 outputs a sampling clock according to the sampling clock frequency command received from the CPU 1 to a sampling rate converter 2. The sampling rate converter 2 converts the digital sound program material input into a sampling clock to record to a recording medium 3. The recording medium 3 outputs the digital sound program material of a reference sampling clock. A D/A converter 4 converts the digital sound program material from the recording medium 3 from digital to analog. The analog signal output from the D/A converter 4 is output as an analog sound program material, after removing frequency component which is 1/2 or more of the reference sampling clock through a low-pass filter 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital recorder, and more particularly to a digital recorder capable of adjusting a program transmission time.

[0002]

2. Description of the Related Art A program broadcasting operation of a radio broadcasting station has been performed for a long time by an automatic program controller (APS), which is a kind of computer, according to a program operation table (cue sheet). Therefore, all broadcast programs need to be of a fixed length (temporal). Television broadcasts are rarely offset in time (although they are rare in Japan, but may vary in time for U.S. local stations), In that case, the time length of the program may vary (for example, ± 5%) due to past customs.

[0003] All revenue sources of commercial broadcasting stations depend on CM (commercial message) program broadcasting fees. Therefore, the broadcasting of the CM program is extremely important, and it is absolutely necessary to avoid a part of the CM program being cut or a long silent period before and after the CM program. Also, since many CM program materials are brought in from a sponsor, it is difficult for the broadcast station to control the time length of the CM program.

[0004] An audio file (digital recording) device, for example, converts an analog audio signal into a digital signal by A / D conversion.
This device converts the digital signal into a CM digital signal, stores it in a recording medium such as a semiconductor memory or a magnetic disk, reads out the stored PCM digital signal, performs D / A conversion, and reproduces an analog audio signal.

[0005] This audio file device is a recording / reproducing device mainly for an audio program of a radio (television) broadcasting station. In the case of a CM program, it is used repeatedly for a long time, and the recording medium is required to have a high degree of reliability.

When transmitting audio program material such as a CM program and other general (normal) programs, it is necessary to transmit the audio program material so as to fit within a time frame defined as a broadcast frame.

When recording an audio program material in an audio file device, the recording time is usually equal to the audio program material reproduction time. For example, an audio program material having a reproduction time of 10 seconds is recorded as 10 seconds. On the other hand, when an audio program material recorded in an audio file device is transmitted as a radio (television) broadcast, the transmission time is strictly determined. For example, in a broadcast frame of 10 seconds, there is no choice but to broadcast audio program material within 10 seconds.
If it is longer than 10 seconds, the portion exceeding 10 seconds will not be cut and broadcast, resulting in an unnatural sound and the broadcast will be ugly (particularly, in the case of CM programs, it will affect the payment of the broadcast fee. It will be treated as a disability or broadcast accident). Also, when the audio program material is too short compared to the broadcast frame of 10 seconds, silence continues and becomes unnatural.

On the other hand, the audio program material brought into the broadcasting station has a length of about ± 5% with respect to the reproduction time designated as the broadcast frame. For example, the audio program material for a 10-second broadcast frame is 9.5. From about 1 second to about 10.5 seconds, it is cut for 0.5 seconds or becomes silent.

JP-A-58-172078 and JP-A-58-1982
Japanese Patent No. 172079 proposes a method of adjusting the time length of audio program material using a variable speed playback mode of a broadcast VTR. In the case of this proposal, it is considered that the time length is adjusted mainly with the video program material. Therefore, it is inconvenient when considering the audio program material. Stretching or shrinking).

Japanese Patent Laid-Open Publication No. 1-21000 discloses a clock used for D / A conversion when a digital audio signal reproduced from a recording medium is D / A converted and converted into analog audio through a low-pass filter circuit. Changing the frequency changes the temporal length of the analog audio signal. That is, if the clock frequency of the D / A conversion is increased with respect to the clock frequency of the digital audio signal reproduced from the recording medium, the time length of the analog audio signal becomes shorter. Further, a method has been proposed in which the cutoff frequency of the low-pass filter circuit is changed according to the clock frequency of the D / A conversion.

