JP2012204991A - Communication system, mobile terminal, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a user of a video display device at a remote location to view a picked-up video with video quality intended by the photographer without requiring the photographer to perform a cumbersome operation.SOLUTION: A mobile terminal incorporating therein a camera for picking up a video and outputting video data representing the video is provided with movement detection means for detecting a magnitude of movement of the terminal, the movement generated in association with a body movement of the user. In order to display the video data representing the video picked up by the camera on a video display device via a communication network, a process is executed to transmit the video data while adjusting, in accordance with the magnitude of the movement detected by the movement detection means, at least either of a per-frame data volume of the video data and a frame rate at which the video data is transmitted via the communication network.

Description

  The present invention relates to a technique for transmitting moving image data via a communication network and allowing a remote viewer to view a moving image represented by the moving image data.

  For example, it is generally performed that a moving image captured by a video camera or the like is displayed on a moving image display device at a remote location and viewed by a user of the moving image display device. Patent Document 1 discloses a remote monitoring system that transmits moving image data representing a captured moving image from a video camera held by a security guard to a remote monitor via a communication network, and displays the moving image on the monitor ( Paragraph 0035). Patent Document 1 discloses a frame rate (the number of transmission frames per unit time) when moving image data is transmitted from the video camera, or compression of moving image compression and coding when an impact is applied to the video camera. It is described that the rate is adjusted to obtain high video quality. This is because, in the event of an unforeseen situation where some impact is applied to the video camera, a video that clearly captures the occurrence situation is provided as evidence material without requiring any special operation by the security guard as the photographer. It is intended to be left behind.

JP 2003-274360 A JP 2009-49691 A JP 2010-3110 A Patent 4175354

  The video quality of a moving image reproduced in the moving image display apparatus is determined by the resolution and frame rate of each still image (hereinafter referred to as a frame) constituting the moving image and the compression rate of compression encoding of the moving image data. In general, compression encoding of video data employs lossy compression encoding that can achieve a high compression rate but cannot completely decode the video before compression. The higher the compression rate, the lower the video quality of the decoded video. Because it does. Therefore, when a video shooter wants a remote person to view a video with his intended video quality, the resolution, the compression rate and the frame rate are set so that the video quality can be obtained. It is necessary to perform troublesome work such as adjusting. Such a problem cannot be solved even if the technique disclosed in Patent Document 1 is used. The technique disclosed in Patent Document 1 realizes adjustment of the frame rate and the compression rate of compression coding without causing the photographer to perform a special operation. This is because it does not reflect the intention of the photographer.

  The present invention has been made in view of the above-described problems, and enables a remote person to view a captured moving image with intended video quality without causing a photographer to perform complicated operations. The purpose is to provide technology.

  In order to solve the above problems, the present invention incorporates or connects a moving image display device that displays a moving image represented by moving image data received via a communication network, and a camera that captures the moving image and outputs the moving image data representing the moving image. A portable terminal that transmits the moving image data to the moving image display device via the communication network, and the portable terminal detects a movement of the camera caused by a user's body movement. Adjusting at least one of a data amount per frame of the moving image data and a frame rate when the moving image data is transmitted to the moving image display device via the communication network according to the magnitude of the movement of the camera. A communication system characterized by transmitting to the moving image display device is provided.

  In the communication system, the amount of data per frame of moving image data transmitted from the mobile terminal to the moving image display device is determined by the resolution of each frame and the compression rate in compression encoding. The higher the resolution, the lower the compression rate. A high-definition moving image can be displayed on the moving image display device. Also, the higher the frame rate, the smoother the moving image can be displayed on the moving image display device. In the present invention, at least one of the data amount per frame and the frame rate of the moving image data transmitted from the mobile terminal to the moving image display device is determined by the magnitude of the movement of the camera (in other words, the body of the user who takes an image with the camera). The reason why the adjustment is made according to the magnitude of the movement is that it is considered that the intention of the user (that is, the photographer) appears in the body movement of the user who captures the moving image.

