JPH0779410A - Video signal waveform equalization processing unit for decoding system - Google Patents

Abstract

PURPOSE:To obtain a waveform equalization device for a video signal in which equalization is implemented immediately after special reproduction is released. CONSTITUTION:A CPU 19 compares a time T1 when an iteration flag detected by an iteration flag detection circuit 16 is at a high level with a maximum required time T2 for special reproduction in a video signal reproduction system 1. As a result, in the case of T1<T2, the CPU 19 judges the special reproduction and an equalization filter coefficient used before entering the iteration state is set to an equalizer 18 of an equalization processing section 12 of a decode system 4 under the control of the CPU 19. On the other hand, in the case of T1>T2, the CPU 19 judges the operation to be other than the special reproduction, a new equalization filter coefficient is obtained based on the transmission characteristic of a transmission line 3 under the control of the CPU 19 and the equalization filter coefficient is set to an equalization device 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform equalizer for video signals such as MUSE signals.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram of a MUSE signal in the MUSE system which is a kind of multiple sampling system for band compression. Although three coaxial cables are used for studio transmission of high-definition signals, coaxial cables have transmission loss, which increases with cable length and signal frequency. The equalizing amplifier compensates for this. Normal,
Automatic equalization of the MUSE signal according to the transmission characteristics of the transmission line
This is performed on the MUSE encoder side, and at that time, training pulses called VIT signals # 1 and # 2 on the scanning lines No1 and No. 2 in FIG. 6 are used.

The VIT signals # 1 and # 2 are as shown in FIG.
As shown in (b), each is composed of negative and positive monopulses. The MUSE signal in which the VIT signal is inserted is received by the reference receiver provided on the decoder side after passing through the transmission path. The waveform of the received MUSE signal at that time is as shown in FIGS. 8A to 8C showing the signal waveform of the scanning line No2 of each frame. As can be seen from FIG. 8, the VIT pulse is shifted in phase for each frame. That is, the control code CS of the MUSE signal
Corresponding to S of "0" and "1", the phase modulation is applied only for one clock at 32.4 MHz. The automatic equalization of the MUSE signal according to the transmission characteristic of the transmission path performed on the encoder side is performed by comparing the waveform of the VIT signal in the MUSE signal received by the reference receiver with the waveform of the ideal VIT signal. According to.

On the other hand, on the decoder side, when the MUSE signal is not automatically equalized on the encoder side, that is, after the equalization coefficient of the equalization process on the encoder side has settled down to a constant level, the decoder side is the same as the encoder side. The equalization processing of the MUSE signal according to the transmission characteristic of the transmission path is performed according to the waveform of the VIT signal input to the decoder side. The reason why the MUSE signal equalization processing on the decoder side is not performed at the same time as the equalization processing on the encoder side is that competition with the encoder side occurs and the equalization processing on the decoder side is not performed satisfactorily. is there. Therefore, conventionally, MUSE is used on the encoder side.
While the signal is being automatically equalized, an iteration flag is set in the control signal portion of the MUSE signal, and whether or not automatic equalization is being performed on the encoder side is determined based on the presence or absence of the flag. The decoder side knows so.

FIG. 9 is a schematic diagram for explaining the operation during MUSE-LD reproduction. For example, MUSE-LDP
When a normal reproducing operation is performed by the (laser disc player), at that time, a signal according to the MUSE standard as shown in FIG. 5 is output. However, during chapter search (CL
V, CAV) (example in FIG. 9), pause (CLV only), picture search (CLV only), and so on.
No signal is inserted.

The reason for this is that when the LDP cannot read the MUSE signal from the LD board, the LDP instead generates a simple MUSE signal such as blue on the whole surface.
Even if a fixed pattern VIT signal is inserted into the signal, L
This is because the VIT signal is not inserted because it is different from the characteristic of the VIT signal recorded on the D board. If the decoder equalizes regardless of the absence of such a VIT signal, there is a risk of erroneous equalization. Therefore, during special playback, the equalization operation on the decoder side is stopped. Therefore, the iteration flag is set even if the MUSE signal is not automatically equalized on the encoder side.

FIG. 10 is a schematic diagram showing the relation between the equalization processing operation on the decoder side and the image displayed on the screen before and after the special reproduction operation is performed in the conventional LDP. Conventionally, the operation of the waveform equalizer in the MUSE decoder when the iteration flag of the MUSE signal is "H" and after the iteration flag changes from "H" to "L" is as shown in FIG. When the iteration flag is "H", equalization is turned off. After the iteration flag changes from "H" to "L", the characteristics of the transmission line are measured, and the equalization coefficient corresponding to that is obtained. It was a method to change. In this method, when the MUSE signal source is broadcasting, most of the adjustments are made to the iteration state by adjusting the encoder, and there is no problem in changing the image quality after the cancellation of the iteration state.

