# Patent

## Title
Distribution control system, distribution control method, and computer-readable storage medium

## Abstract

A system distributes, to a communication terminal, first frame data reproduced singly by the terminal or second frame data as a difference with the previous frame data distributed to the terminal. The system includes a generating unit configured to generate the first or the second frame data from certain frame data; and a transmitting unit configured to transmit third frame data with the contents not updated or non-update information indicating that the contents are not updated, in place of the first or the second frame data, to the terminal when contents of the certain frame data are not updated over a certain range as compared with contents of the frame data previously generated. The transmitting unit is configured to transmit fourth frame data higher in image quality than the first frame data to the terminal before the third frame data or the non-update information is transmitted to the terminal.

## Background
TECHNICAL FIELD
The present invention relates to a system that generates first frame data such as I frame data or second frame data such as P frame data and distributes these pieces of data to communication terminals such as personal computers and electronic blackboards.
BACKGROUND ART
With the recent widespread use of the Internet, cloud computing has been used in various fields. Cloud computing is a service usage pattern in which users use services (cloud services) provided by a server on the Internet, using a communication terminal connected to the Internet and pay for the service.
When the server provides a service distributing video data, unnecessary data is reduced or removed by video compression techniques. In the video compression techniques, MPEG-4 and H.264, using inter-frame data encoding, predicts inter-frame data changes to reduce the amount of video data. This method includes the differential coding technique that compares frame data with frame data to be referred to and encodes only changed pixels. Using this differential coding reduces the number of pixels to be encoded and transmitted. When the thus encoded video data is displayed, it can appear as if each differential data generated by the differential coding is included in the original video data. In the prediction of the inter-frame data changes, pieces of frame data within the video data are classified into frame types such as the I frame data and the P frame data.
However, because the I frame data and the P frame data are frame data constituting video data that is lower in image quality than still image data, when the contents of the frame data continue not to be updated, the state is equivalent to a state in which low image quality still image data continues to be reproduced. This causes a problem in that a state continues in which an image is difficult to be viewed by a user of a communication terminal.
DISCLOSURE OF INVENTION
It is an object of the present invention to at least partially solve the problems in the conventional technology.
According to an embodiment, there is provided a distribution control system that distributes, to a communication terminal, first frame data capable of being reproduced singly by the communication terminal or second frame data as a difference with the previous frame data distributed to the communication terminal. The distribution control system includes a generating unit configured to generate the first frame data or the second frame data from certain frame data; and a transmitting unit configured to transmit third frame data with the contents being not updated or non-update information indicating that the contents are not updated, in place of the first frame data or the second frame data, to the communication terminal when contents of the certain frame data are not updated over a certain range or more as compared with contents of the frame data previously generated. The transmitting unit is configured to transmit fourth frame data that is higher in image quality than the first frame data to the communication terminal before the third frame data or the non-update information is transmitted to the communication terminal.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.



BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagram of a distribution system according to an embodiment.
FIG. 2 is a conceptual view when a dongle is attached to a communication terminal.
FIG. 3 is a conceptual diagram illustrating a basic distribution method.
FIG. 4 is a conceptual diagram of multicast.
FIG. 5 is a conceptual diagram of multidisplay.
FIG. 6 is a conceptual diagram of composite distribution using a plurality of communication terminals through a distribution control system.
FIG. 7 is a logical hardware configuration diagram of a distribution control system, a communication terminal, a terminal management system, and a web server.
FIG. 8 is a logical hardware configuration diagram of the dongle.
FIG. 9 is a functional block diagram illustrating mainly the functions of the distribution control system.
FIG. 10 is a functional block diagram illustrating mainly the functions of the communication terminal.
FIG. 11 is a functional block diagram illustrating the functions of the terminal management system.
FIG. 12 is a conceptual view of a distribution destination selection menu screen.
FIG. 13 is a conceptual view of a terminal management table.
FIG. 14 is a conceptual view of an available terminal management table.
FIG. 15 is a detailed diagram of an encoder bridge unit.
FIG. 16 is a functional block diagram illustrating the functions of a converter.
FIG. 17 is a sequence diagram illustrating basic distribution processing of the distribution control system.
FIG. 18 is a sequence diagram illustrating communication processing using a plurality of communication terminals through the distribution control system.
FIG. 19 is a sequence diagram illustrating the processing of time adjustment.
FIG. 20 is a sequence diagram illustrating the processing of channel adaptive control on data transmitted from the distribution control system to the communication terminal.
FIG. 21 is a sequence diagram illustrating the processing of channel adaptive control on data transmitted from the communication terminal to the distribution control system.
FIG. 22 is a sequence diagram illustrating the processing of multidisplay.
FIG. 23 is a sequence diagram illustrating the processing of multidisplay.
FIG. 24 is a sequence diagram illustrating the processing of multidisplay.
FIG. 25 is a conceptual diagram of various types of frame data.
FIG. 26 is a flowchart for generating the various types of frame data.



