JP2646472B2 - Audio signal storage and playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention transmits a high-quality audio signal processed by a PCM method via a digital line, and stores and reproduces the audio signal on a variable-speed tape recorder. The present invention relates to an audio signal storage / playback apparatus as described above.

[Conventional technology and its problems]

In general, music processed by the PCM method has a huge data capacity per song, so if this is transmitted via a digital line and once stored on the terminal side, a large-capacity memory or a hard disk capable of high-speed processing is required. There is a problem that the cost of the storage device is excessive, such as the need to prepare it.

Even when a hard disk is used, a large amount of audio information is divided and stored in the hard disk. However, when playing this music, it must be processed seamlessly as a single piece of music, but with the current technology, the control speed of the head is limited,
There is also a problem in the reproduction technique that the higher the quality of the audio information, the longer the time lag occurs between the divided information.

According to the present invention, an audio signal is digitized and then transmitted through a digital line, and this signal is temporarily converted to an analog signal on the terminal side and stored in a tape recorder.
It is an object of the present invention to provide an audio signal storage / playback apparatus that plays back at a predetermined double speed.

[Means for solving the problem]

The present inventor has paid attention to the fact that the permissible range of error in auditory information is generally wider than data communication including characters, images, and the like. And in order to achieve the above-mentioned purpose,
An audio signal output from a music playback device is digitally encoded by an A / D converter, and the digital signal is transmitted to a terminal side through a digital line and stored and played back, and a CPU that controls the digital signal; A D / A converter that converts a digital signal to an analog signal, and a tape recorder that stores the analog signal as it is and reproduces the audio signal by reproducing the audio tape at a predetermined speed during reproduction at a running speed of the audio tape. Means were used.

Further, following the tape recorder, a means having a low-pass filter for cutting a waveform at a certain frequency or higher was used.

[Action]

In the present invention, it is assumed that analog processing is performed in signal source and storage and reproduction, and digital processing is performed only in the transmission means. Here, A / D converter and D
The / A converter is used for converting analog and digital information, and functions as a pair with each other. Further, the CPU performs an operation of sequentially transmitting the transmitted digital signals to the D / A converter, and is used for control processing of a sequence of digital codes. The tape recorder functions as a storage device and a playback device for analog signals.In consideration of the processing time required for transmission, the waveform extended along the time axis by transmission is used to determine the running speed of the audio tape during storage and playback. By performing the above operation, the original waveform of the audio signal can be reproduced.

Further, the low-pass filter has a function of cutting noise caused by harmonics or the like generated during reproduction.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in further detail with reference to the drawings. 1 is a music reproducing apparatus such as a record compact disk / tape recorder recorded in a PCM system, and 2 is an A / A
The D converter performs a function of digitally encoding an audio output output from the playback device 1. Reference numeral 3 denotes a host computer that processes digital codes, 4 denotes a digital line connecting the host computer 3 and the terminal via modems 5 and 6, 7 denotes a CPU that processes transmitted audio signals as the terminal, and 8 denotes the digital A D / A converter 9 converts a code into an analog signal. A tape recorder 9 stores and reproduces an analog audio signal. The rotational speed of the capstan for storage and the rotational speed for reproduction are different. Things. Reference numeral 10 denotes an output device including an amplifier and a speaker connected to the tape recorder 9.

Next, the operation of the audio signal storage / playback apparatus of the present invention will be described. First, an existing record or audio tape recorded in the PCM system is played back by the music playback apparatus 1,
Using the audio signal as an original waveform, general voltage processing is performed by the A / D converter 2 and digitally encoded.
This is processed by the host computer 3 for digital transmission, and transmitted to the terminal via a digital line via the modems 5 and 6. On the terminal side, the digital signal of the original waveform is processed in real time by the CPU 7, converted into an analog waveform by the D / A converter 8, and then stored in the tape recorder 9. In this case, the transmission time of the original waveform is set as follows. That is, if the sampling frequency of the original waveform is S, the resolution of the original waveform is B bits, and the transmission capability of the digital line for one second is D kilobits, the time required for transmitting the original waveform is S × the reproduction time of the original music. B / D times. Now, in order to make the reproduced sound high-quality, the sampling frequency S is 42 kHz, the resolution B is 12 bits,
If the transmission capacity per second is 64 Kbps of the current digital line, the required transmission time is 7.875 times. Therefore, according to the present invention, the digital signal is converted to analog and stored in the tape recorder as it is, and when the digital signal is reproduced, the original waveform is reproduced as it is by increasing the running speed of the tape to 7.875 times. . The change of the original waveform during this time is shown in the waveform diagram of FIG. In this embodiment, the transmission time is long because high quality is required for the reproduced sound. However, if the sampling frequency is lowered and the resolution is lowered according to the use and purpose of music, the transmission time is shortened. In the tape recorder 9, since the running speed at the time of reproduction is faster than the running speed of the tape at the time of storage, the distortion factor due to wow and flutter can be suppressed to a small value. However, on the contrary, since the reproduction of noise at a high frequency is large, an appropriate frequency is set in the output device 10 and a low-pass filter is applied to cut harmonics and the like.

In addition, in the apparatus of the present invention, the tape recorder 9
Are provided in parallel, and storage and reproduction are sequentially performed for each song, whereby music can be continuously reproduced.

〔The invention's effect〕

The audio signal storage / playback apparatus of the present invention reproduces the state of the original waveform by converting the signal transmitted through the digital line into an analog signal, storing the analog signal in a tape recorder as it is, and playing it back at a predetermined speed during playback. Can be. Therefore, it is possible to provide a device capable of reproducing high-quality music with a simple configuration such as a tape recorder while using a highly reliable digital line.

Also, since a tape recorder was used as a storage device,
Large amounts of information can be easily stored, and this content can be played back in real time. Playback is now possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the apparatus of the present invention, and FIG.
The figure is a waveform diagram showing a change in the original waveform. In addition, in the figure, 1 ... music reproduction device, 2 ... A / D converter,
3 ... host computer, 4 ... digital line, 5
6 ... Modem, 7 ... CPU, 8 ... D / A converter, 9 ...
…Tape recorder.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-51-101506 (JP, A) JP-A-64-30069 (JP, A) JP-A-1-128264 (JP, A) 136025 (JP, U) Actually open 63-84764 (JP, U)

Claims (2)

(57) [Claims] 1. An apparatus for digitally encoding an audio signal output from a music reproducing apparatus 1 by an A / D converter 2, transmitting the digital signal to a terminal via a digital line, and storing and reproducing the digital signal. CP to control
U7 and D / A to convert the above digital signal to analog signal
The converter 8 and the analog signal are stored as they are,
An audio signal storage / reproducing apparatus, comprising: a tape recorder 9 for reproducing the audio signal by reproducing the audio tape at a preset magnification at the time of reproduction. 2. The audio signal storage / reproducing apparatus according to claim 1, further comprising a low-pass filter that cuts a waveform at a predetermined frequency or higher after the tape recorder.