JPH05183934A - Input and/or output device for transmitting video signal - Google Patents

Abstract

PURPOSE:To transmit identification information corresponding to signal forms without providing any new transmission line by transmitting and outputting output chrominance signals obtained by mixing identification information signals and chrominance signals related to video signals. CONSTITUTION:During a vertical blanking period VT of luminance signals related to video signals, output chrominance signals (A) are transmitted and outputted, and these output chrominance signals are obtained by mixing identification information signals (B), which have a rise edge EU and a fall edge ED and have a comparatively low frequency component, and chrominance signals (C), which have a comparatively high frequency component and are related to video signals, so as to transmit and output the identification information signals (B) with a high impedance and to transmit and output the chrominance signals (C) with a low impedance. Namely, since the identification information signal (B) has the rise edge EU and the fall edge ED in the vertical blanking period VT, the output chrominance signals (A) separatable without degrading the quality of the chrominance signals can be transmitted and outputted without affecting validity CC of the chrominance signals (C).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal transmission input and / or output device which is a video signal transmission input device, a video signal transmission output device or a video signal transmission input / output device.

[0002]

2. Description of the Related Art FIG. 4 is a diagram for explaining types of signal forms, FIG. 5 is a diagram for explaining control signals having VISS / VASS information, and FIG. 6 is a diagram for explaining back track reproduction prevention. Is. A conventional technique will be described below with reference to the drawings.

In recent years, the widening of the screen has been promoted with the widespread use of the high-definition system characterized by the aspect ratio of 16: 9, and various video signals have been used in order to maintain compatibility with the existing 4: 3 aspect ratio. The signal form of is considered.

The signal forms are, for example, 1
A squeeze mode signal (also called a full mode or shrink mode signal) that allocates a video signal having an aspect ratio of 6: 9 to all effective scanning lines of a video signal having an aspect ratio of 4: 3, maintaining an aspect ratio of 16: 9 In addition, the first letterbox signal in which the upper and lower parts of the 4: 3 aspect ratio screen are black parts, and the second letterbox signal in which video additional information such as vertical resolution correction information is superimposed on the upper and lower parts, etc. Is being considered.

Here, the case where these signals described above are displayed on a 4: 3 aspect ratio screen will be described with reference to FIG. 4, and FIG. 4A shows the existing 4: 3 aspect ratio for comparison. 7 illustrates a screen of a video signal having a ratio. Further, the screen shown in FIG. 7B shows the case of the squeeze mode signal, and the circle at the center of the screen is a vertically long ellipse in order to be assigned to all the effective scanning lines of the 4: 3 aspect ratio screen.
Further, the screen shown in FIG. 7C shows the case of the first and second letterbox signals, and unlike the case of the squeeze mode signal, the circle at the center of the screen is a perfect circle, 16: 9.
The upper and lower parts of the screen are black to maintain the aspect ratio. In the case of the second letterbox signal, the video additional information is superimposed during the period corresponding to this black portion.

In order to cope with such various signal forms, V
There are cases where it is desired to record the identification information obtained by discriminating the signal form in TR on the control track of the magnetic tape by varying the duty ratio of the control signal and transmitting this identification information to a video device such as a television receiver.

[0007] Conventionally, in the VHS system home VTR, there is a VISS / VASS system for recording the cue information of a program as a means for recording the information other than the servo information by varying the duty ratio of the control signal. Further, in the camera-integrated VTR with four heads wound around 270 degrees, the duty ratio of the control signal is varied in order to prevent so-called back track reproduction while maintaining compatibility with the VISS / VASS system.

First, a control signal used in the VISS / VASS system will be described with reference to FIG.
Is a control signal that does not have normal VISS / VASS information, and one cycle thereof is a period corresponding to one frame of a video signal. For example, in the case of the NTSC system, 1 /
It is 30 sec and 1/25 sec in the case of the PAL system. In such a control signal, the information required as servo information is only the timing of the rising edge aa.

Therefore, in the VISS / VASS system, information is recorded by changing the duty ratio of the control signal so that an unnecessary falling edge is used as servo information. That is, the control signal of 60% duty ratio shown in FIG. 7B means “0”, and the control signal of 27.5% duty ratio shown in FIG. 2C means “1”. It records the cue information and address information of the program.

