JPS63155880A - Video signal converting system - Google Patents

Abstract

PURPOSE:To convert a field frequency of a video signal into other frequency by writing all of or part of one pattern of video signals into a image memory and reading out the written signal partly duplicated or without any modification as the video signal by one pattern. CONSTITUTION:The video signal of the CCIR system is read from a memory device 2 and 50 fields pass with respect to a signal outputted from an NTSC signal processing circuit 1. As a result, the NTSC signal outputted from the circuit 1 and the field start point of the CCIR signal outputted from the memory device 2 are made coincident. Thus, the memory device 2 writes the NTSC signal outputted from the circuit 1 into a memory 21 by the memory device 2 in a timing when the field start point of both the signals is coincident. The NTSC signal is written once per 50 fields and the similar reading is applied further. The CCIR signal reproduced and outputted from a CCIR signal processing circuit 3 is displayed on a monitor receiver 4 of the CCIR system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a video signal conversion method for converting the field frequency (vertical frequency) of a video signal to a frequency of another method.

(Prior art) The television standard systems currently adopted in various countries are roughly divided into NTSC, PAL, and SEC.
There are AM systems, and television receivers and magnetic recording/reproducing devices (VTRs) dedicated to each system are used. For this reason, for example, video tapes produced in areas where NTSC broadcasting is available cannot be played in PAL or SECAM format.
If you want to play back in an area where NTSC broadcasting is being performed, you must prepare an NTSC VTR and an NTSC monitor, which is extremely inconvenient.

By the way, the difference between the standard television systems is the scanning system,
There are a wide variety of color signal transmission methods, but the most important one is the difference in scanning method, and the most important one is the difference in field frequency (vertical frequency). Therefore, there is a need for a conversion device that can convert this field frequency and play back video tapes recorded in other formats. However, it is necessary to write the playback video signal of this method into a memory such as a BBD (packet, block, device), and then change the clock frequency when reading it out to convert it into a video signal with a field frequency of another method. However, this had the disadvantage of requiring a large amount of memory. Additionally, although there have been devices for converting standard television formats into other formats, these devices are mainly used for broadcasting stations, are extremely expensive, and are not intended for the general public. Therefore, during recording, the video signal of the television system in this region can be recorded, while during playback, a video tape containing the video signal of the television system of another region can be recorded on a monitor receiver dedicated to the television system of this region. There is a need for the development of a video tape recorder with a simple configuration that can play and output.

(Problems to be Solved by the Invention) Conventionally, there is a simple video signal that can convert a video tape on which a video signal of the standard format of one television is recorded into a playback video signal of the standard format of another television and output it. There were no general-use VTRs equipped with conversion devices, and it was necessary to prepare monitors and VTRs specifically for each television standard, which was both inconvenient and uneconomical. SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks, and aims to provide a video signal conversion system capable of converting the field frequency of a video signal to another frequency with a simple configuration.

[Structure of the Invention] (Means for Solving the Problems) The video signal conversion method of the present invention is an apparatus for converting the field frequency of a video signal, in which one screen of a video signal having a first field frequency is converted. A writing means for writing all or a part of the writing signal into the image memory, and a second field frequency by reading one part of the writing signal from the image memory overlappingly or as it is to obtain a video signal for one screen. and a readout means for obtaining a video signal.

(Function) In the video signal conversion method of the present invention, the writing means writes all one field of the video signal having the first field frequency into the image memory, and the reading means writes one part of the video signal in duplicate. A video signal is read out from the image memory and used as a video signal for one field. As a result, the video signal read from the image memory becomes a video signal having a second field frequency higher than the first field frequency. Further, the writing means may omit a part of one field of the video signal having the first field frequency and write it into the image memory, and the reading means may read out the entire video signal from the image memory. This is assumed to be a video signal for one field. As a result, the video signal read from the image memory becomes a video signal having a second field frequency lower than the first field frequency.

(Example) An example of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram illustrating an embodiment of the video signal conversion method of the present invention. 1, the number of 1 horizontal period (1H) included in 1 frame is 525, and 1 horizontal period is 63.5 μs
2 is an NTSC signal processing circuit that processes the NTSC signal, converts it into a digital signal, and outputs it;
A memory device that writes data (digital) and reads out one copy of the written signal at a predetermined timing.
1. It consists of an embedded reading means 22 and an adder circuit 23.

3 is a CCIR signal processing circuit that converts the digital signal read from the memory device into an analog signal, performs various processing, and outputs it as a simple CCIR signal; 4 is a CCIR signal processing circuit;
A monitor receiver for signals is used.

Next, a case will be described in which this embodiment is used to convert a reproduced signal of a VTR. First, the VTR used the so-called helical scan method, in which the tape was wound around a diagonal opening over an angular range of just over 180 degrees around a rotating drum with two rotating magnetic heads mounted at 180 degrees apart. do. To record an NTSC signal with a field frequency of 60H2 and 525 horizontal periods included in one frame on such a VTR, the rotating magnetic head is used while the tape is running at a constant speed. must be rotated by 30H2, which corresponds to the frame frequency.

Therefore, during playback, if the tape is run at the same speed as during recording, and the rotating magnetic head is rotated at the same rotation speed of 30H2 as during recording, the playback signal will have a field frequency of 60H2, the same as the original signal, and a horizontal field in one field. The number of periods is 262.5. Therefore, from the NTSC signal processing circuit 1, one field 262 as shown in FIG.
．． 5) -1 NTSC signal is output. The memory device 2 stores data for one field 26 of the NTSC signal output from the NTSC signal processing circuit 1 during the W period in FIG. 2(A).
A signal corresponding to two horizontal periods is written into the memory 21.

