KR100284055B1 - Video signal recording method and device - Google Patents

Abstract

Disclosed are divided into clock signals for driving a plurality of video cameras, and a reference clock signal generated to perform a vertical synchronization signal and an isochronous transmission mode of the video camera, each having the same period, and divided clock cycle periods. The present invention relates to a video signal recording method and apparatus for implementing a clock synchronization between a video camera and a recording device by means of a start packet.

The disclosed video signal recording method comprises the steps of: receiving a first clock signal from a moving image camera and processing a video signal of a photographed subject into a digital video signal; After the digital video signal processing, generating a second clock signal to generate a vertical synchronization signal of the video camera to synchronize the clock frequency of the video recording device with the clock frequency of the video camera; And dividing each of the first clock signal and the second clock signal of the video camera as a predetermined signal so as to have the same clock period, and synchronizing the video signal obtained through the division according to the start packet signal of the clock period. Accordingly, synchronization of video signals is possible without equipment for implementing separate synchronization, and cable configuration between devices is simplified.

Description

METHOD AND APPARATUS FOR RECORDING OF VIDEO SIGNAL

The present invention relates to a video signal storage control method, and more particularly, to synchronize a driving clock frequency of a video camera photographing a subject using an IEEE 1394 (Institute of Electrical & Electronic Engineer) cable which is a multimedia transmission standard. The present invention relates to a video signal recording method and apparatus for storing a recorded video signal in a single recording device.

The IEEE1394 multimedia transmission standard is a transmission technology or standard between digital devices, and is an interface standard that enables high speed transmission and reception of multimedia data from 100Mbps to 1Gbps by connecting communication devices, computers, and home appliances in a single network. to be.

The IEEE 1394 interface standard is more bidirectional than Universal Serial Bus (USB), which is emerging as another multimedia standard, so that asynchronous transmission that does not require real time operation such as printer and scanner, and synchronous transmission that requires real time operation such as video and voice Support all, can transmit data of communication device, computer, video device.

Recently, the company is accelerating the development of products such as a satellite broadcasting receiver, a digital video tape recorder (VTR), a hard disk drive (HDD), a monitor, and a camcorder employing the IEEE 1394 interface standard.

However, the apparatus for recording and reproducing video data according to the prior art is configured such that a predetermined camera captures a still picture or a moving picture and outputs the captured video data through a recording / playback apparatus.

In other words, a security camera installed in a financial institution will be described as an example. Image data captured by a plurality of video cameras is asynchronously output, and synchronization of the output image data is synchronized through synchronization generating means such as an analog switch device. After recording, the recorder will record it.

As described above, a process of recording an image signal to a recording apparatus using a video camera according to the prior art will be described with reference to FIGS. 1 and 2.

The video camera includes a lens 15 which receives an image according to a subject, an image capturing tube 16 such as a solid-state image pickup device which captures an image of a subject applied from the lens 15 and converts the image into an electrical signal, Sampling / holding unit 18, which samples the electrical signal of 16) and holds it for a predetermined time, and converts the current signal of sampling / holding unit 18 through analog / digital converter 20. A digital signal processing unit 26 for processing the digital signal, and a digital / analog converter 28 for converting the digital signal of the digital signal processing unit 26 to the recording unit 14 and transmitting the analog signal. The clock generator 22 applies a predetermined clock signal to the imaging tube 16 and transmits the clock signal to the digital signal processor 26 according to a control operation of the microprocessor 24 that controls the overall operation of the video camera. Digital signal processing The unit 26 is controlled by the microprocessor 24.

Here, the clock generator 22 oscillates the clock frequency of 27Mhz for driving the video camera and supplies it to the imaging tube 16.

In order to transmit and record the video signal to one recording apparatus by driving at least one video camera configured as described above, as shown in FIG. 1, an analog switching unit (6) is used to synchronize the video signals transmitted from the video cameras 10a to 10n. 12) shall be provided.

That is, since the video signals of the video cameras 10a to 10n are asynchronously output, the analog switching unit 12 synchronizes these video signals and transmits them to the recording unit 14.

A process of recording a plurality of video cameras configured as described above and video signals captured by the video camera to a recording apparatus will be described below.

The moving image camera described herein may be replaced with a camera for capturing a still image. Hereinafter, the moving image camera will be described as being capable of capturing both moving image and still image as a moving image camera.

