Video Processor, Method, Computer Program

Abstract

To provide a practical technique with which video data can be transmitted with a wireless LAN from a video output device having a function of processing video data to a terminal device having a display unit such as a mobile terminal.

A video output device 100 outputs video data via a line. A video processor 200 transmits compressed data obtained by JPEG-compressing data of the received video for each frame data to a terminal device 300 from a wireless LAN communication unit, from time to time. The terminal device 300 decompresses the compressed data to restore the frame data, and displays an image based on the video data on a display unit 301.

Claims

1. A video processor used in combination with a video output device for outputting a video data via a line, the video data being a data of a video comprising a large number of frame data, each frame data being data of each of continuous sequence of frames, the video processor comprising: receiving means for receiving a video data supplied from the video output device; compression means for executing a process of compressing data of each frame in the video data received by the receiving means into compressed data in a digital format; and output means for sequentially supplying the compressed data generated by the compression means to a transmission device having transmission means for transmitting the compressed data to a terminal device via communication with a wireless LAN.

2. The video processor according to claim 1, wherein the video processor is formed as a single unit having the transmission device by comprising the transmission means.

3. The video processor according to claim 1 or 2, wherein the compression means compresses each of the frame data of the video data received by the receiving means, as a single still image without any other processing.

4. The video processor according to claim 3, wherein the compression means performs JPEG compression.

5. The video processor according to claim 3, wherein the compression means is configured to compress a portion of each of the frame data in the order of being received from the receiving means.

6. The video processor according to claim 1 or 2, wherein the compression means is configured to compress the frame data of the video data received by the receiving means into the compressed data by using at least one of frame data preceding the frame data to be compressed and frame data following the frame data to be compressed.

7. The video processor according to claim 6, wherein the compression means performs MPEG compression.

8. The video processor according to claim 3 or 6, wherein the compression means is configured to complete the process of compressing a target frame data into the compressed data before the receiving means starts to receive a frame data incoming three frame data later than the target frame data.

9. The video processor according to claim 3 or 6, wherein the compression means is configured to complete the process of compressing the frame data into the compressed data before the expiration of 200 ms after the receiving means has received the frame data.

10. The video processor according to claim 9, wherein the compression means is configured to complete the process of compressing the frame data into the compressed data before the expiration of 100 ms after the receiving means has received the frame data.

11. The video processor according to claim 2, wherein the transmission means is configured to transmit the compressed data to the terminal device using UDP/IP protocol.

12. The video processor according to claim 2 or 11, wherein the transmission means has a setting of “255.255.255.255” as a destination IP address of the terminal device.

13. The video processor according to claim 2 or 11, wherein the transmission means is configured to arbitrarily set a port number for specifying software to process the compressed data received by the terminal device from software installed on the terminal device, and the video processor comprises port number input means for inputting information to set the port number; and only the terminal device for which the same port number set on the transmission means has been set is able to display a video based on the received compressed data.

14. The video processor according to claim 1 or 2, wherein the compression means is configured to generate the compressed data as having header information and be able to transform at least a portion of the header information according to a certain algorithm, and wherein only the terminal device being able to perform inversion of the transformation of the header information is able to display a video based on the received compressed data.

15. The video processor according to claim 1 or 2, comprising modification means for modifying the frame data in such a manner that at least one of a certain character, symbol, and glyph is overlapped with an image represented by the frame data.

16. The video processor according to claim 2, comprising instruction addition means, the instruction addition means adding modification instruction data to the compressed data transmitted from the transmission means to the terminal device and allowing the transmission means to transmit the compressed data, the modification instruction data being for causing the terminal device to execute a process of modifying the frame data in such a manner that at least one of a certain character, symbol, and glyph is overlapped with an image represented by the frame data.

17. A video processing method executed on a video processor used in combination with a video output device for outputting a video data via a line, the video processor comprising a computer, the video data being a data of a video comprising a large number of frame data, each frame data being data of each of continuous sequence of frames, the video processing method comprising performing, with the computer: a receiving operation for receiving the video data outputted from the video output device; a compression operation for compressing data of each frame in the video data received by the receiving operation into compressed data in a digital format; and an output operation for sequentially outputting the compressed data generated by the compression operation to a transmission device having transmission means, the transmission means transmitting the compressed data to a terminal device via communication with a wireless LAN.

