JP2001203987A - Video signal converting device and method, and video signal conversion and recording system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video signal converting device, etc., which can add frame information at a position that a user optionally sets when P/I conversion is carried out. SOLUTION: The video signal converting device is equipped with a video information acquisition part which obtains a 1st video signal having a 1st vertical synchronizing signal and no frame information, a 1st reference signal generation part which generates a 1st reference signal having the same period with the 1st vertical synchronizing signal, a 2nd reference signal generation part which generates a 2nd reference signal having frame information differently from the 1st reference signal, a synchronous detection part which outputs the detection result of vertical synchronism between the 1st and 2nd reference signals, a reference signal control part which outputs a control signal for selecting the 1st or 2nd reference signal according to the detection result, a frame information generation part which generates frame information by selecting one reference signal according to the control signal, and a conversion part which converts the 1st video signal into the 2nd video signal having the frame information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal conversion apparatus and method for performing video signal format conversion, and a video signal conversion recording system.

[0002]

2. Description of the Related Art A video signal scanning method can be broadly divided into an interlaced scanning method and a progressive scanning method. The characteristics of each are as follows.

[0003] The interlaced scanning method is a method of scanning one image divided into two fields in order to suppress a transmission band and a frequency band handled by a processing circuit. As an example of the interlaced scanning video signal, a “1080I” system in which 1125 horizontal scanning lines are interlaced and 1080 effective image lines are known. SMPTE27
The 1080I format, defined as a 1920 × 1080 / 59.94 / 1: 1 system at 4M, is 30 frames per 1.001 seconds and 60 fields.

On the other hand, the progressive scanning system is a system in which one image is sequentially scanned from the top. Therefore,
The concept of “field” does not exist in the progressive scan video signal. As an example of the video signal of the progressive scanning, a “720P” system in which 750 horizontal scanning lines are progressively scanned and 720 effective image lines are used is known. 1280 × 720/5 with SMPTE296M
The 720P format, defined as a 9.94 / 1: 1 system, is 60 frames per 1.001 seconds.

[0005] The interlaced scanning method and the progressive scanning method each have advantages, and it is expected that both will be used in the future. Therefore, it is useful to mutually convert the scanning method from the viewpoint of effective use of video resources.

However, when a progressive video signal is converted to an interlaced video signal, the concept of "field" does not exist in the original progressive video signal.
It is necessary to add frame information for specifying the field of the interlaced video signal to the converted interlaced video signal. The frame information is information for specifying a first field and a second field among continuous fields. For example, the first position of the frame information is the first
Becomes the first position in the field. In a conventional video signal conversion device, the frequency of a vertical synchronization signal added to a video signal from outside the device is divided, and frame information is randomly added to the converted video signal.

[0007]

If the frame information is added at random or only in order, the mismatch may occur between frames and the resolution may be degraded. This problem will be described with reference to FIG. The VTR 100 converts the progressive signal into an interlace signal A, and similarly generates the interlace signal B in another VTR 200. However, when the interlaced signal C is generated by synthesizing the signal A and the signal B, even if the signals A and B are independently matched between the frames, the signals of the two frames do not match, so that the signals are not matched. In some cases, matching between C frames cannot be achieved. In this case, the resolution of the video signal of the synthesized portion of the interlace signal C is reduced. When a controller or the like is used when synthesizing the signal A and the signal B, the editing operation may be stopped if the matching between the frames is not achieved.

The present invention provides a video signal conversion apparatus, method, and video signal conversion / recording method for converting a progressive signal into an interlaced signal while maintaining the resolution of the video and eliminating the mismatch when two video signals are combined. The purpose is to provide a system.

[0009]

According to the present invention, there is provided a video signal converting apparatus for obtaining a first video signal including a first vertical synchronizing signal and not including frame information;
A first reference signal generation unit that generates a first reference signal having the same cycle as the first vertical synchronization signal; and a second reference signal that generates a second reference signal having frame information different from the first reference signal. (2) a reference signal generator, and detects whether the first reference signal and the second reference signal are vertically synchronized,
A synchronization detection unit that outputs a detection result, a reference signal control unit that outputs a control signal indicating which one of the first reference signal and the second reference signal is to be selected based on at least the detection result, A frame information generating unit that selects one of the first reference signal and the second reference signal based on a control signal to generate frame information;
And a conversion unit for converting the video signal into a second video signal containing the frame information, thereby achieving the object described above.