Next, the prevention of back track reproduction in a camera-integrated VTR having four heads and 270 degrees winding will be described with reference to FIG. In this camera-integrated VTR, the first, second, third, and third components on the rotary drum shown in FIG.
The fourth magnetic heads H1 to H4 are used to obtain the tape patterns shown in FIG. 1B, and the first, second, third and fourth tracks T1 to T4 are the first, the second and the second. Recording is performed in a 4-track sequence corresponding to the third and fourth magnetic heads H1 to H4, respectively. The first and second tracks T1 and T2 are the first frame track, the third and third tracks, respectively.
The fourth tracks T3 and T4 will be called the second frame tracks.

However, since the control signal is recorded for each frame, that is, for each two-track sequence, the first frame track is reproduced by the third and fourth magnetic heads T3, T4 and the second frame track during reproduction. The first and second
In some cases, back track reproduction may occur in which the magnetic heads T1 and T2 of FIG. In such a case, since reproduction is performed by using a magnetic head different from the magnetic head used for recording, it is not possible to follow the bend of the track pattern peculiar to each magnetic head, and the S / N of the reproduction signal deteriorates.

Therefore, information of the type of the magnetic head used during recording is recorded by varying the duty ratio of the control signal so as to correspond to the first and second frame tracks, and is detected during reproduction to detect the magnetic head. It is supposed to control the phase.

However, in order to maintain compatibility with the above-mentioned VISS / VASS system, the duty ratio of the variable control signal must be discriminable from that of the VISS / VASS system.

Therefore, in preventing back track reproduction,
The control signals of 62.5% and 30% duty ratio shown in FIGS. 7C and 7D are respectively “L”, and 57.5% and 25% shown in FIGS. The duty ratio control signal is set to "S", respectively, and these repetitions are recorded to enable discrimination between "0" and "1" used in the VISS / VASS system. That is, when the duty ratio of the control signal is 62.5%, "0" and "L" are set, when it is 30%, "1" and "L" are set, and when it is 57.5%, "0" and "L" are set. "And" S "
When it is 25%, it means "1" and "S", respectively.

Since "L" and "S" are recorded in correspondence with the first and second frame tracks, it is possible to record 4-track sequence information necessary for preventing back track reproduction. it can.

Thus, in the conventional technology, VIS
The back track reproduction prevention compatible with the S.VASS method is realized by changing the duty ratio of the control signal.

[0017]

However, in the prior art, there is no description about the signal form for transmitting the identification information obtained by discriminating the signal form to other video equipment.

Therefore, the present invention has been made to solve the above problems.

[0019]

The present invention provides the following constitution in order to solve the problems.

In a video signal transmission output or input / output device for separately outputting a luminance signal and a chrominance signal related to a video signal, the luminance signal related to the video signal has a rising edge or a falling edge within a vertical blanking period. An identification information signal having a relatively low frequency component and a color signal relating to the video signal having a relatively high frequency component, the identification information signal has a high impedance, and the color signal relating to the video signal has a low impedance. A video signal transmission output or input / output device, which transmits and outputs an output color signal obtained by mixing so as to be transmitted and output.

A video signal transmission input or input / output device to which an output color signal transmitted and output from the video signal transmission / output device according to claim 1 is input, after the output color signal is terminated with high impedance. A video signal transmission input or input / output device, characterized in that it is supplied to an identification information discriminating circuit and is also supplied to a color signal processing circuit via a low impedance termination.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a conceptual diagram for explaining an identification information word of an embodiment according to the present invention, and FIG. 2 is a main portion of a magnetic recording and / or reproducing apparatus according to an embodiment of the present invention. FIG. 3 is a timing chart for explaining the main part of the magnetic recording and / or reproducing apparatus of one embodiment according to the present invention. An embodiment according to the present invention will be described below with reference to the drawings.

One embodiment according to the present invention is VISS / VAS.
In order to maintain compatibility with the S system, the control signal “L” with 62.5% and 30% duty ratio and the control signal “S” with 57.5% and 25% duty ratio used in the above-mentioned back track reproduction prevention are used. Is used to generate an identification information word having a plurality of bits, and the identification information obtained by discriminating the signal form using this identification information word is recorded together with the back track reproduction prevention information, and is reproduced. Then, the identification information is transmitted to other video equipment, and the identification information signal having the identification information is particularly characteristic.

