JPH02252173A - Sound digital signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To make the tape speed freely variable at a variable reproducing speed and to find a variation point by storing a regenerated sound digital signal in memory circuits, reading it by a variable speed signal, making an address counter up and down and stop and providing a digital interpolation circuit. CONSTITUTION:The sound digital signal of the recording and reproducing device is written as a data in a specified place of the memory circuits 1 and 2 as specified in address by a memory write control circuit 3. And, a clock frequency of a read address counter of the circuits 1 and 2 respectively is controlled by a memory read-out control circuit 4 with the variable speed signal. And, the up-and-down and stop operation of a read address value of the circuits 1 and 2 is performed by the circuit 4 with the variable speed signal, and such an alternate operation is carried out that while the circuit 1 is under the write operation, the circuit 2 is operated for the write, and while the circuit 1 is under the read operation, the write takes place in the circuit 2. Then, the read- out signal from the circuits 1 and 2 is freely varied in speed of the sound digital signal by the interpolation circuit 5 to be inputted with the variable speed signal.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to an audio digital signal recording and reproducing apparatus such as a PCM recording and reproducing machine.

2. Description of the Related Art In the past, the common recording method for recording and reproducing devices was to record analog signals directly onto a tape using a fixed head. Audio signals recorded using this method are called linear audio signals.

When performing audio decentralization, the decentralized point was found by freely varying the tape speed using a variable speed playback speed dial and by looking at the changing points of the linear audio signal on the tape.

On the other hand, a method of first converting an audio signal into a digital signal and then recording it has become popular in recent years because it enables recording and reproduction of high-quality audio signals. Institute of Electronics and Communication Engineers Magnetic Recording Study Group MR-86- June 19, 1986
5, a method for recording and reproducing audio signals by converting them into digital signals has been used. FIG. 4 shows the recording signal format on the magnetic tape in this case.

The PCM audio signal is a signal obtained by time-base compressing the digital audio signal during one field period.

Problems to be Solved by the Invention However, the conventional configuration described above has a problem in that it is not possible to find the point of change when changing the tape 2 peed.

The present invention uses the above-mentioned audio digital signal to locate the beginning of a recording/playback device in the same way as a linear audio signal, and allows the tape nuppedo to be freely varied using a variable speed playback speed dial to find a change point. The purpose of the present invention is to provide a recording/playback device.

Means for Solving the Problems To achieve this object, the audio digital signal recording and reproducing device of the present invention includes a memory circuit for recording the reproduced audio digital signal, and a readout circuit for controlling reading and writing of the memory circuit. A write control circuit, a read control circuit that controls readout of the audio digital signal from the memory circuit using a variable playback speed signal, and an interpolation circuit that interpolates the audio digital signal read from the memory circuit using the variable playback speed signal. It has the following configuration.

Function: With this configuration, an audio digital signal is recorded in the memory circuit, the readout of the memory circuit is freely slowed down and stopped by the variable speed playback speed signal, and the reading is interpolated by the variable speed playback speed signal, so that it can be recorded in the same way as a linear audio signal. Change points can be easily found.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a recording and reproducing apparatus for audio digital signals according to a first embodiment of the present invention. Reference numerals 1 and 2 are memory circuits, in which the reproduced audio digital signals are stored frame by frame. The memory circuits 1 and 2 are generally composed of random access memories (RAMs) and store data at designated addresses. Reference numeral 3 designates a memory write control circuit that controls word address designation and write permission.
Controls which ones are allowed to write. Reference numeral 4 denotes a memory read control circuit that controls read address designation and read permission, and also controls a read address counter and clock frequency using speed data.
Instructs the memory circuits 1 and 2 to read the data stored in the memory circuits 1 and 2 in the order in which they were stored, and also instructs the memory circuits 1 and 2 to read out the data stored in the memory circuits 1 and 2 in the order in which they were stored. , controls whether reading is permitted. 5 interpolates the data read from the memory circuit 1.2 using a variable speed signal. The operation of the audio digital signal recording and reproducing apparatus configured as described above will be described below.