BEST MODE FOR CARRYING OUT THE INVENTION
Described below with reference to the accompanying drawings is a distribution system 1 according to an embodiment. Described below in detail is an invention that causes both a web browser (hereinafter referred to as a “browser”) and an encoder to execute in cooperation with each other in the cloud through cloud computing and transmits video data, sound data, and the like to communication terminals.
In the following, “images” include a still image and a moving image. “Videos” basically mean moving images and also include moving images that are stopped to be still images. A “still image (sound)” represents at least either one of a still image and sound. An “image (sound)” represents at least either one of an image and sound. A “video (sound)” represents at least either one of video and sound.
Outline of the Embodiment
Described with reference to FIG. 1 is an outline of the embodiment according to the present invention. FIG. 1 is a schematic diagram of a distribution system according to the present embodiment.
Outline of System Configuration
Described first is an outline of the configuration of the distribution system 1.
As illustrated in FIG. 1, the distribution system 1 according to the present embodiment includes a distribution control system 2, a plurality of communication terminals (5a to 5f), a terminal management system 7, and a web server 8. In the following, any communication terminal among the communication terminals (5a to 5f) can be referred to as a “communication terminal 5”. The distribution control system 2, the terminal management system 7, and the web server 8 are all implemented by server computers.
The communication terminal 5 is a terminal used by a user who receives services of the distribution system 1. The communication terminal 5a is a notebook personal computer (PC). The communication terminal 5b is a mobile terminal such as a smartphone or a tablet terminal. The communication terminal 5c is a multifunction peripheral/printer/product (MFP) in which the functions of copying, scanning, printing, and faxing are combined. The communication terminal 5d is a projector. The communication terminal 5e is a TV (video) conference terminal having a camera, a microphone, and a speaker. The communication terminal 5f is an electronic blackboard (whiteboard) capable of electronically converting drawings drawn by a user or the like.
The communication terminal 5 is not only such terminals as illustrated in FIG. 1, but also may be devices communicable through a communication network such as the Internet, including a watch, a vending machine, a car navigation device, a game console, an air conditioner, a lighting fixture, a camera alone, a microphone alone, and a speaker alone.
The distribution control system 2, the communication terminal 5, the terminal management system 7, and the web server 8 can communicate with each other through a communication network 9 including the Internet and a local area network (LAN). Examples of the communication network 9 may include wireless communication networks such as 3rd Generation (3G), Worldwide Interoperability for Microwave Access (WiMAX), and Long-Term Evolution (LTE).
The communication terminal 5d, for example, among the communication terminals. 5 does not have a function of communicating with the other terminals or systems through the communication network 9. However, as illustrated in FIG. 2, a user inserts a dongle 99 into an interface such as Universal Serial Bus (USB) or High-Definition Multimedia Interface (HDMI) of the communication terminal 5d, thereby enabling it to communicate with the other terminals and systems. FIG. 2 is a conceptual view when the dongle is attached to the communication terminal.
The distribution control system 2 has a browser 20 in the cloud, and through the function of rendering in the browser 20, acquires a single or a plurality of pieces of content data described in a certain description language and performs rendering on the content data, thereby generating frame data including still image data such as bitmap data made up of red, green, and blue (RGB) and sound data such as pulse code modulation (PCM) data (i.e., still image (sound) data). The content data is data acquired from the web server 8, any communication terminal, and the like and includes image (sound) data in Hypertext Markup Language (HTML) and Cascading Style Sheets (CSS), image (sound) data in MP4 (MPEG-4), and sound data in Advanced Audio Coding (AAC).
The distribution control system 2 has an encoding unit 19 in the cloud, and the encoding unit 19 plays a role as an encoder, thereby converting frame data as still image (sound) data into video (sound) data in the compression coding format such as H.264 (MPEG-4 AVC), H.265, and Motion JPEG.
The terminal management system 7 performs login authentication on the communication terminal 5 and manages contract information and the like of the communication terminal 5. The terminal management system 7 has a function of a Simple Mail Transfer Protocol (SMTP) server for transmitting e-mail. The terminal management system 7 can be embodied as, for example, a virtual machine developed on a cloud service (IaaS: Infrastructure as a Service). It is desirable that the terminal management system 7 be operated in a multiplexed manner to provide service continuity in case of unexpected incidents.
The browser 20 enables real-time communication/collaboration (RTC). The distribution control system 2 includes the encoding unit 19 in FIG. 16 described below, and the encoding unit 19 can perform real-time encoding on frame data output by the browser 20 and output video (sound) data generated through conversion compliant with the H.264 standard or the like. As a result, the processing of the distribution control system 2 is different from, for example, processing in a case in which non real-time video (sound) data recorded in a DVD is read and distributed by a DVD player.
Not only the distribution control system 2, but also the communication terminal 5 may have a browser. In this case, updating the browser 20 of the distribution control system 2 eliminates the need to start up the browsers of the respective communication terminals 5.
Outline of Various Kinds of Distribution Methods
Described next is an outline of various distribution methods.
Basic Distribution
FIG. 3 is a conceptual diagram illustrating a basic distribution method. In the distribution system 1, as illustrated in FIG. 3, the browser 20 of the distribution control system 2 acquires web content data [A] as image (sound) data from the web server 8 and renders it, thereby generating pieces of frame data [A] as still image (sound) data. An encoder bridge unit 30 including the encoding unit 19 performs encoding and the like on the pieces of frame data [A], thereby converting them into video (sound) data [A] in the compression coding format such as H.264 (an example of transmission data). The distribution control system 2 distributes the video (sound) data [A] converted to the communication terminal 5.
Thus, the distribution control system 2 can distribute even rich web content data to the communication terminal 5 while converting it from the web content data in HTML or the like into the compressed video (sound) data in H.264 or the like in the cloud. As a result, the communication terminal 5 can reproduce the web content smoothly without time and costs for adding the latest browser or incorporating a higher-spec central processing unit (CPU), operating system (OS), random access memory (RAM), and the like.
Future enrichment in web content will only require higher specifications of the browser 20, the CPU, and the like in the distribution control system 2 in the cloud, without the need for higher specifications of the communication terminal 5.
Applying the above distribution method, as illustrated in FIG. 4 to FIG. 6, the distribution system 1 can also distribute web content data to a plurality of sites as video (sound) data. Described below are distribution methods illustrated in FIG. 4 to FIG. 6.
Multicast
FIG. 4 is a conceptual diagram of multicast. As illustrated in FIG. 4, the single browser 20 of the distribution control system 2 acquires the web content data [A] as image (sound) data from the web server 8 and renders it, thereby generating pieces of frame data [A] as still image (sound) data. The encoder bridge unit 30 encodes the pieces of frame data [A], thereby converting them into video (sound) data. The distribution control system 2 then distributes the video (sound) data [A] (an example of transmission data) to a plurality of communication terminals (5f1, 5f2, 5f3).
Thus, the same video (sound) is reproduced at the sites. In this case, the communication terminals (5f1, 5f2, 5f3) do not need to have the same level of display reproduction capability (e.g., the same resolution). The distribution method like this is called, for example, “multicast”.
Multidisplay
FIG. 5 is a conceptual diagram of multidisplay. As illustrated in FIG. 5, the single browser 20 of the distribution control system 2 acquires web content data [XYZ] as image (sound) data from the web server 8 and renders it, thereby generating pieces of frame data [XYZ] as still image (sound) data. The encoder bridge unit 30 divides each frame data [XYZ] into a plurality of pieces of frame data ([X], [Y], [Z]) and then encodes them, thereby converting them into a plurality of pieces of video (sound) data ([X], [Y], [Z]). The distribution control system 2 then distributes the video (sound) data [X] (an example of transmission data) to the communication terminal 5f1. Similarly, the distribution control system 2 distributes the video (sound) data [Y] (an example of transmission data) to the communication terminal 5f2 and distributes the video (sound) data [Z] (an example of transmission data) to the communication terminal 5f3.
Thus, for example, even for landscape web content [XYZ], video (sound) is reproduced by the communication terminals 5 in a divided manner. As a result, when the communication terminals (5f1, 5f2, 5f3) are installed in a line, the same effect can be obtained as the reproduction of one piece of large video. In this case, the communication terminals (5f1, 5f2, 5f3) need to have the same level of display reproduction capability (e.g., the same resolution). The distribution method like this is called, for example, “multidisplay”.
Composite Distribution
FIG. 6 is a conceptual diagram of composite distribution using a plurality of communication terminals through a distribution control system. As illustrated in FIG. 6, the communication terminal 5f1 as an electronic blackboard and a communication terminal 5e1 as a teleconference terminal are used at a first site (the right side in FIG. 6), whereas at a second site (the left side in FIG. 6), the communication terminal 5f2 as an electronic blackboard and a communication terminal 5e2 as a teleconference terminal are used similarly. At the first site, an electronic pen P1 is used for drawing characters and the like with strokes on the communication terminal 5f1. At the second site, an electronic pen P2 is used for drawing characters and the like with strokes on the communication terminal 5f2.
At the first site, video (sound) data acquired by the communication terminal 5e1 is encoded by an encoding unit 60 and is then transmitted to the distribution control system 2. After that, it is decoded by a decoding unit 40 of the distribution control system 2 and is then input to the browser 20. Operation data indicating the strokes drawn on the communication terminal 5f1 with the electronic pen P1 (in this case, coordinate data on the display of the communication terminal 5f1 or the like) is transmitted to the distribution control system 2 to be input to the browser 20. Also at the second site, video (sound) data acquired by the communication terminal 5e2 is encoded by the encoding unit 60 and is then transmitted to the distribution control system 2. After that, it is decoded by the decoding unit 40 of the distribution control system 2 and is then input to the browser 20. Operation data indicating the strokes drawn on the communication terminal 5f2 with the electronic pen P2 (in this case, coordinate data on the display of the communication terminal 5f2 or the like) is transmitted to the distribution control system 2 to be input to the browser 20.
The browser 20 acquires, for example, web content data [A] as a background image displayed on the displays of the communication terminals (5f1, 5f2) from the web server 8. The browser 20 combines the web content data [A], operation data ([p1], [p2]), and video (sound) content data ([E1], [E2]) and renders them, thereby generating pieces of frame data as still image (sound) data in which the pieces of content data ([A], [p1], [p2], [E1], [E2]) are arranged in a desired layout. The encoder bridge unit 30 encodes the pieces of frame data, and the distribution control system 2 distributes video (sound) data indicating the same content ([A], [p1], [p2], [E1], [E2]) to both sites. At the first site, thereby video ([A], [p1], [p2], [E1 (video part)], and [E2 (video part)]) is displayed on the display of the communication terminal 5f1, and sound [E2 (sound part)] is output from the speaker of the communication terminal 5e1. Also at the second site, the video ([A], [p1], [p2], [E1 (video part)], and [E2 (video part)]) is displayed on the display of the communication terminal 5f2, and sound [E1 (sound part)] is output from the speaker of the communication terminal 5e2. At the first site, the sound of the site itself [E1 (sound part)] is not output owing to an echo cancelling function of the communication terminal 5f1. At the second site, the sound of the site itself [E2 (sound part)] is not output owing to an echo cancelling function of the communication terminal 5f2.
Thus, at the first site and the second site, remote sharing processing can be performed that shares the same information in real time at remote sites, thus making the distribution system 1 according to the present embodiment effective in a teleconference or the like.
DETAILED DESCRIPTION OF THE EMBODIMENT
The following describes the embodiment in detail with reference to FIG. 7 to FIG. 24.
Hardware Configuration of the Embodiment
Described first with reference to FIG. 7 and FIG. 8 is the hardware configuration of the present embodiment. FIG. 7 is a logical hardware configuration diagram of a distribution control system, a communication terminal, a terminal management system, and a web server. FIG. 8 is a logical hardware configuration diagram of a dongle. Because the hardware configuration relating to the communication of the communication terminal is the same as part of the hardware configuration of the communication terminal, the description thereof will be omitted.
As illustrated in FIG. 7, the distribution control system 2 includes: a (host) CPU 201 that controls the entire operation of the distribution control system 2; a read-only memory (ROM) 202 that stores therein a program used for driving the CPU 201 such as IPL; a RAM 203 used as a work area of the CPU 201; an HDD 204 that stores therein various kinds of data such as programs; a hard disk controller (HDC) 205 that controls the reading and writing of the various kinds of data from and into the HDD 204 under the control of the CPU 201; a media drive 207 that controls the reading and writing of data from and into a storage medium 206 such as a flash memory; a display 208 that displays various kinds of information; an interface (I/F) 209 that transmits data through the communication network 9 and to which the dongle 99 is connected; a keyboard 211; a mouse 212; a microphone 213; a speaker 214; a graphics processing unit (GPU) 215; a ROM 216 that stores therein a program used for driving the GPU 215; a RAM 217 used as a work area of the GPU 215; and an expansion bus line 220 such as an address bus or a data bus for electrically connecting the above components as illustrated in FIG. 7. As in the communication terminal 5d as a projector, the GPU may not be provided. Because the hardware configuration of the terminal management system 7 and the web server 8 is the same as the hardware configuration of the distribution control system 2, the description thereof will be omitted.
Described next with reference to FIG. 8 is the hardware configuration of the dongle 99 illustrated in FIG. 2. As illustrated in FIG. 8, the dongle 99 includes: a CPU 91 that controls the entire operation of the dongle 99; a ROM 92 that stores therein a basic input/output program; a RAM 93 used as a work area of the CPU 91; an electrically erasable and programmable ROM (EEPROM) 94 that performs the reading and writing of data under the control of the CPU 91; a GPU 95; a ROM 98a that stores therein a program used for driving the GPU 95; a RAM 98b used as a work area of the GPU 95; an interface I/F 96 for connection to the I/F 209 of the communication terminal 5; an antenna 97a; a communication unit 97 that performs communications by a short-distance wireless technology through the antenna 97a; and a bus line 90 such as an address bus or a data bus for electrically connecting the above units. Examples of the short-distance wireless technology include the Near Field Communication (NFC) standards, Bluetooth (registered trademark), Wireless Fidelity (WiFi), and ZigBee (registered trademark). Because the dongle 99 includes the GPU 95, even when no GPU is included as in the communication terminal 5d, the communication terminal 5 can perform calculation processing needed for graphics display with the dongle 99 attached as illustrated in FIG. 2.
Functional Configuration of the Embodiment
The functional configuration of the embodiment is described next with reference to FIG. 9 to FIG. 16.
Functional Configuration of the Distribution Control System
Described first with reference to FIG. 9 is the functional configuration of the distribution control system 2. FIG. 9 is a functional block diagram illustrating mainly the functions of the distribution control system. FIG. 9 illustrates a functional configuration where the distribution control system 2 distributes video (sound) data to the communication terminal 5f1, and the distribution control system 2 has the same functional configuration also where the distribution destination is other than the communication terminal 5f1. Although the distribution control system 2 includes a plurality of distribution engine servers, the following describes a case where a single distribution engine server is included, in order to simplify the description.
As illustrated in FIG. 9, the distribution control system 2 has functional components in FIG. 9 implemented by the hardware configuration including a processor such as the CPU 201 or the GPU 215 and the programs illustrated in FIG. 7.
Specifically, the distribution control system 2 includes the browser 20, a transmitter/receiver 21, a browser management unit 22, a transmission first-in first-out (FIFO) buffer 24, a time management unit 25, a time acquisition unit 26, a channel adaptive controller 27, the encoder bridge unit 30, a transmitter/receiver 31, a reception FIFO 34, a recognition unit 35, a delay information acquisition unit 37a, a channel adaptive controller 37b, and the decoding unit 40. The distribution control system 2 further includes a storage unit 2000 implemented by the HDD 204 illustrated in FIG. 7. This storage unit 2000 stores therein recognition information (described below) output from the recognition unit 35 and sent through the browser management unit 22. The content data acquired by the browser 20 can be temporarily stored in the storage unit 2000 as a cache.