[0008]

However, MUSE-LD
In the case of P, as described above, the waveform equalizer does not correct the equalization coefficient after the special reproduction of the LDP is released until the equalization coefficient is obtained. There was a problem that the difference in image quality was noticeable and it was an eyesore. For example, as shown in FIG. 10, there is a problem that ringing is conspicuous in an image immediately after cancellation during search until a new equalization coefficient B is determined.

The present invention solves the above-mentioned drawbacks of the prior art,
It is an object of the present invention to provide a video signal waveform equalization processing device for a decoding system, which can perform equalization immediately after canceling special reproduction.

[0010]

In order to achieve the above object, the present invention provides an encoding system for encoding a video signal obtained in normal reproduction and special reproduction, and an encoding system in the encoding system. The transmission path for transmitting the encoded video signal and the encoding system are provided, and at the time of the normal reproduction, waveform equalization processing of the encoded video signal is performed with an equalization coefficient according to the transmission characteristic of the transmission path. Waveform equalization processing apparatus for decoding system of video signal transmission system having video signal waveform equalization processing apparatus for coding system and decoding system for decoding the coded video signal transmitted through the transmission path At the time of the normal reproduction and when the value of the equalization coefficient does not change, the waveform of the coded video signal and the like with the second equalization coefficient according to the transmission characteristic of the transmission line in the decoding system. In the case of performing the normalization process, the normal reproduction is performed from a state other than the normal reproduction. When the state is changed to the state, when the state before the transition is the special reproduction state detecting means for detecting whether or not the special reproduction state is detected, and when the special reproduction state detecting means detects the special reproduction state After the transition to the normal reproduction state, there is provided coefficient setting means for resetting the value set to the second equalization coefficient before the start of the special reproduction state.

Further, according to the present invention, when the coefficient setting means changes to the normal reproduction after a state other than the normal reproduction continues for a predetermined time or longer, the coefficient setting means is adapted to the transmission characteristic of the transmission line after the change. The value of the second equalization coefficient is newly set.

Further, according to the present invention, the video signal is MUS.
It is an E signal, and the special reproduction state detecting means is the MU.
An iteration flag detecting means for detecting an iteration flag in the SE signal, and a comparing means for comparing the time T1 during which the iteration flag has been raised with the maximum required time T2 for performing the special playback in the video signal playback system. And when the result of the comparison by the comparison means is T1 <T2, it is determined to be special reproduction, and when T1> T2, it is determined to be an operation other than special reproduction. The transmission characteristic detecting means for detecting the transmission characteristic of the transmission path, the equalization coefficient calculating means for calculating the value of the second equalization coefficient based on the transmission characteristic detected by the transmission characteristic detecting means, and the judging means. When it is judged to be special playback,
The value calculated by the equalization coefficient calculation means before the iteration flag is set is selected as the second equalization coefficient, and when the determination means determines an operation other than special reproduction, the iteration flag is set. The value is calculated by the equalization coefficient calculation means after the state is changed from the standing state to the non-standing state, and the selection means selects the value as the second equalization coefficient.

Further, according to the present invention, the video signal is MUSE.
Signal, and the special reproduction state detection means is the MUS
The VIT signal detecting means for detecting the VIT signal in the E signal and the time T3 during which the VIT signal has disappeared are the maximum required time T for performing the special reproduction in the video signal reproduction system.
The comparison means for comparing with 2 and the comparison result by the comparison means, when T3 <T2, it is judged as the special reproduction, while T3
> T2, the coefficient setting means determines the operation other than the special reproduction, the coefficient setting means detects the transmission characteristic of the transmission path, and the transmission characteristic detected by the transmission characteristic detecting means. The equalization coefficient calculation means for calculating the second equalization coefficient based on the above, and the value calculated by the equalization coefficient calculation means before the VIT signal disappears when the judgment means judges special reproduction. Is selected as the second equalization coefficient, and when the determination means determines that the operation is other than trick play, the value calculated by the equalization coefficient calculation means after the VIT signal reappears is determined as the second equalization coefficient. And the selection means for selecting as the equalization coefficient of.