  For example, when the photographer is trying to accurately capture the details of the subject, the imager often takes an image of the subject while keeping the camera stationary as if gazing at the subject. When trying to capture the movement of a subject, imaging is often performed while gently moving the camera so as to follow the movement of the subject. When it is determined that the camera is stationary, the image quality intended by the photographer is obtained by giving priority to the data amount per frame over the frame rate so that the data amount per frame is as large as possible. Can be displayed on a moving image display device at a remote location. As will be described later, the data amount per frame and the frame rate are in a trade-off relationship, and if the data amount per frame is prioritized, the frame rate can be kept low. If priority is given to the amount of data per frame and the frame rate is kept low, a moving image that accurately captures the details of the subject in each frame is displayed on the moving image display device, although the smoothness of movement is lacking. On the other hand, when the movement of the mobile terminal is small, priority is given to the frame rate (the amount of data per frame can be kept low), so that the motion of the subject is well reflected, although the detail of each frame is lacking. Can be displayed on the video display device.

  As described above, according to the present invention, a moving image captured using a camera built in or connected to the mobile terminal can be displayed at a remote location with the video quality intended by the user without causing the user of the mobile terminal to perform a special operation. Can be viewed by the user of the video display device. Patent Document 2 describes an invention of an image pickup apparatus that takes an image when the photographer stops moving, thereby preventing camera shake, and Patent Document 3 describes a predetermined size. An invention of a drive recorder that captures an image in response to an impact that exceeds is described. However, these do not display a moving image of the video quality intended by the photographer on a moving image display device at a remote location, and are completely different from the present invention.

  In a more preferred aspect, the portable terminal measures an available bandwidth, which is a bandwidth that can be used in the communication network, and transmits the data amount per frame of the moving image data and the moving image data via the communication network. Then, one of the frame rates when transmitting to the moving image display device is adjusted in accordance with the magnitude of the movement of the camera, and the other is adjusted so that the bit rate is within the available bandwidth. . This is because the bit rate is determined by the product of the data amount per frame and the frame rate, and if the bit rate does not fall within the usable bandwidth, there may be a problem such as interruption of video playback on the video display device. .

  In a more preferred aspect, the mobile terminal is configured to reduce the frame rate to a predetermined minimum value when the magnitude of the movement exceeds a predetermined threshold value. A moving image captured with a large amount of motion is very likely to cause the subject to be blurred greatly, and it is meaningless to transmit moving image data representing such a moving image to a moving image display device at a high frame rate. That is, according to such an aspect, it is possible to suppress the transmission data amount of meaningless moving image data and avoid wasteful bandwidth.

  In order to solve the above-described problem, the present invention relates to the magnitude of the movement of the camera that occurs in association with a user's body movement in a portable terminal that incorporates or connects a camera that captures a moving image and outputs moving image data representing the moving image. Motion detection means for detecting the length, and at least one of the data amount per frame of the moving image data and the frame rate at the time of transmitting the moving image data to another device via a communication network is detected by the motion detection means And a transmission means for transmitting the moving image data to the other device while adjusting according to the magnitude of the movement of the camera. This is because the communication system can be constructed by combining such a portable terminal with a general moving image display device.

  Further, in order to solve the above problems, the present invention provides a computer that incorporates or is connected to a camera that captures a moving image and outputs the moving image data, and is generated in accordance with the body movement of a user of a terminal that incorporates the computer. At least one of a motion detection means for detecting the amount of motion of the video, a data amount per frame of the video data and a frame rate when the video data is transmitted to another device via a communication network, the motion Provided is a program that functions as a transmission unit that transmits the moving image data to the other device while adjusting according to the magnitude of the motion detected by the detection unit. Such a program is installed in a general mobile terminal (for example, a mobile phone with a camera) having an imaging function, and a computer built in the mobile terminal is operated according to the program. This is because a simple camera-equipped mobile phone can function as the mobile terminal of the present invention.

It is a figure which shows the structural example of the communication system 1 of one Embodiment of this invention. 3 is a block diagram illustrating a configuration example of the mobile terminal 10. FIG. It is a flowchart which shows the flow of the moving image data transmission control process which the control part 110 of the said portable terminal 10 performs according to the communication control program 162b.