Among the above functional components, the browser 20 is a browser that operates within the distribution control system 2. The browser 20 is kept updated along with the enrichment of web content at all times. The browser 20 includes Media Player, Flash Player, JavaScript (registered trademark), CSS, and HTML Renderer. JavaScript includes the standardized product and one unique to the distribution system 1.
Media Player is a browser plug-in for reproducing multimedia files such as video (sound) files within the browser 20. Flash Player is a browser plug-in for reproducing flash content within the browser 20. The unique JavaScript is a JavaScript group that provides the application programming interface (API) of services unique to the distribution system 1. CSS is a technology for efficiently defining the appearance and style of web pages described in HTML. HTML Renderer is an HTML rendering engine.
A renderer renders content data such as web content data as image (sound) data, thereby generating pieces of frame data as still image (sound) data. As illustrated in FIG. 6, the renderer is also a layout engine that lays out a plurality of kinds of content ([A], [p1], [p2], [E1], [E2]).
The distribution system 1 according to the present embodiment provides the browsers 20 within the distribution control system 2, and a cloud browser for use in a user session is selected from the browsers 20. The following describes a case where the single browser 20 is provided, in order to simplify the description.
The transmitter/receiver 21 transmits and receives various kinds of data, various kinds of requests, various kinds of instructions, and the like to and from the terminal management system 7 and the web server 8. For example, the transmitter/receiver 21 acquires web content data from a content site at the web server 8. The transmitter/receiver 21 outputs the various kinds of data acquired from the terminal management system 7 to the functional components within the distribution control system 2 and controls the functional components within the distribution control system 2 based on the various kinds of data, various kinds of requests, various kinds of instructions, and the like acquired from the terminal management system 7. For example, for the browsers 20, the transmitter/receiver 21 outputs a request for switching distribution pattern from the terminal management system 7, to the browser management unit 22. The browser management unit 22 then controls switching from one browser to another browser among the browsers. Based on the request for switching distribution from the terminal management system 7, the transmitter/receiver 21 performs the switching of combinations of the components within the encoder bridge unit 30 illustrated in FIG. 15 and FIG. 16.
The browser management unit 22 manages the browser 20. For example, the browser management unit 22 instructs the browser 20 to start up and exit, and numbers an encoder ID at startup or exit. The encoder ID is identification information that the browser management unit 22 numbers in order to manage the process of the encoder bridge unit 30. The browser management unit 22 numbers and manages a browser ID every time the browser 20 is started up. The browser ID is identification information that the browser management unit 22 numbers in order to manage the process of the browser 20 to identify the browser 20.
The browser management unit 22 acquires various kinds of operation data from the communication terminal 5 through the transmitter/receiver 31 and outputs them to the browser 20. The operation data is data generated through operation events (operations through the keyboard 211, the mouse 212, and the like, strokes with an electronic pen P and the like) on the communication terminal 5. When the communication terminal 5 provides various sensors such as a temperature sensor, a humidity sensor, and an acceleration sensor, the browser management unit 22 acquires sensor information that contains output signals of the sensors from the communication terminal 5 and outputs it to the browser 20. The browser management unit 22 further acquires image (sound) data from the recognition unit 35 and outputs it to the browser 20, and acquires recognition information described below from the recognition unit 35 and stores it in the storage unit 2000. The browser management unit 22 acquires video (sound) data from the reception FIFO buffer 34 and outputs it to the browser 20.
The transmission FIFO 24 is a buffer that stores therein pieces of frame data as still image (sound) data generated by the browser 20.
The time management unit 25 manages time T unique to the distribution control system 2.
The time acquisition unit 26 performs time adjustment processing in conjunction with a time controller 56 in the communication terminal 5 described below. Specifically, the time acquisition unit 26 acquires time information (T) indicating time T in the distribution control system 2 from the time management unit 25, receives time information (t) indicating time t in the communication terminal 5 from the time controller 56 described below through the transmitter/receiver 31 and a transmitter/receiver 51, and transmits the time information (t) and the time information (T) to the time controller 56.
The channel adaptive controller 27 calculates reproduction delay time U based on transmission delay time information (D) and calculates operation conditions such as the frame rate and the data resolution of a converter 10 in the encoder bridge unit 30. This reproduction delay time U is time for delaying reproduction through the buffering of data until being reproduced. In other words, the channel adaptive controller 27 changes the operation of the encoder bridge unit 30 based on the transmission delay time information (D) and the size of the data (e.g., the number of bits or the number of bytes). As described later, the transmission delay time information (D) indicates frequency distribution information based on a plurality of pieces of transmission delay time D1 acquired from a reproduction controller 53 by a delay information acquisition unit 57 of the communication terminal 5. Each piece of transmission delay time D1 indicates time from the point when the video (sound) data is transmitted from the distribution control system 2 to the point when it is received by the communication terminal 5.
The encoder bridge unit 30 outputs pieces of frame data as still image (sound) data generated by the browser 20 to the converter 10 in the encoder bridge unit 30 described below. Respective processings are performed based on the operation conditions calculated by the channel adaptive controller 27. The encoder bridge unit 30 will be described in more detail with reference to FIG. 15 and FIG. 16. FIG. 15 is a detailed diagram of the encoder bridge unit. FIG. 16 is a functional block diagram illustrating the functions of the converter.
As illustrated in FIG. 15, the encoder bridge unit 30 includes a creating/selecting/transferring unit 310, a selecting unit 320, and a plurality of converters (10a, 10b, 10c) provided therebetween. Although the three converters are illustrated here, any number of them may be provided. In the following, any converter is referred to as a “converter 10”.
The converter 10 converts the data format of the pieces of frame data as still image (sound) data generated by the browser 20 into a data format of H.264 or the like allowing distribution of the data to the communication terminal 5 through the communication network 9. For that purpose, as illustrated in FIG. 16, the converter 10 includes a trimming unit 11, a resizing unit 12, a dividing unit 13, and the encoding unit 19, thereby performing a variety of processings on the frame data. The trimming unit 11, the resizing unit 12, and the dividing unit 13 do not perform any processing on sound data.
The trimming unit 11 performs processing to cut out part of a still image. The resizing unit 12 changes the scale of a still image. The dividing unit 13 divides a still image as illustrated in FIG. 5.
The encoding unit 19 encodes the pieces of frame data as still image (sound) data generated by the browser 20, thereby converting them to distribute video (sound) data to the communication terminal 5 through the communication network 9. When the video is not in motion (when there is no inter-frame update (change)), a skip frame (may be sometimes referred to as frame skip) is thereafter inserted until the video moves to save a band.
When sound data is generated together with still image data by rendering, both pieces of data are encoded, and when only sound data is generated, only encoding is performed to compress data without trimming, resizing, and dividing.
The creating/selecting/transferring unit 310 creates a new converter 10, selects pieces of frame data as still image (sound) data to be input to a converter 10 that is already generated, and transfers the pieces of frame data. In the creation, the creating/selecting/transferring unit 310 creates a converter 10 capable of conversion according to the capability of the communication terminal 5 to reproduce video (sound) data. In the selection, the creating/selecting/transferring unit 310 selects a converter 10 that is already generated. For example, in starting distribution to the communication terminal 5b in addition to distribution to the communication terminal 5a, the same video (sound) data as video (sound) data being distributed to the communication terminal 5a may be distributed to the communication terminal 5b. In such a case, furthermore, when the communication terminal 5b has the same level of capability as the capability of the communication terminal 5a to reproduce video (sound) data, the creating/selecting/transferring unit 310 uses the converter 10a that is already created for the communication terminal 5a, without creating a new converter 10b for the communication terminal 5b. In the transfer, the creating/selecting/transferring unit 310 transfers the pieces of frame data stored in the transmission FIFO 24 to the converter 10.
The selecting unit 320 selects a desired one from the converters 10 that are already generated. The selection by the creating/selecting/transferring unit 310 and the selecting unit 320 allows distribution in various patterns as illustrated in FIG. 6.
The transmitter/receiver 31 transmits and receives various data, requests, and the like to and from the communication terminal 5. This transmitter/receiver 31 transmits various data, requests, and the like to the communication terminal 5 through the communication network 9 from the cloud, thereby allowing the distribution control system 2 to distribute various data, requests, and the like to the communication terminal 5. For example, in the login processing of the communication terminal 5, the transmitter/receiver 31 transmits, to the transmitter/receiver 51 of the communication terminal 5, authentication screen data for prompting a user for a login request. The transmitter/receiver 31 also performs data transmission and data reception to and from user applications of the communication terminal 5 and device applications of the communication terminal 5 by a protocol unique to the distribution system 1 through a Hypertext Transfer Protocol over Secure Socket Layer (HTTPS) server. This unique protocol is an HTTPS-based application layer protocol for transmitting and receiving data in real time without being interrupted between the distribution control system 2 and the communication terminal. The transmitter/receiver 31 also performs transmission response control, real-time data creation, command transmission, reception response control, reception data analysis, and gesture conversion.
The transmission response control is processing to manage an HTTPS session for downloading requested from the communication terminal 5 in order to transmit data from the distribution control system 2 to the communication terminal 5. The response of the HTTPS session for downloading does not end immediately and holds for a certain period of time (one to several minutes). The transmitter/receiver 31 dynamically writes data to be sent to the communication terminal 5 in the body part of the response. In order to eliminate costs for reconnection, another request is allowed to reach from the communication terminal before the previous session ends. By putting the transmitter/receiver 31 on standby until the previous request is completed, overhead can be eliminated even when reconnection is performed.
The real-time data creation is processing to give a unique header to the data of compressed video (and a compressed sound) generated by the encoding unit 19 in FIG. 16 and write it in the body part of HTTPS.
The command transmission is processing to generate command data to be transmitted to the communication terminal 5 and write it in the body part of HTTPS directed to the communication terminal 5.
The reception response control is processing to manage an HTTPS session requested from the communication terminal 5 in order for the distribution control system 2 to receive data from the communication terminal 5. The response of this HTTPS session does not end immediately and is held for a certain period of time (one to several minutes). The communication terminal 5 dynamically writes data to be sent to the transmitter/receiver 31 of the distribution control system 2 in the body part of the request.
The reception data analysis is processing to analyze the data transmitted from the communication terminal 5 by type and deliver the data to a necessary process.
The gesture conversion is processing to convert a gesture event input to the communication terminal 5f as the electronic blackboard by a user with an electronic pen or in handwriting into data in a format receivable by the browser 20.
The reception FIFO 34 is a buffer that stores therein video (sound) data decoded by the decoding unit 40.
The recognition unit 35 performs processing on image (sound) data received from the communication terminal 5. Specifically, for example, the recognition unit 35 recognizes the face, age, sex, and the like of a human or animal based on images taken by a camera 62 for signage. In a workplace, the recognition unit 35 performs name tagging by face recognition and processing of replacing a background image based on images taken by the camera 62. The recognition unit 35 stores recognition information indicating the recognized details in the storage unit 2000. The recognition unit 35 achieves speeding up by performing processing with a recognition expansion board.
The delay information acquisition unit 37a is used for the processing of upstream channel adaptive control and corresponds to the delay information acquisition unit 57 for the communication terminal 5 for use in the processing of downstream channel adaptive control. Specifically, the delay information acquisition unit 37a acquires transmission delay time information (d1) indicating transmission delay time d1 from the decoding unit 40 and holds it for a certain period of time, and when a plurality of pieces of transmission delay time information (d1) are acquired, outputs to the channel adaptive controller 37b transmission delay time information (d) indicating frequency distribution information based on a plurality of pieces of transmission delay time d1. The transmission delay time information (d1) indicates time from the point when the video (sound) data is transmitted from the communication terminal 5 to the point when it is received by the distribution control system 2.
The channel adaptive controller 37b is used for the processing of the upstream channel adaptive control and corresponds to the channel adaptive controller 27 for use in the processing of the downstream channel adaptive control. Specifically, the channel adaptive controller 37b calculates the operation conditions of the encoding unit 60 for the communication terminal 5 based on the transmission delay time information (d). The channel adaptive controller 37b transmits a channel adaptive control signal indicating operation conditions such as a frame rate and data resolution to the encoding unit 60 of the communication terminal 5 through the transmitter/receiver 31 and the transmitter/receiver 51.
The decoding unit 40 decodes the video (sound) data transmitted from the communication terminal 5. The decoding unit 40 also outputs the transmission delay time information (d1) indicating transmission delay time d1 to the delay information acquisition unit 37a. 
Functional Configuration of Communication Terminal
The functional configuration of the communication terminal 5 is described with reference to FIG. 10. FIG. 10 is a functional block diagram illustrating mainly the functions of the communication terminal. The communication terminal 5 is a terminal serving as an interface for a user to perform a login to the distribution system 1, start and stop the distribution of video (sound) data, and the like.
As illustrated in FIG. 10, the communication terminal 5 has functional components in FIG. 10 implemented by the hardware configuration including the CPU 201 and the programs illustrated in FIG. 7. When the communication terminal 5 becomes communicable with the other terminals and systems through the communication network 9 by the insertion of the dongle 99 as illustrated in FIG. 2, the communication terminal 5 has the functional components in FIG. 10 implemented by the hardware configuration and the programs illustrated in FIG. 7 and FIG. 8.
Specifically, the communication terminal 5 includes a decoding unit 50, the transmitter/receiver 51, an operating unit 52, the reproduction controller 53, a rendering unit 55, the time controller 56, the delay information acquisition unit 57, a display unit 58, and the encoding unit 60. The communication terminal 5 further includes a storage unit 5000 implemented by the RAM 203 illustrated in FIG. 7. This storage unit 5000 stores therein time difference information (Δ) indicating a time difference Δ described below and time information (t) indicating time t in the communication terminal 5.
The decoding unit 50 decodes video (sound) data distributed from the distribution control system 2 and output from the reproduction controller 53.
The transmitter/receiver 51 transmits and receives various data, requests, and the like to and from the transmitter/receiver 31 of the distribution control system 2 and a transmitter/receiver 71a of the terminal management system 7. For example, in the login processing of the communication terminal 5, the transmitter/receiver 51 performs a login request to the transmitter/receiver 71 of the terminal management system 7 in response to the startup of the communication terminal 5 by the operating unit 52.
The operating unit 52 performs processing to receive operations input by a user, such as input and selection with a power switch, a keyboard, a mouse, the electronic pen P, and the like, and transmits them as operation data to the browser management unit 22 of the distribution control system 2.
The reproduction controller 53 buffers the video (sound) data (a packet of real-time data) received from the transmitter/receiver 51 and outputs it to the decoding unit 50 with the reproduction delay time U taken into account. The reproduction controller 53 also calculates the transmission delay time information (D1) indicating transmission delay time D1, and outputs the transmission delay time information (D1) to the delay information acquisition unit 57.
The rendering unit 55 renders the data decoded by the decoding unit 50.