[0014]

In the decoding system video signal waveform equalization processing apparatus of the present invention, the waveform equalization operation is not performed while the video signal reproduction system is performing the special reproduction, and the normal reproduction is resumed after the special reproduction is completed. At times, the equalization processing is performed with the value of the second equalization coefficient set before the special reproduction operation. Further, when a state other than the normal reproduction continues for a predetermined time or more and then transitions to the normal reproduction, it is assumed that the waveform equalization operation is being performed on the encoding system side, and the transmission line is changed after the transition to the normal reproduction. The value of the second equalization coefficient is newly set according to the transmission characteristic of, and the equalization processing is performed with the new value of the second equalization coefficient. In addition,
In this case, whether the state other than the normal reproduction is caused by the waveform equalization operation on the encoding system side or the special reproduction operation is determined by, for example, when the video signal is the MUSE video, the iteration is performed. This can be performed based on whether or not the flag has been raised, the length of time that the flag has been raised, whether the VIT signal has disappeared, the length of time that the VIT signal has disappeared, and the like. Further, as the video signal reproducing system, LDP, VTR, etc. can be considered.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a main part of an LDP equipped with a signal waveform equalizer according to a first embodiment of the present invention. The LDP of the present embodiment shown in the figure includes a video signal reproducing system 1 for reproducing a MUSE signal from an LD, an encoding system 2 for encoding a reproduced MUSE signal, a transmission line 3 for transmitting the encoded MUSE signal, and a transmission. MU transmitted on path 3
A decoding system 4 for decoding the SE signal is provided, and the encoding system 2 uses the MUS according to the transmission characteristics of the transmission line 3.
The signal equalization processing of the E signal is performed, and the decoding system 4 performs the signal equalization processing of the MUSE signal in cooperation with the signal equalization processing of the encoding system 2.

The video signal reproduction system 1 includes operation switches for reproduction, chapter search, pause, picture search, etc.
In addition to a reproducing head and a disk running unit (neither of which is shown) that performs an operation according to the operation, a simple MUSE signal generating circuit 5 and the like are provided. Simple MUSE signal generation circuit 5
Is chapter search, pose, picture search, etc.
When the MUSE signal output from the LDP cannot read the MUSE signal from the LD (not shown), a simple MUSE signal such as blue is generated instead.

The encoding system 2 includes a transmission matching filter 6 for transmission path equalization, a D / A conversion-LPF 7, a modulation transmitter 8, a CPU 9 for setting an equalization coefficient for the transmission matching filter 6, and a MUSE signal. An iteration flag setting circuit 10 for setting an iteration flag in the control signal portion therein is provided. The iteration flag setting circuit 10 operates the operation switch when the transmission matching filter 6 performs signal equalization processing of the MUSE signal, that is, when the equalization coefficient set by the CPU 9 is changed. By special playback such as chapter search, pause, picture search, etc., when the VIT signal is no longer inserted in the MUSE signal, the control signal part in the MUSE signal is changed to "
An iteration flag is set to the H "level, and at other times, the control signal portion in the MUSE signal is set to the" L "level.

The decoding system 4 connected to the encoding system 2 via the transmission line 3 receives the M signal input from the transmission line 3.
It includes a reference receiver 11 in the preceding stage for receiving the USE signal, an equalization processing unit 12 in the succeeding stage for performing the equalization process of the MUSE signal in cooperation with the signal equalization process on the encoding system 2 side. The reference receiver 11 includes a demodulator 13 and an A / D converter-L.
The equalization processing unit 1 includes a PF 14 and a VIT pulse detector 15 that detects a VIT pulse in the MUSE signal.
Reference numeral 2 denotes an iteration flag detection circuit 16 for detecting an iteration flag in the MUSE signal passing through the transmission line 3 and the reference receiver 11, a VIT pulse detector 17 similar to the VIT pulse detector 15, and an iteration flag detection. An equalizer 18 for equalizing the MUSE signal according to the detection results of the circuit 16 and the VIT pulse detector 17, and the equalizer 1.
8 and a CPU 19 for setting an equalization coefficient. The present invention relates to the equalization processing unit 12 of the decoding system 4.

In the LDP of this embodiment, the video signal reproducing system 1 performs the reproducing operation according to the operation of the operation switch. For example, in the case of a normal reproduction operation, the MUSE signal containing the VIT pulse is reproduced from the LD by the reproduction head, and in the case of special reproduction, the reproduction head displays a still screen, a fast forward / rewind screen, or the like.
The MUSE signal which does not include the VIT pulse is reproduced from the LD, or the simple MUSE signal which does not include the VIT pulse is generated from the simple MUSE signal generation circuit 5 and is MUSE signal of these MUSE signals. Is output to the encoding system 2.