Embodiments of the present invention will be described below with reference to the drawings.
<A: Configuration>
FIG. 1 is a diagram illustrating a configuration example of a communication system 1 according to an embodiment of the present invention.
As shown in FIG. 1, the communication system 1 includes a mobile terminal 10 to which a camera 12 is connected, and a moving image display device 30 connected to a communication network 20 that houses the mobile terminal 10. The camera 12 is, for example, a CCD (Charge Coupled Device) image sensor, which captures an image captured on the sensor surface as a moving image, and a series of frames (640 × 480 resolution frames in the present embodiment) constituting the moving image. The represented moving image data is output to the mobile terminal 10. The camera 12 is attached to the user's head with a hair band or the like so that the imaging direction is in the line of sight of the user of the mobile terminal 10. For this reason, the camera 12 moves according to the body movement of the user of the mobile terminal 10. In this embodiment, an application example of the present invention for a camera mounted on a user's head by a hairband or the like will be described. However, the present invention may be applied to a camera of a type that is captured by hand. Of course it is good.

  The communication network 20 includes a mobile communication network (in FIG. 1, only a base station (indicated as BS in FIG. 1) included in the mobile communication network is illustrated) and a gateway device (not illustrated). And a general public line network (not shown in FIG. 1) connected to the mobile communication network. Although detailed illustration is omitted in FIG. 1, the mobile communication network includes a mobile telephone network and a mobile packet communication network. The mobile communication network includes a large number of base stations (only one is illustrated in FIG. 1), and accommodates mobile terminals 10 located in the service area of each base station. The general public line network is a communication network shared by an unspecified number of users. The Internet is an example of a general public line network. The moving image display device 30 is a personal computer, for example, and is connected to the general public network.

  In the mobile terminal 10 of FIG. 1, a communication address (for example, an IP (Internet Protocol) address) of the moving image display device 30 is stored in advance as a transmission destination address (hereinafter referred to as a moving image transmission destination address) of moving image data output from the camera 12. Has been. For this reason, in the communication system shown in FIG. 1, the moving image captured by the camera 12 can be displayed on the moving image display device 30 in the following manner, and the user of the moving image display device 30 can view the moving image. That is, when the mobile terminal 10 receives the moving image data from the camera 12, it performs lossy compression encoding on the moving image data and transmits it to the moving image transmission destination address. The moving image data transmitted from the portable terminal 10 reaches the moving image display device 30 via the mobile packet communication network in the communication network 20 and the general public line network. The moving image display device 30 decodes the moving image data received via the communication network 20 and displays the moving image according to the decoding result.

  Transmission of moving image data from the mobile terminal 10 to the moving image display device 30 is performed via a mobile packet communication network and a general public line network included in the mobile communication network. The available bandwidth of data communication via the communication network 20 varies depending on the radio wave condition in the wireless section accommodating the mobile terminal 10 and the congestion level of the general public line network. For this reason, when the user of the video display device 30 views the video captured by the camera 12 as described above, the bit rate can be used depending on the radio wave condition in the wireless section of the communication network 20 and the congestion of the general public line network. It seems that the user may feel a lot of stress by exceeding the bandwidth and interrupting the reproduction of the moving image on the moving image display device 30.

However, in the present embodiment, by causing the mobile terminal 10 to execute processing that significantly shows the characteristics of the present embodiment, the user of the video display device 30 can view the video captured by the mobile terminal 10 without feeling great stress. Is realized. Further, in the present embodiment, by causing the mobile terminal 10 to execute a process that significantly shows the features of the present embodiment, the moving image captured by the camera 12 can be captured without requiring the user of the mobile terminal 10 to perform a special operation. It is also possible to allow the user of the video display device 30 to view with the video quality intended by the user.
Hereinafter, the portable terminal 10 that clearly shows the features of the present embodiment will be mainly described.

FIG. 2 is a block diagram illustrating a configuration example of the mobile terminal 10.
As shown in FIG. 2, the mobile terminal 10 includes a control unit 110, a communication interface (hereinafter abbreviated as “I / F”) unit 120, an external device I / F unit 130, an acceleration sensor 140, and a user I / F unit. 150, a storage unit 160, and a bus 170 that mediates data exchange between these components. The control unit 110 is a CPU (Central Processing Unit). The control unit 110 functions as a control center of the mobile terminal 10 by executing a program stored in the storage unit 160.

  The communication I / F unit 120 is a wireless communication interface including an antenna (not shown) and a baseband IC (Integrated Circuit). The communication I / F unit 120 receives, for example, data related to transmitted voice and data for packet communication from the control unit 110 under the control of the control unit 110, and generates a transmission signal by superimposing these data on a carrier wave. Then, this signal is transmitted to the base station of the mobile communication network via the antenna. Further, the communication I / F unit 120 receives a radio signal transmitted from the base station via the antenna, demodulates this signal, data related to received voice addressed to its own terminal, data for packet communication, etc. And hand over these data to the control unit 110.

