JP3827192B2 - Multimedia communication terminal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multimedia communication terminal that compensates for fluctuations in the processing capability of a receiving communication terminal when multimedia communication is realized by a personal computer or the like.
[0002]
[Prior art]
Video media, audio media, and multimedia data obtained by multiplexing these media have a large amount of information. In general, these data are transmitted and recorded after being compressed. On the receiving side, the received compressed data is decompressed and displayed / reproduced. Depending on the application, the decompression process may have to be processed in real time. Examples of this include two-way communication such as a TV phone, and reproduction of large-capacity data from a storage medium. Real-time processing is required in order to save the storage space for decompressed data when reproducing large-capacity data because conversation is established in two-way communication.
[0003]
Various forms of multimedia communication are conceivable, such as communication that requires transmission of high-quality video data and communication using text and voice. Since the amount of processing at the terminal varies greatly depending on the communication form, a system that smoothly controls communication at various levels is required.
For example, in the document (TTC standard “Terminal for H.324 Low Bit Rate Multimedia Communication” pp.1, 2, 14-16 Telegraph and Telephone Technical Committee (1996)), technology related to capability exchange is introduced. The capability exchange is a mechanism provided so that terminals having different processing capabilities can communicate with each other on the premise of real-time processing.
[0004]
In the capability exchange, each terminal indicates its terminal capability to the game. The terminal capability is an item and capability that can be processed by the receiving side as defined in Document 1. Specific examples include supported video / audio compression algorithms, data communication protocols, video image sizes, frame rates, encoding rates, and the like. The generation side of the encoded data, that is, the transmission side can recognize the reception capability of the game through capability exchange. By generating / transmitting encoded data that can be decoded within this capability range during communication, real-time processing on the receiving side is guaranteed. That is, real-time processing on the receiving side is realized by notifying each other of the capabilities of the terminals.
[0005]
[Problems to be solved by the invention]
By the way, the conventional techniques as described above have the following problems to be solved. Since terminals such as Document 1 include heavy processing such as video encoding / decoding, it is generally realized by dedicated hardware. However, in recent years, multimedia communication can be realized even with software on a PC as the processing speed of a personal computer (hereinafter referred to as a PC) increases. By realizing it on a PC, processing such as editing a document file while performing multimedia communication and transmitting the document as data during communication can be easily performed.
[0006]
However, personal computers have a problem of fluctuations in processing speed. If the processing speed changes, that is, if the reception capability changes, real-time processing becomes impossible, and in an extreme case, the reception data is lost on the receiving side, and the playback processing of each medium fails. In particular, when inter-frame prediction is used in the encoding of moving images, if received data is lost, this effect will spread to subsequent images, resulting in significant quality degradation.
[0007]
A general PC has an environment for executing a plurality of applications in parallel. Therefore, other processing (for example, document editing) can be performed while performing multimedia communication. However, since PC resources such as CPU and memory are fixed, when other applications are executed during multimedia communication, the PC resources allocated to multimedia communication are more than those with only a single application. Will decrease. In this way, a mismatch occurs between the reception capability notified at the initial setting and the reception capability at the time of communication.
[0008]
Such a problem does not occur in the case of single task processing in which only a single application can be executed at the same time. However, since multitask processing is a feature of PCs, the solution by single task conversion loses the feature. End up. There is also a method for solving the problem by using an OS suitable for real-time processing. In this method, fluctuations in capability are suppressed by preliminarily securing PC resources necessary for multimedia communication. However, depending on the priority relationship with other applications, resource allocation for multimedia communication may be reduced, and conversely, other applications may not be activated / executed.
[0009]
Document 1 provides a mechanism for notifying a change in capability during communication in response to such a change in reception capability. However, notification of the capability change requires a response from the game and takes time for matching. In addition, there is a problem that the reception capability varies regularly in the PC, so it is necessary to frequently notify the capability change, which is not realistic.