[0011]

Generally, in a digital audio system for business use, a sampling (clock) frequency is fixed to a certain reference frequency (for example, 48 kHz). In the case of the proposal described in JP-A-1-21000,
Since the clock (sampling) frequency of the D / A conversion is variable, only an analog audio signal output can be obtained. If the time length of the audio program material is adjusted on the reading side of the storage medium as in the proposal described in Japanese Patent Application Laid-Open No. 1-21000, the setting of the audio file device (digital recorder) for transmission will be incorrect. In this case, there is a possibility that a broadcast failure (accident) may occur as described above. Therefore, it is not appropriate to adjust the time length of the audio program material on the reading side of the recording medium.

It is an object of the present invention to provide a digital recorder that adjusts the time length of audio program material on the writing side of a recording medium.

[0013]

A first storage means for digitally writing a digital audio program material according to the present invention, and the digital audio program material is read out from the first storage means with a reference sampling clock and transmitted. A digital clock recorder comprising: a readout unit; a reference clock generating unit for generating the reference sampling clock; and a ratio of a broadcast frame time corresponding to the digital audio program material to a standard reproduction time of the digital audio program material. Variable clock generating means for generating a sampling clock proportional to, a clock conversion means for converting a quantization clock of the digital audio program material provided on the input side of the first storage means to the sampling clock, The digital audio program material output from the clock conversion means with the standardized clock is stored in the storage means. Characterized in that it comprises a means for burn them.

Further, the present invention is characterized in that a quantization clock of the input digital audio program material is equal in frequency to the reference sampling clock.

Further, the sampling clock is equal to a ratio of a broadcast frame time corresponding to the digital audio program material to a standard reproduction time of the digital audio program material multiplied by the reference sampling clock. And

Still further, the clock conversion means digitally writes the digital audio program material in the second storage means, and writes the digital audio program material in the second storage means using the quantized clock. ,
Means for reading out the digital audio program material written in the second storage means with the sampling clock.

Still further, the first or second storage means is constituted by a semiconductor storage element.

Still further, the first storage means is constituted by a magnetic or optical disk device.

The operation of the present invention is as follows. A digital audio signal sampling rate converter is provided on the writing (input) side of the recording medium, and the sampling (clock) frequency (sampling clock) of the digital audio signal on the writing side is changed to change the reference frequency (reference sampling clock). When the audio program material is reproduced from the recording medium in the step (1), the audio program material is written on the recording medium in a time-adjusted manner.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a digital recorder according to the present invention.

In FIG. 1, a digital recorder according to the present invention includes a CPU 1 for controlling the entire digital recorder, a sampling rate converter 2 for converting a sampling (quantized clock) frequency of an input digital audio program material, and an input digital audio. A recording medium 3 for storing a program material, for example, a semiconductor storage element or a magnetic (or optical) disk, and a D / A converter 4 for converting a digital audio program material read from the recording medium 3 into an analog audio program material. , A low-pass filter 5 for removing harmonic components, a reference sampling clock (for example, 48 kHz) (frequency; f2), and a variable frequency sampling clock (for adjusting the time length of audio program material) (frequency; f1) , And a sampling clock generator 6.

The operation of the embodiment of the present invention is as follows. The CPU 1 provides the CPU 1 with a broadcast time frame of an audio program material to be inputted and a reproduction time of the audio program material when the sampling clock is used as a reference sampling clock (standard reproduction time). Time; T1), and the inverse ratio (T2 / T1) between the broadcast frame time (T2) and the standard reproduction time of the audio program material is obtained. The sampling clock frequency (f1) is supplied to the sampling clock generator 6. Command (f
1 = f2 × T2 / T1).

The sampling clock generator 6 outputs a sampling clock (f 1 = f 2 × T 2 / T 1) having a frequency according to the standardized clock frequency command received from the CPU 1 to the sampling rate converter 2. Further, the reference sampling clock is output to the recording medium 3 and the D / A converter 4.