First, an identification information word having a plurality of bits formed by combining "L" and "S" will be generally described. The basic condition required for this identification information word is a plurality of distinguishable identifications. It is necessary to have the first condition of having information and the second condition of being able to detect the back track reproduction prevention information by discriminating the 4-track sequence.

Here, in order to satisfy the second condition, the start of the 4-track sequence is determined to correspond to the first bit of the word, and the start of the 4-track sequence is determined by determining this. The same word is continuously recorded during a certain state (for example, when recording a squeeze mode signal), and the number of bits per identification information word is set to 2N (N is a natural number). To do.

In order to discriminate the first bit from the same continuous identification information word, it is at least necessary that the sign of the last bit and the sign of the first bit are inverted. Identification information words that satisfy the above second condition are shown in FIGS. 1 (A) and 1 (B), respectively. That is, the first bit is "L (S)" and the last bit is "S (S)".
(L) ”and is an identification information word consisting of 2N bits.

The identification information word must be discriminable under the first condition. However, since the same identification information word is continuously recorded, the first bit and the last bit in one identification information word are recorded. "L" is added to the removed intermediate bit string.
If there is an inversion from (S) ”to“ S (L) ”, the start of the identification information word may be confused and it may be impossible to determine.

This will be described with reference to FIG. 3C by taking the case of N = 3 as an example. The identification information word "LLLSLS" is the identification information word "LSLLLS" starting from the fifth bit, and the identification information word "LLSLSS" is the identification information word "LSSLLS" starting from the fourth bit and "LLSSLS". The identification information word is indistinguishable from the identification information word "LSLLSS" starting from the fifth bit, and the identification information word "LSLSSS" is indistinguishable from the identification information word "LSSSLS" starting from the third bit. If only one of these indiscernible identification information words is used, the discriminable information is reduced but can be used.

Therefore, in order to remove these unidentifiable identification information words, one identification information word is selected from a combination of 2 ^{2 (N-2)} identification information words in which the first bit and the last bit are fixed. An identification information word starting from the second identification information word is determined, and it is sequentially discriminated whether or not this coincides with other identification information words up to the identification information word starting from the (N-1) th identification word. It is possible to do all the information words.

However, "LLSLLS", "LSSLS"
In the identification information word having the periodicity of N (= 3) bits of S ″, it is not possible to determine whether the start of the identification information word is the first bit (first bit) or the third bit, and thus the above-mentioned second It cannot be used because the two-track sequence is shifted when the start of the two-track sequence, which is a condition, is erroneously determined.However, when N is an even number, even if the identification information word starts from the 2 / Nth bit. Since the 2-track sequence can be discriminated even if it is discriminated, the discrimination information word is also used in such a case, that is, discrimination having a periodicity of M bits (M is an odd number and 2 ≦ M <N). Information words are excluded.

Therefore, valid identification information word combinations that can be used in the case of N = 3 are, for example, "LLLLLS" and "LLLL" marked with stars in FIG.
SS "," LLLSLS "," LLLSSS "," LL
SLSS ”,“ LLSSLS ”,“ LLSSSS ”,
"LSLSLS", "LSLSSS", "LSSSSS"
S ”, and the number of recordable identification information is“ 10 ”. Also, valid combinations of identification information words that can be used when the same work is performed with N = 2 are, for example, "LLLS", "LLSS", "LSLS", "LSS".
S ”, and the number of recordable identification information is“ 4 ”.

Here, the conditions of valid identification information words that can be used are summarized as follows: (1) 2N (N is an integer of 2 or more)
Consists of a bit string of bits, (2) the sign of the first bit and the last bit of the word are inverted,
(3) 2 in which the first bit and the last bit are fixed
One word is defined from a combination of ^{2 (N-2)} identification information words, an identification information word starting from the second identification information word is created, and it is sequentially determined whether the identification information word coincides with other identification information words N-1. Discrimination up to the identification information word starting from the second, and performing the above discrimination for all other identification information words to remove one of the identification information words that cannot be discriminated. (4) M bits (M is an odd number and 2 ≦ M <N)
The identification information word having the periodicity of is excluded.

That is, the first bit of a word consisting of 2N (N is a natural number of 2 or more) bits is fixed to either "L" or "S", and the sign between the first bit and the last bit is fixed. From the inverted 2 ^{2 (N−2)} kinds of words, the other words that are indistinguishable from other words when one word is continuous are removed except the one word, and M bits (M Is an odd number and a bit string obtained by removing a word having a periodicity of 2 ≦ M <N from the 2 ^{2 (N−2)} 2 (N−2) types of words may be a valid identification information word. ..

