JPH01125763A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce abnormal sound at a consecutive part and unnatural audible sense in a sector area by storing the data of an overlapping part by superposing in a memory part, and performing a cross fade processing by performing the bit shift of sound data read out from the memory part and changing a reproducing gain. CONSTITUTION:In the overlapping part, the same voice signal as the one provided in a prescribed section at the termination of a preceding sector area is recorded at the start end of the sector areas 0-3 provided at a prescribed interval and on which the voice signal is divided and recorded. In other words, the memory part 3 stores the sound data of the overlapping part by superposing, and performs the cross fads processing to change the reproducing gain of the sound data in the overlapping part read out from the memory part 3 from a high level to a low level or vice versa. In such a way, it is possible to reduce the abnormal sound at the consecutive part between the sector areas, or to prevent the unnatural audible sense from being generated even when the fluctuation in the time base due to, for example, jitter, etc., is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording/reproducing device such as a video floppy recorder.

BACKGROUND OF THE INVENTION In recent years, instead of cameras that use film, video floppy recorders have been commercialized that record still images on a video floppy with a built-in magnetic disk. A function has been added to compress the time axis and record approximately 20 seconds per track.

The magnetic recording and reproducing apparatus as described above will be described below with reference to the drawings.

Fig. 6 is a block diagram of a video floppy audio reproducing device as an example of a conventional magnetic recording/reproducing device, Fig. 7 is a timing diagram of a memory write signal, Fig. 8 is a timing diagram of a memory read signal, and Fig. 9 is an audio signal FIG. 4A is a diagram showing a recording format of , in which (a) shows a track format, (b) a sector format, and (C) each period of the sector format.

First, the recording format of the audio signal will be explained using FIG. 9. Note that this audio signal is time-axis compressed and recorded on concentric tracks, but this time-axis compression ratio has a 3
There are three options: 20x, 640x, and 1280x, and each track can record approximately 5 seconds, 10 seconds, and 20 seconds of audio.

(a) is a diagram showing a track format.

DSP stands for data start point and corresponds to the conventional PG yoke. The compressed audio signal and control code are recorded divided into four sectors, and each sector has a space. (b) and (C) are diagrams showing sector formats. The start flag and end flag indicate the beginning and end of a sector, and serve as a time axis reference when reproducing a compressed audio signal. The control code is information possessed by the audio signal (for example, the track number where the corresponding video signal is recorded, the audio compression ratio, the track number where the continuation of this compressed audio signal is recorded, etc.).

The same compressed audio signal as the last part of the compressed audio signal of the previous sector is recorded in the overlap. Also, the 9th
Although the start flag is a positive signal in FIG. 3B, it becomes a negative signal if, for example, no compressed overlap portion is recorded in this sector. Further, the end flag is a negative signal, but becomes a positive signal when, for example, recording of the compressed audio signal ends in this sector and does not continue to the next sector.

The operation of reproducing a compressed audio signal of one track recorded in the above format will be explained with reference to FIGS. 6, 7, and 8.

In FIG. 6, 11 is a reproduction means for reproducing the compressed audio signal recorded on the magnetic disk, 12 is an AD converter for converting the compressed audio signal outputted from the reproduction means 11 from analog to digital, and 13 is an AD converter. 14 is an address control unit that controls the address of the memory unit 13 and expands the compressed audio data on the time axis; 15 is a memory unit that records the compressed audio signal data output from the memory unit 13; - A DA converter that performs analog conversion and outputs an audio output signal.

The compressed audio signal reproduced by the reproducing means 11 is converted into, for example, 8-bit compressed audio data by the AD converter 12 and stored in the memory section 13.

The memory unit 13 has, for example, one chip for one sector of compressed audio data. Further, the address of the memory unit 13 is controlled by an address control unit 14, and when reading data, the compressed audio data is time-axis expanded by being read out at a clock rate that is, for example, 1280 times faster than writing. Thereafter, the signal is again converted into an analog signal by the DA converter 15 and output as an audio output signal.

FIG. 7 shows the timing of the memory write signal when reproducing the compressed audio signal of one track complete, and the compressed audio data is written to the memory section 13 during the period when the memory write signal is positive.

Here, the memory unit 13 has, for example, a 1-chip configuration for one sector of compressed data, with memory 0 for sector O, memory 1 for sector 1, memory 2 for sector 2, memory 2 for sector 2, and memory 1 for sector 1. Memory 3 is allocated for 3.

When the reproduced output signal is obtained in FIG. 7, the memory 0 write signal becomes a positive signal during the compressed audio signal period excluding the overlap portion of sector O, and the compressed audio signal data for this period is written to memory O. Similarly, the compressed audio data except for the overlap portion of sectors 2 and 3 is written to memorites 2 and 3.

On the other hand, FIG. 8 shows the timing of the memory read signal when reproducing a compressed audio signal that completes one track. During the period when the memory read signal is positive, the compressed audio data is time-axis expanded by, for example, 1280 times. The data is read out from the memory unit 13 as decompressed audio data.

