KR100243230B1 - Serial communication method from digital video camera to computer for image transmission - Google Patents

Abstract

Provided are a serial communication method for transmitting images from a digital video camera to a computer having high transmission efficiency and capable of monitoring a digital video camera image on a computer. In the serial communication method for image transmission from a digital video camera to a computer according to the present invention, a) a predetermined control command code received from a computer via a serial communication line in which a serial communication interface built into the digital video camera corresponds to itself; Determining whether the command code corresponds to the command code corresponding to the microcomputer; and b) determining that the control command code received in the step a) is a control command code corresponding to the serial communication interface unit. Interpreting a code to perform a corresponding function; and c) if the control command code received in step a) is determined to be a control command code corresponding to the micom, transferring the control command code to the micom. And d) the micom performs a corresponding function in response to the control command code. Thus, by implementing a monitor function for displaying an image of a digital video camera on a computer monitor, not only the movement of the screen can be directly seen from the computer but also there is an advantage of directly controlling the digital video camera.

Description

Serial communication method from digital video camera to computer for image transmission}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image transmission method of a digital video camera, and more particularly, a method for monitoring an image of a digital video camera on a computer, a serial communication method for transmitting an image from a digital video camera to a computer, and a digital video camera directly The present invention relates to a communication protocol that can be controlled in a.

The simplest method of transferring images from a digital video camera to a computer is a method of serially transmitting images using an RS232 port. However, the conventional image transmission method unilaterally transmits video data from a digital video camera to a computer according to a data transmission signal of a computer. When an error occurs during data transmission, the transmission efficiency is low because the image is retransmitted from the beginning. Not only can the computer not monitor the image of the digital video camera, but also can not control the digital video camera directly, there is a problem that can not check the operation state of the digital video camera.

The technical problem to be solved by the present invention is to retransmit only a specific part in case of an error, to increase the transmission efficiency, to monitor the image of the digital video camera from the computer, and to control the digital video camera directly from the image from the digital video camera to the computer It is to provide a serial communication method for transmission.

1 is a block diagram of a system to which a serial communication method for image transmission from a digital video camera to a computer according to the present invention is applied.

2 is a flowchart of a serial communication method for image transmission from a digital video camera to a computer according to the present invention.

3 is a diagram illustrating a data transmission format between a computer and an RS232 serial communication interface in a serial communication method for image transmission from a digital video camera to a computer according to the present invention.

4 is a diagram illustrating a data transmission format between a microcomputer and an RS232 interface in a serial communication method for image transmission from a digital video camera to a computer according to the present invention.

5 is a diagram illustrating a data transfer path of the system shown in FIG. 1.

6 is a diagram illustrating a format of a control command code.

7 is a diagram illustrating a format of an error block retransmission request control command code.

8 is a detailed block diagram of the RS232 serial communication interface.

<Explanation of symbols for main parts of drawing>

S20 ... control command code determination step,

S22 ... Step of executing control command code of RS232 serial communication interface,

S24 ... control command code passing step,

S26 ... Execution step of microcom's control command code.

In order to achieve the above object, a serial communication method for image transmission from a digital video camera to a computer according to the present invention comprises: a) a predetermined control received from a computer via a serial communication line by a serial communication interface built into the digital video camera; Determining whether the command code corresponds to a command code corresponding to itself or a command code corresponding to a micom; b) if it is determined that the control command code received in step a) is a control command code corresponding to the serial communication interface unit, interpreting the control command code to perform a corresponding function; c) if it is determined that the control command code received in step a) is a control command code corresponding to the micom, transferring the control command code to the micom; And d) performing a corresponding function by the micom in response to the control command code.

If the control command code is a capture command for requesting an image captured by the digital video camera, the computer transmits the video data of the captured image stored in the capture controller in the serial communication interface unit in the step b) through the serial communication line. It is desirable to send to.

If the control command code is a monitor command for requesting continuous display of the image of the digital video camera on the monitor of the computer, the serial communication interface unit down-samples the video data in the capture control unit in step b). By reducing the size, it is desirable to reduce the capacity of the video data and transmit it to the computer.

When the serial communication interface unit transmits the video data to the computer, the video data is transmitted in block units to confirm a transmission error, and a start code and an end code are added to each block to generate an error when a transmission error occurs. It is desirable to retransmit only.

The size of the block is preferably 2882 bytes including one byte of start code and one byte of end code.

If the control command code is a status confirmation request command for requesting confirmation of the current status of the digital video camera, the microcomputer checks the current status in step c) and sends status data to the computer through the serial communication interface. It is desirable to transmit.