The MUSE signal output to the encoding system 2 in this way is transmitted to the transmission matching filter 6 and D / A.
After the conversion-LPF 8 and the modulation transmitter 9, an iteration flag is set by an iteration flag setting circuit 10, the iteration flag is received by a reference receiver 11 of a decoding system 4 through a transmission line 3, and a normal reproduction is performed. In the case of, the VIT pulse detector 15 of the reference receiver 11 causes the transmission line 3
The VIT pulse in the MUSE signal including the transmission characteristic of M. The waveform of the extracted VIT pulse is CPU10
Is compared with the ideal VIT pulse waveform, and the equalization coefficient of the transmission matching filter 6 is set by the CPU 10 so that the difference becomes zero. The value of the equalization coefficient of the transmission matching filter 6 is constantly changing until the equalization coefficient is completely set. Therefore, during normal reproduction in which the transmission line equalization processing of the MUSE signal is performed by the transmission matching filter 6 of the encoding system 2 and during special reproduction in which the VIT signal is not inserted in the MUSE signal,
The iteration flag is set by the iteration flag setting circuit 10.

The MUSE signal that has passed through the encoding system 2, the transmission line 3, and the reference receiver 11 through the above processing is input to the equalization processing unit 12, and the iteration flag detection circuit 16 detects the iteration flag. Done. Figure 2
Is the equalization processing operation of the equalizer 18 under the control of the CPU 19 before and after the special reproduction operation is performed in the LDP of the present embodiment shown in FIG. 1, and an image displayed on a screen (not shown). 3 is a schematic diagram showing the relationship between FIG. 3 and FIG. 3, which is a flow chart showing the control operation of the CPU 19 before and after the special reproduction operation. The LDP of the first embodiment will be described with reference to FIG.
The flow of the equalization processing of the MUSE signal on the decoding system 4 side in FIG.

First, the CPU 19 sets in advance the maximum time (eg, 30 seconds) T2 required for special reproduction such as chapter search.
Set in the internal memory of. Next, it is determined whether the iteration flag detected by the iteration flag detection circuit 16 is 1, that is, whether it is at "H" level (S1). If the iteration flag is 0, the CPU 19 compares the waveform of the VIT pulse in the MUSE signal including the transmission characteristic of the transmission line 3 extracted by the VIT pulse detector 17 with the waveform of the ideal VIT pulse. Then, the equalization coefficient of the equalizer 18 is set so that the difference becomes zero. On the other hand, if the iteration flag is 1, the value of the equalization filter coefficient set in the equalizer 18 until then is stored in the internal memory of the CPU 19 and the equalization filter coefficient of the equalizer 18 is set. Set to 0 (S
2) The time during the iteration is measured (S3).

Next, when the iteration flag becomes 0, that is, when the iteration flag falls to the "L" level (Y in S4), it is determined whether the time T1 when the iteration flag is 1 is shorter than T2. (S5), if it is short, "special reproduction was performed in the video signal reproduction system 1"
Then, the equalization filter coefficient of the equalizer 18 is set to a value before entering the iteration state stored in the internal memory (S6). As is apparent from the above description, in this embodiment, the iteration flag detection circuit 16 and the CPU 19 constitute special reproduction state detection means, and the CPU 19 constitutes coefficient setting means.
By doing so, the MUSE extracted by the VIT pulse detector 17 after the iteration state is released
Since it is not necessary to compare the waveform of the VIT pulse in the signal with the waveform of the ideal VIT pulse again and find the equalization filter coefficient of the equalizer 18 corresponding thereto, immediately after the cancellation of the iteration state. Good image quality can be obtained.

If the time T1 when the iteration flag is 1 is longer than the time T2, "the MUSE signal transmission line equalization process was performed on the encoding system 2 side, or the LD was exchanged. Was performed. ”, And the normal equalization operation is performed. That is, as described above, VIT
The CPU 19 compares the waveform of the VIT pulse in the MUSE signal including the transmission characteristic of the transmission line 3 extracted by the pulse detector 17 with the ideal waveform of the VIT pulse to measure the transmission line characteristic (S7). ), A new equalization filter coefficient of the equalizer 18 is calculated so that the difference becomes 0 (S
8) Use the obtained coefficient value as the filter coefficient (S
9).