[0010]
[Means for Solving the Problems]
  The present invention adopts the following configuration in order to solve the above points.
<Configuration 1>
  A multimedia communication terminal connected to a player side that transmits multimedia data including video data, and when receiving the multimedia data, separates the video data from the data and performs error detection processing of the video data. Separation unit for storing normally received video data in the reception buffer, video processing unit for fetching and processing the video data from the reception buffer, and data processing capacity decreased when the data occupancy of the reception buffer exceeds a threshold value A reception buffer monitoring unit that determines whether the data processing capability is reduced and the abnormal reception based on the error detection processing transmits a retransmission request to the game and the separation unit when the data processing capability is reduced. Provided in the retransmission request unit for notifying the number of video data requested to be retransmitted and the separation unit. , Multimedia communication terminal number of the separated video data, characterized in that it comprises a retransmission data discarding unit for discarding the video data to match the number that received the notification.
[0011]
<Configuration 2>
  A multimedia communication terminal connected to an opposite side that transmits multimedia data including video data, and upon receiving the multimedia data, separates the video data from the data and performs error detection processing on the video data. The data processing capability declined when the usage rate of the processor of the local station exceeded the threshold, the separation unit for storing normally received video data in the reception buffer, the video processing unit for fetching and processing the video data from the reception buffer A processing capability monitoring unit that determines that the data processing capability is reduced and the abnormal reception based on the error detection processing transmits a retransmission request to the player and the separation unit when the data processing capability is reduced. Is provided in the above-mentioned separation unit and the retransmission request unit for notifying the number of video data requested for retransmission to Multimedia communication terminal number of the video data, characterized in that it comprises a retransmission data discarding unit for discarding the video data to match the number that received the notification.
[0012]
<Configuration 3>
  A reception buffer monitoring unit that determines that the data processing capacity is reduced when the data occupation amount of the reception buffer is equal to or greater than a threshold; the retransmission request unit is configured by either the reception buffer monitoring unit or the processing capacity monitoring unit. 3. The multimedia communication terminal according to claim 2, wherein when it is determined that the data processing capability is reduced, the retransmission request is transmitted and the number is notified.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described using specific examples.
<Specific example 1>
[0016]
FIG. 1 is a block diagram of the main part of the multimedia communication system of the present invention. Prior to this description, the overall configuration of the multimedia communication system will be described.
FIG. 2 is a block diagram illustrating a specific example of the multimedia communication system of the first specific example.
In the system shown in the figure, data is transmitted in the direction of the right arrow in the figure at the time of transmission, and data is transmitted in the direction of the arrow in the left direction in the figure at the time of reception.
[0017]
On the data transmission side, various sources (not shown) for generating multimedia data are provided. In order to receive data from these sources, a video input / output unit 21, an audio input / output unit 22, other data input / output units 23, a control signal input / output unit 24, and a modem control signal input / output unit 25 are provided. Video data is processed by the video encoding / decoding unit 4. The audio data is processed by the audio encoding / decoding unit 5. Other data is processed by the data protocol processing unit 6. The control signal is processed by the control protocol processing unit 7. The processed data is transmitted via the multiplexer / demultiplexer 3 and the modem 8.
[0018]
An encoded data input / output unit 20 is provided on the receiving side. Here, the same functional block as that on the transmission side is provided, and data reception processing is performed.
[0019]
The video encoding / decoding unit 4 compresses / decompresses video data. The audio encoding / decoding unit 5 compresses / decompresses audio data. The data protocol processing unit 6 compresses / decompresses data such as text and performs data communication protocol processing as necessary. The control protocol processing unit 7 provides a user interface and exchanges end-to-end terminal information. The multiplexing / demultiplexing unit 3 multiplexes each input data and outputs it to the modem 8. The multiplexer / demultiplexer 3 separates the data from the modem 8 and outputs it to each functional block connected on the left side of the figure. The multiplexing / demultiplexing unit 3 also performs error correction processing by retransmission when there is an error in the data input from the modem 8. The modem 8 performs modulation to output the encoded data output from the multiplexing / demultiplexing unit 3 to the analog line and performs demodulation to output data input from the analog line to the multiplexing / demultiplexing unit 3.