Preferably, the control command code is dualized to independently control the serial communication interface unit and the digital video camera.

Preferably, the control command code is a command code of 1 byte and a side information code of 2 bytes.

If the control command code is a command for directly controlling the digital video camera, such as play, stop, still, zoom in, zoom out, etc., in step c), the microcomputer performs a function corresponding to the control command code, thereby causing the computer to operate. It is desirable to directly control the digital video camera.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of a serial communication method for image transmission from a digital video camera to a computer according to the present invention.

1 is a block diagram of a system to which a serial communication method for image transmission from a digital video camera to a computer according to the present invention is applied.

In the system shown in FIG. 1, reference numeral 10 denotes a computer, reference numeral 12 denotes an RS232 serial communication interface embedded in a digital video camera (not shown), reference numeral 14 denotes a microcomputer embedded in a digital video camera, and reference numeral 16 denotes luminance. A shuffle memory for outputting data (ydata) and color data (cdata), reference numeral 18 denotes a video encoder for inputting luminance data (ydata) and color data (cdata) to output a composite video signal.

In the serial communication method for image transmission from a digital video camera to a computer according to the present invention, when the computer 10 outputs a control command code to the RS232 serial communication port, the RS232 serial communication interface unit 12 of the digital video camera controls the control. It is determined whether the command code is a command corresponding to itself or a command corresponding to the microcomputer 14, and if the control command code is a command corresponding to the microcomputer 14, it is transmitted to the microcomputer 14 so that the microcomputer 14 causes the microcomputer 14 to perform the command. In response to the control command code, the corresponding function is performed, and if it is determined as a command corresponding to the RS232 serial communication interface unit 12, the corresponding function such as video data transmission is performed.

A serial communication method for image transmission from the digital video camera to a computer will be described in detail with reference to FIG. 2. 2 is a flowchart of a serial communication method for transmitting an image from a digital video camera to a computer according to the present invention. When the control command code for requesting the computer 10 to perform a predetermined function is output, RS232 serial communication of the digital video camera is performed. After receiving this, the interface unit 12 determines whether the control command code received in step S20 is a command code corresponding to itself or a command code corresponding to a microcomputer.

In step S22, when it is determined that the control command code received in step S20 is the control command code corresponding to the RS232 serial communication interface unit 12, the control command code is interpreted to perform the corresponding function. In step S24, when it is determined that the control command code received in step S22 is the control command code corresponding to the microcomputer 14, the control command code is transmitted to the microcomputer 14. In step S26, the microcomputer 14 performs the corresponding function in response to the control command code.

On the other hand, when the control command code of the computer 10 in step S22 is a capture command requesting the transmission of the captured image of the digital video camera, the RS232 serial communication interface unit 12 is located in the RS232 serial communication interface unit 12. The video data of the captured image stored in the capture control unit (not shown) is transmitted to the computer 10 through the serial communication line.

In addition, when the control command code is a monitor command requesting to display the current image of the digital video camera 14 on the monitor of the computer 10 in step S22, the RS232 serial communication interface unit 12 receives an RS232 serial communication interface. By down-sampling the video data in the capture control section in the section 12 to reduce the size of the image, the video data is reduced in size and transmitted to the computer 10 so that the image of the digital video camera reduced on the monitor of the computer 10 is reduced. It should be displayed continuously.

In the present invention, data transmission between the computer 10 and the RS232 serial communication interface 12 uses a conventional RS232 data encoding technique. 3 shows a data transmission format between the computer 10 and the RS232 serial communication interface 12 used in the present invention. As shown in Fig. 3, the data transmission format between the computer 10 and the RS232 serial communication interface 12 is composed of start bits, 8 bits of data, and stop bits.

In addition, in the data transmission format between the microcomputer 14 and the RS232 serial communication interface unit 12, as shown in FIG. 4, the data D0, D1,..., D7 has a strobe signal mstrb of the microcomputer 14. Is sent according to.

5 shows a data transfer path of the system shown in FIG. As shown in FIG. 5, the communication between the devices in the method is limited to three cases of a control command code, a response code, and data. The control command code is basically generated in the computer 10 to generate an RS232 serial communication interface 12. After processing in the microcomputer 14 via the (), the basic principle is that the microcomputer 14 transmits the corresponding response code or data to the computer 10. Here, the control command code is a code for requesting to perform a specific function from the computer 10 to the digital video camera, and the response code is an RS232 serial communication interface unit 12 after the control command code of the computer 10 is transferred to the microcomputer 14. ) Or code generated after the control command code is interpreted by the microcomputer 14 and the system is converted into a ready state. The data represents video data or state data output from a video memory (not shown).