  The external device I / F unit 130 is for connecting other external devices such as a serial interface. The external device I / F unit 130 hands over the data received from the connected external device to the control unit 110, and outputs the data given from the control unit 110 to the external device. In the present embodiment, the camera 12 is connected to the external device I / F unit 130. The acceleration sensor 140 detects acceleration generated by the external force applied to the acceleration sensor 140 by decomposing the acceleration into three axial components orthogonal to each other, and controls acceleration data indicating the magnitude of each axial component. The process given to the unit 110 is executed at a predetermined cycle (for example, a cycle of 100 milliseconds). For example, when a user carrying the mobile terminal 10 performs some body movement, an external force corresponding to the body movement is applied to the acceleration sensor 140 via a housing (not shown) of the mobile terminal 10, and the acceleration sensor 140 Acceleration data representing the acceleration generated according to the external force is output. As described above, in this embodiment, since the camera 12 is mounted on the user's head of the mobile terminal 10, when the user performs some body movement, the movement caused by the body movement is transferred to the camera 12. Arise. The acceleration sensor 140 according to the present embodiment serves as a motion detection unit that detects the magnitude of the motion of the camera 12 caused by the body movement of the user of the mobile terminal 10. The user I / F unit 150 includes, for example, a display unit configured by a liquid crystal display and its drive circuit, and an operation unit including a plurality of operators such as a numeric keypad (all of which are not shown in FIG. 2).

As shown in FIG. 2, the storage unit 160 includes a nonvolatile storage unit 162 and a volatile storage unit 164. The nonvolatile storage unit 162 is configured by a nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read-Only Memory), for example, and the volatile storage unit 164 is a RAM (Random).
It consists of volatile memory such as Access Memory. The nonvolatile storage unit 162 stores a moving image transmission destination address 162a and a communication control program 162b. On the other hand, the volatile storage unit 164 is used by the control unit 110 as a work area when the communication control program 162b is executed.

  The communication control program 162b is read from the nonvolatile storage unit 162 to the volatile storage unit 164 by the control unit 110 when the power (not shown) of the mobile terminal 10 is turned on, and its execution is started. The processing executed by the control unit 110 according to the communication control program 162b includes call connection control processing and call control processing in addition to the moving image data transmission control processing shown in FIG. The call connection control process is a process for responding to an outgoing call or incoming call. The call control process is a process for controlling sound collection of the user of the mobile terminal 10, sound emission of the other party's voice, and transmission / reception of voice data representing these voices. Since the call connection control process and the call control process are the same as those in a general mobile phone, a detailed description thereof will be omitted, and the following description will focus on the video data transmission control process.

In the moving image data transmission control process, when the moving image data output from the camera 12 is transmitted to the moving image transmission destination address 162a, the available bandwidth of the communication network 20 at the time of transmission is measured and falls within the available bandwidth. In this way, the video data is transmitted while adjusting the bit rate. The bit rate of moving image data is calculated by the product of the data amount per frame of a series of frames constituting the moving image data and the frame rate. The amount of data per frame is determined by the resolution of each frame constituting the moving image and the compression rate at the time of compression encoding. Although details will be clarified in the operation example in order to avoid duplication, in the present embodiment, the control unit 110 first determines the resolution of each frame constituting the moving image and the compression rate at the time of the compression encoding in the motion of the camera 12. The amount of data per frame is adjusted by adjusting according to the size of. Then, the control unit 110 adjusts the frame rate so that the bit rate is within the available bandwidth at that time, and transmits the moving image data whose data amount per frame is adjusted to the moving image transmission destination address 162a. It is.
The above is the configuration of the mobile terminal 10.

<B: Operation>
Next, operations performed by the mobile terminal 10 will be described focusing on operations in the moving image data transmission control process. When a user who wears the camera 12 on the head and carries the mobile terminal 10 gives an instruction to transmit moving image data by operating the operation unit of the user I / F unit 150, the control unit 110 sends the communication control program 162b. Therefore, the moving image data transmission control process is executed.