The time controller 56 performs time adjustment processing in conjunction with the time acquisition unit 26 of the distribution control system 2. Specifically, the time controller 56 acquires time information (t) indicating time t in the communication terminal 5 from the storage unit 5000. The time controller 56 issues a request for time information (T) indicating time T in the distribution control system 2 to the time acquisition unit 26 of the distribution control system 2 through the transmitter/receiver 51 and the transmitter/receiver 31. In this case, the time information (t) is transmitted concurrently with the request for the time information (T).
The delay information acquisition unit 57 acquires from a reproduction controller 53 the transmission delay time information (D1) indicating transmission delay time D1 and holds it for a certain period of time, and when a plurality of pieces of transmission delay time information (D1) are acquired, outputs transmission delay time information (D) indicating frequency distribution information based on a plurality of pieces of transmission delay time D1 to the channel adaptive controller 27 through the transmitter/receiver 51 and the transmitter/receiver 31. The transmission delay time information (D) is transmitted, for example, once in a hundred frames.
The display unit 58 reproduces the data rendered by the rendering unit 55.
The encoding unit 60 transmits video (sound) data [E] that is acquired from a built-in microphone 213 or the camera 62 and a microphone 63 that are externally attached, and is encoded; time information (t0) that indicates the current time t0 in the communication terminal 5 and is acquired from the storage unit 5000; and the time difference information (Δ) that indicates the time difference Δ in between the distribution control system 2 and the communication terminal 5 and is acquired from the storage unit 5000, to the decoding unit 40 of the distribution control system 2 through the transmitter/receiver 51 and the transmitter/receiver 31. The time difference Δ indicates a difference between the time managed independently by the distribution control system 2 and the time managed independently by the communication terminal 5. The encoding unit 60 changes the operation conditions of the encoding unit 60 based on the operation conditions indicated by the channel adaptive control signal received from the channel adaptive controller 37b. The encoding unit 60, in accordance with the new operation conditions, transmits the video (sound) data [E] that is acquired from the camera 62 and the microphone 63 and is encoded; the time information (t0) that indicates the current time t0 in the communication terminal 5 and is acquired from the storage unit 5000; and the time difference information (Δ) that indicates the time difference Δ and is acquired from the storage unit 5000, to the decoding unit 40 of the distribution control system 2 through the transmitter/receiver 51 and the transmitter/receiver 31.
The built-in microphone 213, the externally attached camera 62 and microphone 63, and the like are examples of an inputting unit and are devices that need encoding and decoding. The inputting unit may output touch data and smell data in addition to video (sound) data.
The inputting unit includes various sensors such as a temperature sensor, a direction sensor, an acceleration sensor, and the like.
Functional Configuration of the Terminal Management System
The functional configuration of the terminal management system 7 is described with reference to FIG. 11.
FIG. 11 is a functional block diagram illustrating the functions of the terminal management system.
As illustrated in FIG. 11, the terminal management system 7 has functional components in FIG. 11 implemented by the hardware configuration including the CPU 201 and the programs illustrated in FIG. 7.
Specifically, the terminal management system 7 includes the transmitter/receiver 71a, a transmitter/receiver 71b, and an authentication unit 75. The terminal management system 7 further includes a storage unit 7000 implemented by the HDD 204 illustrated in FIG. 7. The storage unit 7000 stores therein distribution destination selection menu data, a terminal management table 7010, and an available terminal management table 7020.
The distribution destination selection menu is data indicating such a destination selection menu screen as illustrated in FIG. 12.
As illustrated in FIG. 13, the terminal management table 7010 manages the terminal ID of the communication terminal 5, a user certificate, contract information when a user uses the services of the distribution system 1, the terminal type of the communication terminal 5, setting information indicating the home uniform resource locators (URLs) of the respective communication terminals 5, the execution environment information of the communication terminals 5, a shared ID, installation position information, and display name information in association with each other. The execution environment information includes “favorites”, “previous Cookie information”, and “cache file” of each communication terminal 5, which are sent to the distribution control system 2 together with the setting information after the login of the communication terminal 5 and are used for performing an individual service on the communication terminal 5.
The shared ID is an ID that is used when each user distributes the same video (sound) data as video (sound) data being distributed to his/her own communication terminal 5 to the other communication terminals 5, thereby performing remote sharing processing, and is identification information that identifies the other communication terminals and the other communication terminal group. For example, the shared ID of the terminal ID “t006” is “v006”, the shared ID of the terminal ID “t007” is “v006”, and the shared ID of the terminal ID “t008” is “v006”. When the communication terminal 5a with the terminal ID “t001” issues a request for remote sharing processing with the communication terminals (5f1, 5f2, 5f3) with the terminal ID “v006”, the distribution control system 2 distributes the same video (sound) data as video (sound) data being distributed to the communication terminals 5a to the communication terminals (5f1, 5f2, 5f3). However, when the communication terminals 5a and the communication terminals (5f1, 5f2, 5f3) are different in the resolution of the display unit 58, the distribution control system 2 distributes the video (sound) data accordingly.
As illustrated in FIG. 5, for example, the installation position information indicates an installation position when the communication terminals (5f1, 5f2, 5f3) are arranged side by side. The display name information is information indicating the details of the display name in the distribution destination selection menu illustrated in FIG. 12.
As illustrated in FIG. 14, the available terminal management table 7020 manages, in association with each terminal ID, a shared ID indicating a communication terminal or a communication terminal group with which the communication terminal 5 indicated by the terminal ID can perform remote sharing processing.
The functional components are described with reference to FIG. 11.
The transmitter/receiver 71a transmits and receives various data, requests, and the like to and from the communication terminal 5. For example, the transmitter/receiver 71a receives a login request from the transmitter/receiver 51 of the communication terminal 5 and transmits an authentication result of the login request to the transmitter/receiver 51.
The transmitter/receiver 71b transmits and receives various data, requests, and the like to and from the distribution control system 2. For example, the transmitter/receiver 71b receives a request for the data of the distribution destination selection menu from the transmitter/receiver 21 of the distribution control system 2 and transmits the data of the distribution destination selection menu to the transmitter/receiver 21.
The authentication unit 75 searches the terminal management table 7010 based on the terminal. ID and the user certificate received from the communication terminal 5, thereby determining whether there is the same combination of a terminal ID and a user certificate, thereby authenticating the communication terminal 5.
Operations and Processing of the Embodiment
Operations and pieces of processing of the present embodiment are described with reference to FIG. 17 to FIG. 24. These pieces of processing are performed by the CPUs of the distribution control system 2, the communication terminal 5, the terminal management system 7, and the web server 8 in accordance with the respective programs stored therein.
Basic Distribution Processing
Specific distribution processing in the basic distribution method illustrated in FIG. 3 is described with reference to FIG. 17. FIG. 17 is a sequence diagram illustrating the basic distribution processing of the distribution control system. Although described here is a case of issuing a login request through the communication terminal 5a, a login may be performed through the communication terminal 5 other than the communication terminal 5a. 
As illustrated in FIG. 17, when a user turns on the communication terminal 5a, the transmitter/receiver 51 of the communication terminal 5a issues a login request to the transmitter/receiver 71a of the terminal management system (Step S21). The transmitter/receiver 71a receives the login request. This login request includes the terminal ID and the user certificate of the communication terminal 5a. The authentication unit 75 then acquires the terminal ID and the user certificate of the communication terminal 5a. 
The authentication unit 75 searches the terminal management table 7010 based on the terminal ID and the user certificate, thereby determining whether there is the same combination of a terminal ID and a user certificate, thereby authenticating the communication terminal 5a (Step S22). The following describes a case where the same combination of a terminal ID and a user certificate is present in the terminal management table 7010, that is, where the communication terminal 5a is determined as a valid terminal in the distribution system 1.
The transmitter/receiver 71a of the terminal management system 7 transmits the IP address of the distribution control system 2 to the transmitter/receiver 51 of the communication terminal 5a (Step S23). The IP address of the distribution control system 2 is acquired from the distribution control system 2 by the terminal management system 7 and is stored in the storage unit 7000 in advance.
The transmitter/receiver 71b of the terminal management system 7 issues a startup request of the browser 20 to the transmitter/receiver 21 of the distribution control system 2 (Step S24). The transmitter/receiver 21 receives the startup request of the browser 20. The browser management unit 22 starts up the browser 20 based on the startup request received by the transmitter/receiver 21 (Step S25).
The creating/selecting/transferring unit 310 of the encoder bridge unit 30 creates the converter 10 in accordance with the capability of the communication terminal 5a to reproduce video (sound) data (the resolution of the display and the like) and the type of content (Step S26). Next, the transmitter/receiver 21 issues a request for content data [A] to the web server 8 in accordance with an instruction by the browser 20 (Step S27). In response thereto, the web server 8 reads the requested content data [A] from its own storage unit (not illustrated) (Step S28). The web server 8 then transmits the content data [A] to the transmitter/receiver 21 of the distribution control system 2 (Step S29).
The browser 20 renders the content data [A] received by the transmitter/receiver 21, thereby generating pieces of frame data as still image (sound) data and outputs them to the transmission FIFO 24 (Step S30). The converter 10 encodes the pieces of frame data stored in the transmission FIFO 24, thereby converting them into video (sound) data [A] to be distributed to the communication terminal 5a (Step S31).
The transmitter/receiver 31 transmits the video (sound) data [A] to the transmitter/receiver 51 of the communication terminal 5a (Step S32). The transmitter/receiver 51 of the communication terminal 5a receives the video (sound) data [A] and outputs it to the reproduction controller 53.
In the communication terminal 5a, the decoding unit 50 acquires the video (sound) data [A] from the reproduction controller 53 and decodes it (Step S33). After that, a speaker 61 reproduces sound based on decoded sound data [A], and the display unit 58 reproduces video based on video data [A] acquired from the decoding unit 50 and rendered by the rendering unit 55 (Step S34).
Processing of Composite Distribution Using a Plurality of Communication Terminals
The following describes communication processing using a plurality of communication terminals through the distribution control system with reference to FIG. 18. FIG. 18 is a sequence diagram illustrating distribution processing using a plurality of communication terminals through the distribution control system. Described here is specific processing for the communication terminals 5 in the pattern illustrated in FIG. 6. Because the processing here includes login processing, browser startup, and the like similar to Steps S21 to S29, description starts with the processing corresponding to Step S29.
As illustrated in FIG. 18, the transmitter/receiver 21 of the distribution control system 2 receives content data [A] from the web server 8 (Step S41). The browser 20 renders the content data [A], thereby generating pieces of frame data as still image (sound) data and outputs them to the transmission FIFO 24 (Step S42).
When the encoding unit 60 of the communication terminal 5f1 receives the input of content data as video (sound) data [E] from the camera 62 and the microphone 63 (Step S43), the encoding unit 60 encodes the content data [E] (Step S44). The transmitter/receiver 51 transmits the content data [E] encoded by the encoding unit 60 to the transmitter/receiver 31 of the distribution control system 2 (Step S45). The transmitter/receiver 31 of the distribution control system 2 receives the content data [E].
The decoding unit 40 of the distribution control system 2 decodes the content data [E] received by the transmitter/receiver 31 and outputs it to the reception FIFO 34 (Step S46). The browser 20 renders the content data [E] stored in the reception FIFO 34, thereby generating frame data [E] as still image (sound) data and outputs it to the transmission FIFO 24 (Step S47). In this case, the browser 20 outputs the data in a layout in which the content data [E] is combined with the content data [A] already acquired.
In addition, when the operating unit 52 of the communication terminal 5f1 receives the input of a stroke operation with the electronic pen P1 (Step S48), the transmitter/receiver 51 transmits operation data [p] indicating the details of the stroke operation received by the operating unit 52 to the transmitter/receiver 31 of the distribution control system 2 (Step S49). The transmitter/receiver 31 of the distribution control system 2 receives the operation data [p]. The browser management unit 22 outputs the operation data [p] received by the transmitter/receiver 31 to the browser 20.
The browser 20 renders the operation data [p], thereby generating frame data [p] as still image (sound) data and outputs it to the transmission FIFO 24 (Step S50). In this case, the browser 20 outputs the data in a layout in which the operation data [p] is combined with the content data ([A], [E]) already acquired.
The converter 10 encodes pieces of frame data ([A], [E], [p]) as still image (sound) data stored in the transmission FIFO 24, thereby converting them into video (sound) data ([A], [E], [p]) to be distributed to the communication terminals 5f1 and 5f2 (Step S51).
The transmitter/receiver 31 acquires the encoded video (sound) data ([A], [E], [p]) from the encoder bridge unit 30 including the converter 10 and transmits it to the transmitter/receiver 51 of the communication terminal 5f1 (Step S52-1). The transmitter/receiver 51 of the communication terminal 5f1 receives the video (sound) data ([A], [E], [p]), and the reproduction controller 53 of the communication terminal 5f1 acquires the video (sound) data ([A], [E], [p]) from the transmitter/receiver 51. In the communication terminal 5f1, the decoding unit 50 acquires the video (sound) data ([A], [E], [p]) from the reproduction controller 53 and decodes it (Step S53-1). After that, the speaker 61 reproduces sound based on decoded sound data ([A], [E]), and the display unit 58 reproduces video based on video data ([A], [E], [p]) acquired from the decoding unit 50 and rendered by the rendering unit 55 (Step S54-1).
For the communication terminal 5f2, as is the case with Step S52-1, the transmitter/receiver 31 acquires the encoded video (sound) data ([A], [E], [p]) from the encoder bridge unit 30 and transmits it to the transmitter/receiver 51 of the communication terminal 5f2 (Step S52-2). The reproduction controller 53 of the communication terminal 5f2 acquires the video (sound) data ([A], [E], [p]). In the communication terminal 5f1, the decoding unit 50 acquires the video (sound) data ([A], [E], [p]) from the reproduction controller 53 and decodes it (Step S53-2). After that, the speaker 61 reproduces sound based on decoded sound data ([A], [E]), and the display unit 58 reproduces video based on video data ([A], [E], [p]) acquired from the decoding unit 50 and rendered by the rendering unit 55 (Step S54-2).
Thus, the same video (sound) as the video (sound) output to the communication terminal 5f1 is output also to the communication terminal 5f2.
Processing of Time Adjustment
The processing of time adjustment is described with reference to FIG. 19. FIG. 19 is a sequence diagram illustrating the processing of time adjustment.
In order to acquire time indicating when the transmitter/receiver 51 issues a request for the time information (T) to the distribution control system 2, the time controller 56 of the communication terminal 5 acquires time information (ts) in the communication terminal 5 from the storage unit 5000 (Step S81). The transmitter/receiver 51 issues a request for the time information (T) to the transmitter/receiver 31 (Step S82). In this case, the time information (ts) is transmitted concurrently with the request for the time information (T).
In order to acquire time indicating when the transmitter/receiver 31 received the request at Step S82, the time acquisition unit 26 of the distribution control system 2 acquires time information (Tr) in the distribution control system 2 from the time management unit 25 (Step S83). In order to acquire time indicating when the transmitter/receiver 31 responds to the request at Step S82, the time acquisition unit 26 further acquires time information (Ts) in the distribution control system 2 from the time management unit 25 (Step S84). The transmitter/receiver 31 then transmits the time information (ts, Tr, Ts) to the transmitter/receiver 51 (Step S85).
In order to acquire time indicating when the transmitter/receiver 51 received the response at Step S85, the time controller 56 of the communication terminal 5 acquires time information (tr) in the communication terminal 5 from the storage unit 5000 (Step S86).
The time controller 56 of the communication terminal 5 calculates the time difference Δ between the distribution control system 2 and the communication terminal 5 (Step S87). This time difference Δ is given by Equation (1) below.