As shown in Fig. 6, the control command code is a command code of 1 byte and a side information code of 2 bytes. In this case, the command code distinguishes the type of command, and the additional information code is data including additional information according to the command code. This additional information code is used for retransmitting, for example, by transmitting an ID of the place where the error occurred when the error is checked by the computer 10 during transmission of the video data.

On the other hand, video data transmitted from the RS232 serial communication interface unit 14 to the computer 10 is transmitted in units of blocks in order to retransmit only the portion in which an error occurs when an error occurs, and the size of the unit block is initially set to start code "0." 2882 bytes of "," followed by two bytes of end code "255", and the computer 10 discards the start code and the end code after reception. In addition, when an error occurs, the computer 10 sends a transmission hold command code to the RS232 serial communication interface 12 to stop data transmission, clear the RS232 buffer, and then an error block retransmission request control command code as shown in FIG. Is sent along with the block ID to retransmit the data block that caused the error. Therefore, transmission efficiency can be improved when an error occurs.

In addition, since the present invention includes a monitor function for continuously viewing the current image of the digital video camera on the monitor of the computer 10 as described above, the moving image can be monitored. In order to achieve this, the present invention uses a method of reducing the size of an image to reduce the amount of video data for transmission.

Since the amount of data in one field of a digital video camera is 345,600 bytes (720 × 240 × 2, Y: Cr: Cb = 2: 1: 1), the time required to transfer video data in one field at a transmission rate of 115,200 bps is minimal. 30 seconds. Therefore, if the image size is reduced to 1/16, the data size is reduced to 10,800 bytes (90 × 60 × 2), so that one screen can be viewed in about 1 second. When the transmission speed is increased four times, four screens can be viewed in one second, so that the image of the digital video camera can be seen on the monitor of the computer 10 near the moving picture.

For reference, Table 1 shows the data transfer speeds and the screen display times.

Baud rate Data block size in bytes Field (seconds) Frames in seconds Monitor (1/64, second) 57.6K 180 64 128 3 115.2K 360 32 64 1.5 230.4K 540 16 32 0.75 345.6K 720 5.34 10.67 0.5 460.8K 1,440 8 16 0.375 921.6K 2,880 4 8 0.1875

8 is a detailed block diagram of the RS232 serial communication interface 10. The RS232 serial communication interface 10 shown in FIG. 8 is a RS232 receiver 96 for receiving a signal tx output from the microcomputer 12 and a first for temporarily storing a signal output from the RS232 receiver 96. Microcomputer serial transmitter 80 for transmitting the serial buffer 84, the output of the first serial buffer 84 to the microcomputer 14, microcomputer serial receiver for receiving the signal sd_ma output from the microcomputer 14 82, a second serial buffer 88 for temporarily storing the output of the microcomputer serial receiver 82, a command decoder 86 for interpreting command codes, a clock divider 92 for dividing a clock, and luminance Control signals of the capture control unit 90 and the command decoder 86 that input data ydata [7: 0] and color data cdata [7: 0] to be temporarily stored and then output the stored data according to the transmission format. A signal for selectively outputting the outputs of the second serial buffer 88 and the capture controller 90 according to By entering the output of taekbu 94, the signal selection unit 94, and a RS232 transmission unit 98 for transmission to the computer 10. Here, sd_am represents a response code or the like output from the RS232 serial communication interface unit 12 to the microcomputer 14, mstrb represents a strobe signal of the microcomputer 14, and mclk represents a clock signal of the microcomputer 14.

The RS232 serial communication interface unit 12 configured as described above controls transmission rate setting, transmission start, transmission end, and transmission status according to the control command code output from the computer 10, and the RS232 serial communication interface unit 12 The control command code transmitted has a most significant bit of 1 to distinguish it from the control command code transmitted to the microcomputer 14. In addition, an ID of a data block received so far is added to an error code and a hold code generated during a transmission error to identify a block in which an error has occurred.

Table 2 shows the control command codes transmitted from the computer 10 to the RS232 serial communication interface 12.

Information Command code (hex) D7 = 1, D6 = 1, D5 = 1 data 0 data 1 not used E0 not used not used capture start E1 field / frame capture size monitor start E2 field / frame not used capture hold E3 not used not used capture stop E4 not used not used capture jump E5 data block Ids data block Ids capture block E6 data block Ids data block Ids not used E7-FF reserved reserved

In addition, Table 3 shows control command codes transmitted from the computer 10 to the microcomputer 14.