First, the reproduced audio digital signal is written as data to a predetermined location of the memory circuits 1 and 2 addressed by the memory write control circuit 3. The variable speed signal causes the memory read control circuit 4 to control the clock frequency of the read address counter of the memory circuit 1.2. In addition, the memory read control circuit 4 controls up, down, and stop of the read address value of the memory circuit 12 by the variable speed signal.
・＼－・ Do. While writing to the memory circuit 1, the memory circuit 2 reads, and while reading to the memory circuit 1, the memory circuit 2 writes, and so on. FIG. 2 shows the operation of the magnetic recording/reproducing apparatus of this embodiment, and the operation will be explained below using FIG. 2. PC with time axis compressed for each field
For the M audio signal, a signal obtained by time axis expansion for each field is used as an audio digital signal input. When the variable speed signal is at 1x speed, the audio digital signal input is first written into the memory circuits 1 and 2, and then read from the memory circuit 2.1 using the same sample clock as when writing.

In that case, the interpolator will not operate.

As shown in Figure 2B, when the variable speed signal is % double speed, P
As for the CM audio signal, the same signal is output twice. Therefore, the same signal is output twice in the audio digital signal input. The 1-field audio digital signal is written to the memory circuit using the same sample clock as at 1x speed, and the clock of the read address counter of the memory circuit is read out from the memory circuit by locking the sample clock.

FIG. 3 shows the operation of the interpolation circuit at % double speed. In the above case, since the period of the data read from the memory circuit is the limit of the sample clock, the cutoff frequency of the low-pass fill after D/A conversion must also be set to %. To compensate for this, digital interpolation of % double speed is performed using the variable speed signal.

When the variable speed signal is at % double speed, as shown in the operation at % double speed in Figure 3C, the same track is scanned four times in the rotary head, so the PCM audio signal is
It comes out one by one. Therefore, the same digital signal is output four times each. The 1-field audio digital signal is written into the memory circuit using the same sample clock as at 1x speed, and the clock of the read address counter of the memory circuit is read from the memory circuit at % clock of the sample clock. % in Figure 4 C
The operation of the interpolation circuit at double speed is shown. In the above case, since the cycle of data read from the memory circuit is % of the sample clock, the cutoff frequency of the Laubanu filter after D/A conversion must also be %. To compensate for this, digital interpolation of the variable speed signal % double speed is performed. Variable speed speed signal is closed.

%r'A2+ is the clock of the read address counter of the memory circuit as a percentage of the sampling clock.

Then, it is changed to 1152 and output from the memory circuit.

Also, the period of data read from the memory circuit is %.

%, 1/32, so the cutoff frequency of low-pass filter after D/A conversion is 1/32.
To compensate for the need to increase the speed to 32, digital interpolation is performed according to the speed. Also, turn the variable speed dial clockwise.
The state of counterclockwise rotation and stop is transmitted by a variable speed signal,
When the read address counter of the memory circuit is turned clockwise, it goes up, when it is turned counterclockwise, it goes down, and when it stops, it stops counting.

As described above, according to this embodiment, the clock of the read address counter of the memory circuit is varied by the variable speed signal, and the clock of the read address counter of the memory circuit is increased.
By providing down, stop, and digital interpolation, changing points can be found in the same way as with linear audio signals.

Effects of the Invention As described above, the present invention records an audio digital signal in a memory circuit, and uses a variable speed signal to increment, decrement, and stop the read address counter of the memory circuit, and provides digital interpolation. Similarly, it is possible to realize an excellent audio digital signal recording and reproducing apparatus in which the tape speed can be freely varied and changing points can be found using a variable speed reproduction speed dial.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an audio digital signal recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a timing chart showing the same operation, FIG. 3 is a waveform diagram of the same, and FIG. 4 is a signal trunk of a magnetic tape. FIG. 1.2... Memory circuit, 3... Memory write control circuit, 4... Memory read control circuit, 5... Interpolation circuit.

Claims (1)

[Claims] a memory circuit for reproducing an audio digital signal recorded on a recording medium and recording the audio digital signal; a read/write control circuit for controlling reading/writing of the memory circuit; A recording and reproducing apparatus for audio digital signals, comprising: a readout control circuit that controls reading from the circuit; and an interpolation circuit that interpolates the audio digital signal read from the memory circuit using the variable reproduction speed signal.