[0020]
The multimedia communication terminal described above operates as follows.
When communication is started, a call connection using an analog line is first performed between the transmission side and the reception side. When the call connection is completed, digital communication via the modem is established. The above processing is controlled by a modem control command input from the modem control signal input / output unit 25 to the modem 8. When digital communication between terminals becomes possible, initialization for communication is performed. Specifically, the control protocol processing unit 7 exchanges terminal capabilities of each other, determines a master / slave terminal, sets / opens a logical channel used by the multiplexing / demultiplexing unit 3, and the like. The setting information obtained here is notified to the video encoding / decoding unit 4, the audio encoding / decoding unit 5, the data protocol processing unit 6, and the multiplexing / demultiplexing unit 3.
[0021]
When the above processing is completed, communication of multimedia data using the video encoding / decoding unit 4, the audio encoding / decoding unit 5, the data protocol processing unit 6, and the multiplexing / demultiplexing unit 3 is started. Note that the parameters set in the initial setting can be arbitrarily changed during communication. When the multimedia communication is completed, the logical channel is terminated, a communication end message is transmitted to the other party, and the line is disconnected.
As long as the processing capability fluctuation on the receiving side can be ignored, real-time processing can be realized by capability exchange in the initial setting. However, in a personal computer or the like, this processing capacity fluctuation cannot be ignored.
[0022]
Therefore, in this specific example, in order to absorb the fluctuation of the processing capability, the transmission side is requested to retransmit the data when the load becomes high. The conventional multiplexing / demultiplexing unit of the multimedia communication terminal also has a function of outputting a data retransmission request when a communication channel error occurs. In this specific example, the apparent data transmission rate is reduced by outputting a retransmission request when the reception capability is reduced. Since no new data is received during the retransmission data reception, the processing delay is recovered during that time. The received retransmission data is already received normally and is actually unnecessary, so it can be discarded.
[0023]
Returning to FIG. 1, the main part of the present invention will be described.
Since the present invention mainly relates to the control of the receiving terminal, as shown in the figure, a multiplexing / demultiplexing unit 3 that receives data from the right game 1 and a video that temporarily stores a relatively large amount of received data, for example. The encoding / decoding unit 4 is shown as a representative. The multiplexing / separating unit 3 is provided with a separating unit 31 and a multiplexing unit 32. The video encoding / decoding unit 4 is provided with a reception buffer 40 and a video decoding unit 42. The terminal on the receiving side is indicated as own station 2.
[0024]
In the present invention, a processing capacity monitoring unit 10 is newly provided here. The processing capacity monitoring unit 10 is provided with a reception buffer monitoring unit 11 in the first specific example. As shown in FIG. 2, the reception buffer monitoring unit 11 determines the operation of the multiplexing / demultiplexing unit 3 and the status of the reception buffers of the video encoding / decoding unit 4, the audio encoding / decoding unit 5, and the data protocol processing unit 6. Configured to monitor. Each functional block of the multimedia communication system may be configured by hardware, or may be configured by a functional module of a computer program recorded in a terminal storage medium.
[0025]
The reception buffer monitoring unit 11 has a function of calculating a data occupancy amount of the reception buffer 40 and comparing the buffer occupancy amount with a certain threshold value to detect a decrease in processing capability by the own station.
[0026]
<Operation>
The system of FIG. 1 operates as follows.
From the game 1, multimedia multiplexed data obtained by multiplexing various media data such as video, audio, and text is input. The separation unit 31 separates the received multimedia multiplexed data into data for each medium. The separation unit 31 performs error detection processing on the data of each separated medium. When a communication channel error is detected, the mobile station 1 is requested to retransmit the data in which the error has occurred via the multiplexing unit 32. The multiplexing unit 32 having this function is called a retransmission request unit.