Next, the identification information can be recorded / reproduced by using the combination of usable valid identification information words satisfying the above conditions (1) to (4) and the identification information can be transmitted to other video equipment. The VTR will be described. here,
As an example of the identification information, four kinds of identification information of a normal video signal, a squeeze mode signal, and first and second letterbox signals are assumed, and the above-mentioned N = 2 identification information words are used.

The identification information is transmitted through a color signal terminal in the so-called S terminal used for YC separation transmission of a video signal, which is modulated with a color subcarrier frequency having no low frequency component. An identification information signal that does not have a high frequency component that can be frequency separated from this color signal is superimposed and transmitted.

In FIG. 2, a video signal is input to the VTR via a so-called S terminal used for YC separation transmission. That is, the terminal YIN is a luminance signal input terminal in the S input terminal, through which the input luminance signal Ya related to the input video signal is supplied to the luminance signal recording / reproducing system 1 and the vertical sync separation circuit 2 (SS). To be done. On the other hand, the terminal CIN is a color signal input terminal in the S input terminal, and a resistor R whose one end is grounded by the input color signal Ca related to the input video signal via the terminal CIN.
1 is supplied to the other end.

This input color signal Ca is supplied from other video equipment with the same DC output impedance as the resistance R4 (10 kΩ) and with the same AC output impedance as the resistance R3 (75 Ω). R1 (100k, which is the equivalent resistance of the DC input impedance of
Ω), and the other end of the resistor R1 is terminated with a resistor R2 (75Ω) from the other end via the capacitor C1.

The waveform of the input color signal Ca at the other end of the resistor R1 is shown in FIG. 3 (A). This waveform is obtained by superposing the identification information signal shown in FIG. 2B on the color signal shown in FIG. 3C, and the rising edge EU and the falling edge ED of this identification information signal are the input color signal. In order not to adversely affect the effective period CC of the color signal frequency-separated from Ca, the output of the vertical synchronization signal separation circuit 5 (SS) described later, which is the vertical blanking period VT
Is set to occur during the high level period shown in FIG. Also, this identification information signal is 1
/ 30SEC (1 frame) composes 1 word with 4 bits, which is "L" in the case of normal video signal.
"LH", "HHH" for squeeze mode signal
"H", "HHH" for the first letterbox signal
L "(illustrated in FIG. 3B) corresponds to" HLLL "in the case of the first letterbox signal.

The input color signal Ca supplied to the other end of the resistor R1 is supplied to the identification information discriminating circuit 8 (DSDET) and connected to the other end of the resistor R2 whose one end is grounded via the capacitor C1. Color signal recording / reproducing system 1
3 is supplied.

The identification information discriminating circuit 8 has a reference voltage (3.75) having the waveform shown in FIG.
V), and the above "LLLL""HH
Information such as "HH", "HHHL" and "HLLL" is obtained and supplied to the duty ratio control signal generation circuit 7. When the input color signal Ca without the identification information signal is supplied or the S terminal output Considering the case where the video signal is supplied to the input terminal (not shown) from the video equipment without the VTR,
The third and fourth switch circuits SW3 and SW4 are provided so that the user can record the identification information. That is, the third
The switch circuit SW3 is for determining that it is a manual input, and indicates that it is a manual input in the closed state. In this state, the fourth switch circuit SW4
Becomes valid, and the third and fourth switch circuits SW3 and SW
A predetermined terminal of the identification information discriminating circuit 8 is grounded via 4, so that the type of the form of the video signal is supplied to the identification information discriminating circuit 8. On the other hand, when the third switch circuit SW3 is released, the fourth switch circuit SW4 is ignored.

In this way, the output of the identification information discriminating circuit 8 is supplied to the duty ratio control signal generating circuit 7, and the duty ratio of the control pulse is determined based on this output. That is, "LLLL" representing a normal video signal is "L
"SH" indicates "squeeze mode signal"
To “LLSS”, “HHHL” to represent the first letterbox signal to “LLLS”, and “HLLL” to represent the second letterbox signal to “LSSS”, respectively. 1 duty ratio control signal 7a
Is getting Since the 1-bit period of the identification information signal and the 1-bit period of the identification information word are set to the same time, the configuration of the duty ratio control signal generation circuit 7 can be simplified, and further, the identification superimposed on the input color signal can be identified. Information signal "LLL
"HLHL", "HHL" instead of "L", "HHHH"
By setting to "L", "H" and "L" constituting the identification information signal can correspond to "L" and "S", respectively, and the configuration of the duty ratio control signal generating circuit 7 can be simplified. There are advantages.