Δ=((Tr+Ts)/2)−((tr+ts)/2)  (1)

The time controller 56 stores the time difference information (Δ) indicating the time difference Δ in the storage unit 5000 (Step S88). The series of processing of time adjustment is performed, for example, regularly every minute.
Processing of Downstream Channel Adaptive Control
Described next with reference to FIG. 20 is the processing of channel adaptive control on data transmitted from the distribution control system 2 to the communication terminal 5 (downstream). FIG. 20 is a sequence diagram illustrating the processing of channel adaptive control on data transmitted from the distribution control system to the communication terminal.
First, the channel adaptive controller 27 of the distribution control system 2 calculates reproduction delay time information (U) indicating reproduction delay time U for delaying reproduction by buffering until the reproduction controller 53 of the communication terminal 5 reproduces video (sound) data, and outputs the reproduction delay time information (U) to the encoder bridge unit 30 (Step S101).
The transmitter/receiver 31 then acquires the reproduction delay time information (U) from the encoder bridge unit 30 and transmits it to the transmitter/receiver 51 of the communication terminal 5 (Step S102). The transmitter/receiver 51 of the communication terminal 5 receives the reproduction delay time information (U). The encoder bridge unit 30 adds time information (T0) indicating time T0 acquired from the time management unit 25, as a time stamp to the video (sound) data [A] acquired from the transmission FIFO 24 and encoded, for example (Step S103). The transmitter/receiver 31 transmits the video (sound) data and the time information (T0) of the distribution control system 2 to the transmitter/receiver 51 of the communication terminal 5 (Step S104). The transmitter/receiver 51 of the communication terminal 5 receives the time information (T0) of the distribution control system 2 and outputs the video (sound) data and the time information (T0) to the reproduction controller 53.
In the communication terminal 5, based on the reproduction delay time information (U) acquired at Step S102, the time information (T0) acquired at Step S104, and the time difference information (Δ) stored in the storage unit 5000 at Step S88, the reproduction controller 53 waits until the time (T0+U−Δ) in the communication terminal 5 and then outputs the video (sound) data acquired at Step S104 to the decoding unit 50. This causes the speaker 61 to output sound and the display unit 58 to reproduce video through the rendering unit 55 (Step S105). This causes only video (sound) data received by the communication terminal 5 within the range of the reproduction delay time U given by Equation (2) below to be reproduced, while video (sound) data out of the range is delayed excessively and is deleted without being reproduced.