[0027]
The multiplexing unit 32 multiplexes the retransmission request from the separation unit 31 with the transmission data and transmits it to the game 1. The game 1 that has received the retransmission request retransmits the corresponding data. In this way, errors occurring in the communication path are corrected. On the other hand, the data of each medium for which no error is detected by the separation unit 31 is written in the reception buffer in the processing unit of each medium. In FIG. 1, only the reception buffer 40 of the video encoding / decoding unit 4 is illustrated.
[0028]
The processing unit of each medium, for example, the video decoding unit 42 reads the data written in the reception buffer 40 according to the progress of the decoding process. The read data is decoded by the video decoding unit 42 and output as uncompressed video data from the video input / output unit 21 shown in FIG.
[0029]
When there is no change in reception capability, data within the capability range specified at the start of communication is transmitted from the game. That is, the data reading speed is faster than the data writing speed of the reception buffer 40. However, when the reception capability decreases, the reading speed from the reception buffer 40 decreases, and data is accumulated in the reception buffer 40.
[0030]
The reception buffer monitoring unit 11 compares the amount of data written to and read from the reception buffer 40 and calculates the amount of data stored in the buffer (buffer occupancy). Further, the reception buffer monitoring unit 11 compares the buffer occupancy with a predetermined threshold, and when the buffer occupancy exceeds this threshold, the reception buffer monitoring unit 11 requests the game to retransmit the data via the multiplexing unit 32. The multiplexing unit 32 multiplexes the retransmission request with the transmission data and transmits it to the other party. In addition, when the multiplexing unit 32 makes a retransmission request at the request of the reception buffer monitoring unit 11, the multiplexing unit 32 notifies the separation unit 31 of the number of the data requested for retransmission. This is because, as will be described later, it is handled differently from the data requested for retransmission by error detection.
[0031]
As described above, since the game 1 continues to transmit data within the processing capability range of the receiving device, the fact that the buffer occupancy of the receiving device exceeds the threshold indicates that the processing capability is reduced.
Upon receiving the retransmission request, the game 1 retransmits the corresponding data. The separation unit 31 that has received the retransmission data recognizes that the received data is retransmission data due to a decrease in processing capability by the notification from the multiplexing unit 32, and discards the retransmission data. Therefore, no new data is written to the reception buffer 40, and the buffer occupancy falls below the threshold as the processing of the video decoding unit 42 proceeds. In this manner, the separation unit 31 that performs retransmission data discard control is referred to as a retransmission data discard unit.
[0032]
FIG. 3 shows a system operation time chart of the first specific example.
(A) of a figure is a graph which shows the transition of the occupation state of a receiving buffer. The FULL line indicates a state where data is filled in the buffer, and the EMPTY line indicates a state where data is not held in the buffer. The buffer occupancy begins to operate below the initial threshold. The section “A” is a state in which the reception capability is higher than that at the time of capability exchange, and the zone “B” is a state in which the reception capability is lowered below that at the time of capability exchange. (B) shows a retransmission request signal, and (c) shows the contents of received data.
[0033]
In the section “A”, the buffer occupancy is almost constant and stable, but the occupancy of the reception buffer 40 starts to increase from time t1 due to a decrease in the capacity of the receiving apparatus. When the occupation amount of the reception buffer 40 exceeds the threshold at time t2, a retransmission request signal is output as shown in (b). Thus, as shown in (c), retransmission data is sent from the game at time t3. Since retransmission data is not written in the reception buffer 40, the buffer occupation amount gradually decreases, and the retransmission request is stopped at time t4 when the value is equal to or less than the threshold value. After a while, new data starts to be transmitted from time t5. Thereafter, the buffer occupation amount starts increasing again, and a retransmission request is output exceeding the threshold at time t6. At time t7, retransmission data is received and the buffer occupancy begins to decrease. When the reception capability is restored to the initial state from time t8 to time t9, the buffer occupancy thereafter is stabilized below the threshold value. As described above, the multimedia data is decoded without causing the reception buffer 40 to overflow.