Then, the first duty ratio control signal 7a
Is supplied to the second mono-multi circuit 4 and a back track control signal 7b indicating the start of a word is supplied to the servo system 11, and the phase of the rotating drum (not shown) can be discriminated by the above-described four track sequence based on this. It is controlled so that

Then, the above-mentioned second mono-multi circuit 4
The first mono-multi circuit output signal 3a supplied to is generated as follows. That is, the vertical sync separation circuit 2
The vertical sync separation circuit output signal 2a of one field period obtained by separating the input luminance signal Ya from the input Ya and waveform shaping
(Shown in FIG. 3D) is the first mono-multi circuit 3 (M
M1), where it rises in synchronization with the rising edge of the vertical sync separation circuit output signal 2a, maintains a high level for a period of 1 field or more and less than 1 frame, and then falls, to the next vertical sync separation circuit output signal. The first mono-multi circuit output signal 3a illustrated in FIG. 7E, which maintains a low level until the rising edge of 2a comes in.
Is getting

Then, this signal is supplied to the second mono-multi circuit 4 (MM1), where the control signal 4a which rises in synchronization with the rising edge of the first mono-multi circuit output signal 3a is generated.

Now, the control signal 4a will be described in detail. When the control signal 4a is at a high level, the first duty ratio control signal 7a described above and VI (not shown) are used.
It is determined by the voltage obtained by adding the second duty ratio control signal 4b supplied from the SS / VASS signal generating circuit in the second monomulti circuit 4. For example, the first duty ratio control signal 7a has information "LLLS", and at the same time, the second duty ratio control signal 4b is "0".
Considering the case of having the information "101", these first and second duty ratio control signals 7a and 4b are shown in FIGS. 7F and 7G. Here, FIG. The potential difference E1 shown in the figure is 5 for one cycle of the control signal 4a.
% (= 62.5-57.5 = 30-25), and the potential differences F1 and F2 in the same figure (G) are the potential differences corresponding to the time of 57.5% and 25% of the above 1 cycle, respectively. Is.
The control signal 4a in such a case is shown in FIG.
It illustrates in.

In this way, the ratio of the high level period and the low level period of the control signal 4a is set to the first and second levels.
The identification information and the VISS / VASS information can be recorded by modulating using the duty ratio control signals 7a and 4b of 1), and the start of the identification information word coincides with the start of the two-track sequence for preventing the back track. Therefore, the back track prevention information can be recorded substantially.

The control signal 4a is amplified to a predetermined level by the recording amplifier circuit 5 (RECAMP), and then supplied to the control head 6 via the first switch circuit SW1 (state shown in the figure) and the magnetic tape TT. Is recorded on a control track formed in the longitudinal direction of the. During reproduction, the movable piece in the first switch circuit SW1 is switched and connected from the recording side (REC) to the reproduction side (PB), and the reproduced control signal 4a is reproduced and amplified via the first switch circuit SW1. Circuit 10 (PBAM
P), where it is amplified to a predetermined level and subjected to waveform shaping, and then supplied to the servo system 11 and the reproducing side (PB) in the second switch circuit SW2, and the movable piece is recorded. Side (REC) to the reproducing side (PB) are switched and connected, and the control signal discrimination circuit 12 (CTLD) is connected.
ET). Further, at the time of recording, the control signal 4a changes the recording side (RE) in the second switch circuit SW2.
C) and is supplied to the control signal discrimination circuit 12 via the movable piece.

The control signal discrimination circuit 1
2 discriminates the identification information word from the control signal 4a and generates the above-mentioned identification information signal. That is, the identification information word “LSLS” “LLSS” “LLLS” “L
When SSS ”is input, the identification information signal“ LLLL ”“ HH
HH ”“ HHHL ”“ HLLL ”“ LSSS ”are respectively generated, and these are generated via the resistor R 4 and the color signal recording / reproducing system 13 is generated.
Is mixed with the signal obtained through the resistor R3 and the capacitor C2 at the connection point X1 to obtain the output color signal Cb on which the identification information signal is superimposed. Then, the output color signal Cb is output together with the output brightness signal Yb output from the brightness signal recording / reproducing system through the color output terminal COUT and the brightness output terminal YOUT in the output S terminal, respectively. Transmit to device and output.