According to the present invention, the first reference signal and the second reference signal
It detects whether or not the reference signals are synchronized, and if synchronized, generates frame information of the converted interlace signal using the frame information of the second reference signal. As a result, frame information of an appropriate phase can be automatically added to the interlace signal, and degradation of the resolution of the video can be prevented.

When the detection result indicates that the first reference signal and the second reference signal are vertically synchronized, the reference signal control unit controls the selection of the second reference signal. A signal may be output.

[0012] The video signal conversion device further includes a user interface unit for receiving an instruction from a user indicating which of a first reference signal and a second reference signal is to be selected, and the reference signal control unit includes: The control signal may be output based on the detection result and an instruction from the user.

[0013] The conversion section may determine a reference signal based on the control signal, and convert the first video signal into the second video signal according to the determined reference signal.

[0014] The video signal conversion device may further include a phase control unit that changes a phase of a frame signal representing the frame information based on an instruction from the user and outputs the frame signal to the conversion unit.

According to the present invention, since the user can add frame information to the interlace signal at an arbitrary phase, matching between frames can be easily achieved. Therefore, it is possible to prevent the resolution of the video from deteriorating.

A video signal conversion and recording system according to the present invention comprises at least two video signal conversion devices according to claim 5,
A switcher that receives and selectively outputs each of the second video signals obtained by the at least two video signal conversion devices, and a recording device that records the second video signals output from the switchers And the above object is achieved.

According to the present invention, since a user can add frame information to an interlace signal at an arbitrary phase, matching between frames can be easily achieved even when a plurality of interlace signals are mixed. Therefore, it is possible to prevent the resolution of the video from deteriorating.

The video signal conversion method according to the present invention includes a first vertical synchronizing signal and a first vertical synchronizing signal which do not include frame information.
Obtaining a video signal, generating a first reference signal having the same cycle as the first vertical synchronization signal, and generating a second reference signal having frame information different from the first reference signal. Generating, detecting whether the first reference signal and the second reference signal are vertically synchronized, and outputting a detection result, based on at least the detection result, Outputting a control signal indicating which one of the first reference signal and the second reference signal is to be selected, and selecting one of the first reference signal or the second reference signal based on the control signal And generating the frame information, and converting the first video signal into a second video signal including the frame information, thereby achieving the above object.

According to the present invention, the first reference signal and the second reference signal
It detects whether or not the reference signals are synchronized, and if synchronized, generates frame information of the converted interlace signal using the frame information of the second reference signal. As a result, frame information of an appropriate phase can be automatically added to the interlace signal, and degradation of the resolution of the video can be prevented.

In the video signal conversion method, in the step of outputting a control signal, when the detection result indicates that the first reference signal and the second reference signal are vertically synchronized, A control signal for selecting the second reference signal may be output.

The video signal conversion method may further include a step of receiving an instruction from a user indicating which one of a first reference signal and a second reference signal is to be selected, and the step of outputting the control signal includes: The control signal may be output based on the detection result and an instruction from the user.

The step of converting may include determining a reference signal based on the control signal, and converting the first video signal into the second video signal according to the determined reference signal.

[0023] The video signal conversion method further includes a step of changing a phase of a frame signal representing the frame information based on an instruction from the user, and the converting step includes converting the frame signal whose phase has been changed. May be used for conversion.

According to the present invention, since a user can add frame information to an interlace signal at an arbitrary phase, matching between frames can be easily achieved. Therefore, it is possible to prevent the resolution of the video from deteriorating.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same elements.

In this embodiment, when converting a progressive scan video signal into an interlaced scan video signal in the conversion of a video signal, it is detected whether or not the external reference SD signal and the external reference HD signal are synchronized. . If synchronization is detected, frame information of the converted interlace signal is generated using the frame information of the reference SD signal, and thereby, frame information of an appropriate phase is automatically added to the interlace signal. can do. “Frame information” refers to information that specifies a first field and a second field of continuous fields. For example, the first position of the frame information is the first position of the first field. In the following, it is assumed that the progressive signal is “720P” (750 horizontal scanning lines for performing progressive scanning, 720 effective image lines, and 1/60 second scanning for one screen), and the interlace signal is “1080I”. (The total horizontal scanning lines for interlaced scanning are 1125 lines, the effective image lines are 1080 lines, and the scanning of one field screen is 1/60 second signal)
Referred to as Also, 720P or 1080
I signal is a high-resolution video signal (hereinafter "HD signal")
525 horizontal scanning lines for interlaced scanning,
A video signal in which one field screen is scanned for 1/60 second is referred to as a standard resolution video signal (hereinafter, “SD signal”).