18. A computer program causing the computer to function as a video processor used in combination with a video output device for outputting a video data via a line, the video processor including a computer, the video data being a data of a video comprising a large number of frame data, each frame data being data of each of continuous sequence of frames, the computer program causing the computer to execute: a receiving operation for receiving the video data supplied from the video output device; a compression operation for compressing data of each frame in the video data received by the receiving operation into compressed data in a digital format; and an output operation for sequentially outputting the compressed data generated by the compression operation to a transmission device having transmission means, the transmission means transmitting the compressed data to a terminal device via communication with a wireless LAN.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG. 1 is a view schematically showing a communication system according to a first embodiment;

[0056] FIG. 2 is a view showing a hardware configuration of a video processor included in the communication system shown in FIG. 1;

[0057] FIG. 3 is a block diagram showing a functional block generated inside the video processor included in the communication system shown in FIG. 1;

[0058] FIG. 4 is a view schematically showing an exemplified compression process executed in the communication system shown in FIG. 1;

[0059] FIG. 5 is a view showing a hardware configuration of a terminal device included in the communication system shown in FIG. 1;

[0060] FIG. 6 is a block diagram showing a functional block generated inside the terminal device included in the communication system shown in FIG. 1; and

[0061] FIG. 7 is a view schematically showing a communication system according to a second embodiment.

MODES FOR CARRYING OUT THE INVENTION

[0062] First and second embodiments of the present invention are described below.

[0063] In the description of these embodiments, similar components are depicted by similar reference numerals, and redundant description will be omitted in some cases.

First Embodiment

[0064] In this embodiment, a communication system including a video output device, a video processor according to the present invention, and a terminal device adapted to receive compressed data described later from the video processor is described. FIG. 1 schematically shows the communication system of this embodiment.

[0065] The communication system is configured with a video output device 100, a video processor 200, and a terminal device or devices 300.

[0066] The video output device 100 is a device for outputting video data via a line. The video output device 100 may be any one of devices as long as it can achieve this operation.

[0067] For example, the video output device 100 may be a video camera (e.g., a video camera for shooting videos for television broadcasting and a video camera built in an endoscope are the examples) capable of outputting video data for a captured video at the same time as shooting, an apparatus of a video conference system capable of receiving video data from a remote site and typically supplying the video data to a large display device at a local site, a laptop or desktop computer, or a tablet computer such as iPad (trademark) sold by Apple Japan.

[0068] In a first embodiment, the video output device 100 is a computer, more specifically, a laptop computer. The communication system in this embodiment is, but not limited to, a presentation system used for presentations at a conference.

[0069] The video output device 100 and the video processor 200 are operated by a presenter (or his or her assistant, the same applies hereinafter) for making a presentation, and the terminal devices 300 are controlled by participants. The terminal devices 300 may be personal belongings of the participants or may be distributed or lent to the participants by a presenter or a collaborator of the presenter.

[0070] The terminal device 300 needs to be able to perform communication with a wireless LAN. The terminal device 300 has a display unit and is preferably portable. The terminal device 300 may be a smartphone, a tablet computer or a laptop computer. Examples of the tablet computers are as described for the video output device 100, and the smartphone is, for example, an iPhone which is manufactured and sold by Apple Japan. This embodiment exemplifies a case where the communication system is a presentation system and thus more than one terminal device 300 is expected to be associated with. It is, however, not necessarily required that there are two or more terminal devices 300.

[0071] The description of the video output device 100 is now continued.

[0072] The video output device 100 is a laptop computer having a display unit 101. The hardware configuration and the installed computer program(s) can be those known in the art. The video output device 100 also includes an input device 102. The input device 102 of this embodiment is a keyboard, but in addition or alternative to this, another input device such as a trackball, a mouse, and a touch panel may be provided in the video output device 100. The video output device 100 has an output terminal which is not shown. The output terminal may be any known output terminal. The output terminal is capable of outputting video data.

[0073] The output terminal may output video data as an analog signal or as a digital signal. Analog RGB terminals are examples for the former case and HDMI terminals and thunder bolt terminals are examples for the latter case.

[0074] The video output device 100 is equipped with known presentation software so that presentations can be performed. Examples of the presentation software include PowerPoint (trademark) manufactured by Japan Microsoft Corporation. An image used for presentation is reproduced on the display unit 101, and the presenter performs his or her presentation while watching it.

[0075] Next, the video processor 200 is described.

[0076] The video processor 200 is connected to the video output device 100 and has a function of compressing the video data received from the video output device 100 and transmitting the compressed video data to each of the terminal devices 300. As a result, the image that is substantially the same as the one displayed on the display unit 101 of the video output device 100 is reproduced on the display unit of the terminal device 300 as described later.

[0077] The video processor 200 is a computer. The video processor 200 also has an input device 202. Although the input device 202 of this embodiment is a ten-key pad, a keyboard, a mouse or a touch panel can be used as the input device 202.

[0078] The video processor 200 includes an input terminal which is not shown. The input terminal is paired with the output terminal of the video output device 100 and receives the video data supplied from the output terminal. The input terminal is connected to the output terminal of the video output device 100 via a line. A cable 100A connects the input terminal and the output terminal.