Next, a second embodiment of the present invention will be described. FIG. 4 is a block diagram of the essential parts of an LDP equipped with a signal waveform equalizer according to the second embodiment.
The same reference numerals are attached to the same portions as. In the LDP of the second embodiment shown in FIG. 4, the equalization filter coefficient setting of the equalizer 18 after cancellation of the iteration state is not based on the length of time the iteration flag is 1 but MUSE. This is done based on the length of time the VIT pulse in the signal has disappeared. Therefore, as shown in FIG. 4, in the LDP of this embodiment, the iteration flag detection circuit 16 of the decoding system 4 is omitted. Figure 5
Is C before and after the special reproduction operation by the LDP in FIG.
6 is a flowchart showing the control operation of the PU 19, and the flow of the equalization processing of the MUSE signal on the decoding system 4 side in the LDP of the second embodiment will be described with reference to FIG.

First, the CPU 19 sets in advance a maximum time (eg, 30 seconds) T2 required for special reproduction such as chapter search.
Set in the internal memory of. Next, it is determined whether or not the VIT pulse has disappeared based on the detection result of the VIT pulse detector 17 (S11). If the VIT pulse has not disappeared, VI in the MUSE signal extracted by the VIT pulse detector 17 and including the transmission characteristic of the transmission line 3
The T pulse waveform and the ideal VIT pulse waveform are C
Equalizer 1 that compares by PU19 and the difference becomes 0
Set an equalization factor of 8. On the other hand, if the VIT pulse has disappeared, the value of the equalization filter coefficient set in the equalizer 18 until then is stored in the internal memory of the CPU 19, and the equalization filter coefficient of the equalizer 18 is set. It is set to 0 (S12), and the time during which the VIT pulse disappears is measured (S13).

Next, when the VIT pulse reappears (S14)
Y), the time T3 when the VIT pulse has disappeared is T
It is determined whether it is shorter than 2 (S15), and if it is shorter, it is determined that "special reproduction has been performed in the video signal reproduction system 1", and the equalization filter coefficient of the equalizer 18 is stored in the internal memory. The value before the disappearance of the VIT pulse that has been set is set (S16). Further, when the time T3 during which the VIT pulse disappeared is longer than the time T2, "the MUSE signal transmission line equalization processing was performed on the encoding system 2 side,
Or, the LD has been exchanged ", and the normal equalization operation is performed. That is, after the VIT pulse reappears, VIT
The CPU 19 compares the waveform of the VIT pulse in the MUSE signal including the transmission characteristic of the transmission line 3 extracted by the pulse detector 17 with the ideal VIT pulse waveform to measure the transmission line characteristic (S17). ), And newly calculates the equalization filter coefficient of the equalizer 18 such that the difference becomes 0 (S1
8) Use the obtained coefficient value as the filter coefficient (S1)
9). As is apparent from the above description, in this embodiment, the VIT pulse detector 17 and the CPU 19 constitute special reproduction state detecting means, and the CPU 19 constitutes coefficient setting means. Such LDP of the second embodiment
However, the same effect as the first embodiment can be obtained.

In the first and second embodiments described above, the VIT pulse detector 17 of the equalization processing unit 12 may be omitted and the VIT pulse detector 15 of the reference receiver 11 may be used instead. Further, although the LDP has been described as an example in each of the above-described embodiments, the present invention can be applied to other video reproducing devices such as a VTR, and the signal to be equalized is M.
It is not limited to the USE signal.

[0029]

As described above, according to the present invention,
When the normal reproduction is restarted after the special reproduction in the video signal reproduction system is finished, the waveform equalization processing on the decoding system side is performed with the value of the second equalization coefficient set before the special reproduction operation. When canceling special playback, it is not necessary to re-examine the transmission characteristics of the transmission line to recalculate the equalization coefficient, and the video after equalization can be output immediately, and good image quality without ringing is always maintained. Obtainable.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of an LDP equipped with a signal waveform equalizer according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing the relationship between the equalization processing operation of the equalizer and the image displayed on the screen before and after the special reproduction operation is performed in the LDP of the first embodiment shown in FIG. Is.

FIG. 3 is a flowchart showing a control operation of the CPU of FIG. 1 before and after a trick play operation.

FIG. 4 is a block diagram of an essential part of an LDP including a signal waveform equalizer according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing a control operation of the CPU of FIG. 4 before and after a trick play operation.

FIG. 6 is a configuration diagram of a MUSE signal.

7A and 7B are waveform diagrams of a VIT signal.