U≧(t0+Δ)−T0  (2)

The reproduction controller 53 reads the current time t0 in the communication terminal 5 from the storage unit 5000 (Step S106). This time t0 indicates time in the communication terminal 5 when the communication terminal 5 received video (sound) data from the distribution control system 2. The reproduction controller 53 further reads the time difference information (Δ) indicating the time difference Δ stored at Step S86 in the storage unit 5000 (Step S107). The reproduction controller 53 then calculates the transmission delay time D1 indicating time from the point when the video (sound) data is transmitted from the distribution control system 2 to the point when it is received by the communication terminal 5 (Step S108). This calculation is performed with Equation (3) below; when the communication network 9 becomes congested, the transmission delay time D1 becomes longer.

D1=(t0+Δ)−T0  (3)

The delay information acquisition unit 57 acquires transmission delay time information (D1) indicating the transmission delay time D1 from the reproduction controller 53 and holds it for a certain period of time, and when a plurality of pieces of transmission delay time information (D1) are acquired, outputs to the transmitter/receiver 51 the transmission delay time information (D) indicating frequency distribution information based on a plurality of pieces of transmission delay time D1 (Step S109). The transmitter/receiver 51 transmits the transmission delay time information (D) to the transmitter/receiver 31 of the distribution control system 2 (Step S110). The transmitter/receiver 31 of the distribution control system 2 receives the transmission delay time information (D) and outputs the transmission delay time information (D) to the channel adaptive controller 27.
The channel adaptive controller 27 of the distribution control system 2 newly calculates reproduction delay information U′ based on the transmission delay time information (D) and calculates the operation conditions such as the frame rate and the data resolution of the converter 10 and outputs them to the encoder bridge unit 30 (Step S111). In other words, the channel adaptive controller 27 changes the operation of the encoder bridge unit 30 based on the transmission delay time information (D) and the size of the data (e.g., the number of bits or the number of bytes).
The transmitter/receiver 31 acquires reproduction delay time information (U′) indicating the new reproduction delay time U′ calculated at Step S111 from the encoder bridge unit 30 and transmits the reproduction delay time information (U′) to the transmitter/receiver 51 of the communication terminal 5 (Step S112). The transmitter/receiver 51 of the communication terminal 5 receives the reproduction delay time information (U′).
The converter 10 of the encoder bridge unit 30 changes the operation conditions of the converter 10 based on the channel adaptive control signal indicating the operation conditions (Step S113). For example, when the transmission delay time D1 is excessively long and the reproduction delay time U is made longer in accordance with the transmission delay time D1, reproduction time at the speaker 61 and the display unit 58 becomes delayed excessively. As a result, there is a limit to making the reproduction delay time U longer. In view of this, the channel adaptive controller 27 not only causes the encoder bridge unit 30 to change the reproduction delay time U to be the reproduction delay time U′ but also causes the converter 10 to decrease the frame rate of video (sound) data and to decrease the resolution of video (sound) data, thereby addressing the congestion of the communication network 9. This causes the encoder bridge unit 30, as with Step S103, to add the current time information (T0) to the video (sound) data [A] as a time stamp in accordance with the changed operation conditions (Step S104). The video (sound) data is thus added (Step S114). The transmitter/receiver 31 transmits the video (sound) data and the time information (T0) of the distribution control system 2 to the transmitter/receiver 51 of the communication terminal 5 (Step S115). The transmitter/receiver 51 of the communication terminal 5 receives the video (sound) data and the time information (T0) of the distribution control system 2 and outputs the video (sound) data and the time information (T0) to the reproduction controller 53.
In the communication terminal 5, based on the reproduction delay time information (U′) acquired at Step S112, the time information (T0) acquired at Step S115, and the time difference information (Δ) stored in the storage unit 5000 at Step S88, the reproduction controller 53 waits until the time (T0+U′−Δ) in the communication terminal 5 and then outputs the video (sound) data to the decoding unit 50, thereby, as with Step S105, causing the speaker 61 to output sound and the display unit 58 to reproduce video through the rendering unit 55 (Step S116). This is followed by the processing at and after Step S106. Thus, the processing of the downstream channel adaptive control is performed continuously.
Processing of Upstream Channel Adaptive Control
Described next with reference to FIG. 21 is the processing of channel adaptive control on data transmitted from the communication terminal 5 to the distribution control system 2 (upstream). FIG. 20 is a sequence diagram illustrating the processing of channel adaptive control on data transmitted from the communication terminal to the distribution control system.
First, the encoding unit 60 of the communication terminal 5 encodes content data as video (sound) data [E] input from the camera 62 and the microphone 63 (Step S121). In this situation, the encoding unit 60 acquires the time information (t0) indicating the current time t0 in the communication terminal 5 and the time difference information (Δ) indicating the time difference Δ from the storage unit 5000 and does not encode them. The transmitter/receiver 51 transmits the video (sound) data [E], the time information (t0), and the time difference information (Δ) to the transmitter/receiver 31 of the distribution control system 2 (Step S122). The transmitter/receiver 31 of the distribution control system 2 receives the video (sound) data [E], the time information (t0), and the time difference information (Δ).
In the distribution control system 2, the decoding unit 40 reads time T0 indicating when the video (sound) data [E] and the like were received at Step S112 from the time management unit 25 (Step S123). The decoding unit 40 then calculates transmission delay time d1 indicating time from the point when the video (sound) data is transmitted from the communication terminal 5 to the point when it is received by the distribution control system 2 (Step S124). This calculation is performed by Equation (4) below; when the communication network 9 becomes congested, the transmission delay time d1 becomes longer.

d1=T0−(t0+Δ)  (4)