FIG. 3 is a flowchart showing the flow of the moving image data transmission control process.
As shown in FIG. 3, the control unit 110 first measures the available bandwidth and analyzes the acceleration data output from the acceleration sensor 140 to determine the magnitude of the movement of the camera 12 (hereinafter, “motion state”). (Step SA100).

  Although various aspects can be considered as a method for measuring the available bandwidth, in the present embodiment, the available bandwidth is measured in the following manner. First, prior to the measurement of the available bandwidth, time adjustment of the internal clocks of the mobile terminal 10 and the moving image display device 30 is performed in advance. For example, the portable terminal 10 is provided with a time stamp indicating the transmission time of the available bandwidth measurement data having a predetermined data size such as 500 kilobytes (hereinafter abbreviated as KB) and transmits the data to the moving image display device 30. A process for storing the transmission time is executed. On the other hand, the moving image display device 30 is caused to send back a response message (so-called ACK) to which a time stamp indicating the reception time is given in response to reception of the available bandwidth measurement data. Then, with the reception of the response message, the mobile terminal 10 calculates the time difference between the time indicated by the time stamp included in the response message and the transmission time, and the data size of the available bandwidth measurement data Is divided by the time difference to calculate the available bandwidth. As described above, in this embodiment, the available bandwidth is measured by transmitting and receiving the available bandwidth measurement data. However, in such an aspect, an extra load may be applied to the communication network 20. Therefore, as a matter of course, a method of measuring the available bandwidth without applying an extra load to the communication network 20 as in the measurement method disclosed in Patent Document 4 may be adopted.

On the other hand, the determination of the exercise state is performed as follows.
The control unit 110 writes the acceleration data output from the acceleration sensor 140 into the ring buffer in the volatile storage unit 164 at a constant time interval (as described above, in this embodiment, at an interval of 100 milliseconds). The difference value of the acceleration component in the three axial directions is calculated for each axis with reference to the data and the acceleration data immediately before. Then, the control unit 110 compares the maximum of these three difference values with a predetermined threshold value (in this embodiment, two types of 0.2G and 1.0G), and the procedure shown in Table 1 below. To determine the motion state of the camera 12. That is, the control unit 110 determines that the camera 12 is in a stationary state (hereinafter referred to as a stationary state) if the maximum of the three difference values is less than 0.2 G, and determines that 0.2 G If it is less than 1.0 G, it is determined that the state is a small motion state with small movement, and if it is 1.0 G or more, it is determined that the state is a large motion state with large motion.

In Table 1, 1.0 G is a value representing the magnitude of acceleration corresponding to gravitational acceleration (about 9.8 m / s ² ). In the present embodiment, 0.2 G and 1.0 G are used as threshold values for determining the motion state of the camera 12, but the threshold values are not limited to these values and are suitable by performing experiments as appropriate. A value may be used. In the present embodiment, the motion state of the camera 12 is determined based on the maximum value of the difference values of the acceleration components in the three axial directions, and represents the latest acceleration data output from the acceleration sensor 140. Of course, the motion state of the camera 12 may be determined by comparing the magnitude of acceleration (or the sum of squares of acceleration components in the respective axial directions) with a threshold value.

  Next, the control unit 110 performs resolution conversion and compression encoding on the data amount per frame of the moving image data to be transmitted according to the motion state determined in step SA100 in the manner shown in Table 2 below. (Step SA110). In Table 2, VGA represents a resolution of 640 × 480, and QVGA represents a resolution of 1/4 of VGA (that is, 320 × 240). The reason why the resolution and compression rate in each motion state are determined as shown in Table 2 below will be clarified later.

As described above, the resolution of each frame of the moving image data output from the camera 12 is VGA. For this reason, when it is determined in step SA100 that the image is stationary, the control unit 110 performs only compression encoding with a low compression rate on the moving image data, and the amount of data per frame of the moving image data. Adjust. On the other hand, if it is determined in step SA100 that the state is the small motion state (or the large motion state), the control unit 110 performs resolution conversion for converting the resolution of the moving image data from VGA to QVGA, Compression encoding with a high compression rate (compression encoding with a medium compression rate in the case of a large motion state) is performed to adjust the data amount per frame of the moving image data. It should be noted that well-known algorithms may be adopted as appropriate for resolution conversion and compression encoding.