[0079] In addition, the video processor 200 implements a function of the wireless LAN. The function of the wireless LAN is achieved by a wireless LAN communication unit with an antenna, which is not shown. As will be described later, the wireless LAN communication unit is controlled by a wireless LAN control unit, and performs communication with the terminal device 300 with a wireless LAN. The wireless LAN communication unit of this embodiment may be a known wireless LAN communication unit capable of performing Wi-Fi communication.

[0080] The video processor 200 has a hardware configuration as shown in FIG. 2.

[0081] This hardware configuration includes a CPU 211, a ROM 212, a RAM 213, and an interface 214, which are connected to each other via a bus 216.

[0082] The CPU 211 is an arithmetic unit that performs arithmetic operations. The CPU 211 executes a processing which is described later by executing, for example, a computer program stored in the ROM 212. The computer program herein includes at least a computer program for allowing the video processor 200 to function as the video processor of the present invention. This computer program may be preinstalled in the video processor 200 or may be installed afterwards. Installation of this computer program in the video processor 200 may be performed via a predetermined storage medium such as a memory card or via a communication line such as a LAN or the Internet.

[0083] The ROM 212 stores computer programs and data necessary for the CPU 211 to execute processing described later.

[0084] The RAM 213 provides a work area necessary for the CPU 211 to perform processing. A part of the RAM 213 serves as a frame buffer described later.

[0085] The interface 214 allows the CPU 211, the RAM 213, etc. connected via the bus 216 to send and receive data to and from the outside. The interface 214 is connected to the aforementioned input device 202, an input terminal which is not shown, and the aforementioned wireless LAN communication unit. A user input from the input device 202 and the input from the input terminal are supplied to the bus 216 through the interface 214 and the compressed data described later supplied from the interface 214 to the wireless LAN communication unit is supplied from the wireless LAN communication unit to the terminal device 300.

[0086] When the CPU 211 executes a computer program, a function block as shown in FIG. 3 is generated inside the video processor 200. It should be noted that the following functional blocks may be generated by the aforementioned computer program alone, but may be generated by the aforementioned computer program in cooperation with the operating system or other computer program run on the video processor 200. Furthermore, at least a part of the process performed in the following functional blocks may be executed by hardware, not by a computer program.

[0087] An operation signal analyzing unit 221, a control unit 222, a video data receiving unit 223, an image data processing unit 224, a compression unit 225, and a wireless LAN control unit 226 are generated inside the video processor 200.

[0088] The operation signal analyzing unit 221 analyzes an operation signal supplied from the input device 202. In this embodiment, from the input device 202, numerical values are entered as information for setting an IP address and a port number described later. When an operation signal associated with the numerical values is entered from the input device 202, the operation signal analyzing unit 221 analyzes a numerical value designated by the operation signal. The result of the analysis by the operation signal analyzing unit 221, that is, the numerical value is transmitted to the control unit 222. Note that the information on the numerical value may be provided from the input device 102 of the video output device 100 rather than from the input device 202.

[0089] The operation signal analyzing unit 221 is also provided with an operation signal for character/symbol information from the input device 202. The character/symbol information is for determining whether the data on at least one of characters, symbols, and glyphs (hereinafter, sometimes collectively referred to as a “character”) described later is to be included in the frame data or for determining which characters are included in the frame data if the characters are included in frame data described later. In response to the reception of the operation signal for the character/symbol information, the operation signal analyzing unit 221 analyzes it and sends it to the control unit 222.

[0090] The control unit 222 transmits necessary data to the image data processing unit 224 and the wireless LAN control unit 226. Specifically, the control unit 222 transmits, to the image data processing unit 224, what is specified by the character/symbol information received from the operation signal analyzing unit 221, i.e., information for determining whether at least one of characters, symbols, and glyphs is to be included in the frame data or for determining which at least one character, symbol, or glyph is included in the frame data if the character, symbol, or glyph is included in frame data. Furthermore, the control unit 222 transmits numerical values for identifying an IP address and a port number received from the operation signal analyzing unit 221 to the wireless LAN control unit 226.

[0091] It should be noted that the control unit 222 may use, as the port number, a numerical value itself entered with the input device 202 or a numerical value determined after a predetermined arithmetic operation is performed on the entered numerical value. In this embodiment, the latter is used but not limited thereto.

[0092] To the video data receiving unit 223, the video data received by the input terminal is entered via the interface 214. The video data is a sequence of consecutive frame data for identifying individual frames. If the frame rate for videos is, for example, 60 fps, the frame data are received by the video data receiving unit 223 at 60 times per second. The video data receiving unit 223 transmits the frame data to the image data processing unit 224, every time when it receives the frame data.

[0093] The image data processing unit 224 executes necessary image processing on the frame data.

[0094] The image processing executed by the image data processing unit 224 is as follows.

[0095] First, when the frame data is an analog signal, the image data processing unit 224 converts it into a digital signal.