In FIG. 8, first, the memory O read signal becomes a positive signal, and the expanded audio data of sector O is read from memory 0. Next, when the reading of the decompressed audio data of sector O from memory O is completed, the memory 1
The decompressed audio data of sector 1 begins to be read. Thereafter, the decompressed audio data is read out continuously up to sector 3 in the same manner.

In this way, in the conventional magnetic recording and reproducing apparatus described above, compressed audio data excluding the overlap portion of the compressed audio signal divided and recorded in the sector area is written to the memory section 13,
Thereafter, by expanding the time axis and reading out the expanded audio data without interruption, it is possible to obtain an audio output signal without interruption (continuously) between sector areas.

Problems to be Solved by the Invention However, in conventional magnetic recording and reproducing devices, audio data in overlap areas is not stored, and data correction is not performed on connections between sector areas. In such cases, the missing areas of audio data overlap at the joints between sector areas, resulting in abnormal sounds and unnatural audibility.

The present invention solves these conventional problems. For example, even when there are time axis fluctuations due to jitter, etc.,
It is an object of the present invention to provide an excellent magnetic recording and reproducing device that can reduce the occurrence of abnormal noise and unnaturalness in hearing at the joints between sector areas.

Means for Solving the Problems In order to achieve the above object, the present invention provides a sector area provided at predetermined intervals in which audio signals are divided and recorded, and a sector area provided at a predetermined interval at the start end of the sector area to record the previous sector area. an overlap portion where the same audio signal as the end of the audio signal is recorded; a reproducing means for reproducing the magnetic medium on which an audio signal of an arbitrary length is recorded;
An AD converter that performs digital conversion, a memory unit that stores audio data output from the AD converter, an address control unit that controls the address of the memory unit, and a shifter that receives audio data read from the memory unit and performs bit shifting. A register section, a shift register control section that controls the bit shift amount of the shift register section, an adder that adds the outputs of the shift register section, and a digital-to-analog converter for the audio output data output from the adder to generate an audio output signal. It is equipped with a DA converter that outputs .

According to the above-described structure, the memory section stores the audio data of the overlap section redundantly, and changes the playback gain of the overlap section audio data read from the memory section from high to low or from low to high to prevent cross-over. By performing the fade processing, it is possible to reduce the occurrence of abnormal sounds or unnaturalness in hearing at the joints between sector areas, even if there is a time axis fluctuation due to, for example, jitter.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

Fig. 1 is a block diagram of a video floppy audio playback device according to an embodiment of the present invention, Fig. 2 is a timing diagram of a memory write signal, Fig. 3 is a timing diagram of a memory read signal, and Fig. 4 is an audio data playback gain. FIG. 5 is a diagram showing audio output data in an overlap portion between sector areas.

In FIG. 1, 1 is a reproduction means, 2 is an AD converter, 3 is a memory section, and 4 is an address control section, which have the same structure as the conventional example. Reference numeral 5 denotes a shift register section that shifts the decompressed audio data read out from the memory section 3 by, for example, 1 or 2 bits, 6 a shift register control section that controls the bit shift amount of the shift register section 5, and 7 an output of the shift register section 5. 8 is a DA converter that converts the output of the adder 7 from digital to analog.

The compressed audio signal reproduced by the reproducing means 1 is converted into, for example, 8-bit compressed audio data by the AD converter 2, and is stored in the memory section 3. The memory unit 3 has, for example, a one-chip configuration for one sector of compressed audio data. Furthermore, the address of the memory section 3 is controlled by the address control section 4, and when reading out the data, the compressed audio data is time-axis expanded by being read out at a clock rate that is, for example, 1280 times faster than that of writing. The above reproduction operation is the same as in the conventional example.

Figure 2 shows the timing of the memory write signal when reproducing a compressed audio signal that completes one track.
The compressed audio data is written to the memory unit 3 during the period when the memory write signal is positive. Here, in the memory section 3, memory 0 is allocated to sector 0, memory 1 is allocated to sector 1, memory 2 is allocated to sector 2, and memory 3 is allocated to sector 3.

In FIG. 2, when the reproduced output signal is obtained, the Mekuri 0 write signal becomes a positive signal during the compressed audio signal period excluding the overlap portion of sector 0, and the compressed audio signal data for this period is written to memory 0. Similarly, the compressed audio data except for the overlap portion of sectors 2 and 3 is written to memorites 2 and 3.

In other words, the overlapping compressed audio data of sectors 2 and 3 will be written redundantly to memory 0, memory 1, memory 2, memory 2, and memory 3.

On the other hand, Fig. 3 shows the timing of the memory read signal when reproducing the compressed audio signal that completes one track. During the period when the memory read signal is positive, the compressed audio data is time-axis expanded by, for example, 1280 times. and is read out from the memory unit 3 as decompressed audio data.

In FIG. 3, first, the memory O read signal becomes a positive signal, and the expanded audio data including the overlap portion of sector 0 is read out from memory O. Next, the decompressed audio data overlapping with the overlap part of sector 1 starts to be read out from memory O, and at the same time, the decompressed audio data including the overlap part of sector 1 starts to be read out from memory 1. In the same way, the decompressed audio data including the overlap part is read out continuously up to sector 3. In other words, the decompressed audio data of the overlap part of sector 2 and sector 3 is read out from memory O, memorized memo IJ 1 and memory 2, memory 2 and memory 3. will be written to repeatedly.

