JPH10164533A - Image communication method and apparatus - Google Patents

Abstract

(57) [Summary] [Problem] When computer resources reach their limits,
It realizes transmission of important data such as audio preferentially, and adjusts the quality of video to meet user requirements. SOLUTION: A user previously specifies an upper limit value of a used band of all transmission data and a priority of each medium to a used band allocating module 2-11. 2-2
When 3, 2-24 is detected, the used band allocation module 2-11 controls the band allocation of the media according to the priority.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image communication method and apparatus, and more particularly, to a technique for managing the quality of moving images and audio when digital moving images are transmitted over a network.

[0002]

2. Description of the Related Art In an application for transmitting a plurality of data streams of video and audio, such as a TV conference system, the transmission capacity of a network and the CPU are limited.
If all the data cannot be processed due to the limitation of the processing capacity of the data, data loss occurs in both the video data and the audio data.

[0003]

Therefore, in a tool such as the TV conference system described above, it has been difficult to achieve communication when audio data loss occurs. Further, when the band for transmitting the video data is insufficient, there may be different video qualities such as a video that prioritizes image quality and a video that prioritizes motion even within the same transmission band.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and realizes priority transmission of important data such as audio when computer resources reach a limit. It is an object of the present invention to provide an image communication method and apparatus capable of adjusting the quality of an image according to a user's request.

[0005]

To achieve the above object, an image communication apparatus according to the present invention has the following arrangement.

That is, an image communication apparatus for communicating video and audio via a network, wherein the control means controls the transmission rate from an application layer in accordance with the reception status of the video and audio on the receiving side; Transmitting means for transmitting the video and audio at a transmission rate controlled by the control means.

In order to achieve the above object, another image communication apparatus according to the present invention has the following configuration.

[0008] That is, an image communication apparatus for communicating video and audio via a network, wherein control means for controlling a transmission rate from an application layer in accordance with a received packet on a video and audio receiving side; Transmitting means for transmitting the video and audio at a transmission rate controlled by the control means.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIG. 1 is a block diagram showing the configuration of an image communication apparatus according to the first embodiment. Referring to FIG. 1, reference numeral 1-1 denotes a video transmission / audio data device which captures video and audio and transmits the video and audio to a network. 1-
Reference numerals 2 and 1-3 denote video / audio data receiving devices.
Display / reproduce transmission data transmitted through the −0 network. In the embodiment, only the case where there is one type of video and one type of audio will be described. However, the present invention can be easily extended to the case where a plurality of types of video or audio data exist. It goes without saying that the present invention can be easily extended even when data other than video and audio data exists.

Here, the above-described video transmission / audio data device 1-1 and video / audio data receiving devices 1-2, 1-3 are described.
Will be described in detail.

First, in the video transmission / audio data device 1-1, 1-1a is an analog video source such as a video camera, and 1-1b is a microphone, which is connected to the device 1-1 via an interface device described later. Is done. 1-
Reference numeral 11 denotes a video capture device, which functions as an interface device for the analog video source 1-1a, and converts a captured analog signal into a digital signal. 1-12
Is a CODEC, which compresses the A / D converted video data based on a predetermined compression method. Reference numeral 1-13 denotes a voice capturing device, which functions as an interface device for the microphone 1-1b, and converts a captured analog voice signal into digital voice data.

Reference numeral 1-14 denotes a CPU, which controls the entire apparatus. Reference numeral 1-15 denotes a main memory, which stores the captured video data and audio data. Reference numeral 1-16 denotes a secondary storage device, which stores a processing procedure (program) of the CPU 1-14 and various data. Reference numeral 1-17 denotes a network I / F, which exchanges video and audio data with the network 1-0.

In the above configuration, the analog video signal captured from the analog video source 1-1a is converted into video data by the video capture device 1-11,
The data is compressed by the ODEC 1-12 and temporarily stored in the main memory 1-14.
Is stored in The analog audio signal captured from the microphone 1-1b is converted into voice data by the voice capturing device 1-13, and is temporarily stored in the main memory 1-14. After that, the stored video and audio data is transmitted to the network 1-0 via the network I / F 1-17.