[0034]
<Effect of specific example 1>
The multimedia communication terminal of the specific example 1 described above has a mechanism for detecting that the reception capability is reduced from the reception buffer occupancy and outputting a retransmission request when the buffer occupancy exceeds a certain value. is doing. When a retransmission request is made, data is retransmitted on the transmission side, and transmission of newly generated data on the transmission side is limited. That is, the transmission side stops transmitting new data and transmits only retransmission data. Therefore, the apparent transmission rate can be reduced. Even if the receiving side receives the same data a plurality of times, the decoding process is performed only once. Therefore, the decoding process can be performed even with low reception capability. That is, by outputting a retransmission request, data that can be processed is transmitted even if the receiving side's ability is reduced.
For this reason, there is an effect that a PC-based terminal whose capability frequently fluctuates does not need to notify the player of a capability change, and the communication load is reduced.
[0035]
<Specific example 2>
In the first specific example, the problem of the prior art is solved by using the occupancy of the reception buffer as a criterion for determining a decrease in reception capability and outputting a retransmission request based on this. On the other hand, in the second specific example, the determination of a decrease in reception capability is performed using the PC processor usage rate. The processor usage rate is the ratio of the load to the processor capacity. When this usage rate approaches 100%, the processing speed of tasks being processed in parallel may not be maintained.
[0036]
FIG. 4 is a block diagram of the multimedia communication system of the second specific example.
The video input / output unit 21, the audio input / output unit 22, the data input / output unit 23, the control signal input / output unit 24, and the modem control signal input / output unit 25 in this figure are the same as those of the first specific example shown in FIG. It is. The connection relationship between the video encoding / decoding unit 4, the audio encoding / decoding unit 5, the data protocol processing unit 6, the control protocol processing unit 7, the multiplexing / demultiplexing unit 3, the modem 8, and the encoded data input / output unit 20 is also concrete. Similar to Example 1. This specific example is different from the specific example 1 in that the processor usage rate input unit 26 and the processing capacity monitoring unit 10 are connected to the multiplexing / demultiplexing unit 3.
[0037]
<Operation>
Of the operation of the system of the specific example 2, the method is the same as that of the specific example 1 except for the method for determining the decrease in reception capability. In other words, the main operation of determining a decrease in reception capability, outputting a retransmission request, and discarding the retransmitted data in the received data from the game is the same as in the first specific example. Hereinafter, the operation of parts different from the specific example 1 will be described.
[0038]
Processor usage rate information is input from the processor usage rate input unit 26. This information is information managed by the OS. The processing capacity monitoring unit 10 determines the receiving capacity based on the processor usage rate information. Specifically, when the processor usage rate exceeds a certain value, for example, 90%, it is determined that the reception capability is reduced. Further, a medium for which a retransmission request is made is selected, and a retransmission request signal is output to the multiplexing / demultiplexing unit 3. That is, the retransmission request signal is output to the multiplexing unit 32 in FIG.
[0039]
The media for which a retransmission request is made can be freely selected. The processing capacity monitoring unit 10 is preferably controlled so as to preferentially request retransmission of data that does not require real-time performance. For example, since text data does not hinder communication even if there is a delay, control is performed so that a retransmission request is output preferentially.
[0040]
FIG. 5 shows the processor usage rate and the retransmission control operation.
FIG. 5A is a graph showing the processor usage rate, in which a 100% line indicates a maximum load state and a 0% line indicates a no load state. Further, the section “A” is a state in which the reception capability is higher than that at the time of capability exchange, and the zone “B” is a state in which the reception capability is lowered below that at the time of capability exchange. (B) shows the timing of the retransmission request, and (c) shows the contents of the received data.