As is the case with the delay information acquisition unit 57, the delay information acquisition unit 37a of the distribution control system 2 acquires transmission delay time information (d1) indicating the transmission delay time d1 from the decoding unit 40 and holds it for a certain period of time, and when a plurality of pieces of transmission delay time information (d1) are acquired, outputs to the channel adaptive controller 37b the transmission delay time information (d) indicating frequency distribution information based on a plurality of pieces of the transmission delay time d1 (Step S125).
Based on the transmission delay time information (d), the channel adaptive controller 37b calculates the operation conditions of the encoding unit 60 (Step S126). The transmitter/receiver 31 transmits a channel adaptive control signal indicating the operation conditions such as a frame rate and data resolution to the transmitter/receiver 51 of the communication terminal 5 (Step S127). The transmitter/receiver 51 of the communication terminal 5 receives the channel adaptive control signal. In other words, in the case of the channel adaptive control illustrated in FIG. 20 (downstream), the channel adaptive control signal is output to the encoder bridge unit 30 within the same distribution control system 2, and in contrast, in the case of the channel adaptive control illustrated in FIG. 21 (upstream), the channel adaptive control signal is transmitted to the communication terminal 5 from the distribution control system 2 through the communication network 9.
Based on the operation conditions received by the transmitter/receiver 51, the encoding unit 60 changes the operation conditions of the encoding unit 60 (Step S128). The encoding unit 60 then performs the same processing as Step S121 based on the new operation conditions (Step S129). The transmitter/receiver 51, as with Step S122, transmits the video (sound) data [E] acquired from the camera 62 and the microphone 63 and encoded, the time information (t0) indicating the current time t0 in the communication terminal 5 acquired from the storage unit 5000, and the time difference information (Δ) indicating the time difference Δ also acquired from the storage unit 5000 to the transmitter/receiver 31 of the distribution control system 2 (Step S130). The transmitter/receiver 31 of the distribution control system 2 receives the video (sound) data [E], the time information (t0), and the time difference information (Δ). This is followed by the processing at and after Step S123. Thus, the processing of the upstream channel adaptive control is performed continuously.
Processing of Multidisplay
The processing of multidisplay is described next with reference to FIG. 22 to FIG. 24. FIG. 22 to FIG. 24 are sequence diagrams illustrating the processing of multidisplay illustrated in FIG. 5.
The following describes an example of reproducing video (sound) [XYZ] being reproduced on the communication terminal 5a also on the communication terminals (5f1, 5f2, 5f3) in a divided manner.
The browser 20 for displaying web content is referred to as a “browser 20a”, and the browser 20 for displaying a setting screen for a user is referred to as a “browser 20b”. Described first is the processing corresponding to Step S30 in FIG. 17.
First, the browser 20a of the distribution control system 2 renders the web content data [XYZ] acquired from the web server 8, thereby generating pieces of frame data as still image (sound) data and outputs them to the transmission FIFO 24 (Step S201). The converter 10 encodes the pieces of frame data stored in the transmission FIFO 24, thereby converting them into video (sound) data [XYZ] in a data format distributable to the communication terminal 5a (Step S202).
The transmitter/receiver 31 transmits the video (sound) data [XYZ] converted by the converter 10 to the transmitter/receiver 51 of the communication terminal 5a (Step S203). The transmitter/receiver 51 of the communication terminal 5a receives the video (sound) data [XYZ] and outputs it to the reproduction controller 53.
In the communication terminal 5a, the decoding unit 50 acquires the video (sound) data [XYZ] from the reproduction controller 53 and decodes it (Step S204). After that, the speaker 61 reproduces sound based on decoded sound data [XYZ], and the display unit 58 reproduces video based on video data [XYZ] acquired from the decoding unit 50 and rendered by the rendering unit 55 (Step S205).
A screen displayed on the display unit 58 is switched to a menu request screen (not illustrated) by the user of the communication terminal 5a, and the operating unit 52 receives the pressing of a “distribution destination selection menu” (not illustrated) on the menu request screen (Step S206). This causes the transmitter/receiver 51 to transmit a request for switching to the distribution destination selection menu to the transmitter/receiver 71a of the terminal management system 7 (Step S207). The transmitter/receiver 71a of the terminal management system 7 receives the request for switching to the distribution destination selection menu. This request includes the terminal ID of the communication terminal 5a. 
The transmitter/receiver 71b transmits a startup request of the browser 20b to the transmitter/receiver 21 of the distribution control system 2 (Step S208). The transmitter/receiver 21 of the distribution control system 2 receives the startup request of the browser 20b and issues the startup request of the browser 20b to the browser management unit 22.
The browser management unit 22 then starts up the browser 20b (Step S209). The creating/selecting/transferring unit 310 of the encoder bridge unit 30 switches the output from the browser 20a to the converter 10 (e.g., the converter 10a) to the output from the browser 20b to the converter 10 (e.g., the converter 10b) (Step S210). When the communication terminal 5a and another communication terminal 5 (e.g., the communication terminal 5b) are sharing the converter 10 (e.g., the converter 10a) to receive the video (sound) data at Step S203, the creating/selecting/transferring unit 310 of the encoder bridge unit 30 newly creates the converter 10 (e.g., the converter 10b), because the other communication terminal 5 (e.g., the communication terminal 5b) is using the converter 10 (e.g., the converter 10a) for the browser 20a. 
The transmitter/receiver 21 transmits a request for a distribution destination selection menu to the transmitter/receiver 71b of the terminal management system 7 in accordance with an instruction by the browser 20b (Step S211). In this situation, the terminal ID of the communication terminal 5a is also transmitted. The transmitter/receiver 71b of the terminal management system 7 receives the request for a distribution destination selection menu and outputs the terminal ID of the communication terminal 5a to the storage unit 7000.
In response thereto, the storage unit 7000 of the terminal management system 7 searches the available terminal management table 7020 based on the terminal ID, thereby extracting the corresponding shared ID (Step S212). This shared ID indicates a communication terminal 5 available for the communication terminal 5a to perform remote sharing processing. As illustrated in FIG. 14, because the terminal ID of the communication terminal 5a is “t001”, the shared IDs to be extracted are “v003” and “v006”.
The storage unit 7000 further searches the terminal management table 7010 based on the extracted shared ID, thereby extracting display name information indicating the corresponding display name (Step S213). As illustrated in FIG. 13, the display names corresponding to the extracted shared IDs “v003” and “v006” are “Tokyo head office 10F MFP” and “Osaka exhibition hall 1F multidisplay”, respectively.
The transmitter/receiver 71b transmits distribution destination selection menu data [M] as content data to the transmitter/receiver 21 of the distribution control system 2 (Step S214). The transmitter/receiver 21 of the distribution control system 2 receives the distribution destination selection menu data [M] and outputs it to the browser 20b. As illustrated in FIG. 12, this distribution destination selection menu data [M] includes check boxes, shared IDs, and display names.
As illustrated in FIG. 23, the browser 20b renders the content data indicating the distribution destination selection menu data [M] acquired from the terminal management system 7, thereby generating pieces of frame data as still image (sound) data and outputs them to the transmission FIFO 24 (Step S221). The converter 10 encodes the pieces of image (sound) data [M] stored in the transmission FIFO 24, thereby converting them into video (sound) data [M] in a data format distributable to the communication terminal 5a (Step S222).
The transmitter/receiver 31 transmits the video (sound) data [M] converted by the converter 10 to the transmitter/receiver 51 of the communication terminal 5a (Step S223). The transmitter/receiver 51 of the communication terminal 5a receives the video (sound) data [M] and outputs it to the reproduction controller 53.
In the communication terminal 5a, the decoding unit 50 acquires the video (sound) data [M] from the reproduction controller 53 and decodes it (Step S224). After that, the display unit 58 reproduces video as illustrated in FIG. 12 based on the video data [XYZ] acquired from the decoding unit 50 and rendered by the rendering unit 55 (Step S225).
In the distribution destination selection menu illustrated in FIG. 12, when the check box of the shared ID “v006” is checked and the “OK” button is pressed by the user, the operating unit 52 receives the operation input by the user (Step S226).
The transmitter/receiver 51 transmits a check result as operation data to the transmitter/receiver 31 of the distribution control system 2 (Step S227). The transmitter/receiver 31 of the distribution control system 2 receives the check result as operation data and outputs it to the browser 20b. 
The browser 20b selects the shared ID from the check result (Step S228). The transmitter/receiver 21 transmits a request for adding a distribution destination, to the transmitter/receiver 71b of the terminal management system 7 in accordance with an instruction by the browser 20b (Step S229). This request for adding a distribution destination includes the shared ID selected at Step S227. The transmitter/receiver 71b of the terminal management system 7 receives the request for adding a distribution destination and outputs the shared ID to the storage unit 7000. The browser 20b then ends (Step S230). This causes the creating/selecting/transferring unit 310 of the encoder bridge unit 30 to switch the output from the browser 20b to the converter 10 back to the output from the browser 20a to the converter 10 (Step S231).
As illustrated in FIG. 24, in the storage unit 7000 of the terminal management system 7, the terminal management table 7010 is searched based on the shared ID sent at Step S229, thereby extracting the corresponding terminal ID and installation position information (Step S241). The transmitter/receiver 71b transmits an instruction to add a distribution destination, to the transmitter/receiver 21 of the distribution control system 2 (Step S242). This instruction to add a distribution destination includes the terminal ID and the installation position information extracted at Step S241. The transmitter/receiver 21 of the distribution control system 2 receives the instruction to add a distribution destination and outputs the instruction to add a distribution destination to the browser management unit 22. Included here are three sets of the terminal ID and the installation position information, that is, the terminal ID and the installation position information being “t006” and “left”, respectively, the terminal ID and the installation position information being “t007” and “middle”, respectively, and the terminal ID and the installation position information being “t008” and “right”, respectively.
The creating/selecting/transferring unit 310 of the encoder bridge unit 30 creates a converter 10 for multidisplay (Step S243). In this case, the creating/selecting/transferring unit 310 of the encoder bridge unit 30 acquires the terminal ID and the installation position information from the browser management unit 22.
The dividing unit 13 of the converter 10 created at Step S243 divides the pieces of frame data [XYZ] as still image (sound) data stored in the transmission FIFO 24, and the encoding unit 19 encodes the divided pieces of frame data (Step S244).
The transmitter/receiver 31 transmits video (sound) data [X] encoded by the encoder bridge unit 30 to the transmitter/receiver 51 of the communication terminal 5f1 based on the terminal ID (“t006”) and the installation position information (“left”) (Step S245-1). The transmitter/receiver 51 of the communication terminal 5f1 receives the video (sound) data [X] and outputs it to the reproduction controller 53.
In the communication terminal 5f1, the decoding unit 50 acquires the video (sound) data [X] from the reproduction controller 53 and decodes it (Step S246-1). After that, the speaker 61 reproduces sound based on decoded sound data [X], and the display unit 58 reproduces video based on video data [X] acquired from the decoding unit 50 and rendered by the rendering unit 55 (Step S247-1).
Similarly, the transmitter/receiver 31 transmits video (sound) data [Y] encoded by the encoder bridge unit 30 to the transmitter/receiver 51 of the communication terminal 5f2 based on the terminal ID (“t007”) and the installation position information (“middle”) (Step S245-2). The transmitter/receiver 51 of the communication terminal 5f2 receives the video (sound) data [Y] and outputs it to the reproduction controller 53.
In the communication terminal 5f2, the decoding unit 50 acquires the video (sound) data [Y] from the reproduction controller 53 and decodes it (Step S246-2). After that, the speaker 61 reproduces sound based on decoded sound data [Y], and the display unit 58 reproduces video based on video data [Y] acquired from the decoding unit 50 and rendered by the rendering unit 55 (Step S247-2).
Similarly, the transmitter/receiver 31 transmits video (sound) data [Z] encoded by the encoder bridge unit 30 to the transmitter/receiver 51 of the communication terminal 5f3 based on the terminal ID (“t008”) and the installation position information (“right”) (Step S235-3). The transmitter/receiver 51 of the communication terminal 5f3 receives the video (sound) data [Z] and outputs it to the reproduction controller 53.
In the communication terminal 5f3, the decoding unit 50 acquires the video (sound) data [Z] from the reproduction controller 53 and decodes it (Step S246-3). After that, the speaker 61 reproduces sound based on decoded sound data [Z], and the display unit 58 reproduces video based on video data [Z] acquired from the decoding unit 50 and rendered by the rendering unit 55 (Step S247-3).
Processing to Generate Various Types of Frame Data
Described next with reference to FIG. 25 and FIG. 26 is processing to generate various types of frame data. FIG. 25 is a conceptual diagram of various types of frame data. The present embodiment generates four types of frame data. The four types of frame data include “periodically generated I frame data” and “P frame data”, and “skip frame data” and “forcefully generated I frame data”. The “periodically generated I frame data” will be indicated as “periodic I frame data” below, and the “forcefully generated I frame data” will be indicated as “forceful I frame data” below. The periodic I frame data is an example of first frame data, the P frame data is an example of second frame data, the skip frame data is an example of third frame data, and the forceful I frame data is an example of fourth frame data.
Described first is the generation of the periodic I frame data and the P frame data as known techniques. In general, in order to transmit video data through a communication network efficiently, unnecessary data is reduced or removed by a video compression technique. The video compression technique causes an encoder to encode pieces of frame data within the video data and generate the periodic I frame data or the P frame data.
The periodic I frame (intra frame) data is frame data that a communication terminal can reproduce by decoding independently (singly) without referring to other images. As illustrated in FIG. 25, the first image of the video data is always periodic I frame data. For ease of description, illustrated here is a case in which the distribution of one piece of periodic I frame data and four pieces of P frame data is repeated. Specifically, the encoding unit 19 repeats the generation of periodic I frame data and P frame data, namely, generates periodic I frame data M1 constituting the video data, then generates four pieces of P frame data (M11, M12, M13, M14) constituting the video data successively, and subsequently generates periodic I frame data M2 constituting the video data, and then generates P frame data (M21, M22, M23, M24) constituting the video data successively, for example.
The periodic I frame data is used for implementing a starting point of a new user who views video data, a resynchronization point when a problem occurs in a bit stream under transmission, fast forwarding and rewinding, and a random access function. The encoding unit 19 generates the periodic I frame data automatically at regular intervals and generates the periodic I frame data as needed when, for example, a user who views the video data is newly added. Although the periodic I frame data has the drawback of requiring a larger bit numbers (large in the amount of data) because it is not differential data, the periodic I frame data has the advantage of not causing noise or the like due to a loss of data.
The P frame (predictive inter frame) data, which is constituted by differential data as a difference with the previous frame data, is frame data that is encoded with part of the previous periodic I frame data or P frame data referred to by the encoding unit 19. Although having the advantage of requiring a smaller bit numbers than the periodic I frame data, the P frame data has the drawback of being susceptible to distribution errors, because being in complicated dependence relation with the previous P frame data or periodic I frame data Because the user datagram protocol (UDP), which makes data transfer at high speed but low quality, is used for distributing video data, the frame data may be lost on a communication network. In this case, the present P frame data is susceptible to distribution errors because the video data distributed to a user (the communication terminal 5) collapses due to an influence of the lost previous P frame data. However, owing to the periodic I frame data periodically inserted, the collapse of the video data is eliminated.
Described next is the generation of the skip frame data and the forceful I data unique to the present embodiment.
As described above, because the P frame data is differential data with the previous frame data (the P frame data or the forceful I frame data), if there is no updated part with respect to the previous one, differential calculation executed by the encoding unit 19 is wasted.
The periodic I frame data is not subjected to differential calculation by the encoding unit 19, but subjected to compression calculation for encoding. The amount of data of the periodic I frame data generated by this encoding is larger than that of the P frame data. For this reason, for the periodic I frame data, if there is no updated part with respect to the previous one, the compression calculation is wasted. In addition, because the amount of data of the periodic I frame data is large, it takes a longer transmission time on the bus line 220 within the distribution control system.
For example, in FIG. 25, the P frame data (M22, M23, M24), periodic I frame data M3, and P frame data M31 are not updated (changed) continuously. In this state, the processing of differential calculation or compression calculation by the encoding unit 19 is wasted.
Given this situation, in the present embodiment, when the frame data sent from the browser 20 to the transmission FIFO 24 is not updated a certain number of times, the encoding unit 19 generates the skip frame data in place of the periodic I frame data or the P frame data.
This skip frame data is frame data with the contents being not updated (changed) as compared with the contents of the previous frame data. The skip frame data can also indicate that there is no update (change) with respect to the previous frame data. For example, as illustrated in FIG. 25, when there is no change in the contents of the frame data about five times as the certain number of times, the sixth frame data is generated as skip frame data m32 in place of P frame data M32. When the state of not being updated continues after that, the seventh frame data is generated as skip frame data m33 in place of P frame data M33. The skip frame data is generated in this manner until an update is resumed.
This can avoid a situation in which frame data processing becomes congested in the distribution control system 2, thereby providing the effect of, in the distribution control system 2, distributing content data acquired from the web server 8 or the like to the communication terminal 5 at higher speed as video data.
Furthermore, in the present embodiment, the encoding unit 19 generates the forceful I frame data in place of the frame data immediately before the skip frame data is generated (that is, the last frame data within the certain number of times).
The forceful I frame data, which is still image data, is less compressed (higher image quality) frame data than the periodic I frame data constituting the video data. For example, as illustrated in FIG. 25, when there is no change in the contents of the frame data about five times as the certain number of times, the fifth frame data is generated by the encoding unit 19 as forceful I frame data S3 in place of P frame data M31. When the fifth frame data in the state of no change is periodic I frame data M3, the forceful I frame S3 is generated by the encoding unit 19 in place of the periodic I frame data M31.
This causes high image quality frame data to be distributed to the communication terminal 5, thereby reproducing a high image quality image on the communication terminal 5. Consequently, a high image quality image continues to be reproduced on the communication terminal 5 even when an image continues not to be updated, and the skip frame data continues to be distributed, thereby providing the effect of making a state continue in which the image is easy to be viewed by the user of the communication terminal 5.
Described next with reference to FIG. 26 is processing in which the distribution control system 2 generates various types of frame data. FIG. 26 is a flowchart for generating the various types of frame data First, the renderer function of the browser 20 stores frame data in the transmission FIFO 24 and stores therein an update flag indicating whether the contents of the frame data are updated. The update flag is an example of update information and is indicated as “1” when there is any update and indicated as “0” when there is no update, for example. The browser 20 may set the update flag to be “0”, not only when the contents of the frame data are not updated at all as compared with the contents of the frame data previously generated, but also when not updated over a certain range as compared with the contents of the frame data previously generated. For example, when only around a corner of video reproduced by the communication terminal 5 is updated, and the central part is not updated, the update flag is set to be “0”.
The creating/selecting/transferring unit 310 illustrated in FIG. 15 starts a timer (Step S301). This timer is used at the timing when the creating/selecting/transferring unit 310 periodically acquires frame data from the transmission FIFO 24 illustrated in FIG. 9. The creating/selecting/transferring unit 310 determines whether it is time to acquire the next frame data (Step S302). The creating/selecting/transferring unit 310 waits for the time when acquiring the next frame data (No at Step S302). If it is the time to acquire the next frame data (Yes at Step S302), the creating/selecting/transferring unit 310 acquires the frame data from the transmission FIFO 24 and transfers the frame data to the converter 10 (Step S303).
In the converter 10, the trimming unit 11, the resizing unit 12, or the dividing unit 13 performs image processing such as trimming, resizing, or dividing, respectively, on the frame data, for example (Step S304).
The encoding unit 19 determines whether there is any update in the frame data based on the update flag (Step S305). If the update flag is “1”, the encoding unit 19 determines that there is any update in the frame data transferred by the creating/selecting/transferring unit 310 (Yes at Step S305) and sets a counter (hereinafter called an “SFC”) used for generating the skip frame data to be zero (Step S306). This counter is stored in the RAM 21 of the GPU 215 by the encoding unit 19.
The encoding unit 19 determines the type of frame date to be generated (Step S307). For example, in the case illustrated in FIG. 25, it is prescribed in advance that after one piece of periodic I frame data is generated, four pieces of P frame data are generated. If determining to generate the periodic I frame data at Step S307, the encoding unit 19 generates the periodic I frame data (Step S308). If determining to generate the P frame data at Step S307, the generating unit 19 generates the P frame data (Step S309).
Returning back to Step S305, if the update flag is “0”, the encoding unit 19 determines that there is no change in the frame data transferred by the creating/selecting/transferring unit 310 (No at Step S305) and increases the SFC by one to increment (Step S311).
The encoding unit 19 determines whether the SFC exceeds a certain number of times (Step S312). In other words, the encoding unit 19 determines whether the update of the contents of the content data output from the browser 20 is not performed continuously for a certain number of times. In the case illustrated in FIG. 25, it is determined whether the SFC exceeds five times. If the encoding unit 19 determines that the SFC does not exceed (is less than) the certain number of times at Step S312 (Yes), the flow advances to Step S307. If determining that the SFC exceeds the processing number of times at Step S312 (No), the encoding unit 19 further determines whether the SFC is the certain number of times (Step S313).
If determining that the SFC is the certain number of times at Step S313 (Yes), the encoding unit 19 generates the forceful I frame (Step S314). If determining that the SFC is not the certain number of times at Step S313 (No), the encoding unit 19 generates the skip frame data (Step S315).
When the creating/selecting/transferring unit 310 acquires an update flag “1” from the transmission FIFO due to another change in the contents of the content data, the encoding unit 19 generates again the periodic I frame data or the P frame data. In the case illustrated in FIG. 25, when the contents of the frame data are updated after the encoding unit 19 generates skip frame data m33, the encoding unit 19 generates P frame data M34. In this case, the encoding unit 19 generates the P frame data as differential data with the forceful I frame data generated based on the content data updated last. When the contents of the frame data are changed after the encoding unit 19 generates skip frame data m34, the encoding unit 19 generates periodic I frame data M4.
Main Effects of the Embodiment
As described above, in the present embodiment, when the frame data sent from the browser 20 to the transmission FIFO 24 is not updated a certain number of times, the encoding unit 19 generates the skip frame data in place of the periodic I frame data or the P frame data. This can avoid a situation in which frame data processing becomes congested in the distribution control system 2, thereby providing the effect of, in the distribution control system 2, distributing content data acquired from the web server 8 or the like to the communication terminal 5 at higher speed as video data.
In the present embodiment, the encoding unit 19 generates the forceful I frame data (an example of second I frame data), which is higher in image quality than the periodic I frame data (an example of first frame data), in place of the frame data immediately before the skip frame data is generated (that is, the last frame data within the certain number of times). This causes high image quality frame data to be distributed to the communication terminal 5, which enables the communication terminal 5 to reproduce a high image quality image. Consequently, a high image quality image continues to be reproduced on the communication terminal 5 even when an image continues not to be updated, and the skip frame data continues to be distributed, thereby providing the effect of making a state continue in which the image is easy to be viewed by the user of the communication terminal 5.
In the distribution system 1 according to the present embodiment, the distribution control system 2 includes the browser 20 that performs rendering and the encoder bridge unit 30 that performs encoding and the like in the cloud. The browser 20 generates pieces of frame data as still image (sound) data based on content data described in a certain description language. The encoder bridge unit 30 converts the pieces of frame data into video (sound) data distributable through the communication network 9. After that, the distribution control system 2 distributes the video (sound) data to the communication terminal 5. As a result, the communication terminal 5 can smoothly reproduce web content without update of its browser or time and costs for upgrading the specifications of a CPU, an OS, a RAM, and the like. This eliminates the problem in that enriched content increases a load on the communication terminal 5.
In particular, the browser 20 enables real-time communication, and the converter 10 performs real-time encoding on the frame data generated by the browser 20. Consequently, unlike a case in which a DVD player selects and distributes non real-time (that is, pre-encoded) video (sound) data as seen in, for example, on-demand distribution of video (sound) data, the distribution control system 2 renders content acquired immediately before being distributed, thereby generating pieces of frame data and then encoding them. This allows real-time distribution of video (sound) data.
Supplementary Description
Although the encoding unit 19 determines whether the SFC exceeds the certain number of times at Step S312 in the above embodiment, the embodiment is not limited to this. For example, the encoding unit 19 may determine whether a certain period of time, not the certain number of times, is exceeded.
Although the forceful I frame data is less compressed (higher image quality) frame data than the periodic I frame data in the above embodiment, the embodiment is not limited to this. For example, the encoding unit 19 may generate a plurality of pieces of highly compressed (lower image quality) frame data than the periodic I frame data, and the transmitter/receiver 31 may transmit them successively to the communication terminal 5. In this case, the communication terminal 5 reproduces high image quality video similar to one piece of forceful I frame data from the pieces of frame data successively received.
Although the distribution control system 2 distributes the skip frame data generated at Step S315 in the above embodiment, the embodiment is not limited to this. For example, the distribution control system 2 may, without distributing the skip frame data, distribute non-update information indicating that the contents of the present frame data are not updated with respect to the contents of the previous frame data. In this case, the communication terminal 5 performs similar processing to the case when the skip frame data is received based on the non-update information.
The distribution system 1 according to the present embodiment includes the terminal management system 7 and the distribution control system 2 as separate systems. For example, the terminal management system 7 and the distribution control system 2 may be constructed as an integral system by, for example, causing the distribution control system 2 to have the functions of the terminal management system 7.
The distribution control system 2 and the terminal management system 7 according to the above embodiment may be implemented by a single computer or may be implemented by a plurality of computers in which individual parts (functions, means, or storage units) are divided and assigned in any desirable unit.
Storage media such as CD-ROMs and HDDs in which the programs of the above embodiment are recorded can be provided as program products domestically or abroad.
According to an embodiment, the fourth frame data that is higher in image quality than the first frame data is transmitted in place of the first frame data or the second frame data before the third frame data or the non-update information is transmitted. This causes high image quality frame data to be distributed to the communication terminal, thereby reproducing a high image quality image on the communication terminal 5. Consequently, a high image quality image continues to be reproduced on the communication terminal 5 even when an image continues not to be updated, and skip frame data continues to be distributed, thereby providing the effect of making a state continue in which the image is easy to be viewed by the user of the communication terminal.
Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.