It is assumed that the rate at which the video and audio data are transmitted can be adjusted by the CPU 1-14. Also, as a compression method, for example,
MotionJPEG or the like is used, but is not limited to a compression method. However, the frame rate, compression ratio, image size, and the like can be changed during capture / compression, and the CPU 1-14
Can set the values of those parameters.

On the other hand, the video / audio data receiving device 1-2,
In 1-3, 1-21 is a bitmap display, 1-22 is a CODEC, 1-23 is a speaker,
-24 is a mouse, 1-25 CPU, 1-26 is main memory,
1-27 is a secondary storage device, 1-28 is a network I /
F.

In the above configuration, when video and audio data are received from the video transmission / audio data device 1-1 via the network I / F 1-28, the video data is COD
After being decompressed by the EC 1-22, it is displayed as a moving image on the bitmap display 1-21, and after audio data is D / A converted, it is reproduced by the speaker 1/23.

Hereinafter, the operation in the embodiment will be described in more detail. FIG. 2 is a diagram showing a process configuration and data flow in the CPU.

First, the user specifies in advance the upper limit value of the used band of all transmission data and the priority of each data to the used band allocation module 2-11 using a main panel described later. FIG. 3 is a diagram illustrating an example of a GUI for designating the upper limit value of the used bandwidth and the priority of each data. In the figure, reference numeral 3-1 denotes a main panel, which can be set by a left toggle button whether or not transmission is performed with priority on voice. By writing a numerical value in the right upper limit text box, the upper limit of the total transmission rate can be set. These settings become effective when the setting button is pressed. The numerical value displayed in the right-hand column of the control value is the sum of the bands actually allocated to the transmission data. Reference numeral 3-2 denotes a confirmation screen displayed when the assigned band confirmation button is pressed.

Referring back to FIG. 2, when the video and audio data capturing modules 2-12 and 2-13 are activated, it is necessary to determine whether the medium is video or audio and to sufficiently transmit the respective data. The required bandwidth required is reported to the used bandwidth allocation module 2-11.

Here, the module 2-11 is software in the application layer. Therefore, the user can relatively freely modify.

On the other hand, the used band allocation module 2-1
1 assigns an upper limit value of all set transmission data to video and audio. Here, in the case of audio priority, a band according to the requested band is allocated to the audio data, and the remaining band is allocated to the video data. In the case of the example shown in FIG. 3, the audio priority is set, and the priority of the audio is “1”, so that 240 Kbps is allocated to the audio data according to the required bandwidth. When the priority is not set to the audio, the upper limit value of the entire transmission band is allocated according to the ratio of the required bandwidth of each of the video and the audio.

Next, the video capturing module 2-12,
The video and audio data captured by the audio capture module 2-13 is divided into packets by the data transmission units 2-14 and 2-15, transmitted over the network 1-0, and transmitted to the target video / audio data receiving device. Is sent. It is assumed that the transmitted packet has a sequence number. Further, the data transmission modules 2-14 and 2-15 have a function of transmitting data in a designated band.

The transmitted packet is received by the data receiving modules 2-23 and 2-24, which are processes executed by the CPU 1-25 of the video / audio data receiving apparatus, and the packet is reconstructed. The video data is displayed on the bitmap display 1-21 by the image display module 2-21, while the audio data is reproduced by the speaker 1-23 via the audio reproduction module 2-22.

The data receiving modules 2-23, 2-
24 can detect that a packet loss has occurred on the network 1-0 based on the sequence number assigned to the packet.

Then, the data receiving module 2-23,
2-24, the packet loss rate / reception rate is periodically (eg, every second) by the data transmission modules 2-13, 2-2.
14 via the network 1-0. As a result, the data transmission modules 2-14 and 2-15 determine the transmission rate / reception rate in addition to the reported packet loss rate / reception rate.
Information on the number of transmission nodes is provided, and the information is reported to the used band allocation module 2-11. Then, the used band allocation module periodically (for example, every 10 seconds) allocates a band based on the transmission / reception information.

