JPH01272387A - Time axis compressing device for television signal - Google Patents

Abstract

PURPOSE:To hold the continuity of an image and to suppress the increment of deterioration in picture quality by executing switching between a non-delayed TV signal and a delayed TV signal within a horizontal blanking period. CONSTITUTION:A sampled TV signal is written in time axis compressing memories 1, 1'. Television(TV) signals 1d, 1d' are read out from the memories 1, 1' by a clock signal 1c with a required frequency band. The TV signal 1d is supplied to a multiplexer 6 and the TV signal 1d' is supplied to the multiplexer 6 through a 1/2 period delay circuit 5. The multiplexer 6 switches these TV signals within the horizontal blanking period and outputs the switched signal.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention samples an analog television signal at a certain frequency, performs digital signal processing, expands and contracts the time axis of the television signal, and improves the image quality. The present invention relates to a time axis compression device for television signals that is suitable for application to technologies such as improving the quality of images (for example, high-resolution image receiving systems such as IDT).

[Prior Art] In recent years, with the development of digital signal processing technology, analog television signals are sampled at a certain frequency and digitally processed (U processing is performed to expand or contract the time axis of the television signal. There is an increasing demand for technologies that improve image quality.

A high-resolution image receiving system such as TDTV is a suitable example.

As a device that satisfies these requirements, a time base compression 'A' has been proposed which is capable of compressing the horizontal time base of a television signal sampled at a certain frequency to 1/2.

An example is shown in FIG. In the figure, an analog television signal IA is clocked by a clock 1b having a frequency fa.
The signal is sampled by the /D converter 20 and then input to the memory 1 which compresses the time axis.

The memory 1 that compresses the time axis is configured with separate information write and read addresses.
It is a memory in which each address generation circuit can be driven by a separate clock, and it is possible to expand or contract the time axis of written information.

The binarized horizontal opening signal 1'' extracted from the analog television signal 1Δ by the synchronization separation circuit 21 is synchronized by the clock signal 1b by the clock synchronization circuit 22.

By this synchronized No. 43, the time axis compression memory 1
The reset timing of the write address is controlled. Further, the reset timing of the read address of the time axis compression memory 1 is controlled by a 1/2 period signal outputted from the circuit 23 which generates a 1/2 period signal of the synchronized horizontal synchronization signal.

A sampled television signal is written to the time-base compression memory 1 which is controlled by the address reset signals 2a' and 3a' by the clock signal 1b of frequency "a". Reading is performed by the IC.

As a result, the time axis compression memory 1 outputs a television signal I whose time axis is compressed to 1/2 in the horizontal direction.
D is obtained.

By the way, as is well known, the binarized horizontal synchronizing signal 1f shown in FIG. 6 includes a jitter component Y on the time axis at its edge portion. Therefore, if the signal 1f is synchronized with the clock signal 1b, a write reset signal 2a' as shown in FIG. 6C will be obtained.

That is, when the falling edge of the binarized horizontal synchronization signal 1f does not match the clock signal 1b, the write reset signal 2a' synchronized by the clock signal 1b is jittered in units of one clock of the clock signal 3 1b. will be included.

FIG. 7 shows a case where the address reset timing of the time-base compression memory 1 is controlled by a signal 2a' including such a sick signal.

As shown in the figure, the period of the television (g IA is H+
If the period of the write reset signal 2a' becomes H due to the jitter component Y even though α, the period of the read reset signal 3a' becomes I4/2, and the period H
The data of A1, which is a signal within period α, remains as it is even after time axis compression, but the data of X portion, which is a signal within period α, disappears.

As a result, when the television signal ID after time axis compression is output to a monitor driven at twice the horizontal frequency, horizontal jitter occurs, making the image extremely difficult to view. Ta.

Therefore, instead of using a horizontal synchronizing signal including jitter, we controlled the write timing with a fixed period signal that was extremely equal to the horizontal period of television (No. 8), and controlled the read timing with a fixed period signal that was half the period. When time axis compression is performed while
No. 3 is obtained.

FIG. 8 shows that fixed period signals 6a and 6b whose phases are located within the horizontal display period (horizontal scanning period) of the television signal are used to control write and read address reset of the time axis compression memory 1. This shows how the horizontal time axis of a television signal is compressed to 1/2.