At the same time, the memory device 2 reads out the signals written in the memory 21 from the memory 21 as shown in FIG. A signal corresponding to the horizontal period is read from the memory 21. Therefore, the memory device 2 outputs 312 horizontal periods as shown in FIG. 2(B).
The video signal to be used as a field is read out, and this is the CC
The signal is output to the IR signal processing circuit 3. After the next NTSG signal field, writing to the memory 21 is not performed, and only reading from the memory 21 is performed. That is, after the memory device 2 reads out the signals corresponding to the above-mentioned 312 horizontal periods, it again reads out the signals corresponding to 262 horizontal periods from the memory 21, and furthermore, the embedded reading means 22 reads the signals corresponding to the 51 horizontal periods from the memory 21. A corresponding signal is read out, and a video signal with one field in 313 horizontal periods is read out and output to the CCIR processing circuit 3. In the end, 312 .
A CCIR video signal in which each field consists of 313 horizontal periods and one frame consists of 625 horizontal periods is sequentially read out as shown in FIG. 2(B).

When the CCIR video signal is read out from the memory device 2 in this way and 50 fields (0.83 seconds) have elapsed regarding the signal output from the NTSC signal processing circuit, the signals shown in FIGS. 2(A) and (B) are displayed. As shown, the field start points of the NTSC signal output from the NTSC signal processing circuit 1 and the CCIR signal output from the memory device @2 coincide. Therefore, the memory device 2 writes the NTSC signal output from the NTSC signal processing circuit 1 into the memory 21 at the timing when the field start points of both the signals coincide. This writing is performed once every 50 fields of the NTSC signal, and thereafter the same read operation as described above is performed. The CCIR signal reproduced and outputted by the CCIR signal processing circuit 4 (actually, it is a strobe-like reproduced image, so it is not a complete CCIR signal) is displayed by a monitor receiver 4 of the CCIR system.

According to this embodiment, the field frequency of an NTSC video signal is converted to the field frequency of a CCIR video signal using a simple circuit using a memory 21 that can record signals for one field. can be displayed on a CCJR monitor receiver 4. Therefore, in a VTR equipped with one image memory for special playback, this memory can be used to easily configure a video signal conversion device, and it is possible to play back a tape recorded with an NTSC signal and convert it to a CC signal.
It is possible to output an IR type reproduced video signal.

FIG. 3 is a block diagram illustrating another embodiment of the video signal conversion system of the present invention. The CCIR signal processing circuit 6 converts the CCIR signal, which has a field frequency of 50H2 and includes a horizontal period of 625 in one frame, that is, 312.5 in one field, into a fourth
The data is output to the memory device 2 as shown in FIG. The memory device 2 stores 2 of the signals corresponding to 312.5 horizontal periods corresponding to one field of the CCIR signal during the P period of FIG. 4(A).
A signal corresponding to 63 horizontal periods is written into the memory 21.

At the same time, the memory device 2 reads signals corresponding to 263 horizontal periods from the memory 21 and outputs them as one field to the NTSC signal processing circuit 7, as shown in FIG. 4(B). In the next field, the memory device 2 reads signals corresponding to 262 horizontal periods as shown in FIG. 4(B) and outputs them as one field to the NTSC signal processing circuit 7. In other words, the station memory device 2 alternately reads signals corresponding to 263.262 horizontal periods for one field and outputs them to the NTSC signal processing circuit 7 as a signal including one frame of 525 horizontal periods.
The TSC signal processing circuit 7 reproduces the NTSC video signal and outputs it to the NTSC monitor receiver 8 .

However, one horizontal period of this NTSC video signal is CC
The time is 64 μs, which is the same as that of the IR method. Note that the write operation to the memory 21 of the memory device 2 is performed using the CCIR signal output from the CCIR signal processing circuit 6 and the memory device 2.
As shown in FIG. 4(B), the data is written at a timing when the field start points of the NTSC signal read from the CCIR signal coincide with each other, that is, once every 42 fields of the CCIR signal.

According to this embodiment, the memory 21 having a storage capacity for one field is used to convert a CCIR video signal into an NTSC video signal.
It can be converted into a video signal of the same format, and has the same effect as the previous embodiment.

Note that by combining the conversion devices shown in both of the above embodiments, the NT
It is easy to install a conversion device capable of mutually converting video signals of the SC system and the CCIR system into a VTR or the like.

[Effects of the Invention] As described above, according to the video signal conversion method of the present invention,
This has the effect of converting the field frequency of a video signal to another frequency with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a system explaining one embodiment of the video signal conversion method of the present invention, FIG. 2 is an operation timing chart of the device shown in FIG. 1, and FIG. 3 is a video signal conversion method of the present invention. FIG. 4 is a block diagram of a system for explaining another embodiment of the present invention, and FIG. 4 is an operation timing chart of the apparatus shown in FIG. 1.7...NTSC signal processing circuit 2...Memory device 4.6...CCIR signal processing circuit 5.8...Monitor receiver 21...Memory Agent Patent attorney Nori Ken Chika Yudo Uji Hiroshi

Claims (1)

[Claims] In a device that converts the field frequency of a video signal,
writing means for omitting all or part of one screen of a video signal having a first field frequency and writing it into the image memory; and writing means for writing one screen of the video signal having a first field frequency into the image memory; 1. A video signal conversion system comprising: reading means for obtaining a video signal having a second field frequency by converting the video signal into a video signal.