WO2015012297A1

WO2015012297A1 - Reception device, method, and computer program

Info

Publication number: WO2015012297A1
Application number: PCT/JP2014/069408
Authority: WO
Inventors: 山本　正男; 小林　進
Original assignee: スカラ株式会社
Priority date: 2013-07-23
Filing date: 2014-07-23
Publication date: 2015-01-29
Also published as: JPWO2015012297A1; JP6485352B2

Abstract

Provided is a practical technology with which it is possible to transmit video data via a wireless LAN from a transmission device having the function to process video data to a reception device provided with a display, such as a portable terminal. A transmission-side computer (100) transmits analog data, which are data of a display image displayed on a display (101), to a communication device (200) via an analog cable (101A). The communication device (200) has the function to establish wireless LAN communication by means of Wi-Fi. Compressed data, which are obtained by subjecting the analog data to time-lapse processing and then subjecting the data of each of the remaining frames (data of one image) to JPEG compression, are sent to the reception-side computer (300) having a similar function as the communication device (200). The reception-side computer (300) displays the display image on the display (301) of the reception-side computer (300) only using the image data which is obtained by decompressing the compressed data and which have no changes in size.

Description

Receiving apparatus, method, computer program

The present application relates to a technique for transmitting moving image data to a receiving device using a wireless LAN from a transmitting device having a function of processing moving image data.

As a device having a function of processing moving image data, for example, there is a digital video camera. The video camera generates moving image data. Most video cameras record moving picture data on a recording medium built in the video camera, and in many cases, the moving picture data can be output to an external device by wire.
By the way, when an external device is provided with a display, especially when the video camera does not have a display, the display of the external device can be used as a display (monitor) of the video camera. In addition, when an external device and a video camera are connected wirelessly, the video caused by the trouble of connecting the video camera and the external device with a cable, the annoyance of the cable itself, the length of the cable, etc. Since there is no restriction on the positional relationship between the camera and external devices, nothing is more convenient.
The mobile terminals that are now very popular can be external devices as described above. The portable terminal includes a notebook personal computer, a smartphone, a tablet, and the like, but these are provided with a display, and most of them are equipped with a wireless LAN function.

An apparatus having a function of processing moving image data includes a computer such as a notebook personal computer. If an image displayed on a display of a notebook personal computer can be displayed on a display of a portable terminal such as another notebook personal computer, it is convenient in the following cases, for example.
Projectors are known for presentations at conferences. When giving a presentation, the presenter projects a desired image on a screen or the like from a projector connected to a notebook computer or the like. The audience attending the conference listens to the presentation of the presenter while viewing the projected image. Here, it is convenient if the image displayed on the display of the notebook computer operated by the presenter can be displayed on the display of the portable terminal held by the audience. That way, paper handouts are no longer needed, and people far from the image projected by the projector have a hard time recognizing the image, especially if the image contains small letters. Nothing will happen. This is not only applied to presentations, but it is also possible to send desired information to visitors from a single notebook computer, etc. to visitors who watch theater, watch concerts, or watch sports. Application is also possible. Speaking of the mechanism as described above, it is like a “small scale, simplified television broadcasting system”, and if such a system can be realized, there is a possibility that a completely new demand can be generated.

Each of the above examples is a system that can be realized by transmitting moving image data over a wireless LAN from a transmitting device having a function of processing moving image data to a receiving device including a display such as a portable terminal.
However, there are also restrictions on realizing such things.
That is, it is difficult to send general moving image data at the line speed of an existing wireless LAN. Therefore, it is necessary to lower the frame rate of the moving image to be transmitted.
However, although the inventors of the present application tried to make such a product, further problems occurred. In the transmission / reception of data by a wireless LAN, a situation in which transmitted / received data is often damaged occurs. In such a case, if an unscheduled frame is mixed with a moving image with a reduced frame rate, the moving image becomes very unsightly.

The present invention is capable of transmitting moving image data over a wireless LAN from a transmitting device having a function of processing moving image data to a receiving device having a display such as a portable terminal. The problem is to provide a practical technique that can prevent the problem from being unsightly.

The present inventor proposes the following invention in order to solve the above-mentioned problems.
The invention of the present application has a function of processing moving image data, and means for compressing image data, which is data for one screen appropriately extracted from the processed moving image data, into compressed data, And a transmission device including means for transmitting compressed data via a wireless LAN, and can communicate with the transmission device via a wireless LAN. Receiving device.
The receiving device includes a display, a receiving unit that receives the compressed data from the transmitting device as needed, a decompressing unit that decompresses the compressed data received by the receiving unit, and the image data before being compressed into the image data. A determination unit that determines whether there is a change from the image data; an image based on the decompressed image data that has been determined by the determination unit to be unchanged from the original image data is displayed on the display; and the determination unit Display control means for controlling not to display an image based on the decompressed image data determined to have changed from the original image data on the display.
The receiving device receives moving image data from the transmitting device via a wireless LAN. The moving image data received by the receiving device is a sequence of image data appropriately extracted from moving image data processed by the transmitting device. The image data is image data for one screen, and is image data for one frame. In short, this corresponds to data that has been dropped appropriately from the original moving image data to be processed by the transmission device to the extent that there is no problem in transmitting at the transmission speed of the wireless LAN.
Furthermore, the image data sent from the transmission device via the wireless LAN is compressed by a predetermined format, for example, the JPEG method, and then sent to the reception device after being reduced in capacity. This restriction is not a problem in the sense that it can be used at least in the receiving apparatus of the present application.
In addition, the receiving device of the present application determines whether there is a change in the image data (including the meanings of both the decompressed image data and the decompressed image data) from the image data before the compressed data. And an image based on the decompressed image data determined to be unchanged from the original image data by the determining means and displayed on the display, and decompressed as determined by the determining means to have changed from the original image data. Display control means for controlling the image based on the image data not to be displayed on the display.
Therefore, the receiving device of the present application basically displays the moving image data dropped on the frame as described above by the continuous image data on the display, but the unplanned image ( Further, the frame) is dropped from the data of the moving image that has been dropped. As a result, the number of frames of the moving image displayed on the display of the receiving device may be further reduced, but the unpleasant image (frame) is mixed with the moving image displayed on the display of the receiving device. According to the evaluation by the present inventor, it has been found that a moving image excluding images (frames) that are not planned even if the number of frames is further reduced gives a better impression to what to see.
Therefore, the receiving device of the present application is a technology that can transmit moving image data over a wireless LAN from a transmitting device having a function of processing moving image data to a receiving device having a display, and in particular, the display of the receiving device. It will provide practical technology that can keep the video you see on the screen from unsightly.
By the way, the present invention is very compatible with a technique using UDP (User Datagram Protocol) when transmitting data from a transmitting device to a receiving device. Unlike TCP (Transmission Control Protocol), which is a well-known communication protocol alongside it, UDP is a protocol that allows one-to-many communication from a transmission device to a reception device, not just one-to-one. This protocol does not perform a so-called shake hand between the transmission device and the reception device, and has a characteristic that the communication speed is high. This is one-to-many in the present invention in which image data is transmitted from the transmitting apparatus to the receiving apparatus, although the capacity has been reduced by compression, and in particular in many cases where the present invention is applied to presentations. If you need communication, it's just right. However, communication using UDP differs from communication using TCP in that delivery confirmation is omitted, and data integrity is not guaranteed. Therefore, the process of further dropping unscheduled images (frames) from the damaged image data from the moving image data with dropped frames compensates for the disadvantages of UDP communication and emphasizes only the UDP communication store.