[0096] Furthermore, when the frame data is the compressed one, the image data processing unit 224 decompresses it. For example, some recent digital video cameras are capable of outputting compressed MPEG images via a line. If the video output device 100 is for outputting such compressed frame data, the image data processing unit 224 decompresses that frame data.

[0097] The image data processing unit 224 also receives the data on the character/symbol information from the control unit 222. When the information indicates to add at least one character, symbol, and glyph of “XXXX (any character(s) or symbol(s))” to the frame data, the image data processing unit 224 executes an appropriate processing for the frame data. More specifically, a process is executed to incorporate the character(s) “XXXX” into the frame data or frames for the frame data, i.e., basically all frame data. In this embodiment, the characters are static and shared by all frame data. The characters to be added in this embodiment are for indicating that the original video data is protected by copyright, but not limited thereto. For example, the characters can be “this video is protected by copyright,” “author Yamamoto,” a combination of characters and a symbol such as “(c) YAMAMOTO,” a corporate logo mark or other pattern protected by copyright or a combination of a pattern and letters indicating the corporate name, and the like.

[0098] The process of adding a character or characters to each frame data can be executed according to, for example, the following 1 to 3. [0099] 1. The frame data is compressed as described later, but in the previous state, the frame data is expanded on an image memory such as RGB or YUV (which may be a part of the aforementioned RAM 213). The aforementioned object can be achieved by overwriting, every time the frame data is expanded on the image memory, the character(s) in, for example, the BMP (Microsoft Windows Bitmap Image: “Microsoft” and “Windows” are both trademarks) format previously loaded, to the frame or image provided by the frame data in question. [0100] 2. If an alpha channel of a layer that is different from the frame or image expanded in the image memory is present in the image memory as described above, and if the character(s) has/have been written in that alpha channel, then the character(s) is/are automatically added to a subsequent frame or image when it is expanded in the image memory. [0101] 3. If an integrated circuit that can be configured by a purchaser or a designer after the production of FPGA (field-programmable gate array) or the like is present ahead of the image memory, the aforementioned object can be achieved by keeping the data of the character(s) in the FPGA and overlaying the data of the character(s) directly on the frame data passing through the FPGA.

[0102] When the image data processing unit 224 finishes image processing, the processed frame data is sequentially transmitted to the compression unit 225.

[0103] The compression unit 225 sequentially compresses each frame data received from the image data processing unit 224. The compression method may be a known method such as a standardized method. Compressed frame data is compressed data.

[0104] The compression unit 225 may compress each of the frame data into the compressed data as a single still image without any other processing. An example of such compression is, for example, JPEG compression.

[0105] When the compression unit 225 compresses each of the frame data as a single still image, the compression unit 225 may be configured to compress a portion of the frame data in the order of being received from the image data processing unit 224. A frame data is typically read in the following order: the top row of a frame is read from left to right, then the second row under the top is read from left to right, . . . the bottom row is read from left to right. For example, in the example of FIG. 4, it is assumed that a portion of a frame data for a frame F corresponding to the hatched range has already been read, that is, the data has been received by the compression unit 225. The frame data (more precisely, a portion of the frame data) has already been read for zones (a) to (f) of zones (a) to (x) making up the frame F, so that compression can be performed prior to the compression of other zones.

[0106] The compression unit 225 may be configured to compress a frame data of the video data into a compressed data in such a manner that at least one frame data preceding a target frame data to be compressed and at least one frame data following the target frame data are used for the compression. Such compression techniques include, for example, MPEG compression and h.264 compression. In MPEG 4 which is a kind of MPEG compression, in order to compress a certain frame, motion compensation using the data of past two frames and future two frames relative to the target frame is used in addition to the discrete cosine transformation and the entropy coding technique to increase the compression rate. If, however, it is more important to avoid a problem associated with a delay of video, it is preferable that the compression unit 225 uses only the preceding frame data without any subsequent frame data to compress a target frame data, though the compression rate will be lowered. When the compression rate is high, a problem associated with a delay of video is less likely to occur even if the time required for compression becomes somewhat long because it takes a shorter time to transmit the compressed data from the video processor 200 to the terminal device 300.

[0107] The compression unit 225 in this embodiment is configured to compress a frame data into a compressed data within 200 ms, preferably within 100 ms after the video data receiving unit 223 has received the frame data.

[0108] The compression unit 225 may be configured to complete the process of compressing a target frame data into the compressed data before the video data receiving unit 223 starts to receive a frame data incoming three frame data later than 0the target frame data. In the case of video data at 60 fps, a delay time to the end of the compression in this case is 50 ms. In the case of video data at 30 fps, a delay time to the end of the compression in this case is 100 ms.