## Claims

1. A distribution control system configured to distribute, to a communication terminal, first frame data capable of being reproduced singly by the communication terminal or second frame data as a difference with previous frame data distributed to the communication terminal, the distribution control system comprising:
processing circuitry configured to
generate certain frame data from content data and generate update information every certain period of time, the update information indicating whether contents of the certain frame data are different by a certain amount or more from contents of previous certain frame data, and
generate the first frame data or the second frame data from the certain frame data and determine whether a state where the contents of the certain frame data are not different by the certain amount or more from the contents of the previous certain frame data has continued for more than a predetermined number of successive frames based on the update information, wherein the first frame data is I frame data of an H.264/MPEG-4 video stream and the second frame data is P frame data of the H.264/MPEG-4 video stream; and
a transmitter configured to transmit third frame data or non-update information indicating that the contents are not updated, in place of the first frame data or the second frame data, to the communication terminal, when the processing circuitry determines that the state has continued for more than the predetermined number of successive frames, the third frame data being a skip frame indicating no frame data, wherein
the transmitter is further configured to transmit fourth frame data that is higher in image quality than the first frame data to the communication terminal before the third frame data or the non-update information is transmitted to the communication terminal.

2. The distribution control system according to claim 1, wherein the processing circuitry is configured to generate the first frame data or the second frame data in place of the third frame data when the processing circuitry determines that the contents of the frame data are updated based on new change information, after generating and transmitting the third frame data.

3. The distribution control system according to claim 1, wherein the processing circuitry implements a browser and an encoder.

4. The distribution control system of claim 1, wherein the processing circuitry is further configured to transmit the fourth frame data when determining that the state has continued for exactly the predetermined number of successive frames.

5. The distribution control system of claim 1, wherein the processing circuitry is further configured to transmit the third frame data at each certain period of time as long as the state continues and the contents of the certain frame data are not different by the certain amount or more from the contents of the previous certain frame data.

6. The distribution control system of claim 1, wherein the transmitter is configured to transmit the second frame data after transmitting the first frame data.

7. A distribution control method executed by a distribution control system that distributes, to a communication terminal, first frame data capable of being reproduced singly by the communication terminal or second frame data as a difference with previous frame data distributed to the communication terminal, the distribution control method comprising:
generating certain frame data from content data and generating update information every certain period of time, the update information indicating whether contents of the frame data are different by a certain amount or more from contents of previous certain frame data,
generating the first frame data or the second frame data from the certain frame data and determining whether a state where the contents of the certain frame data are not different by the certain amount or more from the contents of the previous certain frame data has continued for more than a predetermined number of successive frames based on the update information, wherein the first frame data is I frame data of an H264/MPEG-4 video stream and the second frame data is P frame data of the H.264/MPEG-4 video stream;
transmitting third frame data or non-update information indicating that the contents are not updated, in place of the first frame data or the second frame data, to the communication terminal when, determining that the state has continued for more than the predetermined number of successive frames, the third frame data being a skip frame indicating no frame data, and
transmitting fourth frame data that is higher in image quality than the first frame data to the communication terminal before the third frame data or the non-update information is transmitted to the communication terminal.

8. A non-transitory computer-readable storage medium with an executable program stored thereon which when executed by a computer, instructs the computer to perform the distribution control method according to claim 7.