Hereinafter, a video signal conversion device according to the present invention will be described. FIG. 1 mainly shows a configuration of a video signal conversion device (hereinafter, “VTR”) 100 according to the present invention. V
TR100 is, for example, a V used for business such as a broadcasting station.
It is a TR, acquires an HD progressive signal 720P, and converts it into an HD interlaced signal 1080I. VT
R100 is an external standard resolution reference signal (hereinafter, "external SD reference signal") for the purpose of synchronizing signals throughout the broadcasting station.
From the external SD reference signal generator 120 and an external high resolution reference signal (hereinafter, “external HD reference signal”) from the external HD reference signal generator 140. Note that, in addition to the external SD reference signal generator 120 and the external HD reference signal generator 140, the VTR 100 may receive another reference signal from, for example, an external time code generator (not shown). Further, the VTR 100 includes an external SD reference signal generator 1
20 and the external HD reference signal generator 140 are not present, the SD reference signal and the HD reference signal are generated using the first reference signal generation unit 12 and the second reference signal generation unit 14 (described later) provided inside. Can work. In the following, only the frame information addition function among the functions of the VTR 100 will be described, but other configurations for reproducing / recording a video may be included.

Hereinafter, each component of the VTR 100 will be described, and then the operation will be described. The VTR 100 includes a reference signal generator 10 and an HD progressive signal acquirer 20.
, A frame information generation unit 30, a synchronization detection unit 40, a user interface 50, a reference signal control unit 60
, A phase control unit 70, and a conversion unit 80.

First, the reference signal generator 10 is provided for generating each of the reference HD signal and SD signal, and includes a first reference signal generator 12 and a second reference signal generator 1.
4 is included. This first reference signal generation unit 12 is connected to an external SD
An external SD reference signal is received from the reference signal generator 120, and an SD signal reference signal synchronized with the external SD reference signal is generated.
Note that the first reference signal generation unit 12 can generate a reference signal when there is no external input. In this case, the first reference signal generation unit 12 also generates an SD reference signal having the same pulse width and cycle as the SD signal. The first reference signal generator 12 sends the frame reset pulse generated based on the SD reference signal to the frame information generator 30 as a reference signal. Next, the second reference signal generator 14 will be described. The second reference signal generation unit 14
An external HD reference signal is received from the external HD reference signal generator 140, and a reference signal synchronized with the signal is generated. The second reference signal generator 14 can also generate an HD reference signal even when no external HD reference signal is input,
In that case, an HD reference signal having the same pulse width as the HD signal is generated. The second reference signal generator 14 sends the frame reset pulse generated based on the HD reference signal to the frame information generator 30 as a reference signal. The second reference signal generation unit 14 sends the vertical synchronization signal and the horizontal synchronization signal of the HD signal to the HD signal acquisition unit 20 and the synchronization detection unit 40.

The HD progressive signal acquiring section 20 outputs H
This is a reproducing unit that reproduces the D progressive signal 720P from a video tape or the like. HD progressive signal acquisition unit 2
0 receives a vertical synchronization signal and a horizontal synchronization signal, which are synchronization pulses of the HD signal, from the second reference signal generation unit 14,
The 720P reproduced based on the synchronizing signal is
Send to

The frame information generator 30 generates frame information to be added to 1080I after format conversion. Using the frame information, the generated signal is 1080
It is possible to specify which frame signal of I and which field signal. The frame information generation unit 30 includes the first reference signal generation unit 12 and the second
From the reference signal generator 14, the SD signal and the HD
A reference signal (frame reset pulse) generated based on the signal is received. Further, the frame information generation unit 30
Receives a control signal from the reference signal control unit 60. The control signal is a signal for controlling whether to select a reference signal based on the SD signal or a reference signal based on the HD signal. The frame information generating unit 30 outputs the control signal to the reference signal selected by the control signal. The frame information is generated based on the frame information. The generated frame information is transmitted to the phase control unit 7
The phase is adjusted by 0 or directly input to the conversion unit 80.