[0109] The compression unit 225 of this embodiment compresses the frame data using JPEG compression, but not limited thereto. The compression rate is lower than that for the MPEG compression, but the compression is completed prominently faster. Even in a prototype machine created by the applicant of the present application, it has already found that the compression unit 225 can compress a frame data into a compressed data within 200 ms, preferably within 100 ms after the video data receiving unit 223 has received the frame data, and can complete the process of compressing the target frame data into the compressed data before the video data receiving unit 223 starts to receive a frame data incoming three frame data later than the target frame data in the case of a video at 60 fps.

[0110] The applicant has found that, even in the case where the compression unit 225 performs MPEG compression, the compression unit 225 can compress a frame data into a compressed data within 200 ms, preferably within 100 ms after the video data receiving unit 223 has received the frame data.

[0111] The compression unit 225 can apply the following transformation to the header of the compressed data. In JPEG and MPEG compression, header information is attached to data after the compression is performed with an existing technique. In the header information, data such as the type of compression and a reference table required for performing decompression are written according to a standardized rule. The terminal device 300 which has received the compressed data thus needs the data written in the header when it performs decompression of the compressed data. Decompression of the compressed data cannot be completed without it. The compression unit 225 of this embodiment transforms a part of the header information according to a predetermined algorithm, but not necessarily limited thereto. This is for the purpose of allowing only the terminal device 300 having such an algorithm to perform the inverse transformation of the header information of the compressed data to decompress the compressed data. The transformation of the header information may be performed, for example, by reversing the order of the character strings making up of the header information with respect to a part of the header information, dividing the header information into several pieces and changing the order of some pieces, or adding a character as a noise every few characters to at least a part of the character strings making up of the header information, although the size of the data for the header information is increased in the last case. In this embodiment, it is assumed that the aforementioned algorithm executed by the compression unit 225 is set from the time of shipment of the video processor 200, but it can also be set using an input from the input device 202.

[0112] The wireless LAN control unit 226 receives numerical values for identifying an IP address and a port number from the operation signal analyzing unit 221 and receives the compressed data from the compression unit 225. The wireless LAN control unit 226 receives the compressed data sequentially transmitted from the compression unit 225, and sequentially transmits the received compressed data to the wireless LAN communication unit.

[0113] On the other hand, the wireless LAN control unit 226 sets the IP address received from the operation signal analyzing unit 221 to the wireless LAN communication unit, as described above. The IP address is for identifying the terminal device 300 to which the compressed data is wirelessly transmitted from the wireless LAN communication unit. The IP address can be set according to a known technique. The numerical value set as the IP address can be a known value. In this embodiment, the destination IP address of the terminal device 300 is set to “255.255.255.255”. With this setting, the number of terminal devices 300 that can receive the compressed data is substantially infinite.

[0114] On the other hand, the wireless LAN control unit 226 sets the port number received from the operation signal analyzing unit 221 to the wireless LAN communication unit, as described above. The port number is a numerical value for specifying which software installed in the terminal device 300 that has received the compressed data wirelessly transmitted from the wireless LAN communication unit is used to process the compressed data.

[0115] The wireless LAN communication unit has a function of transmitting the compressed data received from the wireless LAN control unit 226 to the terminal device(s) 300 by the function of the wireless LAN. The wireless LAN communication unit in this embodiment is configured to transmit the compressed data to the terminal device(s) 300 using Wi-Fi, but not limited thereto. The IP address for specifying the terminal device(s) 300 is “255.255.255.255,” as described above.

[0116] Next, the terminal device 300 is described.

[0117] Each terminal device 300 is a portable computer.

[0118] The terminal device 300 includes a display unit 301. The terminal device 300 also includes an input device 302. The input device 302 can also be formed with a touch panel integrated with the display unit 301, as is well known, rather than physical keys as shown in FIG. 1.

[0119] The terminal device 300 has a function of the wireless LAN. The function of the wireless LAN is achieved by a wireless LAN communication unit which is not shown. The wireless LAN in this embodiment is Wi-Fi, but not limited thereto. The wireless LAN communication unit of the terminal device 300 can communicate with the wireless LAN communication unit of the video processor 200.

[0120] The terminal device 300 has a hardware configuration as shown in FIG. 5.

[0121] In this hardware configuration, a CPU 311, a ROM 312, a RAM 313, and an interface 314 are connected to each other via a bus 315. The hardware configuration may include a hard disk drive similar to that provided in the video processor 200.

[0122] The functions of the CPU 311, the ROM 312, the RAM 313, the interface 314, and the bus 315 are basically the same as those of the CPU 211, the ROM 212, the RAM 213, the interface 214, and the bus 215, respectively, in the video processor 200.

[0123] The ROM 312, however, stores a computer program required for achieving the following processes executed by the terminal device 300. Furthermore, the ROM 312 also stores software required for executing processes for zooming (e.g., by pinching) described later and recording of a display image (e.g., by print screen).