First, the imaging tube 16 receives a predetermined subject, for example, a stationary object or a moving video signal, which enters through the lens 15, and converts the signal into an electrical signal.

The electrical signal of the imaging tube 16 samples the analog signal for extension of the processing time in the case where there is not enough discontinuous waveform, that is, conversion time as a digital signal, before quantizing the signal in the analog / digital converter 20, The sampled signal is transmitted to the sampling / holding unit 18 which maintains the sampled signal for a predetermined time.

Then, the current signal of the sampling / holding section 18 is transmitted to the analog / digital converting section 20, where it is converted into a digital signal and then stored in a predetermined memory (not shown in the figure).

Then, the digital signal stored in the memory is converted into a more accurate and stable signal, such as noise removal, spectrum manipulation, etc. included in the digital signal in the digital signal processor 26, and reconverted to an analog signal in the digital / analog converter 28 Then, the data is transmitted to a recording unit 14 such as a VCR (Video Casette Recorder).

The recording unit 14 stores the received analog video signal in recording means such as a video tape or a magnetic tape.

At this time, even if the plurality of video cameras 10a to 10n are sequentially operated for a predetermined time interval or simultaneously driven to capture a video signal of a subject, each analog video signal output from each video camera is output as an asynchronous signal. Therefore, in order to store it in one recording apparatus, synchronization of each video signal must be implemented. Accordingly, the output analog video signal is input to the analog switching unit 12 to realize synchronization.

That is, in order to transmit only the analog video signal output from the predetermined video camera to the recording unit 14, the analog video signal is blocked and held according to the control operation of the analog switching unit 12 to suspend transmission, and the analog video is blocked. Only a signal may be input and transmitted to the recording unit 14. Alternatively, synchronization may be maintained by supplying a synchronization pulse signal, a synchronization frequency, and the like.

However, in the method of recording the video signal to the recording apparatus using the video camera according to the prior art described above, the video signal photographed by several video cameras are asynchronously output, and in order to record it on a single recording device, the video signal Motivation was needed.

Accordingly, a separate device such as a switching device for synchronizing the video signal is required, and the switching device and the plurality of video cameras are inevitably interconnected individually as each connecting cable, and the more video cameras, the more complicated the cable line. There was a problem. This problem is also difficult to install the connecting cable, and in order to prevent the degradation of the transmission efficiency of the video signal transmitted through the connecting cable, it is necessary to install a switching device or recording device at a distance from the respective video cameras there was.

Accordingly, the present invention provides a separate analog switching device for transmitting and storing the video signals captured by the plurality of video cameras to the recording apparatus according to the method of recording the video signals to the recording apparatus using the video camera according to the related art. In the present invention, a reference clock pulse signal and an isochronous transmission mode of a video camera required to capture a subject and digitalize the video signal are excluded. It is an object of the present invention to provide a video signal recording method and apparatus for synchronizing clock pulse signals of a plurality of video signals by dividing the clock pulse signals necessary for the interface between the devices to have the same period.

In another aspect of the present invention, a video signal output from a predetermined video camera is input to another video camera, and the input video signal is connected to two points by providing a transmission module capable of transmitting to another video camera or a recording device. By implementing a point-to-point method, it is aimed at simplifying the cable configuration connecting video cameras and video cameras and recording devices, and reducing the number of connecting cables.

1 is a schematic block diagram for recording a video signal to a recording apparatus using a video camera according to the prior art,

2 is an internal block diagram of the video camera of FIG.

3 is a block diagram for recording an image signal picked up according to the present invention;

4 is an internal block diagram of the video camera of FIG. 3.

<Explanation of symbols for main parts of drawing>

100a to 100n: 1st to nth video camera

104: recording unit 110: imaging tube

114: digital signal processor 116, 122: first and second clock generators

120: phase synchronization control unit 124: transmission protocol unit

According to an aspect of the present invention, a video signal recording method according to an aspect of the present invention is to capture a predetermined subject through at least one video camera, and transmit the captured video signal to a recording device connected with a predetermined cable. A video signal recording method for storing, wherein the video camera receives a first clock signal and processes the captured video signal of the subject into a digital video signal; After the digital video signal processing, generating a second clock signal to generate a vertical synchronization signal of the video camera to synchronize the clock frequency of the recording device with the clock frequency of the video camera; And dividing the first clock signal and the second clock signal of the video camera as a predetermined signal so as to have the same clock period, and synchronizing the video signal obtained through the division according to the start packet signal of the clock period. Include.