The sampling rate converter 2 converts a digital audio program material input quantized by the reference sampling clock f 2 into a digital audio program material synchronized with the sampling clock f 1, and records it on the recording medium 3. The digital audio program material read out from the recording medium 3 by the reference sampling clock f2 and consequently quantized by the reference sampling clock is output.

On the other hand, the D / A converter 4 converts the digital audio program material read from the storage medium 3 by the reference sampling clock input from the sampling clock generator 6 into a digital signal.
/ A conversion. The analog signal output from the D / A converter 4 is subjected to a low-pass filter 5 to １ ／ of the reference sampling clock.
The above frequency components are removed, and the resultant is output as an analog audio program material.

Although the sampling rate converter 2 may have a complicated structure including an operation between bytes, the simplest one is, as shown in FIG. 2, mainly composed of a memory 7 for writing a digital audio program material input. In some cases, the digital audio program material is written in the memory 7 with its quantization clock (for example, a reference sampling clock) and then read again with a sampling clock.

The input digital audio program material is, for example, converted from a 24-bit parallel digital audio signal to serial data and sent together with a clock. Writing to and reading from the memory 7 is, for example, 24 bits (1 byte)
In the form of a parallel digital audio signal (however, serial / parallel conversion is required). There are both parallel and serial connection methods between the memory 7 and the recording medium 3.

The digital audio program material read out from the memory 7 by the sampling clock becomes a digital audio signal using the sampling clock as a quantization clock, but the digital audio program material originally has a clock (quantized clock). In general, the sampling clock (for example, the reference sampling clock) and the sampling clock have different frequencies, so that an overtaking (overtaking by a preceding clock phase or overtaking by a later clock phase) occurs. .

Therefore, at the moment when an overtaking occurs, a digital audio signal is lost or the same byte is repeated in units of 1 byte (for example, 24 bits). However, since the frequency difference between the quantization clock and the sampling clock of the input digital audio program material is 5% at the maximum, such a loss of the digital audio signal and the repetition of the same byte do not pose a practical problem.

[0031]

As described above, the present invention adjusts the standard playback time of an audio program material to a program time frame on the input (write) side of a recording medium to convert the reproduced audio program material into a digital audio signal. In addition to the effect of being able to output, there is also an effect that a highly reliable audio program can be broadcast without erroneous setting of the digital recorder.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a detailed block diagram of a sampling rate converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2 Sampling rate converter 3 Recording medium 4 D / A converter 5 Low-pass filter 6 Sampling clock generator

Claims (6)

[Claims] 1. A digital recording system comprising: first storage means for digitally writing digital audio program material digitally; and read means for reading and sending the digital audio program material from the first storage means with a reference sampling clock. A reference clock generating means for generating the reference sampling clock; and a sampling clock proportional to a ratio between a broadcast frame time corresponding to the digital audio program material and a standard reproduction time of the digital audio program material. Variable clock generating means for generating, clock conversion means for converting a quantized clock of the digital audio program material provided on the input side of the first storage means to the sampling clock,
Means for writing the digital audio program material output from the clock conversion means with the standardized clock in the storage means. 2. The digital recorder according to claim 1, wherein a quantization clock of the input digital audio program material is equal in frequency to the reference sampling clock. 3. The method according to claim 1, wherein the sampling clock is equal to a ratio of a broadcast frame time corresponding to the digital audio program material to a standard reproduction time of the digital audio program material multiplied by the reference sampling clock. The digital recorder according to claim 2, wherein 4. The second storage means, wherein the clock converting means digitally writes the digital audio program material, and the means for writing the digital audio program material into the second storage means using a quantization clock thereof. 4. The digital recorder according to claim 1, further comprising: a unit for reading out the digital audio program material written in the second storage unit with the sampling clock. 5. The apparatus according to claim 1, wherein said first or second storage means is constituted by a semiconductor storage element.
A digital recorder according to 2, 3 or 4. 6. The apparatus according to claim 1, wherein said first storage means is constituted by a magnetic or optical disk device.
A digital recorder according to 2, 3 or 4.