[0124] The interface 314 of the terminal device 300 is connected to the aforementioned wireless LAN communication unit mounted in the terminal device 300, and the wireless LAN communication unit receives the compressed data received from the video processor device 200. The interface 314 is connected to the input device 302, and is configured to receive an instruction indicating operation from the input device 302. This instruction indicating operation includes at least designation information described later. The interface 314 is also connected to the display unit 301 and is configured to transmit data for displaying a predetermined display image on the display unit 301.

[0125] When the CPU 311 executes a computer program, a function block as shown in FIG. 6 is generated inside the terminal device 300. It should be noted that the following functional blocks may be generated by the aforementioned computer program alone, but may be generated by the aforementioned computer program in cooperation with the operating system or other computer program run on the terminal device 300. Furthermore, at least some functions of the following functional blocks may be executed by hardware, not by software.

[0126] An operation signal analyzing unit 321, a control unit 322, a port number determination unit 323, a decompression unit 324, and a display image data generation unit 325 are generated inside the terminal device 300.

[0127] The operation signal analyzing unit 321 analyzes an operation signal supplied from the input device 302. The operation signal related to this embodiment is designation information. The designation information is for specifying a numerical value which is information for determining a port number which is a numerical value for determining software to process the compressed data received by the terminal device 300 from software installed on the terminal device 300. This numerical value is transmitted to the control unit 322.

[0128] The control unit 322 has a function of determining the port number which is a numerical value for determining which software is used to process the compressed data received by the terminal device 300 among software installed on the terminal device 300, when the control unit 322 receives the numerical value from the operation signal analyzing unit 321. This numerical value may be a numerical value itself represented by the operation entered from the operation signal analyzing unit 321, but may be a numerical value obtained as a result of a certain arithmetic operation performed on the numerical value. In this embodiment, as a result of such arithmetic operation, a numerical value for determining software to process the compressed data received by the terminal device 300 among software installed on the terminal device 300. This numerical value is transmitted to the port number determination unit 323.

[0129] The port number determination unit 323 is configured to receive, from time to time, headers and compressed data packets transmitted from the wireless LAN communication unit of the video processor 200 and received by the wireless LAN communication unit of the terminal device 300 via the interface 314.

[0130] The port number determination unit 323 compares the port number specified by the video processor 200 with the port number received from the control unit 322. If they match each other, the port number determination unit 323 receives the compressed data, and if they do not match, it does not receive the compressed data. The comparison described above may be performed only when the first compressed data may be performed only when the first compressed data is received or at every predetermined time interval such as every 10 minutes. In this embodiment, this process is performed only when the first compressed data is received.

[0131] In response to receiving the compressed data, the port number determination unit 323 transmits the received compressed data to the decompression unit 324.

[0132] In response to receiving the compressed data from the port number determination unit 323, the decompression unit 324 decompresses the compressed data and restores the frame data from the compressed data. The decompression unit 324 is configured to transmit the frame data obtained by decompressing the compressed data to the display image data generation unit 325.

[0133] The decompression unit 324 in this embodiment has an algorithm for performing a so-called inverse transformation for transforming the header information of the compressed data back to the original header information. This is achieved by, for example, installing the software specified by a presenter into the terminal devices 300 owned by listeners. For example, if each presenter designates software, it is possible to select listeners who can view the video(s) that he or she has distributed.

[0134] The decompression unit 324 in this embodiment transforms the header information back to the original by the aforementioned inverse transformation, and then decompresses the compressed data using the header information to restore the frame data. A method used to decompressing the compressed data may be a known one.

[0135] The decompression unit 324 transmits the frame data to the display image data generation unit 325 from time to time. The display image data generation unit 325 causes the display unit 301 to display an image based on the frame data received from the decompression unit 324. Each time the display image data generating unit 325 receives the frame data, it causes the display unit 301 to display an image based on that frame data.

[0136] Next, a method of using this communication system and operations thereof are described.

[0137] To use this communication system, a presenter first connects the output terminal of the video output device 100 and the input terminal of the video processor 200 via a cable 100A. In this embodiment, they are connected to each other using an HDMI cable, but not limited thereto.

[0138] Besides, either before or after the aforementioned operation, the presenter operates the input device 202 of the video processor 200 to enter a numerical value for determining the port number to the video processor 200, and lets listeners to enter, into their own terminal devices 300, the numerical value for determining the port number for identifying the software used to process compressed data when the terminal device 300 receives the compressed data. The numerical value is transmitted to the listeners by, for example, verbally or by e-mail or the like.