According to this band allocation method, first, when a packet loss occurs, the allocated band of a medium (for example, video) having a low priority is reduced according to the band in which the packet is lost. For example, when the transmission rate of video data is 4000 Kbps and a packet loss of 10% occurs, the bandwidth is allocated such that the allocated bandwidth is 3600 Kbps.

For media with low priority,
If the transmission rate is smaller than a certain ratio (for example, 70%) compared to the band to which the transmission rate is actually assigned,
Reduce the bandwidth allocated to the data. However,
It is assumed that a band larger than the actual transmission rate (for example, 20% higher than the actual transmission rate) is allocated.

The transmission modules 2-13 and 2-14
Is a certain ratio (for example, 90%) to the allocated bandwidth
If the transmission is performed at the above rate and there is a margin in the upper limit of the total set transmission rate and the required bandwidth, the bandwidth allocated to the transmission module is increased (for example,
10% of the original allocated bandwidth). However, the bandwidth to be allocated is a value equal to or less than the required bandwidth, and is allocated so that the total transmission rate does not exceed the set upper limit.

As described above, according to the embodiment, the upper limit of the bandwidth used for the transmission rate and the priority of each medium are set,
When the bandwidth of the network is insufficient, by reducing the bandwidth used for data of low importance, important data can be transmitted preferentially according to the requested bandwidth.

[Embodiment 2] In Embodiment 1 described above,
The audio data is transmitted preferentially by setting a low priority for the video and limiting the transmission capacity. In this embodiment, the video quality requested by the user is limited within the limited transmission capacity. It is what makes it happen.

In the present embodiment, in order to realize the image quality required by the user within the transmission capacity, three parameters of a frame rate, image quality (compression parameter), and image size (resolution) are assumed as adjustable parameters. ing. However, the present invention is not limited to this, and it goes without saying that the present invention can be applied to other image parameters that can be adjusted.

Hereinafter, a parameter setting process according to the second embodiment will be described. FIG. 4 is a view showing a screen for setting various parameters by the GUI.

First, what quality the user desires is set. Specifically, the priority order of the three parameters is set from “1” to “3” by using a text box on the left side of the panel for each parameter. May be). Then, the required value and the minimum value are set for each parameter by the right scroll bar. Note that the required value is a desired value to be realized, and the minimum value is a value representing the quality to be secured at least.

If the transmission band is insufficient based on such user settings and the quality as required cannot be realized,
Gradually lower quality from lower priority parameters.

Here, the operation will be described by taking as an example a case where the settings are made as shown in FIG. First, the three parameters are set as required, and if the computer resources are insufficient, first, the video quality adjustment module in the video capture module 2-12 shown in FIG. Decrease the set value gradually. If computer resources are sufficient before lowering the frame rate to the minimum value, the set value of the frame rate is controlled between the required value and the minimum value. If computer resources are still insufficient even if the frame rate is lowered to the lowest value, the image quality (compression parameter) having the next lowest priority is gradually lowered.

In this way, when the computer resources are insufficient, the parameters of the video having the lower priority are sequentially reduced to control the value between the required value and the minimum value.

On the other hand, if there is a computer resource margin and there is a parameter that does not satisfy the required value, the quality is gradually increased in the order of the parameter having the higher priority, and the quality is increased within the range where the computer resource is sufficient. Improve quality to required value.

As described above, according to the present embodiment, image parameters are provided in order to realize the image quality required by the user within the limited transmission capacity, and when the computer resources are insufficient, the image quality is improved. It can be controlled to be close to the user's request.

[Embodiment 3] In Embodiment 1 described above,
Although the amount of data transmitted from a single video transmission / audio data device (data transmission device) is controlled within the set upper limit, in this embodiment, when there are a plurality of data transmission devices on the network, A method for suppressing the data amount of the entire network within a certain value will be described.

The used band allocation module of the data transmitting apparatus described in the first embodiment is set to LQM (Local QoS).
Manager). Further, one module for collectively managing information from the LQM of each data transmission device existing on the network is provided in the network as a GQM (Global QoS Manager). Note that the GQM can be implemented as a module in one data transmission device, and may be implemented in a host different from the data transmission device.