[0041]
In the section “A” in the figure, the processor usage rate is almost constant and stable, but when a new application is activated at time t1, the processor usage rate starts to increase. When the processor usage rate exceeds the threshold at time t2, a retransmission request signal is output. In this way, retransmission data is sent from the game at time t3. Since the retransmitted data has already been normally received and has been decoded, there is no need to perform the decoding process even if it is received again. That is, it may be discarded. When the load of other applications decreases after time t4, the processor usage rate decreases, and the retransmission request is stopped when the load becomes lower than the threshold value at time t5. Thereafter, new data starts to be transmitted from time t6. Thereafter, the processor usage rate stabilizes below a threshold value.
The multimedia data is decrypted while performing the above control.
[0042]
<Effect of specific example 2>
In specific example 1, the buffer occupancy was monitored as a cause of the decoding process failing when the reception buffer overflowed. On the other hand, in specific example 2, it is assumed that the cause of the increase in the buffer occupancy is the usage rate of the processor, and this is monitored to determine the reception capability. The increase in the buffer occupancy is one of the causes that the processor load becomes heavy and the PC resources allocated to the decoding process are relatively reduced. Therefore, by monitoring the processor usage rate, it is possible to output a retransmission request earlier than in the first specific example, and it is possible to perform control with high responsiveness.
In the second specific example, only the processor usage rate is monitored and controlled. However, the control may be performed in combination with the monitoring of the reception buffer occupation amount in the first specific example. In this case, more accurate control is possible.
[0043]
<Specific example 3>
Specific Example 3 is characterized in that, when a decrease in reception capability is detected in Specific Example 1 and Specific Example 2, the priority of the data transmission process of the own station is lowered compared to other processes. Note that in multimedia communication, there are many patterns in which both terminals transmit and receive rather than one PC always being the transmitting side and the other PC always being the receiving side. Therefore, in this example, when the PC has a transmission capability and a reception capability, if a decrease in reception capability is detected, the priority of the transmission processing is lowered and the priority of the reception processing is relatively increased. . When the priority of the reception process is increased, the reception capability is improved, and normal communication is continued without notifying the player of the capability change.
[0044]
FIG. 6 shows a block diagram of a multimedia communication system of the third specific example.
FIG. 6 shows each functional block of the system shown in FIG. 5 separately for the transmission side and the reception side. The illustrated system includes a video input unit 21A, an audio input unit 22A, a data input unit 23A, a video encoding unit 41, an audio encoding unit 51, a transmission-side data protocol processing unit 61, a video output unit 21B, and an audio output unit 22B. , Data output unit 23B, video decoding unit 42, audio decoding unit 52, data protocol processing unit 62 on the receiving side, control signal input / output unit 24, control protocol processing unit 7, modem control signal input / output unit 25, processor utilization rate input Unit 26, processing capacity monitoring unit 10, multiplexing / demultiplexing unit 3, modem 8, and encoded data input / output unit 20.
[0045]
<Operation>
In specific example 3, when a change in processing capability by the own station is detected, a retransmission request is output as in specific example 1 and specific example 2. Furthermore, when this retransmission request is issued, the priority of the transmission processing of the own station is lowered and the priority of the reception processing is relatively raised. Hereinafter, the operation will be described on the assumption that the decrease in reception capability is determined based on the processor usage rate as in the second specific example.
[0046]
In FIG. 6, processor usage rate information is input from the processor usage rate input unit 26. This information is information managed by the OS. The reception side processing capacity monitoring unit 10 determines the reception capacity based on the processor usage rate information. Specifically, when the processor usage rate exceeds a certain value, for example, 90%, it is determined that the reception capability is reduced. At this time, the medium for requesting retransmission is selected and a retransmission request signal is output to the multiplexing / demultiplexing unit 3. Furthermore, in this specific example, the retransmission request signal is also input to the video encoding unit 41, the audio encoding unit 51, and the data protocol processing unit 61 on the transmission side.