  In step SA120 subsequent to step SA110, control unit 110 transmits the moving image data in which the data amount per frame has been adjusted in step SA110 to the moving image transmission destination address 162a while adjusting the frame rate. More specifically, if the motion state of the camera 12 determined in step SA100 is a stationary state or a small motion state, the control unit 110 determines the bit rate obtained by the product of the data amount per frame and the frame rate. Is adjusted to be 80% of the available bandwidth measured in step SA100. On the other hand, if the motion state of the camera 12 determined in step SA100 is the large motion state, the control unit 110 sets the frame rate to a predetermined minimum value (in this embodiment, 0.5 frame / Second), and the moving image data whose data amount per frame has been adjusted is transmitted to the moving image transmission destination address 162a.

Table 3 lists the values of resolution, compression rate, frame rate, and bit rate in each motion state when the available bandwidth measured in step SA100 is 800 kbps (800 kbps). Table 4 shows values of resolution, compression rate, frame rate, and bit rate in each motion state when the available bandwidth is 400 kbps.

As is clear from Table 2, Table 3, and Table 4, in the present embodiment, in the stationary state, these two are given priority so that the resolution is high and the compression ratio is low among the resolution, compression ratio, and frame rate. Therefore, the frame rate is kept low accordingly. On the other hand, in the small motion state, priority is given to a higher frame rate, and the two are suppressed so that the resolution is lower and the compression rate is higher.
This is due to the following reason.

  When the camera 12 is in a stationary state, a user who is capturing an image of the subject with the camera 12 stops moving as if he is gazing at the subject in order to accurately capture the details of the subject. It is thought that. In this embodiment, in order to respect the photographer's intention of “accurately capturing the details of the subject”, in the stationary state, the resolution and compression rate of the resolution, compression rate, and frame rate are given priority, and only that much. The frame rate is suppressed. This is because a moving image that accurately captures the details of the subject in each frame is displayed on the moving image display device 30 even though the smoothness of the movement is lacking.

  On the other hand, the fact that the camera 12 is in a small motion state is considered to be a state in which the user moves as if following the subject with his eyes in order to accurately capture the motion of the subject. . In this embodiment, in order to respect the photographer's intention of “capturing the motion of the subject accurately”, the frame rate is prioritized in the small motion state, and the resolution and the compression rate are reduced accordingly. As a result, a smooth moving image in which the motion of the subject is well reflected although not clearly displayed in each frame is displayed on the moving image display device 30. Note that when the mobile terminal 10 is in a large motion state, the frame rate is reduced to the minimum value because the moving image captured in such a state has a large subject blur and the frame rate is reduced to the minimum value. This is because the transmission of useless video data is minimized by reducing the value so that the bandwidth is not wasted. In addition, it is useless to set the compression ratio between the stationary state and the small motion state in the large motion state as low as that in the stationary state. This is because the bit rate can be kept sufficiently low without increasing the compression rate.

  What should be noted here is that the bit rate for transmitting moving image data from the mobile terminal 10 to the moving image display device 30 is always within the available bandwidth in any of the stationary state, the small movement state, and the large movement state. In the moving image display device 30, the moving image is not reproduced intermittently. Thus, according to the present embodiment, a moving image captured using the mobile terminal 10 is displayed on the moving image display device 30 with the image quality intended by the photographer, and the user of the moving image display device 30 feels stress. There is an effect that it is possible to view the moving image without making it. In the present embodiment, the frame rate is adjusted so that the bit rate is 80% of the available bandwidth in the stationary state and the small motion state, but the proportion of the bit rate in the available bandwidth is higher (for example, Of course, the frame rate may be adjusted to be 80%, 5 minutes, 90%, etc., or lower (for example, 70%, 60%, etc.).