When compressing a television signal in the horizontal direction, a writing fixed cycle signal (hereinafter referred to as a writing reset signal) 6
The signal written in one period a is read out twice in two periods of a read fixed cycle signal (hereinafter referred to as readout 7'' 3) 6b, and reading is performed prior to writing. .

Therefore, the same signal may continue multiple times.

As shown in the figure, if there is a reset timing of write reset No. 45 6a within the display period of brightness No. 43, the television signal after time axis compression is the brightness No. 43 of the adjacent display period, for example, the brightness signal. There is a horizontal period consisting of signals of a rear portion h1° of h1 and a signal of a front portion h2° of h2.

Therefore, even when the horizontal time axis is compressed to 1/2, the front portion h2' of the luminance signal h2 and the rear portion h1° of hl are continuously read out during 18 hours.

As a result, there is a problem that the image becomes discontinuous when displayed on a monitor.

Therefore, in consideration of such problems, the fixed period signal generation circuit 2.3 has a fixed period signal 2A as shown in FIG.
, 3A phase as horizontal synchronization signal 1f and vertical synchronization signal 1g
It has been proposed to provide means for correction within the horizontal blanking using

In this example, the phases of the fixed periodic signals 2A and 3A are adjusted during vertical blanking each time the vertical blanking occurs.

In FIG. 9, a sampled television signal IA' is written into a time-base compression memory 1 whose address is controlled by fixed periodic signals 2A and 3A using a clock signal 1b having a frequency Pa, and by a clock signal 1c having a frequency 2Xfa. Read out.

As a result, the time axis compression memory 1 obtains a television signal ID' whose time axis is compressed to 1/2 in the horizontal direction.

television signal], D is a fixed periodic signal 2A.

Time axis compression memory 1 whose address is controlled by 3A
, the time axis is accurately compressed without being affected by the jitter of the horizontal synchronization signal.

This television signal ID' is connected to the 2Xfa clock (8
The timing can be controlled by the signal 1c, and using the D/A converter 24, it can be converted into an analog signal 1e whose time axis is compressed to 1/2.

A specific example of correction of the fixed period generating circuit 2.3 in FIG. 9 is shown in FIG.

As shown in the figure, it has counters 10 and 11, and count outputs from these are used as a write reset signal and a read set signal.

Therefore, these counters 10 and 11 are loaded with fixed load data N during a predetermined period, which will be described later, and are counted by clock signals 1b and 1c, respectively.

This load data N is data that is counted by the clock signals 1b and lc to generate a free-running fixed period signal very close to the horizontal period and a fixed period signal of 1/2 period.

The AND gate 7 is supplied with the horizontal synchronization signal 4B 1f and the vertical synchronization signal 1g, and an ON signal is output to the NAND gate 8.9 within the horizontal blanking period for each field.

Therefore, the load timing of the load data N to the counters 10 and 11 is determined by the output signal from the AND gate 7, the write reset signal, and the read reset signal.

As a result, the timings of the write reset signal 2Δ and the read reset signal 3A can be adjusted for each field, and moreover, within the horizontal blanking period that exists within the vertical blanking period.

FIG. 11 is a diagram showing a state in which the phases of the fixed period signals 2A and 3A are within the horizontal blanking period of the television signal.

In this case, in a writing period of one horizontal cycle (hereinafter referred to as IH), only a signal (for example, hl) of one display period is written in addition to the signal within the horizontal blanking period.

As a result, when the horizontal time axis is compressed by half,
Only the signal of one display period is read out during 18 days. Therefore, even if the television signal after time axis compression is displayed on a monitor, the image will not become discontinuous.

[Problems to be Solved by the Invention] Incidentally, the internally generated fixed period signal may not be set equal to the horizontal period of the television (No. 3).

This is the case, for example, when compressing the time axis of a television signal output from a VTR when the clock signal is locked to the carrier of the color signal.

When such a signal is time-base compressed using this time-base compressor, a television signal as shown in FIG. 12 is obtained.

In other words, 13, when the television signal IA' is sampled at the frequency fa as shown in the figure, the sampling phase becomes Δt for every horizontal period of the television signal IA'.
The height is off.

Therefore, the write reset signal 2A is reset when the period is 81.

In the time axis compression of television signals, writing is the first step.
Since the data written between cycles is read out twice in two read cycles, the same television signal is repeated twice after time axis compression.