[0047]
The video encoding unit 41, the audio encoding unit 51, and the data protocol processing unit 61 on the transmission side handle the retransmission request signal as a processing reduction command. For example, when a retransmission request signal is input to the video encoding unit 41, the video encoding unit 41 shifts to an encoding mode with a low processor load by reducing the frame rate of an image to be encoded. Also, the priority of the video encoding process itself is lowered to control the processor usage rate to be lowered. The other audio encoding unit 51 and the data protocol processing unit 61 on the transmission side perform the same control.
[0048]
Thus, if the priority of the transmission process is lowered, the PC resources allocated to the reception process can be relatively increased. When the processor usage rate falls below the threshold value, the normal operation is resumed.
[0049]
<Effect of specific example 3>
As described above, in this specific example, when a decrease in processing capability is detected, a data retransmission request is output and control is performed so as to lower the priority of transmission processing. The rate is increased, and the decrease in reception capability can be reduced.
Note that the method of detecting a decrease in processing capability may be the method of specific example 1 or the method of specific example 2. If the PC processing speed on the receiving side decreases while the transmission speed remains constant, a buffer overflow occurs on the receiving side and causes a processing failure.However, if the transmission side is automatically controlled to reduce the processing speed, image quality may be reduced. There is an effect that normal communication is maintained even if there is an influence such as interruption of sound.
[Brief description of the drawings]
FIG. 1 is a block diagram of main parts of a multimedia communication system of the present invention.
FIG. 2 is a block diagram showing a specific example of the multimedia communication system of specific example 1;
FIG. 3 is a system operation time chart of the first specific example.
FIG. 4 is a block diagram of a multimedia communication system of a specific example 2;
FIG. 5 is a processor usage rate and retransmission control operation time chart.
FIG. 6 is a block diagram of a multimedia communication system according to a specific example 3;
[Explanation of symbols]
1 game
2 Your station
3 Multiplexer / separator
4 Video encoding / decoding unit
10 Processing capacity monitoring unit
31 Separation unit (Retransmission data discard unit)
32 Multiplexer (Retransmission request unit)

Claims (3)

A multimedia communication terminal connected to the opposite side for transmitting multimedia data including video data,
A separation unit that separates video data from the data when the multimedia data is received, performs error detection processing of the video data, and stores normally received video data in a reception buffer;
A video processing unit for fetching and processing the video data from the reception buffer;
A reception buffer monitoring unit that determines that the data processing capacity has decreased when the data occupation amount of the reception buffer is equal to or greater than a threshold;
A retransmission request is transmitted to the player at any one of the determination of deterioration of the data processing capability and the abnormal reception based on the error detection processing, and the number of video data requested to be retransmitted to the separation unit at the time of the determination of the decrease of the data processing capability A retransmission request section to notify,
A retransmission data discarding unit that is provided in the separation unit and discards the video data when the number of the separated video data matches the received number;
A multimedia communication terminal comprising: A multimedia communication terminal connected to the opposite side for transmitting multimedia data including video data,
A separation unit that separates video data from the data when the multimedia data is received, performs error detection processing of the video data, and stores normally received video data in a reception buffer;
A video processing unit for fetching and processing the video data from the reception buffer;
A processing capacity monitoring unit that determines that the data processing capacity has decreased when the usage rate of the processor of the local station exceeds a threshold;
A retransmission request is transmitted to the player at any one of the determination of deterioration of the data processing capability and the abnormal reception based on the error detection processing, and the number of video data requested to be retransmitted to the separation unit at the time of the determination of the decrease of the data processing capability A retransmission request section to notify,
A retransmission data discarding unit that is provided in the separation unit and discards the video data when the number of the separated video data matches the received number;
A multimedia communication terminal comprising: A reception buffer monitoring unit for determining that the data processing capacity is reduced when the data occupation amount of the reception buffer is equal to or greater than a threshold;
The retransmission request unit transmits the retransmission request and notifies the number when any of the reception buffer monitoring unit and the processing capability monitoring unit determines that the data processing capability is reduced.
The multimedia communication terminal according to claim 2.

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