Command code (hex) D7 = 1, D6 = 1, D5 = 0 Micom response code D7 video / camera D6 normal / emergency C0 not used not used not used C1 status request status status request C2 play C2 play C3 stop C3 stop C4 still C4 still C5 slow C5 slow C6 fast forward C6 fast forward C7 rewind C7 rewind C8 zoom in C8 zoom in C9 zoom out C9 zoom out CA minute request minute minute code CB second request second second code CC frame request frame frame request CD-FF reserved not exist reserved

As shown in Table 3, in the present invention, when the computer 10 sends a desired control command code to the digital video camera, the control command code is determined by the RS232 serial communication interface unit 12, and the RS232 serial communication interface unit 12 Or the corresponding function is performed in the microcomputer 14. When the microcomputer 14 receives the control command code, it generates a response code, which is transmitted to the computer 10 via the RS232 serial communication interface 12. In order to distinguish the control command code corresponding to the microcomputer 14 from the control command code corresponding to the RS232 serial communication interface 12, the fifth bit is set to "0" and there is no additional information in common.

Next, an example of main functions to be performed by transmitting a control command code from the computer 10 to the digital video camera will be described.

1) Capture function

The capture function must stop writing to the video memory for capture from the digital video camera and continue to send the same screen until the end of the capture. The capture function is performed as follows. First, the computer 10 transmits a capture request control command code to the digital video camera, and then receives a capture ready signal from the digital video camera and transmits a capture start control command code to the RS232 serial communication interface unit 12. The RS232 serial communication interface unit 12 performs a capture function in accordance with a capture start control command to transmit video data of the captured image to the computer 10. If an error occurs at this time, the computer 10 transmits an error block retransmission request control command code to re-receive the block in which the error has occurred. When the capturing ends, the computer 10 sends a capturing stop control command code to the digital video camera to terminate the capturing function.

2) Monitor function

The monitor function is performed while the digital video camera is in operation and is independent of the digital video camera. First, after confirming that the monitor function can be performed from the digital video camera, the computer 10 transmits the monitor start control command code to the RS232 serial communication interface 12 to receive the video data from the digital video camera. At this time, if there is no request to perform another function, video data is continuously received and the image of the digital video camera is displayed on the monitor of the computer 10.

3) Status check function

The status checking function is a function of checking the current status of the digital video camera in the computer 10. First, the computer 10 receives status data from the digital video camera by sending a status request control command code to the digital video camera.

4) Digital video camera control function

This function is a function of directly controlling the operation of the digital video camera in the computer 10. For example, the process of playing the digital video camera is as follows. First, the computer 10 sends a status request control command code to the digital video camera to check the status of the digital video camera, and ends if it is not possible to play, and sends a play request control command code to the digital video camera if it is playable. To play the digital video camera. At this time, the computer 10 checks the state of the digital video camera and transmits the play request control command code again when it is not in the play state.

As described above, the serial communication method for image transmission from a digital video camera to a computer according to the present invention can transmit video data in units of blocks to increase transmission efficiency in the event of an error and to display an image of a digital video camera on a monitor of a computer. By implementing the monitor function to display the screen, you can see the movement of the screen directly on the computer, as well as control the digital video camera directly from the computer. In addition, since the state of the digital video camera can always be checked on a computer and a moving picture can be displayed, there is an advantage in that a video file can be produced on the computer using the same.

Claims (2)

a) determining whether a predetermined control command code received from the computer through the serial communication line by the serial communication interface embedded in the digital video camera is a command code corresponding to the same or a command code corresponding to the microcomputer; b) if it is determined that the control command code received in step a) is a control command code corresponding to the serial communication interface unit, the control command code is interpreted and the capture control unit is received if the control command code is a capture command. Transmitting the stored image data to the computer stored in a memory through the serial communication line, and sampling the image data stored in the capture control unit in the case of a monitor command to reduce the capacity and transfer the data to the computer; c) when the serial communication interface unit transmits the video data to the computer, the video data is transmitted in block units to confirm a transmission error, and an error occurs when a transmission error occurs by adding a start code and an end code to each block. Retransmitting the blocked block; d) if it is determined that the control command code received in step a) is a control command code corresponding to the micom, transferring the control command code to the micom; And e) when the microcomputer determines that the control command code is a status check request command in response to the control command code, checks a current state and transmits state data to the computer through the serial communication interface, and directly sends the digital video camera. And executing a corresponding function if it is determined to be a controlling command. The serial communication method for transmitting an image from a digital video camera to a computer. The method of claim 1, wherein the control command code is dualized to independently control the serial communication interface unit and the digital video camera, respectively. .

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