Next, FIG. 4 shows the transition of the decompressed audio data reproduction gain when reproducing a compressed audio signal that completes one track. The shift register section 5 has a bit shift amount controlled by a shift register control section 6, and shifts the decompressed audio data by, for example, 1 bit or 2 bits in the overlap section, thereby changing the playback gain to 1/2 or 1/4. Change from high to low or low to high in two steps.

FIG. 5 is a diagram showing audio output data in the overlap portion between sector O and sector 1 as an example of audio output data in the overlap portion.

In FIG. 5, (a) is the decompressed audio data of sector O read from memory 0, and (b) is the decompressed audio data of sector l read from memory 1. Originally, the expanded audio data in (a) and (b) in the overlap part should be the same overlapping data, but for example, due to time axis fluctuations such as jitter, the expanded audio data in (b) may have a 90 degree phase lead. It shows the case. (C) is the audio output data when the expanded audio data of (a) is switched instantly and without interruption to the expanded audio data of (b) at the end of the overlap portion. In other words, (C) shows the audio output data at the joint between sector areas in the conventional example, where data is missing and the phase rotation and waveform are disturbed. (d) shows the overlap between (a) and (b).
4 shows the audio output data obtained by bit-shifting the expanded audio data by the shift register section 5 and giving the reproduction gain shown in FIG. Compared to the audio output data in (C), the phase rotation and waveform disturbances are reduced. The cross-fade processed audio output data in (d) is then
The A converter 8 converts the signal into an analog signal again and outputs it as an audio output signal.

As described above, according to the above embodiment, the memory section 3 stores the compressed audio signal of the overlap section redundantly, and the overlap section decompressed audio data read from the memory section 3 is stored in 1 bit or 2 bits by the shift register section 5. By bit-shifting the bits, changing the reproduction gain in two steps of 1/2 and 1/4 from high to low or from low to high, and then adding them by the adder 7 and performing cross-fade processing,
For example, even if there are time axis fluctuations due to jitter, etc., it is possible to reduce disturbances in the phase rotation and waveform of audio output data at the joints between sector areas, and to reduce the occurrence of abnormal noises and audible unnaturalness. has.

In the above embodiment, the bit shift amount of the decompressed audio data by the shift register section 51 was set to 1 bit or 2 bits, and the reproduction gain was changed in two steps of 1/2 and 1/4. Even if the amount is shifted up to N bits and the reproduction gain is varied in multiple stages, similar effects can be obtained.

Effects of the Invention As is clear from the above-mentioned embodiments, the present invention stores the audio data of the overlap part redundantly in the memory section, and bit-shifts the audio data read out from the memory section to change the playback gain from high to low. By changing the sound from high to high and performing cross-fade processing, it is possible to reduce the occurrence of abnormal sounds and audible unnaturalness at the joints of sector areas, even when there is time axis fluctuation due to jitter, etc. Even if recording is started and stopped at the beginning and end, the fade-in at the beginning and the fade-out at the end create a soft edge, and no noticeable playback sound is produced (this has a great practical effect).

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic recording/reproducing device according to an embodiment of the present invention, FIG. 2 is a timing diagram of a memory write signal of the same device, FIG. 3 is a timing diagram of a memory read signal of the same device, and FIG. 5 is a waveform diagram showing audio output data in the overlap area between sector areas of the same device, FIG. 6 is a block diagram of a conventional magnetic recording and reproducing device, and FIG. FIG. 8 is a timing diagram of a memory write signal of the same device, FIG. 8 is a timing diagram of a memory read signal of the same device, and FIG. 9 is a recording format diagram of an audio signal. 1... Playback means, 2... AD conversion section,
3... Memory section, 4... Address control section, 5... Shift register section, 6......
Shift register control section, 7... Adder, 8...
...DA converter. Name of agent: Patent attorney Toshio Nakao and one other person Figure 5

Claims (1)

[Claims] A sector area provided at a predetermined interval and in which audio signals are divided and recorded; an overlapping part provided in a predetermined section at the start end of the sector area and in which the same audio signal as at the end of the previous sector area is recorded; a reproducing means for reproducing a magnetic medium on which a length of audio signal is recorded; an AD converter for converting the audio signal output from the reproducing means from analog to digital; and storing the audio data output from the AD converter. an address control unit that controls the address of the memory unit; a shift register unit that inputs audio data read from the memory unit and performs bit shifting;
a shift register control section that controls the bit shift amount of the shift register; an adder that adds the outputs of the shift register section; and a digital-to-analog converter for the audio output data output from the adder and outputs an audio output signal. a DA converter, the memory section stores the audio data of the overlap section redundantly, and the shift register control section controls the amount of bit shift by the shift register control section, and the shift register control section controls the bit shift amount in the overlap section. A magnetic recording and reproducing apparatus characterized in that a reproduction gain of audio data is changed from high to low or from low to high, and then cross-fade processing is performed by the adder.