<C: Deformation>
Although one embodiment of the present invention has been described above, the following modifications may of course be added to this embodiment.
(1) In the embodiment described above, the amount of data per frame is adjusted according to the magnitude of the movement of the camera 12, and the frame rate is adjusted so that the bit rate is within the available bandwidth. However, the frame rate may be determined according to the magnitude of the movement of the camera 12 and the data amount per frame may be adjusted so that the bit rate is within the available bandwidth. For example, the frame rate is 1.0 fps in the stationary state, 8.0 fps in the small motion state, and 0.5 fps in the large motion state. In this case, if the available bandwidth is 800 bps, the resolution and compression rate may be determined as shown in Table 3 above. If it is not necessary to consider whether the bit rate is within the usable bandwidth, both the data amount per frame and the frame rate may be determined according to the movement of the camera 12. good. In short, when it is determined that the motion state of the camera 12 is stationary, the frame rate is reduced by giving priority to the amount of data per frame, and the motion state of the camera 12 is determined to be a small motion state In such a case, a moving image captured using the mobile terminal 10 can be used as long as the data amount per frame and the frame rate are adjusted so that the data rate per frame is kept low by giving priority to the frame rate. It is possible to display on the moving image display device 30 with the video quality intended by the photographer. Needless to say, if it is not necessary to consider whether or not the bit rate is within the available bandwidth, the control unit 110 need not execute the available bandwidth measurement process.

(2) In the above-described embodiment, the triaxial acceleration sensor is used as the motion detection unit. However, the moving image data output from the camera 12 is analyzed to detect the magnitude of the motion of the camera 12 accompanying the user's body movement. But of course. Specifically, the blurring of the subject shown in a series of frames represented by the moving image data is identified by comparing adjacent frames, and the magnitude of the blur is detected as the magnitude of the movement of the camera 12. In such an embodiment, the camera 12 and the control unit 110 that analyzes the captured image serve as a motion detection unit, and thus it is not necessary to provide the acceleration sensor 140 in the mobile terminal 10.

(3) In the embodiment described above, a mobile phone having a data communication function is used as the mobile terminal 10. However, a PDA (Personal Digital Assistant) having a data communication function may be used as the mobile terminal 10. Further, instead of the combination of the camera 12 and the mobile terminal 10, a mobile phone having an imaging function (for example, a mobile phone having a built-in camera 12 as an imaging means instead of the external device I / F unit 130 in FIG. 2). A telephone) may be used. In the above-described embodiment, the case where the video display device 30 is a personal computer has been described. However, any electronic device having a video display function and a communication function can be used as the video display device 30. For example, a PDA or a mobile phone may be used as the moving image display device 30.

(4) In the embodiment described above, the lossy compression encoding is performed on the moving image data transmitted from the mobile terminal 10 to the moving image display device 30. However, the lossless compression encoding may be performed instead of the lossy compression encoding. Further, neither lossy or lossless compression encoding may be performed. Thus, even when lossless compression encoding is performed on moving image data transmitted from the mobile terminal 10 to the moving image display device 30 or when compression encoding is not performed, the amount of data per frame can be adjusted by adjusting the resolution. This is because adjustment is possible. Further, even when irreversible compression coding is applied to moving image data transmitted from the mobile terminal 10 to the moving image display device 30, the data amount per frame is adjusted by adjusting only one of the resolution and the compression rate. You can go.

(5) In the above-described embodiment, the available bandwidth in the communication network 20 is measured by the control unit 110 prior to the start of transmission of moving image data to the moving image display device 30, and the moving image data in which the data amount per frame has been adjusted. The control unit 110 is caused to execute a process for adjusting the frame rate when transmitting the bit rate so that the bit rate is within the usable bandwidth. However, the control unit 110 executes a process of measuring the available bandwidth one or more times during the transmission of the video data in which the data amount per frame is adjusted, and readjusting the frame rate according to the measurement result. Also good. According to such an aspect, even when the available bandwidth in the communication network 20 varies within a short time, the user who uses the moving image display device 30 can receive a large amount of stress on the moving image captured by the mobile terminal 10. This makes it possible for the user of the moving image display device 30 to view without feeling. Note that, in the aspect in which the usable bandwidth is measured again during the transmission of the moving image data in which the data amount per frame has been adjusted as in the present modification, a communication network such as that disclosed in Patent Document 4 described above is used. Needless to say, it is preferable to employ a method of measuring the available bandwidth without applying an extra load to the network.

(6) When moving image data is transmitted at a low frame rate, such as in a stationary state or a large motion state in the above-described embodiment, the contents of a series of frames represented by the moving image data output from the camera 12 are analyzed. A frame (hereinafter referred to as a representative frame) that is actually transmitted to the moving image display device 30 may be selected based on the analysis result. For example, when the available bandwidth is 400 kbps, it is only necessary to transmit at a rate of 1 frame per 2 seconds in a stationary state or a large motion state, and therefore a series of moving image data output from the camera 12 in 2 seconds. Of the frames, a frame with less subject blur or a frame with a specific subject may be selected as a representative frame and transmitted to the moving image display device 30.