In this way, the above-mentioned VTR can record and reproduce the identification information and the VISS / VASS information, and the start of the identification information word is 2 for preventing the back track.
Since it coincides with the start of the track sequence, the back track prevention information can be recorded and reproduced substantially. Then, it is possible to provide a magnetic tape on which these pieces of information are recorded.

Further, since the output color signal Cb on which the identification information signal is superimposed can be transmitted and output to another video device, the identification information representing the types of the plurality of video signals can be transmitted without providing a new transmission path. can do.

Further, since the input color signal Ca on which the identification information signal is superimposed is transmitted and input, the identification information representing the types of a plurality of video signals can be identified using the identification information identification circuit.

In the above-mentioned embodiment, the identification information is not limited to the type of the video signal, and it goes without saying that it may be any information.

Note that in the above-mentioned embodiment, focusing on the point that the output color signal Cb on which the identification information signal is superimposed is transmitted, the VTR inputs / outputs the output color signal Cb on which the identification information signal is superimposed. It may be a video signal transmission input / output device, and a recording-only VTR having only this input system,
It may be a video signal transmission input device such as a television receiver, and further, a reproduction-only VT having only this output system.
It goes without saying that it may be a video signal transmission output device such as R or a video signal generator.

In the above embodiment, the first and second
When the mono-multi circuits 3 and 4 are composed of digital circuits having a counter as a main part, it goes without saying that the first and second duty ratio control signals 7a and 4b may be supplied as digital signals. ..

[0055]

As described above, according to the configuration of the present invention,
An identification information signal having a rising edge or a falling edge within a vertical blanking period of a luminance signal related to a video signal and having a relatively low frequency component and a color signal related to a video signal having a relatively high frequency component are provided. Since the output color signal obtained by mixing is transmitted and output, there is an effect that the identification information signal can be transmitted without providing a new transmission path.

Furthermore, frequency separation can be performed when separating the color signal related to the video signal from the output color signal. Especially, since the identification information signal has a rising edge or a falling edge within the vertical blanking period, it is possible to perform separation after the separation. It is possible to transmit and output an output color signal that can be separated without degrading the quality of the color signal.

Further, as described above, according to the configuration of the present invention, the output color signal is supplied to the identification information discriminating circuit after being terminated with a high impedance and also to the color signal processing circuit via the termination with a low impedance. Therefore, there is an effect that the identification information signal and the color signal can be input without deterioration.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating an identification information word according to an exemplary embodiment of the present invention.

FIG. 2 is a block diagram for explaining a main part of a magnetic recording and / or reproducing apparatus according to an embodiment of the present invention.

FIG. 3 is a timing chart for explaining a main part of a magnetic recording and / or reproducing apparatus according to an embodiment of the present invention.

FIG. 4 is a diagram for explaining types of signal forms.

FIG. 5 is a diagram for explaining a control signal having VISS / VASS information.

FIG. 6 is a diagram for explaining back track reproduction prevention.

[Explanation of symbols]

 8 Identification Information Discrimination Circuit 13 Color Signal Recording / Reproducing System (Color Signal Processing Circuit) Cb Output Color Signal ED Falling Edge EU Rising Edge VT Vertical Blanking Period

Claims (2)

[Claims] 1. A video signal transmission output or input / output device for separately outputting a luminance signal and a chrominance signal relating to a video signal, wherein a rising edge or a falling edge is generated within a vertical blanking period of the luminance signal relating to the video signal. An identification information signal having a relatively low frequency component, and a color signal related to the video signal having a relatively high frequency component,
The video signal transmission output or input / output device, wherein the identification information signal has a high impedance, and the output color signal obtained by mixing the color signal related to the video signal so as to be transmitted and output at a low impedance is transmitted and output. 2. A video signal transmission input or input / output device to which an output color signal transmitted and output from the video signal transmission output device according to claim 1 is input, wherein the output color signal is terminated with high impedance. After that, the video signal transmission input or input / output device is characterized in that it is supplied to an identification information discriminating circuit for discriminating an identification information signal and is also supplied to a color signal processing circuit through a low impedance termination.