8A, 8B, and 8C are diagrams showing the phase of the VIT signal.

FIG. 9 is a schematic diagram for explaining an operation during MUSE-LD reproduction.

FIG. 10 shows equalization processing operations on the decoder side before and after the special reproduction operation is performed in the conventional LDP,
It is a schematic diagram which shows the relationship with the image displayed on a screen.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 video signal reproduction system 2 encoding system (encoding system) 3 transmission line 4 decoding system (decoding system) 6 transmission matching filter 10 CPU 12 equalization processing unit 16 iteration flag detection circuit (special reproduction state detection means) 17 VIT Pulse detector (special reproduction state detection means) 19 CPU (special reproduction state detection means, coefficient setting means)

[Procedure amendment]

[Submission date] April 28, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

FIG. 8 is a diagram showing a phase of a VIT signal.

Claims (4)

[Claims] 1. A coding system for coding a video signal obtained in normal reproduction and special reproduction, a transmission line for transmitting a video signal coded by the coding system, and the coding system. And a video signal waveform equalization processing device for a coding system, which performs waveform equalization processing of the coded video signal with an equalization coefficient according to a transmission characteristic of the transmission line during the normal reproduction, and the transmission line. Is a waveform equalization processing device for a decoding system of a video signal transmission system having a decoding system for decoding the encoded video signal transmitted by In a case where the decoding system performs waveform equalization processing of the coded video signal with a second equalization coefficient according to the transmission characteristic of the transmission line when the value does not change, from the state other than the normal reproduction, When transitioning to the normal playback state, the state before the transition is the special Special reproduction state detection means for detecting whether it is in the reproduction state, and when it is detected that the special reproduction state is in the special reproduction state detection means, after the transition to the normal reproduction state,
A decoding system video signal waveform equalization processing apparatus, comprising: coefficient setting means for resetting the value set for the second equalization coefficient before the start of the special reproduction state. 2. The coefficient setting means, when a state other than the normal reproduction is changed to the normal reproduction after continuing for a predetermined time or more, the second or the like is set according to the transmission characteristic of the transmission line after the change. The decoding system video signal waveform equalization processing device according to claim 1, wherein the value of the equalization coefficient is newly set. 3. The video signal is a MUSE signal, and the special reproduction state detecting means includes an iteration flag detecting means for detecting an iteration flag in the MUSE signal, and a time T1 during which the iteration flag has been raised.
Is compared with the maximum required time T2 for performing the special reproduction in the video signal reproduction system, and when T1 <T2 as a result of the comparison by the comparison means, it is determined that the special reproduction is performed.
On the other hand, when T1> T2, the coefficient setting means comprises a judging means for judging an operation other than special reproduction. The coefficient setting means detects a transmission characteristic of the transmission path and a transmission characteristic detecting means. Equalization coefficient calculation means for calculating the value of the second equalization coefficient based on the transmission characteristic, and the equalization coefficient calculation means before the iteration flag is set when the judgment means judges special reproduction. The value calculated in step 2 is selected as the second equalization coefficient, and when the determination means determines that the operation is other than special reproduction, the above-mentioned change is performed after the transition from the state in which the iteration flag is raised to the state in which it is no longer raised. 3. The decoding system video signal waveform equalization processing apparatus according to claim 1, further comprising a selection unit that selects the value calculated by the equalization coefficient calculation unit as the second equalization coefficient. 4. The video signal is a MUSE signal, and the special reproduction state detecting means is a VI in the MUSE signal.
The VIT signal detecting means for detecting the T signal, the comparing means for comparing the time T3 during which the VIT signal has disappeared with the maximum required time T2 for performing the special reproduction in the video signal reproducing system, and the comparing means. As a result of the comparison, when T3 <T2, it is determined to be special reproduction, and when T3> T2, it is determined to be operation other than special reproduction. The coefficient setting means determines the transmission characteristic of the transmission line. Transmission characteristic detecting means for detecting, equalization coefficient calculating means for calculating the second equalization coefficient based on the transmission characteristic detected by the transmission characteristic detecting means, and when the judging means judges special reproduction,
Before the VIT signal disappears, the value calculated by the equalization coefficient calculating means is selected as the second equalization coefficient, and when the judging means judges an operation other than special reproduction, the VIT signal is 3. The decoding system video signal waveform equalization according to claim 1 or 2, further comprising: selection means for selecting the value calculated by the equalization coefficient calculation means after the reproduction again as the second equalization coefficient. Processing equipment.