As described above, the receiving device of the present application includes a determination unit that determines whether there is a change in the image data before the compressed data.
There is no particular limitation on how the determination means determines whether there is no change from the image data before the compressed image data.
For example, when the image data obtained by decompressing the compressed data has the same size as the planned size, the determination unit determines that there is no change from the original image data, and obtains the compressed data by decompressing. If the image data is different from the planned size, it may be determined that there is a change from the original image data. This is a determination method in which it is assumed that there is no change in the image data when there is no change in the size of the image data.
In this case, when the transmission device transmits the compressed data, the transmission device describes capacity information for specifying the size of the image data that is the source of the compressed data following the header in the header attached to the compressed data. The determination unit may handle the size specified by the capacity information as the planned size of the image data. As described above, in order to determine whether or not the image data is different from the planned size, the receiving apparatus determines the “scheduled” size of the image data, that is, the size of the reference image data. You must know. It can be determined in advance by a computer program or the like installed in advance in the transmission device and the reception device, but there may be a difference in the size of each image data. Therefore, the transmitting device writes the capacity information as described above in the header of data used to transmit the compressed data, and the receiving device determines the size of the image data specified by the capacity information as “scheduled” of the image data. If the size of each image data is different, the receiving apparatus determines whether or not the size of the image data has changed according to the size of the image data. This makes it possible to make a determination based on this, and it is not necessary to determine a reference for the size of image data in advance between the transmission device and the reception device.
Whether or not the size of the image data has changed can be determined, for example, as follows. Prior to the description, the data structure of data to be transmitted including compressed data to be transmitted from the transmission device to the reception device will be described first. The data sent from the transmission device to the reception device is generally a header including information indicating the compression format of the compressed data, a start block that follows the header, a start block that distinguishes the subsequent data portion from the header, and that follows the start block Is provided with a data portion corresponding to the compressed data itself and a stop block indicating the end of the data portion. The data to be transmitted having the above-described data structure is generally divided into a plurality of packets having the same size and transmitted from the transmission device to the reception device. The first packet often includes a header, a start block, and the first portion of the data portion, the second and subsequent packets each include a divided data portion, and the last packet includes The end part of the data part and the stop block are included. (Note that if the data of the data part fits perfectly in the second packet from the end, the data part is not included in the last packet. .) When receiving data having such a data structure, the receiving apparatus can determine whether or not the size of the image data has changed using the following contents as a reference. When the following contents are used as a reference, the receiving computer determines that the size of the image data has changed when the answer to the following contents is Yes, and the answer is No. It is determined that there is no change.
A) Is the data size of the data part between the start block and the stop block different from the data size previously determined between the transmission device and the reception device or described in the header?
B) The size of data included in a packet is different from the size of data that has been determined in advance between the transmitting device and the receiving device or described in the header, and the packet includes a stop block. Absent?
C) Is information indicating the compression format of the compressed data included after the start block?
If the above-mentioned C is made more universal, the transmitting device, when transmitting the compressed data, when information to be included in the header attached to the compressed data is included in the compressed data, It may be determined that there is a change from the original image data. That is, an example of information to be included in the header in this case is information indicating the compression format of the compressed data in the case C.

Alternatively, the determination means determines that the image data obtained by decompressing the compressed data has no change from the original image data when the compressed data has the same size as the planned size, and the compressed data is When it is different from the planned size, it may be determined that there is a change from the original image data. This is a determination method in which it is assumed that there is no change in the image data when there is no change in the size of the compressed data. In the case described above, it is determined whether or not there is a change in the size of the image data on the basis of the size of the image data, and based on this, it is determined whether or not there is a change in the image data. In that case, the determination can be made only after decompressing the compressed data and returning it to the image data. According to this method of assuming that there is no change in the image data when there is no change in the size of the compressed data, it is also possible to determine whether the image data has changed before decompressing the compressed data. Is possible. If there is a change in the size of the compressed data, the compressed data need not be expanded.
In this case, when transmitting the compressed data, the transmitting device describes capacity information for specifying the size of the compressed data following the header in a header attached to the compressed data. The determination means may handle the size specified by the capacity information as the planned size of the compressed data. The same reasoning as when the capacity information about the size of the image data is described in the header, it becomes possible to cope with the case where there is a difference in the size of each compressed data, and between the transmitting device and the receiving device. Thus, it is not necessary to determine a standard for the size of the compressed data in advance.

The transmitting device includes determination data which is data irrelevant to the image data at a predetermined position of the image data, and the determination unit decompresses the compressed data and obtains the image When the determination data having the planned content exists at the planned position of the data, it is determined that there is no change from the original image data, and the image data obtained by decompressing the compressed data If the predetermined content does not exist at the planned position, it may be determined that there is a change from the original image data. This is a determination method in which it is assumed that there is no change in the image data when the determination data of the predetermined content exists at the predetermined position of the image data.
In this case, when transmitting the compressed data, the transmitting device adds the determination data to the header of the compressed data following the header in the header attached to the compressed data. The determination data specifying information for specifying whether or not the data is included is described, and the determination means sets the position specified by the determination data specifying information and the content to the planned position of the image data. In addition, it may be used as a reference when determining whether or not determination data having the scheduled content exists. In order to determine whether or not the determination data of the scheduled content exists at the scheduled position of the image data, the receiving device has a criterion as to what kind of data exists in the image data. You must know the location and the reference content. The reference position and the reference content can be determined in advance by a computer program or the like installed in advance in the transmission device and the reception device, but depending on the type of image data to be handled, If only predetermined ones are used, it may be possible that the above-described determination cannot be made. Therefore, the transmitting apparatus writes the determination data specifying information as described above in the header of the data used for transmitting the compressed data, and the receiving apparatus specifies where and in the image data specified by the determining data specifying information. Such information as to whether or not the determination data is included can be used as a reference for determining whether or not determination data having the predetermined content exists at the predetermined position of the image data. It is possible to avoid a situation in which it is impossible to determine whether or not the size of the image data has changed due to the type of image data to be displayed. There is no need to make arrangements for what kind of data to include.
Alternatively, the transmission device includes determination data that is data irrelevant to the compressed data in a predetermined position of the compressed data, and the determination unit is arranged at a predetermined position of the compressed data. When the determination data having the planned content exists, it is determined that the image data obtained by decompressing the compressed data has no change from the original image data, and the compressed data is located at the planned position. When the determination data having the planned contents does not exist, it may be determined that the image data obtained by decompressing the compressed data has changed from the original image data. This is a determination method in which it is assumed that there is no change in the image data when the predetermined determination data exists at a predetermined position of the compressed data instead of the image data. According to this method, it is possible to determine whether or not there has been a change in the image data before decompressing the compressed data into image data. If it is assumed that the image data has changed, the compressed data need not be expanded.
In this case, when transmitting the compressed data, the transmitting device specifies where and what kind of the determination data is included in the compressed data following the header in the header attached to the compressed data. The determination data specifying information is described, and the determining means sets the position specified by the determination data specifying information and the content at the planned position of the compressed data. It may be used as a reference for determining whether or not determination data exists. Due to the type of image data to be handled or the type of compressed data, it is possible to avoid a situation in which it is not possible to determine whether or not a change has occurred in the image data. There is no need to make an arrangement about where and what kind of data is included in the compressed data.

The compressed data is sent from the transmitting device to the receiving device several times to several tens of times per second, and the receiving means performs the compression from the transmitting device several times to several tens of times per second. Data may be accepted.
If the moving image has such a number of frames, a viewer who sees the moving image on the display of the receiving apparatus can recognize the moving image as a somewhat smooth moving image, and there is no difficulty in transmitting and receiving at the current wireless LAN transmission speed.

The receiving device is a computer (a device including an arithmetic device) having a display capable of communication via a wireless LAN, for example, a portable terminal. The portable terminal includes at least a notebook computer, a smartphone, and a tablet.
The transmission device may process moving image data, and may be a computer (device including an arithmetic device) capable of wireless LAN communication. For example, portable terminals such as notebook computers, smartphones, and tablets are examples. However, this includes desktop computers and devices that do not include a display such as a video camera.

The inventor of the present application also proposes a method for producing the same effect as the receiving apparatus of the present application.
An example of the method has a function of processing moving image data, and means for making compressed data obtained by compressing image data, which is data for one screen appropriately extracted from moving image data to be processed, into a predetermined format The compressed data is used in combination with a transmission device including a means for transmitting the compressed data via a wireless LAN, and can communicate with the transmission device via a wireless LAN. And a method executed by a receiving device having a display.
The method includes a receiving process executed by the receiving apparatus for receiving the compressed data from the transmitting apparatus as needed, a decompressing process for expanding the compressed data received in the receiving process, and compressed image data. A determination process for determining whether or not there is a change from the image data before the display, and an image based on the decompressed image data determined to have no change from the original image data by the determination process is displayed on the display, A display control process for controlling to prevent an image based on the decompressed image data determined to have changed from the original image data in the determination process from being displayed on the display.

The inventor of the present application also proposes a computer program that produces the same effect as the receiving apparatus of the present application.
An example of the computer program has a function of processing moving image data, and means for compressing image data, which is data for one screen appropriately extracted from processed moving image data, into a predetermined format. And a means for transmitting the compressed data via a wireless LAN, in combination with the transmission device, so that communication with the transmitter via the wireless LAN can be performed. The computer having a display accepts the compressed data from the transmission device as needed, the decompression process of decompressing the compressed data received in the acceptance process, and the image data as compressed data. A determination process for determining whether there is a change from the previous image data, and no change from the original image data due to the determination process An image based on the determined expanded image data is displayed on the display, and an image based on the expanded image data determined to have changed from the original image data by the determination process is displayed on the display. And a display control process for performing control so as not to be executed.

The applicant of the present application also proposes a communication system as the same effect as the receiving apparatus of the present application.
The communication system has, for example, a function of processing moving image data, and means for compressing image data, which is data for one screen appropriately extracted from the processed moving image data, into a predetermined format. A transmission device comprising: means for transmitting the compressed data via a wireless LAN; and a reception device adapted to perform communication via the wireless LAN with the transmission device; The receiving device includes a display, a receiving unit that receives the compressed data from the transmitting device as needed, a decompressing unit that decompresses the compressed data received by the receiving unit, and the image Determining means for determining whether there is any change from the image data before the data is compressed data, and if there is no change from the original image data by the determining means An image based on the determined expanded image data is displayed on the display, and an image based on the expanded image data determined to have changed from the original image data by the determination unit is displayed on the display And a display control means for controlling to prevent the communication system.