Therefore, the first time, only the data of A1 and the data of Δt have disappeared, but the second time, the data of Δ7 can be reproduced because it is continuous with the next data A2.

Therefore, the video after time axis compression is horizontally synchronized (random jitter caused by the jitter component of No. 8 does not occur, and the data loss in the portion of Δ above occurs regularly for each scanning line, so When the error amount Δt is small to a certain extent, an image that can be visually improved with regard to horizontal jitter can be obtained as an image after time-base compression.

However, if an error Δt occurs between the fixed period and the horizontal period of the television signal, the write and read reset signal 2A is caused by the error.

The phase of 3A gradually shifts with respect to the video signal.

This is due to the error Δt that occurs because the horizontal period of the television signal is not an integer multiple of the sampling, or ′J for each scanning line.
This is to multiply A.

Therefore, the phase of reset signals 2A and 3A corrected within horizontal blanking within vertical blanking is the first
It gradually shifts as shown in Figure 3.

The phases of the reset signals 2A and 3A cannot be corrected again until the next vertical blanking period arrives, because if the phases are corrected within the display period, the image quality will deteriorate. As a result, depending on the value of the error Δt, the reset signal 2A, 3A
There was a risk that the phase stop water element would deviate from the blanking period and enter the horizontal display period.

For example, in NTS C4g, when compressing the time axis of VTR output by setting the clock signal to a frequency that is four times the frequency of the carrier color signal (subcarrier), N times the clock signal is one horizontal period. Because it doesn't exactly match,
An error of Δt (n) occurs between the clock signal and the horizontal period of the television signal.

The number of effective scanning lines in an NTSC signal is about 240 lines, and if Δt'' is the average error amount of Δt(n), the phase amount displaced during this period is T=240Δt.

Since the horizontal blanking period is about 11 us, there is a problem in that the phase of the reset signal is corrected at the center of the horizontal blanking period, which causes problems for signals whose Δt' exceeds about 23 ns.

In addition, in general, when the above-mentioned value of N is fixed as a television signal, the error amount of Δt (n) is one clock or more (No. 8, for example, a special playback output signal in a VTR, a family computer output signal, etc.) There is a signal.

In such a signal, if the N value is always fixed, the phase amount T and the error amount Δt (n) increase, causing problems such as image quality deterioration.

Therefore, the present invention solves these conventional problems with a simple structure, and even if the cycle of the clock (ffi), which is an integer multiple, does not completely match the horizontal cycle, it is possible to The purpose of the present invention is to propose a time axis compression device for television signals that eliminates discontinuity in the reproduced screen and prevents deterioration of image quality.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a time base compression device that expands and contracts the time base of a television signal sampled at a predetermined frequency. a first means for generating a fixed period signal of 1/2 period; and a means for correcting the fixed period signal so that it has a very close period based on the horizontal period of the input television signal. a means for correcting the phase of the fixed periodic signal so as to fall within the display period of the television signal; a means for delaying the television signal before or after time axis compression by a predetermined period; and a non-delayed television signal. and switching means for switching the delayed television signal within the horizontal blanking period of the television signal after compressing the time axis, and resetting the write address and read address of the time axis expansion/contraction memory using a fixed periodic signal. The timing is controlled, and the switching means maintains the continuity and image quality of the output television signal without depending on the input television No. 4E.

[Function] In this configuration, in the present invention, the television signal 1a sampled at a predetermined frequency is written into the time axis expansion/contraction memory 1 by the clock signal 1b at a predetermined frequency. This time axis expansion/contraction memory 1 has its phase corrected within the display period of the television signal using the horizontal synchronization signal 1f and the vertical synchronization signal 1g, and the horizontal synchronization signal 18
"And using a vertical synchronization signal of 1g, the input television (3
Based on the result of calculating the horizontal period of the signal, the write and read address reset timings are controlled by the fixed period signals 2a and 3a, which are corrected to a period very close to the input horizontal period and a half period thereof.

From the time axis expansion/contraction memory 1, a television signal 1d is generated by a clock signal 1c of a desired frequency.

ld' can be read out.

Either one of the television signals after time axis compression,
For example, the television signal 1d' is delayed by fixed cycle delay means 5 for reading.

The non-delayed television signal 1d and the delayed television signal 1h are switched by the switching means 6 within horizontal blanking after time axis compression.