Preferably, the first clock signal is 27Mhz, the second clock signal is characterized in that 24.576Mhz.

Preferably, 1125 division is performed on the first clock signal, and the second clock signal is divided by 1024 to synchronize the first clock signal and the second clock signal.

In addition, the video signal recording apparatus according to another aspect of the present invention for achieving the above objects, and transmits the image data captured from the at least one video camera according to the synchronization signal, and stores the transmitted image data in the recording means An image data recording apparatus comprising: image pickup means for converting an image signal of a predetermined subject obtained through a lens group into an electrical signal by receiving a predetermined clock signal; Clock generation means for generating a reference clock signal to generate a vertical synchronization signal of the video camera; Phase synchronization means for receiving a reference clock signal generated from the clock generation means and synchronizing a phase of the clock signal of the video camera with the reference clock signal; Digital signal processing means for receiving the synchronized video signal from the phase synchronization means and performing a discretization process to convert the video signal into a digital video signal; And transmitting means for transmitting the digital video signal to the recording apparatus.

The recording means may include receiving and storing the digital video signal in accordance with the isochronous transmission mode from the transmission means.

Preferably, the clock signal applied to the imaging means is 27Mhz, and the reference clock signal of the clock generating means is characterized in that 24.576Mhz.

Preferably, the phase synchronization means is characterized by synchronizing the video signal between the video cameras by the cycle start packet of the isochronous transmission mode.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Here, in describing the embodiments of the present invention, the same parts as in the prior art may be omitted.

3 is a block diagram for recording an image signal captured in accordance with the present invention, Figure 4 is an internal block diagram of a video camera.

As shown in the drawing, the video camera according to the present embodiment captures a lens 106 that receives an image according to a subject, an image of the subject applied from the lens 106, and the first clock generator 116. An imaging tube 110 for converting the captured image signal into an electrical signal and receiving a control signal of the microprocessor 118 and generating a predetermined clock signal for synchronizing the image signal. A phase synchronous controller 120 for receiving the clock signal of the second clock generator 122 and the second clock generator 122 and synchronizing the clock signal of the first clock generator 116 with a phase synchronous controller ( The digital signal processor 114 receives the synchronized clock signal of the 120 and digitizes the video signal according to the operation of the microprocessor 118, and records the digital video signal transmitted from the digital signal processor 114. 104) It consists of a transport protocol 124 for transmission.

The transport protocol unit 124 includes a physical layer and a data link layer related to data transmission in Open System Interconnection (OSI) 7-Layer.

In order to drive and record at least one video camera configured as described above, and to transmit and record video signals to a single recording apparatus, as shown in FIG. 3, a video signal output from a predetermined video camera is input to another video camera, and the input video signal is input. Is configured using a two-point connection method (Point-to-Point) to be transmitted to another video camera or recording unit 104.

Here, the video cameras 100a to 100n are provided with an input / output module (not shown) capable of receiving and re-outputting an image signal transmitted from an IEEE 1394 cable.

Hereinafter, a process of storing the video signals collected from the plurality of video cameras 100a to 100n in the recording apparatus will be described.

First, the imaging tube 110 captures a moving picture or a still image of a subject input through the lens 106 and converts it into an electrical signal.

The imaging tube 110 converting the video signal into an electrical signal receives a driving clock frequency of the video camera, that is, a clock signal of 27 MHz, from the first clock generator 116 and converts the video signal into a digital signal processor. Send to 114.

The digital signal processor 114 transmits the signal converted into the digital video signal to the recording unit 104 through the isochronous transmission mode. In this case, the video signal is an asynchronous signal and synchronization of the video signal must be preceded. .

That is, the interface between the video cameras 100a to 100n and the recording unit 104 uses an isochronous transmission mode that performs channel transmission in a 125 μsec period, and it is necessary to synchronize the clock signals of the video cameras every cycle of the clock signal. .

Synchronization of the clock signal may be performed by one cycle start packet for each clock signal period.

Accordingly, to generate the vertical synchronization signal of the video cameras, the second clock generator 122 generates a 24.576Mhz reference clock signal for performing the isochronous transmission mode according to the operation of the microprocessor 118.

In addition, the phase synchronization controller 120 outputs the clock signal of the reference clock signal 24.576Mhz of the driving clock signal 27Mhz of the video camera generated with the vertical synchronization signal and the transmission protocol unit 124 generated by the second clock generator 122. In order to synchronize, a division process is performed on each clock signal.