1 is a diagram illustrating an overview of a communication system according to a first embodiment. The figure which shows the hardware constitutions of the transmission side computer contained in the communication system shown in FIG. The block diagram which shows the functional block formed inside the transmission side computer contained in the communication system shown in FIG. The figure which shows the hardware constitutions of the communication apparatus contained in the communication system shown in FIG. The block diagram which shows the functional block formed in the inside of the communication apparatus contained in the communication system shown in FIG. The figure for demonstrating the analog signal sent to the communication apparatus contained in the communication system shown in FIG. The figure which shows the hardware constitutions of the receiving computer contained in the communication system shown in FIG. The block diagram which shows the functional block formed in the inside of the receiving computer contained in the communication system shown in FIG. The block diagram which shows the functional block formed in the inside of the receiving computer contained in the communication system of the modification 4. FIG. The figure which shows the external appearance of the communication system of 2nd Embodiment. Sectional drawing for demonstrating the structure of the video camera contained in the communication system of 2nd Embodiment. The block diagram which shows the functional block formed inside the video camera contained in the communication system of 2nd Embodiment. The block diagram which shows the functional block formed inside the receiving computer contained in the communication system of 2nd Embodiment. The figure for demonstrating the data structure of the data transmitted to the receiving side computer from a communication apparatus in the communication system of 1st Embodiment.

Hereinafter, first and second embodiments of the present invention will be described. In the description of each embodiment, common objects are denoted by common reference numerals, and overlapping descriptions are omitted depending on circumstances.

<< First Embodiment >>
FIG. 1 shows an outline of a communication system in the first embodiment.
The communication system includes a transmission side computer 100, a communication device 200, and a plurality of reception side computers 300. Although depending on the way of understanding, the communication apparatus 200 or a combination of the communication apparatus 200 and the transmission side computer 100 is a transmission apparatus in the present application, and the reception side computer 300 is a reception apparatus in the present application.
The communication system in this embodiment is used for presentation at a conference, although not limited thereto. The sending computer 100 and the communication device 200 are operated by a presenter (or an assistant thereof, the same shall apply hereinafter) giving a presentation, and the receiving computer 300 is operated by an audience. The receiving computer 300 may be private to the audience, or may be distributed or lent to the audience by a presenter or a collaborator of the presenter.

The sending computer 100 is a computer. The sending computer 100 of this embodiment is a notebook computer provided with a display 101. Of course, the sending computer 100 may be connected to the external display 101 like a desktop computer. The sending computer 100 also includes an input device 102. Although the input device 102 of this embodiment is a keyboard, the transmitting computer 100 may include other input devices such as a trackball, a mouse, and a touch panel in addition to or instead of the keyboard. The transmitting computer 100 also includes several output terminals not shown. The output terminal may be a known one, and in this embodiment, an analog output terminal (for example, an analog RGB terminal, an HDMI terminal, a DVI terminal, a display port, a thunderbolt terminal, etc.) is assumed to be present in the transmitting computer 100.
The sending computer 100 is equipped with known presentation software so that it can perform a presentation. The presentation software is, for example, PowerPoint (trademark) manufactured by Microsoft Japan. A display image, which is an image used for the presentation, is displayed on the display 101, and the presenter performs the presentation while watching it.

The sending computer 100 includes hardware as shown in FIG.
The hardware includes a CPU 111, a ROM 112, a RAM 113, an interface 114, and a hard disk drive 115, which are connected to each other by a bus 116.
The CPU 111 is an arithmetic device that performs arithmetic operations. For example, the CPU 111 executes processing described later by executing a computer program recorded in the ROM 112 or the hard disk drive 115. Note that the sending computer 100 may execute various functions that can be normally performed by a notebook personal computer, such as sending and receiving e-mails, browsing the Internet, and document creation. The sending computer 100 of this embodiment is also the same. Although it is such, a computer program here is a computer program for functioning this transmission side computer 100 as a transmission side computer of this invention. This computer program may be preinstalled in the transmitting computer 100 or may be installed afterwards. The computer program may be installed on the transmission-side computer 100 via a predetermined recording medium such as a memory card, or via a communication line such as a LAN or the Internet.
The ROM 112 records computer programs and data necessary for the CPU 111 to execute processing to be described later. The same applies to the hard disk drive 115, and some or all of the computer program and data may be recorded. In addition to the above-described presentation software, the hard disk drive stores computer programs for executing various functions that can be normally performed by a notebook personal computer, such as sending and receiving e-mails, browsing the Internet, and document creation.
The RAM 113 provides a work area necessary for the CPU 111 to perform processing. In addition, data generated as a result of processing performed by the CPU 111 can be recorded in the RAM 113. A part of the RAM 113 serves as a frame buffer described later.
The interface 114 exchanges data between the CPU 111 and the RAM 113 connected via the bus 116 and the outside. The interface 114 is connected to the input device 102 described above and an analog output terminal (not shown). The operation content from the input device 102 is input from the interface 114, and the data output from the interface 114 to the analog output terminal is output from the analog output terminal to the outside. A display 101 is connected to the interface 114, and data for controlling a display image displayed on the display 101 is output via the interface 114.

When the CPU 111 executes the computer program, a function block as shown in FIG. 3 is generated in the transmitting computer 100. The following functional blocks may be generated by the functions of the above-described computer program alone, but are generated by the cooperation of the above-described computer program and the OS and other computer programs installed in the transmission-side computer 100. May be.
An operation signal analysis unit 121, a control unit 122, and a display image data generation unit 123 are generated inside the transmission-side computer 100.

The operation signal analysis unit 121 analyzes the content of the operation signal input from the input device 102. As the operation signal related to this embodiment, there is a signal related to the operation of the presentation software. For example, when an operation signal related to page turning or animation execution in presentation software is input from the input device 102, the operation signal analysis unit 121 specifies that the operation signal specifies the above-described contents. , Analyze its contents. The operation content analyzed by the operation signal analysis unit 121 is sent to the control unit 122.
Here, the control unit 122 executes software for presentation. The control unit 122 executes the software for presentation based on the information received from the operation signal analysis unit 121 regarding the content of the operation signal input by the presenter from the input device 102. A signal regarding the execution result is sent to the display image data generation unit 123.
The display image data generation unit 123 generates display image data, which is data about a display image to be displayed on the display 101, based on a signal about the execution result of the presentation software received from the control unit 122. It is. The signal generated by the display image data generation unit 123 is sent to the display 101 and an analog output terminal (not shown). The signal sent to the analog output terminal is an analog signal for the display image currently displayed on the display 101. This analog signal is a moving image signal and is a signal in which frames are continuous.

Next, the communication apparatus 200 will be described.
The communication device 200 is connected to the transmitting computer 100, and receives an image substantially the same as the display image received from the transmitting computer 100 and displayed on the display 101 of the transmitting computer 100. Data to be displayed on the display is transmitted to a plurality of receiving computers 300.

The communication device 200 is a computer. The communication device 200 also includes an input device 202. Although the input device 202 of this embodiment is a numeric keypad, a keyboard, a mouse, a touch panel, or the like can be used as the input device 202. The communication device 200 also includes an input terminal (not shown).
In addition, the communication device 200 has a wireless LAN function. The wireless LAN function is realized by a wireless LAN communication unit (not shown). The wireless LAN is Wi-Fi (trademark) in this embodiment, although not limited thereto. Wi-Fi is a standard by default, and at the same time, 253 computers (when 8-bit data is used for identification data) or 65533 computers (when 16-bit data is used for identification data) And can communicate wirelessly. The wireless LAN communication unit uses UDP (User Datagram Protocol) to send data described below to the receiving computer 300.

The communication device 200 includes hardware as shown in FIG.
The hardware includes a CPU 211, ROM 212, RAM 213, and interface 214, which are connected to each other by a bus 216.
The functions of the CPU 211, ROM 212, RAM 213, interface 214, and bus 216 are basically the same as those of the CPU 111, ROM 112, RAM 113, and interface 114 included in the transmitting computer 100.
However, the RAM 213 stores a computer program and data used for performing processing to be described later executed by the communication device 200. This computer program is not necessarily limited to this, but is preinstalled in the communication apparatus 200. The communication device 200 includes an analog input terminal as an input terminal.
The analog input terminal of this embodiment is connected to the analog output terminal of the transmitting computer 100 by an analog cable 100A. The analog input terminal receives an analog signal for the display image generated by the display image data generation unit 123 of the transmission-side computer 100 and output from the analog output terminal via the analog cable 100A. ing.
The interface 214 exchanges data between the CPU 211, RAM 213, and the like connected via the bus 216 and the outside. The interface 214 is connected to the above-described input device 202 and an analog input terminal (not shown). The operation content from the input device 202 and the data from the analog input terminal are input from the interface 214. Also, compressed data to be sent to each receiving computer 300 is sent from the interface 214 to the wireless LAN communication unit as will be described later.