This prevents signal switching within the effective screen and provides a television signal 1j without discontinuities.

In other words, video continuity can be easily maintained and an increase in image quality deterioration can be suppressed.

[Embodiment] Next, an example of the television signal time axis compression device according to the present invention will be described in which time axis compression is performed on a luminance signal, which is one of the components of a television signal, to 1/2 in the horizontal direction. A case in which the present invention is not applied to an apparatus will be described in detail with reference to FIG. 1 and subsequent figures.

This embodiment shows a case where the luminance signal after time axis compression is composed of a current luminance signal and an interpolated luminance (No. 3) created from this current luminance signal.

Since the interpolated luminance signal can be created using well-known means such as line interpolation, a detailed explanation thereof will be omitted.

In FIG. 1, 1a is a current luminance signal, and la' is an interpolated luminance signal, each of which is sampled with a clock having a frequency fa. These signals 1a.

la' is written into the time axis compression memories 1 and 1', respectively, by the clock signal 1b of frequency fa.

Reference numeral 2 denotes a first means for generating a fixed period signal 2a, which is extremely equal to the horizontal period of television No. 18, and controls the write address reset of the time axis compression memory 1,1°.

Reference numeral 3 denotes a second means for generating a fixed cycle signal 3a of 1/2 cycle for controlling read address reset.

These fixed period signal generation circuits 2 and 3 have a horizontal synchronizing signal 1r delayed by a predetermined period by a delay circuit 4 (no.
Means is provided for correcting the phase of the fixed periodic signal within the display period of the television signal using the signal f' and the vertical synchronizing signal 1g.

Further, an output signal 1k from a horizontal period detection circuit 30 detects the horizontal period of the input television signal that performs time axis compression using the horizontal synchronization signal 1f and the vertical synchronization signal 1g.
The period is corrected based on the horizontal period of the input television signal so that the period is very close to the horizontal period and the period is 1/2 thereof.

The configuration of this horizontal period detection circuit 30 is shown in FIG.

As shown in FIG. 3, the horizontal period detection circuit 30 includes a horizontal period length detection circuit 31 for detecting one horizontal period length,
2. First latch circuit 33, divider 34, rounder 3
5, a second latch circuit 36, a pulse generation circuit 37, and an AND circuit 38.

The horizontal synchronizing signal 1f is supplied to a one-horizontal period length detection circuit 31, a pulse generation circuit 37, and an AND circuit 38.

In the 1 horizontal period length detection circuit 31, the horizontal synchronization signal 1f
Therefore, the period in each horizontal period is detected, and the period length can be outputted to the addition 2 and 32.

The adder 32 adds the data from the one horizontal period length detection circuit 31 and the data stored in the first latch circuit 33, and outputs the result to the first latch circuit 33 again.

The first latch circuit 33 is controlled by the pulse generation circuit 37 and the AND circuit 38, and after the supplied data is temporarily stored,
Sent on 4th.

The divider 34 divides the data by the number of cycles of the added data, 20 (n is any natural number), thereby obtaining the average value of one horizontal cycle length.

The value obtained by the divider 34 is supplied to a rounder 35 and converted to a value of the desired number of digits, and then sent to the second latch circuit 3.
6 is output.

In the second latch circuit 36, data is temporarily stored by the reset signal R from the pulse generating circuit 37 so that the data is not lost.

On the other hand, the pulse generating circuit 37 generates a gate pulse signal P having 20 horizontal cycles within l vertical MrjJ from the horizontal synchronizing signal 1f and the vertical synchronizing signal 1g, using the horizontal synchronizing signal 1f as a trigger signal. When the gate pulse signal P is output 2 degrees, a reset signal R for clearing the data of the latch circuit 33 is output.

38 is an AND circuit, and an output signal is supplied to the latch circuit 33 from the gate pulse signal P and the horizontal synchronization signal 1f, and as a result, the adder 32 and the latch circuit 33 generate a horizontal cycle length of 2n times per vertical cycle. is added.

The output signal 1k of the horizontal period detection circuit 30 having such a configuration
The load data N of the fixed cycle signal generation circuits 2 and 3 is controlled by the above.

As a result, the fixed period signal 2 a * 3 a is configured to have a period very close to the horizontal period of the input television signal.