In the division process, when the 27Mhz clock signal is divided into 1125 and the 24.576Mhz clock signal is performed in 1024 divisions, each clock signal has the same cycle period of 24hz, and generally, the cycle period time in isochronous mode. Becomes 125 mu sec as described above.

By using the cycle period, the cycle start packet signal can be transmitted to the recording unit 104, and the clock signals of the video cameras 100a to 100n can be synchronized.

Subsequently, a clock signal of the same period is calculated, and the digital signal processing unit 114 converts the electrical signal transmitted from the image pickup tube 110 into a digital image signal according to the clock signal, and transmits it to the transmission protocol unit 124. .

Before receiving the digital video signal, the data link layer of the transmission protocol unit 124 receives the request of the data link layer for transmitting the digital video signal and designates the data link layer to be transmitted. .

When the corresponding data link layer is designated, the digital video signal is transmitted to the physical layer through the data link layer, and then the physical layer detects a transmission speed with respect to the digital video signal of the video camera and separates the data and strobe signals. It transmits to the recording unit 104 through a series of processes such as transmitting / receiving.

Thereafter, the recording unit 104 receiving the digital video signal stores the video signal as a digital signal in the case of a digital recording device or converts the digital signal into an analog in the case of an analog recording device.

Meanwhile, an IEEE 1394 interface standard cable connecting video cameras 100a to 100n or recording devices such as video cameras 100a to 100n and a recording unit 104 typically has a limit of 4.5M and has a 400Mbit / second limit. It can transmit / receive multimedia signals such as video signal and audio signal. Thus, a repeater is required to extend the length of the cable.

As described above, in the present embodiment, a division process is performed to have the same period with respect to the clock signal of the video camera and the reference clock signal of the IEEE 1394 for transmitting the video signal to synchronize the video signals captured by the plurality of video cameras. In practice, no equipment is required to synchronize signals separately.

It is clear from the above description that, according to the video signal recording apparatus of the present invention, a reference clock pulse signal of a video camera required for imaging a subject and digitalizing the video signal, and an interface between devices provided with an isochronous transmission mode are required. By dividing the clock pulse signals to have the same period, and synchronizing the clock pulse signals of the plurality of video signals, there is no need for a separate device for synchronizing the asynchronous video signals output from the video cameras. When connecting cables between devices, the two-point connection method can be used to simplify the cable configuration.

Claims (6)

A video signal recording method for photographing a predetermined subject through at least one video camera and transmitting and storing the photographed video signal to a recording device connected with a predetermined cable: The video camera receiving a first clock signal and processing the captured image signal of the subject as a digital image signal; After the digital video signal processing, generating a second clock signal to generate a vertical synchronization signal of the video camera to synchronize the clock frequency of the recording device with the clock frequency of the video camera; And Dividing the first clock signal and the second clock signal of the video camera as a predetermined signal so as to have the same clock period, and synchronizing the video signal obtained through the division according to the start packet signal of the clock period. The video signal recording method characterized in that. The method of claim 1, And the first clock signal is 27 Mhz and the second clock signal is 24.576 Mhz. The method of claim 2, And performing a 1125 division on the first clock signal and dividing the second clock signal by 1024 to synchronize the first clock signal and the second clock signal. An image data recording apparatus for transmitting image data captured from at least one video camera according to a synchronization signal, and storing the transmitted image data in a recording means. The video camera, (1) imaging means for converting an image signal of a predetermined subject obtained through the lens group into an electrical signal by receiving a predetermined clock signal; (2) clock generation means for generating a reference clock signal to generate a vertical synchronization signal of the video camera; (3) phase synchronization means for receiving a reference clock signal generated from said clock generation means and synchronizing the phase of said clock signal of said video camera with said reference clock signal; (4) digital signal processing means for receiving the synchronized video signal from the phase synchronization means and performing a discretization process to convert the video signal into a digital video signal; And (5) transmission means for transmitting the digital video signal to the recording apparatus, The recording means, And receiving and storing the digital video signal in accordance with the isochronous transmission mode from the transmission means. The method of claim 4, wherein And a clock signal applied to the image pickup means is 27 MHz, and a reference clock signal of the clock generation means is 24.576 MHz. The method of claim 5, And the phase synchronizing means synchronizes the video signals between the video cameras by a cycle start packet in the isochronous transmission mode.