When the CPU 211 executes the computer program, a functional block as shown in FIG. 5 is generated in the communication device 200. The following functional blocks may be generated by the functions of the above-described computer program alone, but are generated by the cooperation of the above-described computer program and the OS and other computer programs installed in the communication device 200. Also good.
In the communication device 200, an operation signal analysis unit 221, a control unit 222, an image data generation unit 223, a compression unit 224, and a wireless LAN control unit 225 are generated.

The operation signal analysis unit 221 analyzes the content of the operation signal input from the input device 202. In this embodiment, a numerical value that is information for designating a designation signal described later is input from the input device 202. When an operation signal related to the numerical value is input from the input device 202, the operation signal analysis unit 221 analyzes the numerical value specified by the operation signal. The operation content analyzed by the operation signal analysis unit 221, that is, a numerical value is sent to the control unit 222. Note that the information regarding the numerical value may be input not from the input device 202 but from the input device 102 of the transmission-side computer 100.
Based on the numerical value, the control unit 222 determines a numerical value for designating software in the receiving computer 300 that processes the compressed data sent from the communication device 200 to each receiving computer 300 as described below. This numerical value is a port number or a part thereof in this embodiment. The port number designated by the control unit 222 may be a numerical value itself input from the input device 202, or may be a numerical value obtained by performing some operation on the numerical value. The port number determined by the control unit 222 is sent to the wireless LAN control unit 225.
The image data generation unit 223 receives an analog signal for a display image input from an analog input terminal. The image data generation unit 223 generates image data from the input analog signal. As described above, the analog signal for the display image is a moving image signal, and as shown in FIG. 6, the signals for the frames are continuous. One convex in the signal shown in FIG. 6 is a signal for one frame, that is, one screen of a display image. The image data generation unit 223 extracts a signal for every other screen from the analog signal to perform a work called frame dropping. For example, if the original analog signal is 30 fps, as shown by the arrow in FIG. 6, if one screen signal for every three is extracted, the moving image created by the image data obtained thereby becomes 10 fps. . Such frame drop processing is performed in consideration of the limitation of the communication speed by the wireless LAN. The image data generated by the image data generation unit 223 is sent to the compression unit 224 every time it is created. It is not always necessary to extract frames every certain number of frames when performing the frame dropping process.
Each time the image data is received, the compression unit 224 compresses the received image data. The image data may be compressed in any format, for example, in the MPEG format, but in this embodiment, compression in the JPEG format is performed. Data obtained by compressing image data is compressed data. Each time the compression unit 224 generates compressed data, it sends it to the wireless LAN control unit 225.
The wireless LAN control unit 225 receives the port number from the control unit 222 and the compressed data from the compression unit 224 as described above. The wireless LAN control unit 225 sends it to the wireless LAN communication unit, and causes the wireless LAN communication unit to send it to the receiving computer 300. In order to make this possible, the wireless LAN control unit 225 divides the data to be transmitted, such as compressed data and position data, into packets by an existing method. In addition, a header is added to the leading end of the packet, and the header includes the IP address, the capacity of the data including the compressed data and the position data transmitted from these, and the reception of the software installed in each receiving computer 300. The port number or the like for specifying software for processing the compressed data is written. These headers and a large number of packets are sent to the wireless LAN communication unit, and the wireless LAN communication unit is not limited to this. In this embodiment, it is sent to each receiving computer 300 using UDP / IP. Become. Note that such communication may be performed using another protocol such as TCP / IP instead of UDP / IP.

Next, the receiving computer 300 will be described.
The receiving computer 300 is a portable computer. The receiving computer 300 is, for example, a notebook computer, or a smartphone or a tablet. For example, the smartphone is an iPhone manufactured and sold by Apple Japan LLC, and the tablet is an ipad manufactured and sold by the company.
The receiving computer 300 includes a display 301. The receiving computer 300 also includes an input device 302. In addition to the physical keys as shown in FIG. 1, the input device 302 can be configured by a touch panel integrated with the display 301 as is well known.
In addition, the receiving-side computer 300 has a wireless LAN function. The wireless LAN function is realized by a wireless LAN communication unit (not shown). The wireless LAN is Wi-Fi in this embodiment, although not limited to this. The wireless LAN communication unit of the receiving computer 300 can communicate with the wireless LAN communication unit of the communication device 200.

The receiving computer 300 has hardware as shown in FIG.
The hardware includes a CPU 311, a ROM 312, a RAM 313, an interface 314, and a hard disk drive 315, which are connected to each other by a bus 316.
The functions of the CPU 311, ROM 312, RAM 313, interface 314, hard disk drive 315, and bus 316 are basically the same as the functions of the CPU 111, ROM 112, RAM 113, interface 114, hard disk drive 115, and bus 116 in the sending computer 100. .
However, the ROM 312 or the hard disk drive 315 stores computer programs necessary for realizing the following processing executed by the receiving computer 300. The ROM 312 or the hard disk drive 315 stores software necessary for executing processing of enlargement (for example, pinch) and recording of a display image (for example, print screen) described later.
The interface 314 of the receiving computer 300 is connected to the above-described wireless LAN communication unit mounted on the receiving computer 300 so that the wireless LAN communication unit receives the compressed data received from the communication device 200. It has become. The interface 314 is connected to the input device 302 so as to receive operation contents from the input device 302. This operation content includes at least designation information described later. The interface 314 is also connected to the display 301 so as to send data for displaying a predetermined display image on the display 301.

When the CPU 311 executes the computer program, a functional block as shown in FIG. 8 is generated in the receiving computer 300. The following functional blocks may be generated by the functions of the above-described computer program alone, but are generated by the cooperation of the above-described computer program and the OS and other computer programs installed in the receiving-side computer 300. May be.
An operation signal analysis unit 321, a control unit 322, a designation information analysis unit 323, an identity determination unit 324, an expansion unit 325, and a display image data generation unit 326 are generated inside the reception computer 300.

The operation signal analysis unit 321 analyzes the content of the operation signal input from the input device 302. The operation signal related to this embodiment includes designation information. The designation information designates at least a part of a numerical value for determining which software installed in the receiving computer 300 processes the compressed data received by the receiving computer 300 as will be described later. It is. This numerical value is sent to the control unit 322.
When the control unit 322 receives this numerical value, the control unit 322 determines a numerical value for determining which software installed in the receiving computer 300 should process the compressed data received by the receiving computer 300. Have This numerical value may be the numerical value itself indicated by the operation content input from the operation signal analysis unit 321, or may be a numerical value obtained as a result of performing some operation on the numerical value. In this embodiment, as a result of such calculation, a numerical value for determining which software installed in the receiving computer 300 is to process the compressed data received by the receiving computer 300 is determined. It has become so. This numerical value is sent to the designation information analysis unit 323.
The designation information analysis unit 323 receives the header and the compressed data packet transmitted from the wireless LAN communication unit of the communication apparatus 200 and received by the wireless LAN communication unit of the receiving computer 300 via the interface 314 each time. It is like that. The designation information analysis unit 323 reads the information written in the header of the compressed data packet when receiving them. In addition, the designated information analysis unit 323 receives the port number in the read information and the compressed data received by the receiving computer 300 sent from the control unit 322, which one is installed in the receiving computer 300. A numerical value for deciding whether to process by software is compared. When the numerical values match, the designation information analysis unit 323 sends the compressed data packet received by the receiving computer 300 to the identity determination unit 324. The designation information analysis unit 323 also sends to the identity determination unit 324 capacity information for specifying the capacity of the compressed data read from the header, together with the compressed data packet. Prior to sending the packets of compressed data to the identity determination unit 324, the designation information analysis unit 323 may combine the packets into the original compressed data. On the other hand, the designation information analysis unit 323 is installed in the receiving computer 300 with the port number in the header of the compressed data packet and the compressed data received from the control unit 322 and received by the receiving computer 300. If the numerical value for determining which software is to be processed does not match, the packet of the compressed data received by the receiving computer 300 is not sent to the identity determination unit 324. Yes. Note that the port number in the header of the compressed data packet in the specified information analysis unit 323 and the compressed data received by the receiving computer 300 sent from the control unit 322 are installed in the receiving computer 300. The process of comparing with the numerical value for determining which software is to be processed is performed only when the first compressed data is received or every predetermined time interval such as every 10 minutes. It doesn't matter. In this embodiment, it is assumed that the processing is performed only when the first compressed data is received.
The identity determination unit 324 determines whether or not there is a change from the original image data before being compressed into image data. Although the details of the determination method will be described later, if the identity determination unit 324 determines that there is no change from the original image data before being compressed into the image data, the identity determination unit 324 sends the compressed data to the decompression unit 325, and If it is determined that there is a change from the original image data before being compressed into data, the compressed data is not sent to the decompression unit 325.
When the decompression unit 325 receives compressed data from the identity determination unit 324, the decompression unit 325 decompresses the compressed data and returns it to image data. The decompression unit 325 sends image data obtained by decompressing the compressed data to the display image data generation unit 326.
The display image data generation unit 326 displays an image based on the image data (data for one frame) on the display 301 based on the image data received from the decompression unit 325. Every time image data is received, the display image data generation unit 326 causes the display 301 to display an image (display image) based on the image data. Since the frame dropping process has already been performed as described above, the display image displayed on the display 301 of the receiving computer 300 is basically the same as the display image displayed on the display 101 of the transmitting computer 100 (approximately). Although it is the same in real time, the number of frames is somewhat lower than the display image displayed on the display 101 of the transmitting computer 100. In addition, since an image based on the image data determined to have changed from the original image data before being compressed by the identity determination unit 324 is not displayed on the display 301, the frame of the display image displayed on the display 301 is displayed. The rate may be partially lower than the frame rate when the sending computer 100 drops frames.