FIG. 5 is a conceptual diagram showing a configuration of the data transmitting apparatus according to the third embodiment. GQM5-1 shown in FIG.
, A band usable on the network 5-0 is set. Then, the GQM 5-1 receives a report on the band allocation status from each LQM 5-2. Here, when the upper limit of the used band is not specified for each LQM 5-2, the band usable in the network 5-0 is equally allocated to each LQM 5-2. The band allocated to LQM5-2 is set as the upper limit of the band used by LQM5-2.

When a band smaller than the band allocated evenly is specified as the upper limit in the LQM 5-2, the upper limit is directly used in the LQM 5-2 as the band used by the data transmitting apparatus. Assigned,
The remaining available bandwidth of the network is evenly distributed to each LQM5
Assign to -2.

LQ is assigned to more bands than the equally allocated bands.
Even if it is set as the upper limit value of the used band of M5-2, the value is not reflected.

As described above, according to the present embodiment, when a plurality of data transmitting devices are present on a network, the data amount of the entire network is controlled to be within a certain value, so that each data transmitting device in the entire network is controlled. The used band can be suppressed within the usable band of the network.

[Embodiment 4] In Embodiment 1 described above,
When computer resources are scarce, low-priority media cannot be allocated bandwidth as requested,
For example, in the example shown in FIG. 3, only a band smaller than the requested band is allocated to the video. In this embodiment, in such a case, the user is notified that the required transmission capacity has not been secured.

More specifically, the GUI panel 3 shown in FIG.
In 2, the data (for example, red) is displayed in the column for the data to which the requested bandwidth is not allocated. Further, a means for displaying the allocated bandwidth to the requested bandwidth by a bar graph may be used.

As described above, according to the present embodiment, the user can easily know the media to which the band is not allocated as requested.

[Embodiment 5] In Embodiment 3 described above,
GQM5-1 shown in FIG. 5 is LQM5 of each data transmitting apparatus.
-2 when allocating the bandwidth to LQ-2 depending on the transmittable bandwidth of the network 5-0 set in the GQM 5-1.
There is a possibility that only a band smaller than the upper limit value of the total transmission rate set in M5-2 is allocated to the data transmission device.

In this embodiment, for a certain data transmission device, the bandwidth less than the upper limit of the total transmission rate is G
If allocated by QM5-1, the fact that the bandwidth of the network 5-0 is insufficient is reported by GQM5.
-1 is the network 5-0 via the network 5-0
The above is reported to LQM5-2 of all data transmitting apparatuses. Then, the fact that the bandwidth of the network is insufficient is displayed on the main panel of the LQM of 3-1 shown in FIG. 3 or another window, and can be notified to the user who is transmitting the data.

As described above, according to the present embodiment, by transmitting information indicating that the network bandwidth is insufficient to each data transmitting apparatus, a user who does not need to transmit detailed images or the like can be configured as shown in FIG. By reducing the setting of the upper limit value of the total transmission rate of the main panel of the LQM shown in 3-1 as described above, the transmission rate assigned to a user who wants to transmit large data can be increased.

[Embodiment 6] In Embodiment 2 described above,
Means for transmitting an image similar to the image quality desired by the user has been described. At this time, FIG. 4 is shown as a GUI for setting a user request. In this embodiment, a GUI as shown in FIG. 6 is provided in order to facilitate setting of a request and to make it easier to understand the display of the currently realized image quality.

Specifically, as shown in FIG. 6, the required value, the minimum value, and the actual set value of the three parameters are respectively displayed as triangles. By dragging the vertices of the triangle,
You can change the required value and minimum value settings. The priority is displayed at the end of the axis of each parameter, and the priority can be changed by clicking the numerical value of the priority.

Further, an image quality priority button and a motion priority button are prepared, and when these buttons are pressed, preset request values and priorities are set, respectively. Thereby, the convenience for the user can be further improved.