The synchronization detector 40 detects whether the received signals are synchronized. Here, the signals received by the synchronization detection unit 40 include the vertical and horizontal synchronization signals of the SD signal output from the first reference signal generation unit 12, and the vertical and horizontal synchronization signals of the HD signal output from the second reference signal generation unit 14. This is a synchronization signal. More specifically, the synchronization detection unit 40 pays attention to the vertical synchronization signals and detects whether the vertical synchronization signals are synchronized with each other. That is, both the SD signal and the HD signal are 1/60
Since the vertical retrace is performed in seconds, it is detected whether the retrace timing of the vertical synchronizing signal of the SD signal matches the retrace timing of the vertical synchronizing signal of the HD signal. The result of detecting whether or not both are synchronized is output to the reference signal control unit 60. Note that the synchronization signal used in the synchronization detection unit 40 is a vertical synchronization signal for both the SD signal and the HD signal. Therefore, if at least these synchronization signals can be received, the horizontal synchronization signal is transmitted to the synchronization detection unit 40 in particular. It does not have to be entered.

The user interface 50 is a switch, a button, a touch panel, or the like such as a video deck for inputting an instruction for receiving an instruction from the user. The user interface 50 receives an instruction from the user to perform conversion based on either the SD reference signal or the HD reference signal, that is, to select either the SD reference signal or the HD reference signal. User interface 50 further receives phase information from the user. This phase information is information that defines the amount of delay of a signal (hereinafter, “frame signal”) representing the frame information generated by the frame information generation unit 30. The user interface 50 sends an instruction from the user to the reference signal control unit 60.

The reference signal control unit 60 controls the SD reference signal and H
A control signal indicating which one of the D reference signals is selected is generated. The control signal is generated based on the detection result from the synchronization detection unit 40 and the user's instruction received by the user interface 50. This control signal is sent to the frame information generation unit 30 and the conversion unit 80, and is used for selecting a reference signal for generating frame information and a reference signal used for processing in the conversion unit 80. The reference signal control unit 60 further sends the phase information received by the user interface 50 to the phase control unit 70.

[0035] The phase control unit 70, based on the phase information,
Delay the phase of the frame signal. The phase control unit 70
A frame signal and phase information are received, and the phase of the frame signal is delayed based on the information. Phase control unit 70
Sends a frame signal whose phase is delayed to the conversion unit 80.

The conversion section 80 outputs the HD progressive signal 7
20P is received, the format is converted, and an HD interlace signal 1080I is output. Conversion from 720P having no frame to necessary 1080I of the frame is performed by the converter 82 and the P / I converter 84 of the converter 80 as follows. First, the conversion unit 82 receives 720P output from the HD progressive signal acquisition unit 20, and converts the 720P to 1080P.
Convert to “1080P” means horizontal scanning line 1
This is a video signal in the same format as when 080 lines are progressively scanned. At the time of conversion in the conversion unit 82, one of the SD reference signal and the HD reference signal is selected and used by using the control signal from the reference signal control unit 60. The converted 1080P is
Output to P / I conversion section 84. The P / I conversion unit 84
It receives 1080P from the converter 82 and the frame signal from the phase controller 70, and generates and outputs 1080I including frame information based on the frame signal.
When generating 1080I in the P / I conversion unit 84, the control signal from the reference signal control unit 60 is used to generate SD.
One of the reference signal and the HD reference signal is selected and used. The conversion unit 82 and the P / I conversion unit 84
May be a well-known device, and a specific configuration and operation will be omitted.

The operation of the VTR 100 configured as described above will be described below step by step. First 7
In converting 20P to 1080I, the user uses the user interface 50 to convert the external HD.
It selects which of the reference signal and the external SD reference signal the VTR 100 operates based on. Which to select may be determined according to the system environment or the like in which the user uses the VTR 100. For example, when the user's system operates based on the HD signal, the external HD reference signal is selected. When the external reference signal is not used, the reference signal generated by the reference signal generator 10 may be selected. After that, 720P from video tape etc.
Is started. In parallel with this operation, in the first reference signal generation unit 12, the external SD reference signal generator 120
, And a vertical and horizontal synchronization signal of the SD signal are generated based on the external SD reference signal input to the VTR 100, and are output to the frame information generation unit 30 and the synchronization detection unit 40, respectively. Similarly, the second reference signal generator 1
4, the external HD reference signal generator 140 sends the VTR 10
Based on the external HD reference signal input to 0, a reference signal and a vertical and horizontal synchronization signal of the HD signal are generated and output to the frame information generation unit 30 and the synchronization detection unit 40, respectively.