Next, the usage method and operation of this communication system will be described.

In order to use this communication system, the presenter first connects the analog output terminal of the transmitting computer 100 and the analog input terminal of the communication device 200 with the analog cable 100A.
The presenter then operates the input device 202 of the communication device 200 to process the compressed data sent to each receiving-side computer 300, regardless of whether the above work is performed or not. The software in the receiving computer 300 that inputs the numerical value designating the software in the receiving computer 300 and processes the compressed data sent to the receiving computer 300 to the receiving computer 300 owned by the audience. Enter a part of the numerical value that specifies. The audience inputs the numerical value by operating the input device 302.
Generally, the numerical value of the port number is determined by adding a predetermined numerical value to the default numerical value of 8255. In this embodiment, the presenter operates the input device 202 to input 8255 + predetermined numerical value (for example, 1000) + a numerical value (for example, 10) that is input to an audience to be permitted to receive and decompress compressed data by the receiving computer 300. ), A numerical value obtained by adding a predetermined numerical value (for example, 1000) and a numerical value (for example, 10) that is input to the audience to be permitted to receive and decompress the compressed data by the receiving computer 300 is input. Receiving this, the control unit 222 determines that the port number is 9265.
On the other hand, in this embodiment, 8255 + a predetermined numerical value (for example, 1000) is input in advance in the computer program installed in the receiving computer 300 of the audience, and the audience operates the input device 302. The input numerical value is further added by the control unit 322. And 8255 + predetermined numerical value (for example, 1000) is set so as not to be seen from the audience. The presenter informs the correct number (which is 10 as described above) to be entered by the audience in some way only to the audience who may participate in the presentation and receive and decompress the compressed data. . Only the audience who knows the correct notification will be able to obtain a numerical value of 9265, which is a numerical value that specifies the software at the receiving computer 300 that will process the compressed data sent to the receiving computer 300. As described above, software in the receiving computer 300 that processes the compressed data sent to the receiving computer 300 by a predetermined numerical value (for example, 1000) invisible to the user in addition to the default numerical value 8255 of the port number. Since a malicious third party processes the compressed data sent to the receiving computer 300, it is known that the numerical value specifying the software in the receiving computer 300 is used. It's getting harder.
In communication apparatus 200, the numerical value for the determined port number is sent from control unit 222 to wireless LAN control unit 225.
In the receiving computer 300, the numerical value specifying the software in the receiving computer 300 that processes the compressed data sent to the receiving computer 300 is sent to the designation information analysis unit 323.

In this state, the presenter starts the presentation.
At that time, the presenter operates the input device 102, and the control unit 122 executes known presentation software according to the operation content from the input device 102. A signal regarding the execution result is sent to the display image data generation unit 123.
The display image data generation unit 123 generates data about an image to be displayed on the display 101 of the transmission side computer 100. This data is written to the frame buffer each time and sent to the display 101 each time. In this case, the number of frames is, for example, 30 fps. Based on this data, an image used for presentation is displayed on the display 101. This image is a display image.
On the other hand, the display image data generation unit 123 generates an analog signal for the display image currently displayed on the display 101 and sends it to the analog output terminal. An analog signal that is a moving image signal and a signal in which frames are continuous is sent from the analog output terminal to the analog input terminal of the communication apparatus 200 via the analog cable 100A.

The following processing in the communication device 200 is basically performed automatically.
An analog signal for a display image input from the analog input terminal is sent to the image data generation unit 223. The image data generation unit 223 performs a frame dropping operation from an analog signal in which signals for frames are continuous, for example, a signal of 10 fps. If the speed is 10 fps, ten image signals corresponding to one screen are generated per second. The image data generated by the image data generation unit 223 is sent to the compression unit 224 every time it is created. This frame rate ranges from several times to several tens of times per second, although it depends on the speed of wireless data transmission from the communication device 200 to the receiving computer 300.
Whenever the image data is received, the compression unit 224 compresses the received image data to obtain compressed data. In this embodiment, the image data is compressed in the JPEG format. Of course, the size of the compressed data is smaller than the size of the image data. Each time the compression unit 224 generates compressed data, it sends it to the wireless LAN control unit 225.
The wireless LAN control unit 225 divides the compressed data into packets and attaches a header to the leading end of the packets. The header is written with its own IP address, capacity information which is information indicating the capacity of compressed data transmitted from these, the above-mentioned port number, and the like. Packets of these headers and a large number of compressed data are sent to the wireless LAN communication unit, and are sent from the wireless LAN communication unit to each receiving computer 300.

A series of packets of compressed data starting from the header is received by the wireless LAN communication unit of the receiving computer 300. The received data is sent to the designation information analysis unit 323.
When the designation information analysis unit 323 receives the data, the designation information analysis unit 323 reads the above-described information written in the header. The designation information analyzing unit 323 is installed in the receiving computer 300 with the port number written in the header of the compressed data packet and the compressed data received from the control unit 322 and received by the receiving computer 300. The numerical value for determining which software is to be processed is compared. If the numerical values match, the designation information analysis unit 323 sends the compressed data packet received by the receiving computer 300 to the identity determination unit 324 together with the capacity information.
Which software installed in the receiving computer 300 is used to process the compressed data received by the receiving computer 300 from the control unit 322 in the designation information analysis unit 323 because a correct numerical value cannot be input from the input device 302. In the receiving computer 300 of the audience who has not obtained a correct numerical value for determining, the subsequent processing is not performed.

The identity determination unit 324 determines whether the image data obtained when the compressed data is expanded has changed from the original image data before compression.
When it is determined that the image data obtained when the compressed data is expanded has not changed from the original image data before compression, the identity determination unit 324 sends the compressed data to the expansion unit 325, If it is determined that it has changed, the compressed data is not sent to the decompression unit 325.

For example, if the size of the compressed data received from the designation information analysis unit 323 is the same as the size specified by the capacity information, the identity determination unit 324 obtains image data obtained when the compressed data is expanded. If the size of the compressed data received from the designated information analysis unit 323 is not the same as the size specified by the capacity information unless the original image data before compression is changed, the compressed data is expanded It may be determined that the obtained image data has changed from the original image data before compression.
In this embodiment, the identity determination unit 324 determines whether or not the image data obtained when decompressing the compressed data has changed from the original image data before compression as follows. It is like that.
First, as a premise, in this embodiment, data sent from the communication device 200 to the receiving computer 300 is as shown in FIG. As shown in FIG. 14, the data sent from the communication device 200 to the receiving computer 300 is divided into packets. In this data, the left side at the top is the head and the right side at the bottom is the end. In FIG. 14, each of the data at each stage marked with P is data for one packet. These data are the same size except for the last packet P. For example, except for the last packet P, the size of each packet P is 1460 bytes. The start of the first packet P indicates that the data before it is the header D1, and the data after it is the data to be transmitted (compressed data D3 in this embodiment). There is a block D2. The last packet P has a stop block D4 indicating that the previous data is the compressed data D3. Further, the header D4 includes data D11 indicating the compression format of the compressed data. In this embodiment, the data D11 is a character string “JPEG” indicating that the compressed data is compressed in the JPEG format.
The identity determination unit 324 in this embodiment uses the following criteria A to C to determine whether the image data obtained when the compressed data is expanded from the original image data before compression: Determine whether or not. When the following content is used as a reference, the identity determination unit 324 determines that the size of the image data has changed when the answer to the reference is Yes for any of the following criteria A to C If the answer is No, it is determined that there is no change in the size of the image data. The identity determination unit 324 determines whether or not the image data obtained when decompressing the compressed data has changed from the original image data before compression based on at least one of the following criteria: In this embodiment, all of the following criteria are used to determine whether the image data obtained when decompressing the compressed data has changed from the original image data before compression. It is used as a reference for judging. That is, if the answer to all of the following three criteria is No, the identity determination unit 324 determines that there is no change in the size of the image data, but the answer to at least one of the following three criteria: Is Yes, it is determined that the image data obtained when the compressed data is expanded has changed from the original image data before compression.
A) Is the size of the compressed data D3 between the start block D2 and the stop block D4 different from the size of the data described in the header D1?
B) The size of data included in a packet P is different from the size of data described in the header D1, and the packet P does not include the stop block D4.
C) After the start block D2, information that should originally be included in the header D1 (data D11 indicating the compression format of the compressed data D3 in this embodiment) is included?
Incidentally, the above-mentioned criterion A corresponds to the above-mentioned criterion as to whether or not the size of the received compressed data D3 is the same as the size specified by the capacity information.
The criterion B is to determine whether or not there is any change in the size of the compressed data D3 by monitoring whether or not each packet P is missing or missing data. Whether or not the packet P includes the stop block D4 is used as a criterion for determination. The last packet P including the stop block D4 has a smaller data amount than other packets P. This is because, since it is a normal state, it should be determined that no data is lost or lost even if the data amount of the packet P including the stop block D4 is smaller than the data amount of the other packets P. . In this case, the capacity information includes information for specifying the data capacity of each packet P except for the last packet P, and based on this, the packet P except for the last packet P has no missing or missing data. A determination of whether or not will be made.
The criterion of C is that if the data D11 indicating the compression format of the compressed data D3 is included after the start block D2, the data D11 that should originally be at the head of the header D1 should not exist. Based on the fact that it should be determined that there has been a data change in the compressed data D3.
In any case, as described above, when the identity determination unit 324 determines that the image data obtained when decompressing the compressed data has not changed from the original image data before compression, If the compressed data is sent to the decompression unit 325 and it is determined that the compressed data has changed, the compressed data is not sent to the decompression unit 325.