According to the above embodiment, when transmitting a plurality of data streams such as video and audio such as in a TV conference, important data such as audio can be transmitted with priority. Further, by determining the quality of the video at the time of capturing and compressing the video in accordance with the user's request and the computer resources that can be transmitted, it is possible to transmit the video close to the user's request within the limited resources.

Even if the present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine, a facsimile, etc.) comprising one device Device).

Further, an object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (CPU or MP) of the system or apparatus.
It goes without saying that U) can also be achieved by reading and executing the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowcharts. Each module shown will be stored in a storage medium.

That is, the program codes of at least the “control module” and the “transmission module” may be stored in the storage medium.

[0064]

As described above, according to the present invention, when computer resources reach a limit, transmission of important data such as audio is preferentially performed, and the quality of video is reduced. Can be adjusted from the application layer to the one according to the request.

Therefore, the degree of freedom is relatively high and the user can make adjustments.

[0066]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image communication device according to a first embodiment.

FIG. 2 is a diagram showing a process configuration and a data flow in a CPU.

FIG. 3 is a diagram illustrating an example of a GUI for designating an upper limit value of a used band and a priority of each data.

FIG. 4 is a diagram showing a screen for setting various parameters by a GUI.

FIG. 5 is a conceptual diagram illustrating a configuration of a data transmission device according to a third embodiment.

FIG. 6 is a diagram showing a GUI for adjusting video quality in a sixth embodiment.

FIG. 7 is a diagram showing a memory map of each module stored in a storage medium.

[Explanation of symbols]

 1-1 Video transmission / audio data device 1-2 Video / audio data reception device 1-11 Video capture device 1-12 CODEC 1-13 Audio capture device 1-14 CPU 1-15 Main memory 1-16 Secondary storage device 1-17 Network I / F 1-21 Bitmap Display 1-22 CODEC 1-23 Speaker 1-24 Mouse 1-25 CPU 1-26 Main Memory 1-27 Secondary Storage 1-28 Network I / F

Claims (37)