The synchronization detector 40 detects whether the vertical synchronization signal of the SD signal and the vertical synchronization signal of the HD signal are synchronized. The signal used in the subsequent processing differs depending on the detection result and whether the user has selectively input the SD or HD external reference signal. FIG. 2 shows a table in which the types of signals to be used are classified based on the detection result and the user input. The external HD reference signal is “ExtH
D ", the external SD reference signal is" ExtSD ", the vertical synchronizing signal is" V ", and the horizontal synchronizing signal is" H ". When ExtHD is selected in a conventional VTR, the frame information is always free-run (“Free Run”), the frame information is arbitrarily added, and the resolution may be degraded due to mismatch between frames. This VTR 100
In FIG. 1, when ExtHD is selected and the vertical synchronizing signal of the SD signal and the vertical synchronizing signal of the HD signal are synchronized, the frame information of the external SD reference signal is used as the converted 1080I frame information. Is used as is. As a result, the frames are aligned, and the resolution does not deteriorate. V and H of 1080I after the conversion are generated based on the external HD reference signal as selected by the user. When the vertical synchronizing signal of the SD signal and the vertical synchronizing signal of the HD signal are not synchronized, the frame information is added by free-run.
Here, “free-run” means that the phase of the frame signal is set at random. The edge of the frame signal coincides with V of ExtHD. On the other hand, when ExtSD is selected by the user, regardless of whether the ExtSD is synchronous or asynchronous, one after conversion based on ExtSD is used.
080I frame information, V and H are generated.

FIG. 3 illustrates a reference signal and a frame signal. The pulse shown in the upper part of FIG.
0 (FIG. 1) is a reference signal provided to the frame information generator 30 (FIG. 1). The pulse shown in the lower part of FIG. 3 is transmitted from the frame information generator 30 (FIG. 1) to the phase controller 7.
0 (FIG. 1) is the frame signal provided. The phase of the frame signal generated from the reference signal is delayed as it is or, if necessary, by the phase controller 70 (FIG. 1), and is input to the P / I converter 84 (FIG. 1). As a result, the frame information is added to 1080I after the conversion.

Further, in this embodiment, the user can set an arbitrary delay amount via the user interface 50 and arbitrarily delay the phase of the frame signal. The phase delay amount specified by the user is reflected in the phase of the frame signal in the phase control unit 70 (FIG. 1). In this way, the frame information is generated and input to the P / I converter 84 (FIG. 1).

On the other hand, the HD progressive signal acquisition unit 20
The 720P obtained in (FIG. 1) is input to the conversion unit 82 (FIG. 1) and is converted to 1080P. Thereafter, 1080P is input to the P / I converter 84 (FIG. 1). The P / I converter 84 (FIG. 1) converts 1080P into interlaced video information and generates 1080I together with the separately received frame information. P / I conversion section 84 outputs the generated 1080I to the outside of VTR 100. With the above operation, the VTR 100
Convert 20P to 1080I. In the present embodiment, the SD reference signal is generated by the first reference signal generation unit 12, but an HD reference signal having frame information may be generated. In this case, an external HD reference signal having frame information is input instead of the external SD reference signal. The conversion unit 80 performs only the progressive / interlace conversion, but may perform conversion (so-called down-conversion) from a 720P signal to an SD signal of 525 scanning lines.

Next, another embodiment of the VTR 100 of the present invention will be described. As described above, according to the present invention, an arbitrary delay amount can be set from the user interface 50, and the user can arbitrarily delay the phase of the frame signal, so that the frame can be easily matched with other SD signal frames. Can be taken. A specific example will be described with reference to FIG. FIG. 4 is a diagram showing a video signal conversion and recording system using the switcher 420. The two VTRs 100 and 400 as interlace signal generators are both VTRs of the present invention and are connected to a switcher 420. One of the HD interlace signals A and B from the VTRs 100 and 400 is appropriately selected by the switcher 420, and the HD interlace signal C
It is recorded on the D signal recording device 440. Here, if the VTRs 100 and 400 of the present invention are used, the user can arbitrarily delay the phase of the frame signal, so that the signal C in which the signals A and B are mixed can be easily matched between the frames. . Therefore, the image is not deteriorated. The number of VTRs connected to the switcher 420 is not limited to two, and may be three or more.

The embodiment of the present invention has been described above. In the embodiment, the progressive scanning video signal is set to 720P.
And the interlaced scanning video signal are referred to as 1080I, but other signals can be used for progressive scanning and interlaced scanning, respectively.