When receiving the compressed data from the designation information analyzing unit 323, the decompressing unit 325 decompresses the compressed data and returns it to image data. The decompression unit 325 sends image data obtained by decompressing the compressed data to the display image data generation unit 326.
Based on the image data received from the decompression unit 325, the display image data generation unit 326 causes the display 301 to display an image based on the image data every time the image data is received. The display image displayed on the display 301 of the receiving computer 300 is basically the same as the display image displayed on the display 101 of the transmitting computer 100 (same in real time), but the number of frames is This is somewhat lower than the display image displayed on the display 101 of the transmitting computer 100. The image data used for displaying the display image is only the image data determined to be unchanged from the original image data before compression, and the image data determined to be changed from the original image data before compression Is not used to display a display image.
In other words, the display image data generation unit 326 normally displays an image based on the image data obtained by decompressing the compressed data every time the receiving computer 300 receives the compressed data. The image based on the compressed image data determined that the image data obtained when the compressed data is decompressed by the sex determining unit 324 is not changed from the original image data before compression is displayed on the display 301. Do not show. In that case, the previous image is continuously displayed on the display 301 until the next image is displayed on the display 301.

The audience can listen to the presentation provided by the presenter while viewing the display image displayed on the display 301. Thereby, it is not necessary to distribute the distribution material for presentation on paper.
If the display image is difficult to see because, for example, small characters are displayed on the display image, the audience can enlarge the display image using a function such as pinch if the receiving computer 300 is equipped. By doing so, small characters can be clearly recognized, and a portion of the displayed image that the user particularly wants to focus on can be enlarged and viewed.
In addition, the audience sees the display image displayed on the display 301, and if the receiving computer 300 has the display image to be stored at the timing when the display image is displayed on the display 301, the audience displays the display image such as a print screen. With the saving function, display image data can be saved in, for example, the hard disk drive 315 of the receiving computer 300. As a result, the need to distribute handouts on paper is increasingly reduced.
The mobile terminals of this time, which are scheduled to be used as the receiving computer 300, are usually provided with functions for enlarging the display image and saving the display image. A computer program for causing the computer according to the invention to function as the receiving computer 300 may be provided.

Hereinafter, modifications of the first embodiment will be described. Each modification described below is actually executed by the identity determination unit “determination as to whether the image data obtained when the compressed data is expanded has changed from the original image data before compression” Is a variation of the method.

<Modification 1>
In the identity determination unit 324 of the first embodiment, the size of the compressed data is written in the header attached to the head of the compressed data when the compressed data is transmitted from the transmitting computer 100 to the receiving computer 300. It is determined whether or not the image data obtained when decompressing the compressed data has changed from the original image data before compression depending on whether or not it matches the size specified by the capacity information. It was decided.
In this method, the size of the compressed data specified by the capacity information is used as a reference for determining whether the size of the compressed data has changed. For example, if the reference is determined in advance between the communication device 200 and the receiving computer 300 and the identity determining unit 324 of the receiving computer 300 has the reference in advance, the receiving computer The 300 identity determination unit 324 can determine whether the size of the compressed data has changed without depending on the capacity information, depending on whether the compressed data matches the size indicated by the reference.

For example, the identity determination unit 324 determines whether or not the image data obtained when decompressing the compressed data has changed from the original image data before compression as follows, for example. It may be. Also in this case, it is assumed that data sent from the communication apparatus 200 to the receiving computer 300 has a data structure as shown in FIG.
The identity determination unit 324 according to Modification 1 uses the following criteria D to F to determine whether the image data obtained when decompressing the compressed data has changed from the original image data before compression: Determine whether. When the following content is used as a reference, the identity determination unit 324 determines that the size of the image data has changed when the answer to the reference is Yes for any of the following criteria D to F. If the answer is No, it is determined that there is no change in the size of the image data. The identity determination unit 324 determines whether or not the image data obtained when decompressing the compressed data has changed from the original image data before compression based on at least one of the following criteria: It is also possible to use all of the following criteria to determine whether the image data obtained when decompressing the compressed data has changed from the original image data before compression. It can also be used as a reference.
D) Is the size of the compressed data D3 between the start block D2 and the stop block D4 different from the size of data determined in advance between the communication device 200 and the receiving computer 300?
E) The size of data included in a packet P is different from the size of data determined in advance between the communication apparatus 200 and the receiving computer 300, and the packet P does not include the stop block D4. ?
F) Is information (data D11 indicating the compression format of the compressed data D3 in this embodiment) that should be included in the header D1 after the start block D2 originally included?

<Modification 2>
In the first embodiment, the wireless LAN control unit 225 of the communication device 200 writes capacity information together with other information in a header attached to the head of the compressed data in order to transmit the compressed data.
The wireless LAN control unit 225 of the communication apparatus 200 according to the second modification writes the above-described other information and determination data specifying information instead of the capacity information in the header attached to the head of the compressed data in order to transmit the compressed data. It is. The determination data specifying information is information for specifying where and what determination data is included in the compressed data. The determination data is data that can be used to determine whether or not the image data obtained when decompressing the compressed data has changed from the original image data before compression, depending on whether or not it is at the position where it should be. It is data that is essentially unrelated to image data or compressed data. In other words, the content of the data is irrelevant.
In addition, the identity determination unit 324 of the reception-side computer 300 according to the second modification determines whether or not the image data obtained when the compressed data is expanded has changed from the original image data before compression. However, the specific method is as follows.
The identity determination unit 324 receives the determination data specifying information from the designation information analysis unit 323 that has read it from the header. The determination data specifying information is information for specifying where and what determination data is included in the compressed data. The identity determination unit 324 has the data specified by the determination data specification information at the position specified by the determination data specification information received from the compressed data designation information analysis unit 323 with respect to the compressed data. It is determined whether or not to do so. As a result, if there is determination data of the planned content (content specified by the determination data specifying information) at the planned position (position specified by the determination data specifying information) of the compressed data, The identity determination unit 324 determines that the compressed data has not changed, that is, the image data obtained when the compressed data is expanded has not changed from the original image data before compression. On the other hand, if there is no data for determination of the planned content at the planned position of the compressed data, the identity determination unit 324 has changed the compressed data, that is, when the compressed data is expanded. It is determined that the obtained image data has changed from the original image data before compression.
For example, in the determination data specifying information, “data“ 00000000 ”is written in the compressed data for each XX byte from the top. ". The identity determination unit 324 determines whether or not such data exists in the compressed data, so that the image data obtained when the compressed data is expanded is obtained from the original image data before compression. It can be determined whether or not it has changed. As shown in this example, the determination data may be plural. When there are a plurality of determination data, the determination data need not all be the same.

<Modification 3>
The same relationship as that of Modification 1 with respect to the first embodiment is also established between Modification 2 and Modification 3.
In the identity determination unit 324 of the second modification, the compressed data is changed based on the information that is specified by the determination data specifying information and where the content of the determination data is included in the compressed data. It was decided to determine whether or not there was. The determination data specifying information indicating the reference is written in the header and transmitted from the communication device 200 to the receiving computer 300.
On the other hand, in Modification 3, information serving as a reference for determining whether or not there is a change in the compressed data, such as where the compressed data includes what kind of determination data is included, is stored in advance. Arrangements are made between the communication device 200 and the receiving computer 300. The information is given to the identity determination unit 324 in advance. By doing so, even if there is no determination data specifying information, the identity determination unit 324 of the receiving computer 300 has the determination data of the planned contents at the planned position of the compressed data. It is possible to determine whether or not the compressed data has changed, and further whether or not the image data obtained by decompressing the compressed data has changed from the original image data before compression. .