[Claims] 1. An image communication apparatus for communicating video and audio via a network, comprising: control means for controlling a transmission rate from an application layer in accordance with a reception state of the video and audio on a receiving side; Transmitting means for transmitting the video and audio at a transmission rate controlled by control means. 2. When a plurality of image communication apparatuses are connected via a network, the control means controls an upper limit of a transmission rate based on a transmission / reception state from each image communication apparatus. The image communication device according to claim 1. 3. The image communication apparatus according to claim 2, wherein a transmission rate, a data loss rate of a network, a number of data reception hosts, and a reception rate are used as the transmission / reception status. 4. The apparatus according to claim 1, wherein said control means includes a designating means for designating importance of video and audio, and designates an upper limit of a transmission rate according to the designated importance. Image communication device. 5. The image communication apparatus according to claim 4, wherein voice is given priority as said importance. 6. The image according to claim 1, further comprising an adjustment unit configured to set a user's request regarding the image quality of the digital moving image and adjust the image quality according to the transmission rate and the user's request. Communication device. 7. The image communication apparatus according to claim 6, wherein a frame rate, a compression parameter, and an image size are adjusted as the video quality. 8. The apparatus according to claim 1, wherein said control means includes means for managing information from all the image communication apparatuses existing on said network and allocating a use band to each image communication apparatus. Image communication device. 9. When there is an image communication apparatus on the network to which a band cannot be allocated by the specified upper limit of the transmission rate, the image communication apparatus notifies the image communication apparatus to that effect. Item 10. The image communication device according to Item 8. 10. An image communication method for communicating video and audio via a network, comprising: a control step of controlling a transmission rate from an application layer in accordance with a reception state of the video and audio on a receiving side; Transmitting the video and audio at a transmission rate controlled by the control step. 11. When a plurality of image communication devices are connected via a network, the control step controls an upper limit of a transmission rate based on a transmission / reception status from each image communication device. The image communication method according to claim 10. 12. The transmission / reception status includes a transmission rate,
12. The image communication method according to claim 11, wherein a data loss rate of the network, the number of data reception hosts, and a reception rate are used. 13. The control method according to claim 10, wherein said control step includes a designation step of designating importance of video and audio, and designating an upper limit value of a transmission rate according to the designated importance. Image communication method. 14. The image communication method according to claim 13, wherein voice is given priority as said importance. 15. The image according to claim 10, further comprising an adjusting step of setting a user's request regarding the video quality of the digital moving image, and adjusting the transmission rate and the video quality according to the user's request. Communication method. 16. The image communication method according to claim 15, wherein a frame rate, a compression parameter, and an image size are adjusted as the video quality. 17. The image communication method according to claim 10, wherein the control step manages information from all the image communication devices existing on the network and allocates a use band to each image communication device. . 18. When there is an image communication apparatus on a network to which a bandwidth cannot be allocated by a specified upper limit of a transmission rate, the image communication apparatus notifies the image communication apparatus to that effect. 18. The image communication method according to item 17. 19. An image communication apparatus for communicating video and audio via a network, comprising: control means for controlling a transmission rate from an application layer according to a received packet on a video and audio receiving side; Transmitting means for transmitting the video and audio at a transmission rate controlled by control means. 20. When a plurality of image communication apparatuses are connected via a network, the control means controls an upper limit of a transmission rate based on a transmission / reception state from each image communication apparatus. The image communication device according to claim 19. 21. A transmission rate,
21. The image communication apparatus according to claim 20, wherein a data loss rate of the network, the number of data reception hosts, and a reception rate are used. 22. The apparatus according to claim 19, wherein said control means includes a designation means for designating importance of video and audio, and designates an upper limit value of a transmission rate according to the designated importance. Image communication device. 23. The image communication apparatus according to claim 22, wherein priority is given to voice as said importance. 24. The image according to claim 19, further comprising adjusting means for setting a user's request regarding the image quality of the digital moving image, and adjusting the image quality according to the transmission rate and the user's request. Communication device. 25. The image communication apparatus according to claim 24, wherein a frame rate, a compression parameter, and an image size are adjusted as the video quality. 26. The apparatus according to claim 19, wherein said control means includes means for managing information from all the image communication devices existing on said network and allocating a use band to each image communication device. Image communication device. 27. An upper limit value of a specified transmission rate,
27. The image communication apparatus according to claim 26, wherein when an image communication apparatus to which a band cannot be allocated exists on the network, the image communication apparatus is notified to that effect to each image communication apparatus on the network. 28. An image communication method for communicating video and audio via a network, comprising: a control step of controlling a transmission rate from an application layer in accordance with a received packet on a video and audio receiving side; Transmitting the video and audio at a transmission rate controlled by the control step. 29. When a plurality of image communication devices are connected via a network, the control step controls an upper limit of a transmission rate based on a transmission / reception status from each image communication device. The image communication method according to claim 28. 30. A transmission rate,
30. The image communication method according to claim 29, wherein a data loss rate of the network, the number of data reception hosts, and a reception rate are used. 31. The control method according to claim 28, wherein said control step includes a designation step of designating importance of video and audio, and designating an upper limit value of a transmission rate according to the designated importance. Image communication method. 32. The image communication method according to claim 31, wherein voice is given priority as said importance. 33. The image according to claim 28, further comprising an adjusting step of setting a user's request regarding the image quality of the digital moving image, and adjusting the transmission rate and the image quality according to the user's request. Communication method. 34. The image communication method according to claim 33, wherein a frame rate, a compression parameter, and an image size are adjusted as the video quality. 35. The image communication method according to claim 28, wherein the control step manages information from all the image communication devices existing on the network, and allocates a use band to each image communication device. . 36. When there is an image communication device on the network to which the bandwidth cannot be allocated by the upper limit of the designated transmission rate, the image communication device is notified to that effect to each image communication device on the network. 35. The image communication method according to claim 35. 37. A computer-readable memory storing a program code for image communication for communicating video and audio via a network, wherein a transmission rate is set according to a reception state of the video and audio on a receiving side. A computer readable memory comprising: a code of a control step of controlling from a layer; and a code of a transmission step of transmitting the video and audio at a transmission rate controlled by the code of the control step.