[0044]

According to the present invention, it is detected whether or not the HD reference signal and the SD reference signal are synchronized. If the HD reference signal and the SD reference signal are synchronized, the converted interlaced signal is used by using the frame information of the reference SD signal. By generating frame information of a signal, frame information of an appropriate phase can be automatically added to an interlaced signal. Therefore, it is possible to prevent the resolution of the video from deteriorating.

Further, according to the present invention, since a user can add frame information to an interlace signal at an arbitrary phase, matching between frames can be easily achieved even if a plurality of interlace signals are mixed. Therefore, it is possible to prevent the resolution of the video from deteriorating.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a VTR according to the present invention.

FIG. 2 is a table in which types of signals to be used are classified based on a detection result and a user input.

FIG. 3 is a diagram illustrating a reference signal and a frame signal.

FIG. 4 is a diagram showing a video signal conversion and recording system using a switcher.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reference signal generation part 20 HD progressive signal acquisition part 30 Frame information generation part 40 Synchronization detection part 50 User interface 60 Reference signal control part 70 Phase control part 80 Conversion part 100 VTR 120 External SD reference signal generator 140 External HD reference signal generation vessel

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 5C020 AA01 AA37 BA01 BA10 CA20 5C053 FA14 FA17 FA19 GA19 JA26 KA08 5C063 AA01 AA06 AA08 AA11 BA04 BA06 CA14 CA16 CA23 CA38 CA40

Claims (11)

[Claims] 1. A video information acquisition unit that acquires a first video signal that includes a first vertical synchronization signal and does not include frame information, and a first reference signal having the same cycle as the first vertical synchronization signal. A first reference signal generating unit that generates a second reference signal different from the first reference signal and that has a frame information; and a first reference signal generating unit that generates a second reference signal having frame information. A synchronization detection unit that detects whether the second reference signal is vertically synchronized with the second reference signal and outputs a detection result; and at least one of the first reference signal and the second reference signal based on the detection result. A reference signal control unit that outputs a control signal indicating whether or not to select a frame information generation unit that selects one of the first reference signal or the second reference signal based on the control signal and generates frame information And the first image A converter for converting a signal into a second video signal including the frame information. 2. If the detection result indicates that the first reference signal and the second reference signal are vertically synchronized, the reference signal control unit selects the second reference signal. The video signal conversion device according to claim 1, wherein the video signal conversion device outputs a control signal to be output. 3. The video signal conversion device further comprises: a user interface unit for receiving an instruction from a user indicating which one of a first reference signal and a second reference signal is to be selected; The video signal conversion device according to claim 1, wherein the control unit outputs the control signal based on the detection result and an instruction from the user. 4. The conversion unit determines a reference signal based on the control signal, and converts the first video signal into the second video signal according to the determined reference signal.
The video signal conversion device according to claim 3. 5. The video signal according to claim 1, further comprising a phase control unit that changes a phase of a frame signal representing the frame information based on an instruction from the user and outputs the frame signal to the conversion unit. Conversion device. 6. A video signal converter according to claim 5, wherein each of said second video signals obtained by said at least two video signal converters is received and output alternatively. And a recording device for recording the second video signal output from the switcher. 7. A step of obtaining a first video signal including a first vertical synchronization signal and not including frame information; and generating a first reference signal having the same cycle as the first vertical synchronization signal. Generating a second reference signal different from the first reference signal; detecting whether the first reference signal and the second reference signal are vertically synchronized; Outputting a result, based on at least the detection result, outputting a control signal indicating which one of the first reference signal and the second reference signal is to be selected, based on the control signal, Selecting one of the first reference signal and the second reference signal to generate frame information; and converting the first video signal to a second video signal including the frame information. Video signal conversion method. 8. When the detection result indicates that the first reference signal and the second reference signal are vertically synchronized, in the step of outputting a control signal, a second control signal is output.
The video signal conversion method according to claim 7, wherein a control signal for selecting the reference signal is output. 9. The video signal conversion method further comprises: receiving an instruction from a user indicating which of a first reference signal and a second reference signal is to be selected; and outputting the control signal. 8. The video signal conversion method according to claim 7, wherein the control unit outputs the control signal based on the detection result and an instruction from the user. 10. The step of converting includes determining a reference signal based on the control signal, and converting the first video signal into the second video signal according to the determined reference signal. 2. The video signal conversion method according to 1. 11. The method according to claim 11, further comprising: changing a phase of a frame signal representing the frame information based on an instruction from the user, wherein the converting is performed using the phase-changed frame signal. The video signal conversion method according to claim 7.