The time axis compression memories 1 and 1° are controlled by the write reset signal 2a and the read reset signal 3a from the fixed period signal generation circuits 2 and 3 that generate such fixed period signals 2a and 3a. Time axis compression memory 1. ld and ld' after time axis compression are read out by the clock signal 1c having a frequency of 2Xfa.

Reference numeral 5 denotes a 1/2 period delay circuit that delays the signal after time axis compression, for example, ld' by 1/2 period.

6 is a multiplexer which uses an output select signal 11 to select the signal 1d after time-base compression and the signal 1h obtained by delaying the signals of Signal 1d.

1h and outputs a signal 1j whose time axis is compressed to 1/2.

In the time axis compression device configured as above, each (
The g waveform is shown in Figure 2.

As shown in the figure, the current luminance signal 1a and the interpolated luminance (No. 8 1a
' is corrected during the horizontal blanking period and the display period, and the phases of the write reset signal 2a and the read reset signal 3a are set within the display period of each 4h number 1a and 1a°.

Therefore, in the output signal from the time axis compression memory 1, 1°, as shown as signals 1d and ld', adjacent signals exist within one display period, and discontinuous points in the video signal occur every scanning line. occurs.

When one of these output signals, for example ld', is delayed by the 1/2 period delay circuit 5, a signal 1h is obtained by delaying the scanning line where the video discontinuity occurs by 1/2 period with respect to the signal 1d. can get.

Therefore, by using the output select signal 11 from the signals 1('' and 1h) to alternately select the scanning lines in which the image does not become discontinuous within the horizontal blanking period, the time period during which the discontinuous point does not occur can be determined. No. 43]j after axial compression is obtained.

In addition, in order to obtain the signal 1j after time axis compression in which no discontinuity points occur, the phase of the fixed period signal within one field must be changed between two points (points at which No. 8 1d and lh are switched, that is, the horizontal blanking period). You don't have to go inside.

Therefore, compared to the case where the phase is corrected during horizontal blanking, the allowable range of the error Δ7 between the fixed period and the horizontal period of the television (=) is expanded.

In addition, the period of the fixed period δ generation circuits 2 and 3 is very close to the horizontal period of the input television signal. John (regardless of the horizontal period of No. 3, Δ
When L is 0.5 clock or less, and T=240Δt is 4 times the subcarrier clock υ), it is about 8.4 μs. As a result, if the phase correction of the fixed period is set to 1 near the center of the horizontal display period, the displacement of the fixed period phase can be sufficiently contained within the display period.

As a result, video continuity can be easily maintained regardless of the horizontal period length of the input television signal, and Δ
Image quality deterioration due to t(n) can be suppressed to a maximum of 0.5 clocks or less.

It should be noted that general television signals include signals whose average value of the horizontal period changes on a field-by-field basis due to the characteristics of a servo system, such as the L-reproduction output of a VTR.

If such a television signal is an input signal, it is necessary to use a circuit as shown in FIG. 4, for example.

As shown in FIG. 4, the input television signal 1a is supplied to a field memory 40 and a horizontal and vertical synchronizing signal generating circuit 41.

In the field memory 40, a television signal for one field is stored, and is made to match the signal 1 generated by the horizontal period detection circuit 30.

Therefore, even if the television signal has a horizontal period length that changes field by field, the fixed period generation circuit 2.3 is controlled in the time axis compression processing circuit 42 by the horizontal period data that matches the television signal. Ru.

In the embodiment, the signal 1d' after time axis compression is delayed by 1/2 period, but the signal 1a' before time axis compression is delayed by 1 period, and the fixed value is fixed to control the write reset of the time axis compression memory l'. A similar effect can be obtained even if the phase of the periodic signal 2a is delayed by a certain period.

In addition, although this example is explained using a luminance signal corrected by a current luminance signal and an interpolated luminance signal, the luminance after time axis compression (No. It can also be applied when configured.

In this case, the time axis compression can be performed in the above-described manner by inputting the current luminance signal 1a to the time axis compression memory 1' into which the interpolated luminance signal 1a' is input.

Alternatively, excluding the time axis compression memory 1°, the output signal 1d from the time axis compression memory 1 and this output signal 1d are
Also by inputting the signal delayed by the periodic delay circuit 5 to the multiplexer 6, the luminance signal consisting only of the current signal can be compressed in time.