(7) In the above-described embodiment, the communication control program 162b that causes the control unit 110 to execute the moving image data transmission control processing that clearly shows the features of the present invention is stored in the nonvolatile storage unit 162 of the mobile terminal 10 in advance. However, the communication control program 162b may be distributed by being written on a computer-readable recording medium such as a CD-ROM (Compact Disk-Read Only Memory), or distributed by downloading via an electric communication line such as the Internet. May be. In the above-described embodiment, the moving image data transmission control process that significantly shows the characteristics of the present invention is realized by software. However, the motion detection unit that detects the magnitude of the movement caused by the user's body movement, and the moving image data While adjusting at least one of the amount of data per frame and the frame rate at the time of transmitting the moving image data to another device via the communication network according to the magnitude of the motion detected by the motion detection means The transmission means for transmitting the moving image data to the other device is composed of an electronic circuit, and the portable terminal of the present invention is configured by incorporating these electronic circuits into a general portable terminal with a built-in or connected camera. Of course it is good.

DESCRIPTION OF SYMBOLS 10 ... Portable terminal, 12 ... Camera, 20 ... Communication network, 30 ... Moving image display apparatus, 110 ... Control part, 120 ... Communication I / F part, 130 ... External apparatus I / F part, 140 ... Acceleration sensor, 150 ... User I / F unit, 160 ... storage unit, 162 ... non-volatile storage unit, 162a ... moving image transmission destination address, 162b ... communication control program, 164 ... volatile storage unit, 170 ... bus.

Claims (7)

A moving image display device for displaying a moving image represented by moving image data received via a communication network;
A mobile terminal that captures a moving image and outputs or outputs moving image data representing the moving image, and transmits the moving image data to the moving image display device via the communication network; and
Including
The portable terminal is
At least the amount of data per frame of the moving image data and the frame rate when transmitting the moving image data to the moving image display device via the communication network are detected by detecting the movement of the camera caused by the user's body movement. One of them is transmitted to the moving image display apparatus while being adjusted according to the magnitude of the movement of the camera. The portable terminal is
When it is determined that the camera is stationary, priority is given to the amount of data per frame to keep the frame rate low, and when it is determined that the camera movement is small, priority is given to the frame rate. The communication system according to claim 1, wherein the amount of data per frame is kept low. The portable terminal measures an available bandwidth that is a bandwidth that can be used in the communication network,
Adjusting either the data amount per frame of the moving image data and the frame rate when transmitting the moving image data to the moving image display device via the communication network according to the magnitude of the movement of the camera, The communication system according to claim 1 or 2, wherein the other is adjusted so that a bit rate falls within the available bandwidth. The mobile terminal performs compression encoding on the moving image data to be transmitted to the moving image display device, and transmits the compressed data per frame by adjusting at least one of the compression rate in the compression encoding and the resolution of each frame constituting the moving image. The communication system according to any one of claims 1 to 3, wherein the amount of data is adjusted.   5. The mobile terminal according to claim 1, wherein the mobile terminal reduces the frame rate to a predetermined minimum value when the magnitude of movement of the camera exceeds a predetermined threshold value. The communication system according to claim 1. In a mobile terminal with a built-in or connected camera that captures a video and outputs video data representing the video,
Movement detection means for detecting the magnitude of the movement of the camera caused by the user's body movement;
At least one of the data amount per frame of the moving image data and the frame rate at the time of transmitting the moving image data to another apparatus via a communication network, the magnitude of the motion of the camera detected by the motion detecting means Transmitting means for transmitting the video data to the other device while adjusting according to
A portable terminal characterized by comprising: Computer
A motion detection means for detecting the magnitude of the movement of the camera that occurs with the body motion of the user of the terminal that incorporates or connects a camera that captures a video and outputs the video data;
At least one of the data amount per frame of the moving image data and the frame rate when transmitting the moving image data to another device via a communication network is determined according to the magnitude of motion detected by the motion detecting means. Transmitting means for transmitting the moving image data to the other device while adjusting;
A program characterized by making it function.

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