<Modification 4>
In the first embodiment, the identity determination unit 324 of the reception-side computer 300 determines whether or not the size of the compressed data has changed, and the image data obtained when the compressed data is decompressed is the original data before compression. It is determined whether or not the image data has changed. On the other hand, the identity determination unit 324 of the reception-side computer 300 according to the modified example 4 changes the image data from the original image data before compression depending on whether or not the size of the decompressed image data has changed. It is determined whether or not the error occurred.
Also in the communication apparatus 200 according to the fourth modification, the wireless LAN control unit 225 writes capacity information in a header attached to the head of the compressed data in order to transmit the compressed data. However, this capacity information is different from the capacity information that specifies the size of the compressed data in the case of the first embodiment, and before the compression that is the source of the compressed data to which the header is attached. This is for specifying the size of the image data. In the communication device 200 according to the fourth modification, for example, the size of the image data before compression is transmitted from the image data generation unit 223 or the compression unit 224 to the wireless LAN control unit 225 so that the writing can be performed.
On the other hand, the functional blocks formed in the reception-side computer 300 of the fourth modification are as shown in FIG. Compared with the functional block shown in FIG. 8, this functional block is obtained by replacing the identity determining unit 324 and the extending unit 325.
In the first embodiment, the designation information analysis unit 323 receives the port number written in the header of the compressed data packet and the compressed data received by the receiving computer 300 sent from the control unit 322. A numerical value for determining which software installed in the computer 300 is used for processing is compared, and if the numerical values match, the compressed data is sent to the identity determination unit 324. . However, in the designation information analysis unit 323 of Modification 4, the compressed data destination is not the identity determination unit 324 but the expansion unit 325. The decompressing unit 325 decompresses the compressed data and returns it to the image data as in the first embodiment. The decompression unit 325 according to the modification 4 sends the image data to the identity determination unit 324.
The identity determination unit 324 receives capacity information in advance from the designation information analysis unit 323 that has read it from the header. The identity determination unit 324 determines whether or not the image data has changed from the original image data before compression, based on the size of the image data specified by the capacity information. If the identity determination unit 324 determines that the image data has not changed from the original image data before compression, the identity determination unit 324 sends the image data to the display image data generation unit 326, and the image data is converted to the original image data before compression. If it is determined that a change has occurred, the image data is not sent to the display image data generation unit 326.

<Modification 5>
In the fifth modification, the same modification as the modification to the first modification with respect to the first embodiment is performed on the fourth modification.
In the fifth modification example, the communication device 200 and the receiving computer 300 have a predetermined agreement regarding the size of the image data, and the identity determination unit 324 of the receiving computer 300 has the reference in advance. ing. Thus, even if the capacity information is not written in the header and sent from the communication apparatus 200 to the receiving computer 300, the identity determination unit 324 of the receiving computer 300 matches the image data with the size indicated by the reference. Whether or not there is a change in the size of the compressed data can be determined depending on whether or not the compressed data is received.

<Modification 6>
The capacity information of the first embodiment is replaced with determination data specifying information, and the identity determination unit 324 of the receiving computer 300 is not compressed whether the size of the compressed data is the same as the size specified by the capacity information. In the second modification, it is determined whether or not there is a change in the compressed data depending on whether or not determination data having a predetermined content exists at a predetermined position of the data.
In the sixth modification, the same modification as that obtained when the first embodiment is modified into the second modification is added to the fifth modification. That is, the identity determination unit 324 according to the modification 6 determines whether the image data has the same size as that specified by the capacity information, but does not determine whether the image data has a predetermined position. It is determined whether or not there is a change in the image data depending on whether or not the data exists.

<Modification 7>
Modified example 7 is the same as the modified example added to the modified example 6 when the first embodiment is transformed into the modified example 1 or when the modified example 4 is transformed into the modified example 5. It is.
In the modified example 7, it is determined in advance between the communication apparatus 200 and the receiving computer 300 where and what kind of determination data is included in the image data, and the determined reference is used as the receiving computer. 300 identity determination units 324 have in advance. As a result, even if the determination data specifying information is not written in the header and sent from the communication apparatus 200 to the receiving computer 300, the identity determining unit 324 of the receiving computer 300 can determine whether the above-mentioned standard is included. Whether or not the size of the image data has changed can be determined based on whether or not the determination data as indicated by the reference exists at the indicated position.

<< Second Embodiment >>
A communication system according to the second embodiment is shown in FIG.
The communication system includes a video camera 400, a recording device 500, and a receiving computer 300. The receiving computer 300 is, for example, a portable terminal, like the receiving computer 300 of the first embodiment.
The video camera 400 is a transmitting device referred to in the present invention, and the receiving computer 300 is a receiving device referred to in the present invention.
In this embodiment, the receiving computer 300 is used as a monitor of the video camera 400.

The video camera 400 is configured as shown in FIG.
The video camera has a housing 401 that can be held by hand. A hole 401 </ b> A is formed at the tip of the housing 401.
An imaging element 402 that is, for example, a CCD or a CMOS is provided inside the housing 401. The image sensor 402 captures image light that enters the housing 401 through the hole 401A. The imaging element 402 performs imaging and generates a moving image signal.
Further, a magnifying lens 403 is provided between the image sensor 402 and the hole 401A. The magnifying lens 403 enlarges image light.
Inside the housing 401, a light source 404, for example, an LED is disposed. The light source 404 supplies illumination light necessary for imaging with the image sensor 402. The illumination light is supplied through the hole 401A.
When imaging is performed with the video camera 400, the focal point is adapted to the inner portion of the hole 401A. When imaging is performed by bringing the periphery of the hole 401 </ b> A into contact with an object to be imaged, an enlarged image of the object positioned inside the hole 401 </ b> A is captured by the image sensor 402 without shaking.
The video camera 400 also includes a control circuit 405. The control circuit 405 is a circuit that controls the image sensor 402. The control circuit 405 is connected to the image sensor 402 via a connection line 406, and controls the image sensor 402 via the connection line 406. The control circuit 405 is configured to receive a moving image signal generated by the image sensor 402 from the image sensor 402. The control circuit 405 is connected to the recording apparatus 500 via an output line 408 inside the tube 407. The recording device 500 records a moving image signal sent from the control circuit 405 via the output line 408, and includes, for example, a hard disk drive.

The control circuit 405 has the same hardware configuration as that included in the communication device 200 of the first embodiment, and includes a CPU, a ROM, a RAM, an interface, and a bus. The functions of the CPU, ROM, RAM, interface, and bus are all the same as those in the first embodiment. The control circuit 405 has a function of performing communication via a wireless LAN.
The interface of the control circuit 405 is connected to a connection line 406 so as to receive a moving image signal from the image sensor 402. The interface of the control circuit 405 is connected to the output line 408 so as to send a moving image signal to the recording apparatus 500.

When the CPU executes the computer program, a functional block as shown in FIG. 12 is generated inside the video camera. The following functional blocks may be generated by the functions of the above-described computer program alone, but are generated by the cooperation of the above-described computer program and the OS and other computer programs installed in the video camera 400. Also good.
The functional blocks generated in the video camera 400 are obtained by omitting some of the functional blocks generated in the communication device 200. Specifically, the image data generating unit 223, the compression unit 224, and This is a wireless LAN control unit 225.

The functions of the image data generation unit 223, the compression unit 224, and the wireless LAN control unit 225 are the same as those generated in the communication device 200 of the first embodiment.
The image data generation unit 223 receives a signal regarding the moving image captured by the image sensor 402 input from the image sensor 402 (this signal is not limited to this, but is an analog signal as in the first embodiment). The image data is generated based on this. The image data generation method is the same as that in the image data generation unit 223 of the first embodiment.
The compression unit 224 receives the image data from the image data generation unit 223, and compresses the received image data into compressed data each time the image data is received. The image data can be compressed by the same method as that performed by the compression unit of the first embodiment. Each time the compression unit 224 generates compressed data, it sends it to the wireless LAN control unit 225.
The wireless LAN control unit 225 divides the received compressed data into packets, attaches a header to the packet, and sends the data to the wireless LAN communication unit. The processing is basically the same as that performed by the wireless LAN control unit 225 of the first embodiment, except that the wireless LAN control unit 225 of the second embodiment writes information regarding the port number in the header. I won't do that.
Packets for the header and the compressed data are sent from the wireless LAN communication unit to each receiving computer 300.

The receiving-side computer 300 of the second embodiment has the same hardware as shown in FIG. 7 as in the first embodiment.

When the CPU executes the computer program, functional blocks as shown in FIG. 13 are generated in the receiving computer 300. The following functional blocks may be generated by the functions of the above-described computer program alone, but are generated by the cooperation of the above-described computer program and the OS and other computer programs installed in the receiving-side computer 300. May be.
Inside the reception-side computer 300, an identity determination unit 324, an expansion unit 325, and a display image data generation unit 326 are generated.