[0139] The numerical value supplied from the input device 202 to the video processor 200 is transmitted to the control unit 222 via the operation signal analyzing unit 221. As described above, the control unit 222 of this embodiment determines, as the port number, a numerical value determined after a predetermined arithmetic operation is performed on the numerical value entered by the input device 202. For example, in general, the port number is determined by adding a predetermined numerical value to a default numerical value of 8255. In this embodiment, the presenter operates the input device 202 to enter a numerical value that is equal to the sum of a predetermined numerical value (e.g., 1000) and a numerical value (e.g., 10) that listeners who are allowed to receive and decompress compressed data on their own terminal devices 300 should enter into their own terminal device 300, of 8255 plus the predetermined numerical value (e.g., 1000) plus the numerical value (e.g., 10) that listeners who are allowed to receive and decompress compressed data on their own terminal devices 300 should enter. The control unit 222 determines the numerical value of 9265 obtained by summing them as the port number, and transmits this numerical value to the wireless LAN control unit 226.

[0140] On the other hand, in this embodiment, a sum of 8255 and a predetermined numerical value (e.g., 1000) is included in advance in the computer program installed on the terminal devices 300 of the listeners, and a numerical value entered when a listener operates his or her input device 302 is added to the sum by the control unit 322. The 8255+ the predetermined numerical value (e.g., 1000) is determined without being known by the audience/listeners. The presenter notifies a correct numerical value (which is, for example, 10 as described above) that each listener should enter only to participants of the presentation who are allowed to receive and decompress compressed data to view intended videos. Only the terminal devices 300 of the listeners who know the notified correct number can obtain the correct port number. As described above, since a predetermined numerical value (e.g., 1000) which is not seen from the audience/listeners is used for determining the port number in addition to the numerical value of the default port number of 8255, it is hard for a malicious third party to know the correct port number.

[0141] In the video processor 200, the determined port number is transmitted from the control unit 222 to the wireless LAN control unit 226.

[0142] In the terminal device 300, the port number is transmitted from the control unit 322 to the port number determination unit 323.

[0143] In addition, the presenter enters, with the input device 202, a numerical value for specifying the IP address of the terminal devices 300. The numerical value is transmitted from the operation signal analyzing unit 221 via the control unit 222 to the wireless LAN control unit 226. Here, it is assumed that the IP address of each terminal device 300 is set to “255.255.255.255”. It is also possible to set such an IP address as a default and omit the input by the presenter.

[0144] In this state, the presenter starts his or her presentation.

[0145] When the presenter operates the input device 102, the video output device 100 executes known software for presentation. An image based on the execution result is displayed on the display unit 101 of the video output device 100. It is assumed that this image contains a video at least on a part of the screen in at least a certain time period.

[0146] The video data which is data on the image displayed on the display unit 101 is transmitted from the output terminal to the input terminal of the video processor 200 via the cable 100A.

[0147] The following processes in the video processor 200 are performed basically in an automatic manner.

[0148] A video data including a large number of consecutive frame data supplied from the input terminal is transmitted to the image data processing unit 224. The image data processing unit 224 performs the aforementioned necessary processes on the frame data. For example, it superimposes data of copyright indication on each frame data, and transmits it to the compression unit 225.

[0149] The compression unit 225 compresses the frame data every time it receives the frame data, and performs the aforementioned transformation on the header information of the generated compressed data. The compression unit 225 transforms a target frame data into compressed data within 200 ms, preferably within 100 ms after the video data receiving unit 223 has received that target frame data. Alternatively, the compression unit 225 completes the process of compressing the target frame data into the compressed data before the video data receiving unit 223 starts to receive a frame data incoming three frame data later than the target frame data.

[0150] The compression unit 225 transmits the compressed data to the wireless LAN control unit 226 each time it generates the compressed data.

[0151] The wireless LAN control unit 226 divides the compressed data into packets and adds headers to the heads of the packets. To the header, its own IP address, capacity information which is information indicating the capacity of compressed data to be transmitted, and the aforementioned port number are written. Packets for these headers and a large number of compressed data are transmitted to the wireless LAN communication unit and are, in turn, transmitted from the wireless LAN communication unit to each terminal device 300.

[0152] Since the video processor 200 itself has the wireless LAN communication unit and serves as an adhoc base station, communication with the terminal device 300 can be achieved with a simple network without any other transmission device such as a wireless router.

[0153] A series of packets associated with the compressed data with the header located at the head are received by the wireless LAN communication unit of the terminal device 300. If the IP address is set as described above, the number of terminal devices 300 is not limited. The data received by the terminal devices 300 are transmitted to the port number determination unit 323.

[0154] In response to receiving these data, the port number determination unit 323 reads the port number written in the header. The port number determination unit 323 compares the port number written in the header of the packets of the compressed data with the port number transmitted from the control unit 322. When these numerical values match, the port number determination unit 323 transmits the packets of the compressed data received by the terminal device 300 to the decompression unit 324. If the numerical values of the two port numbers do not match, no subsequent process is performed on that terminal device 300.