Above, we have described an example in which the present invention is applied to a case where time axis compression is applied to a television (luminance of No. g (No. 5). Needless to say, the same applies to cases where

[Effects of the Invention] As explained above, in the present invention, in a time axis compression device that expands or contracts a television signal sampled at a predetermined frequency, the first means for generating a fixed period signal is provided. a second means for generating a fixed periodic signal of 1/2 period; a means for correcting the fixed periodic signal to have a very close period based on the horizontal period of the input television signal; means for correcting the television signal so that it falls within the display period of the television signal; means for delaying the television signal before or after time axis compression by a predetermined cycle; After axial compression, the switching means switches within the horizontal blanking period of the television signal, and the fixed periodic signal is used to control the reset timing of the write address and read address of the time axis expansion/contraction memory, and the above-mentioned The switching means makes it independent of the input television signal.
This is characterized in that the continuity and image quality of the output television signal are maintained.

Therefore, according to the configuration of the present invention, since the write reset signal and the read reset signal have a fixed period, they are not affected by the jitter included in synchronization (No. 3), so it is possible to improve the image quality.

In addition, since the fixed period signal is corrected according to the horizontal period of the input television signal, the error amount between the horizontal period and the fixed period is suppressed to a certain amount or less without depending on the characteristics of the input television signal. Deterioration of image quality due to errors can be suppressed.

Furthermore, since the non-delayed television signal and the delayed television signal are switched by the switching means within horizontal blanking after time axis compression, signal switching within the effective screen is eliminated, and video continuity is easily maintained. It has the characteristics of

Therefore, the television signal time according to this invention.

An axial compression device samples the analog television signal mentioned above at a certain frequency, performs digital signal processing, and stretches or compresses the time axis of the television signal, for example, it is extremely useful when applied to high-resolution reception systems, etc. suitable.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a time-base compression device for television signals according to the present invention, and FIG. 2 is a diagram showing each signal of the time-base compression device for television signals according to the present invention.
FIG. 3 is a system diagram showing the configuration of a horizontal period detection circuit, FIG. 4 is a system diagram showing another embodiment of the television signal time base compression device according to the present invention, and FIG. 5 is a system diagram showing a conventional television signal 6 is a waveform diagram when horizontal synchronization number 18 is synchronized with a predetermined clock, and FIG. 7 is a block diagram showing an example of a time axis compression device in the conventional device. The eighth leap is a diagram showing the case where the phase of the fixed period signal is located within the display period of the television signal, and FIG. FIG. 10 is a block diagram showing an example of a time axis compression device. FIG. 10 is a block diagram showing an example of a fixed period generating circuit. FIG.
Figure 2 is a diagram showing the principle when time axis compression is performed using a fixed period signal that does not match the horizontal period of the television signal.
FIG. 13 is a diagram showing a phase shift of a fixed period signal. 1.1°...Time axis compression memory 1a...Current luminance signal la'...Interpolated luminance signal 1b...Clock signal 1c with frequency fa...Clock I8 ld, ld' with frequency 2Xfa ...Output signal 1r from time axis compression memory...Horizontal synchronization signal 1g...Vertical synchronization signal 18 11...Output selection signal 1j...Brightness signal after time axis compression '2... First means 2a for generating a fixed period (g signal)...Write reset signal 3...Second means 3a for generating a fixed period signal...Read reset signal 4...Horizontal synchronization 4g delay circuit 5...Means for delaying fixed period 6...Switching means 30...Horizontal period detection circuit Fig. 3 Fig. 4

Claims (1)

[Claims] (1) In a time axis compression device configured to expand or contract the time axis of a television signal sampled at a predetermined frequency, the device comprises: a first means for generating a fixed period signal; and fixing a half period of the fixed period signal. second means for generating a periodic signal; means for correcting the identified periodic signal to have a very close period based on the horizontal period of the input television signal; and adjusting the phase of the fixed periodic signal for a display period of the television signal. means for delaying the television signal before or after time axis compression by a predetermined cycle; a switching means that switches within the horizontal blanking period of the signal, and the reset timing of the write address and read address of the time axis expansion/contraction memory is controlled using the fixed periodic signal, and
A time axis compression device for a television signal, characterized in that the switching means maintains the continuity and image quality of the output television signal without depending on the input television signal.