The functions of the identity determination unit 324, the decompression unit 325, and the display image data generation unit 326 in the second embodiment are the same as those provided in the first embodiment. The only difference is that the compressed data is sent to the identity determination unit 324 in the case of the first embodiment, but it is connected to the interface in the case of the second embodiment. The wireless LAN communication unit.

The usage method and operation of the communication system of the second embodiment basically conform to the usage method and operation of the first embodiment. The usage method and operation of this communication system of the second embodiment are the same as the usage method and operation of the first embodiment, except for the part related to the technique of showing the display image only to the audience who wants to show using the port number. be equivalent to.

To use this communication system, first, the video camera 400 takes an image.
The image sensor 402 of the video camera 400 generates a moving image signal. The moving image signal is sent to the recording apparatus 500 via the connection line 406, the control circuit 405, and the output line 408, and is recorded by the recording apparatus 500.
The moving image signal is also sent to the image data generation unit 223 in the video camera 400. The image data generation unit 223 performs a frame dropping operation from an analog signal in which signals for frames are continuous. The image data generated by the image data generation unit 223 is sent to the compression unit 224 every time it is created.
Whenever the image data is received, the compression unit 224 compresses the received image data to obtain compressed data. Each time the compression unit 224 generates compressed data, it sends it to the wireless LAN control unit 225.
The wireless LAN control unit 225 divides the compressed data into packets and attaches a header to the leading end of the packets. Packets of these headers and a large number of compressed data are sent to the wireless LAN communication unit, and are sent from the wireless LAN communication unit to each receiving computer 300.

A series of packets of compressed data starting from the header is received by the wireless LAN communication unit of the receiving computer 300.
A series of packets with compressed data starting from the header is sent to the identity determination unit 324. The identity determination unit 324 determines whether the image data obtained when the compressed data is expanded has changed from the original image data before compression. The method is the same as that in the first embodiment.
When it is determined that the image data obtained when the compressed data is expanded has not changed from the original image data before compression, the identity determination unit 324 sends the compressed data to the expansion unit 325, If it is determined that it has changed, the compressed data is not sent to the decompression unit 325.
When receiving the compressed data from the identity determining unit 324, the decompressing unit 325 decompresses the compressed data and returns it to image data. The decompression unit 325 sends image data obtained by decompressing the compressed data to the display image data generation unit 326.
Based on the image data received from the decompression unit 325, the display image data generation unit 326 causes the display 301 to display an image based on the image data every time the image data is received. This is substantially the same regardless of the difference in the number of frames from the moving image captured by the image sensor 402 of the video camera 400.

An operator of the video camera 400 can use the display 301 of the reception-side computer 300 as a monitor of the video camera 400. For example, the operator can shift the position of the video camera 400 while viewing the image displayed on the display 301 to capture the image. Can be adjusted.

All the modifications of the first embodiment can be applied to the communication system of the second embodiment.

Claims

Means for processing moving picture data, means for converting the image data, which is data for one screen appropriately extracted from the moving picture data to be processed, into compressed data, and the compressed data wirelessly Means for transmitting via a LAN,
A receiving device configured to be able to communicate with the transmitting device via a wireless LAN,
Display,
Accepting means for accepting the compressed data from the transmitting device as needed;
Decompression means for decompressing the compressed data received by the acceptance means;
Determination means for determining whether there is a change from the image data before the image data is compressed data;
An image based on the decompressed image data determined to be unchanged from the original image data by the determining means is displayed on the display, and the decompression determined to have changed from the original image data by the determining means Display control means for controlling not to display an image based on the image data that has been displayed on the display;
A receiving apparatus.
The determination means determines that there is no change from the original image data when the image data obtained by decompressing the compressed data is the same as the expected size, and obtained by decompressing the compressed data When the image data is different from the planned size, it is determined that there is a change from the original image data.
The receiving device according to claim 1.
When transmitting the compressed data, the transmission device describes in the header attached to the compressed data capacity information for specifying the size of the image data that is the source of the compressed data following the header. And
The determination means treats the size specified by the capacity information as a planned size of the image data.
The receiving device according to claim 2.
The determination means determines that the image data obtained by decompressing the compressed data is unchanged from the original image data when the compressed data has the same size as the planned size, and the compressed data is scheduled. If it is different from the size, the original image data is judged to have changed.
The receiving device according to claim 1.
The transmitting device is configured to describe capacity information for specifying the size of the compressed data following the header in a header attached to the compressed data when transmitting the compressed data,
The determination means treats the size specified by the capacity information as the planned size of the compressed data.
The receiving device according to claim 4.
The transmitting device includes determination data which is data irrelevant to the image data at a predetermined position of the image data.
The determination unit determines that there is no change from the original image data when the determination data having the predetermined content is present at a predetermined position of the image data obtained by decompressing the compressed data. Then, when the determination data having the planned content does not exist at the planned position of the image data obtained by decompressing the compressed data, it is determined that the original image data has changed. It has become,
The receiving device according to claim 1.
When transmitting the compressed data, the transmission device determines where and what kind of the determination data is included in the header of the compressed data including the image data that is the source of the compressed data following the header. It has come to describe the data identification information for judgment to identify,
The determination means is a reference for determining whether or not the determination data of the planned content exists at the predetermined position of the image data with respect to the position and the content specified by the determination data specifying information. It has come to be used as
The receiving device according to claim 6.
The transmitter is configured to include determination data, which is data irrelevant to the compressed data, in a predetermined position of the compressed data.
In the case where the determination data having the planned content is present at the planned position of the compressed data, the determination means changes the image data obtained by decompressing the compressed data from the original image data. If the data for determination does not exist at the scheduled position of the compressed data, the image data obtained by decompressing the compressed data is changed from the original image data. It has come to judge that there was,
The receiving device according to claim 1.
The transmission device, when transmitting the compressed data, determination data for specifying where and what determination data is included in the compressed data following the header in a header attached to the compressed data Specific information is provided,
The determination means is a criterion for determining whether or not the determination data of the planned content exists at the predetermined position of the compressed data with respect to the position and content specified by the determination data specifying information. It has come to be used as
The receiving device according to claim 8.
The transmission apparatus determines that there is a change from the original image data when information to be included in a header attached to the compressed data is included in the compressed data when transmitting the compressed data. It looks like
The receiving device according to claim 1.
The compressed data is sent from the transmitting device to the receiving device several times to several tens of times per second,
The accepting means is adapted to accept the compressed data from the transmitting device several times to several tens of times per second.
The receiving device according to claim 1.
The receiving device is a mobile terminal;
The receiving device according to claim 1.
Means for processing moving picture data, means for converting the image data, which is data for one screen appropriately extracted from the moving picture data to be processed, into compressed data, and the compressed data wirelessly Means for transmitting via a LAN,
And is a method executed by a receiving device having a display and capable of communicating with the transmitting device via a wireless LAN,
Executed by the receiving device;
An accepting process for accepting the compressed data from the transmitting device as needed;
A decompression process for decompressing the compressed data received in the acceptance process;
A determination process for determining whether there is a change from the image data before the image data is compressed data;
An image based on the decompressed image data determined to be unchanged from the original image data by the determination process is displayed on the display, and the decompression determined to have changed from the original image data by the determination process A display control process for controlling not to display an image based on the generated image data on the display;
Having a method.
Means for processing moving picture data, means for converting the image data, which is data for one screen appropriately extracted from the moving picture data to be processed, into compressed data, and the compressed data wirelessly Means for transmitting via a LAN,
In addition to being able to communicate with the transmission device via a wireless LAN, a computer having a display is used.
An accepting process for accepting the compressed data from the transmitting device as needed;
A decompression process for decompressing the compressed data received in the acceptance process;
A determination process for determining whether there is a change from the image data before the image data is compressed data;
An image based on the decompressed image data determined to be unchanged from the original image data by the determination process is displayed on the display, and the decompression determined to have changed from the original image data by the determination process A display control process for controlling not to display an image based on the generated image data on the display;
A computer program for running.
Means for processing moving picture data, means for converting the image data, which is data for one screen appropriately extracted from the moving picture data to be processed, into compressed data, and the compressed data wirelessly Means for transmitting via a LAN, and a transmission device comprising:
The transmitting device and a receiving device adapted to perform communication via a wireless LAN;
A communication system comprising:
The receiving device is:
Display,
Accepting means for accepting the compressed data from the transmitting device as needed;
Decompression means for decompressing the compressed data received by the acceptance means;
Determination means for determining whether there is a change from the image data before the image data is compressed data;
An image based on the decompressed image data determined to be unchanged from the original image data by the determining means is displayed on the display, and the decompression determined to have changed from the original image data by the determining means Display control means for controlling not to display an image based on the image data that has been displayed on the display;
Having
Communications system.