[0155] In response to receiving the compressed data from the port number determination unit 323, the decompression unit 324 first performs the aforementioned inverse transformation on the header information to restore the header information to the original. Then, the decompression unit 324 decompresses the compressed data using the restored header information to restore the original frame data. The decompression unit 324 transmits the frame data obtained by decompressing the compressed data to the display image data generation unit 325.

[0156] The display image data generation unit 325 displays an image based on the frame data received from the decompression unit 324 on the display unit 301 every time the frame data is received. As a result, on the display unit 301, a video that can be deemed to be substantially identical to the one displayed on the display unit 101 of the video output device 100 is displayed with little delay.

[0157] The audience can listen to the presentation provided by the presenter while watching the images displayed on the display unit 301 of the terminal device 300. This eliminates paper handouts for presentation, which otherwise would be necessary.

[0158] If an image is difficult to see due to, for example, small characters displayed on the image, a listener can pinch and zoom the image if the terminal device 300 has such a function to recognize these small characters clearly. The listener can also zoom a part of the display image to which he or she wants to pay particular attention.

[0159] In addition, while watching the image(s) displayed on the display unit 301, the listener can save a part of the data of the image in, for example, the RAM 313 of the terminal device 300 using a function of saving screenshot such as print screen if the terminal device 300 is equipped with this, at the time when the image desired to be stored is displayed on the display unit 301. This makes it less and less necessary to distribute paper handouts.

[0160] Recently, most smartphones and the like which are expected to be used as the terminal device 300 are provided with functions of zooming and saving display images, but at least one of these functions can be included in a computer program for causing the computer according to the present invention to function as the terminal device 300.

[0161] In the image, all frames contain the aforementioned character(s) indicating that the video is protected by copyright. Accordingly, it is unlikely that a person who saved a video or a still image captured from the video in the terminal device 300 misuses it.

[0162] In this embodiment, the process of superimposing data of an image such as characters on the frame data is performed by the video processor 200. Such process, however, can be performed by the terminal device 300. In such a case, data of an instruction to cause the terminal device 300 to execute the process of superimposing data of an image such as characters on the frame data is transmitted from the video processor 200 to the terminal device 300. The terminal device 300 executes the process in accordance with the received instruction based on the data of the instruction. The data of this instruction is to write such characters in each frame. That is, the data of the instruction is basically made up of a combination of image information for identifying characters of each frame and an instruction to write the characters identified by the information in each frame. However, when the characters to be written in the frame data are predetermined, the following may apply. When the character is a single character, the data of the instruction may be an instruction to write that single character in each frame. When the characters are two or more different characters, the data of the instruction may be a combination of data for use in selecting characters from different characters and an instruction to write the selected characters in each frame. The transmission of the data of the instruction may be performed only once when the transmission of the compressed data from the video processor 200 to the terminal device 300 is started, or two or more times at appropriate timing. Alternatively, it may be performed every time the compressed data is transmitted. The aforementioned data of the instruction may be generated by the control unit 222 in accordance with an input from the input device 202, and may be transmitted to the terminal device 300 via the wireless LAN control unit 226. It should be noted that how the terminal device 300 executes the process of superimposing the data of an image such as characters on frame data can be determined arbitrary. Any of the aforementioned processes 1 to 3 that can be executed by the video processor 200 can be applied to this, depending on the hardware configuration of the terminal device 300.

Second Embodiment

[0163] FIG. 7 shows a communication system according to a second embodiment.

[0164] This communication system is almost identical to that described in the first embodiment. The video output device 100 and the terminal device 300 are the same as those described in the first embodiment.

[0165] The difference between the communication system of the second embodiment and the communication system of the first embodiment lies in the following. The video processor 200 of the first embodiment has the built-in wireless LAN communication unit, while the video processor 200 of the second embodiment has no built-in wireless LAN communication unit. A wireless router 210 connected to the video processor 200 through a predetermined cable 100B is the counterpart of the wireless LAN communication unit in the second embodiment.

[0166] In the second embodiment, compressed data generated by the compression unit 225 are sequentially transmitted to the wireless router 210 via the cable 100B. The wireless router 210 sequentially transmits the received compressed data to the terminal device 300 in the same way as the wireless LAN communication unit sequentially transmits the compressed data to the terminal device 300 in the first embodiment.

[0167] In the first embodiment, the wireless LAN control unit 226 that controls the wireless LAN communication unit is provided in the functional blocks. In the second embodiment, this may be provided either in the video processor 200 or in the wireless router 210. If the wireless LAN control unit 226 is provided in the wireless router 210, the wireless router 210 is provided with the input device 212, and some functions of the operation signal analyzing unit 221 and the control unit 222 are also provided in the wireless router 210. A numerical value for determining the port number and a numerical value for specifying the IP address of the terminal device 300 can thus be entered from the input device 212.