WO2011036711A1

WO2011036711A1 - Transmitter apparatus and system

Info

Publication number: WO2011036711A1
Application number: PCT/JP2009/004831
Authority: WO
Inventors: 石原丈士; 菅沢延彦; 山口健作; 山浦隆博; 大山裕一郎
Original assignee: 株式会社東芝
Priority date: 2009-09-24
Filing date: 2009-09-24
Publication date: 2011-03-31

Abstract

A transmitter apparatus (100) comprises: a large-capacity storage unit (108) that is operative to store contents to be transmitted to a receiver apparatus (120); a transmission processing unit (102) that is operative to generate packets from contents stored by the large-capacity storage unit (108); a reproduction time calculating unit (104) that is operative to calculate, from the packets generated by the transmission processing unit (102), a predicted first reproduction time in which the receiver apparatus (120) reproduces non-reproduced contents and further operative to calculate a first power-saving-state maintenance time from both the first reproduction time and a buffer amount that is required for the receiver apparatus (120) not to stop the content reproduction; and an operation mode control unit (105) that is operative to establish, when the first reproduction time exceeds a first time, a first power-saving state in which the transmission processing unit (102) exhibits a power-saving state and further operative to maintain the first power-saving state for the first power-saving-state maintenance time.

Description

Transmitter, system

The present invention relates to a transmission device and a system.

In a communication system including a server and a client, there is a communication system in which content stored in the server is transmitted to the client via a network, the received client buffers the content in a memory, and the buffered content is reproduced.

In such a communication system, for example, there is a state in which the client performs only the operation of reproducing the buffered content, such as a state in which the content has been transmitted from the server to the client, and the server and the client are not communicating. In such a case, although the client terminal and the server are not performing communication, the portion used for communication (for example, the communication interface) is not shifted to the power saving state, and is operating (communication is performed). The state and voltage etc. are the same state.) For this reason, electric power was consumed wastefully.

Conventionally, there has been a technique in which a client notifies a server of an amount to be buffered in a memory, and the server that has received the notification transitions the communication interface of the server to a power saving mode based on the buffer amount (Patent Document 1). .

JP 2005-244269 A

However, in this conventional technique, since the time for the server to maintain the power saving mode is not specified, there is a possibility that the client's buffer capacity is cut and the reproduction of the client content is stopped.

Also, this prior art does not describe that the client switches from the operating state to the power saving state.

The present invention achieves a reduction in power consumption of a communication system in a communication system in which content is distributed from a server (transmitting device) to a client (receiving device) without stopping reproduction of the content of the client (receiving device). For the purpose.

To achieve the above object, a transmission device according to an embodiment of the present invention includes a storage unit that stores content to be transmitted to a reception device, a transmission processing unit that generates packets from the content stored in the storage unit, From the packet generated by the transmission processing unit, a first reproduction time that is expected to be taken for the reception device to reproduce the unreproduced content is calculated, and the first reproduction time and the reception device reproduce the content. A calculation unit that calculates a first power saving maintenance time from a buffer amount for preventing the transmission from being stopped, and the transmission processing unit when the first reproduction time exceeds the first time, A power-saving state maintaining time, and a control unit that maintains the first power-saving state in the power-saving state.

According to the present invention, in a communication system in which content is distributed from a server (transmission device) to a client (reception device), power consumption of the communication system can be reduced without stopping reproduction of the content of the client (reception device). Can be achieved.

1 is a block diagram showing a communication system. The figure which shows the information which the reproduction | regeneration time calculation part of a transmitter manages. The sequence diagram which shows operation | movement of a transmitter. The sequence diagram which shows operation | movement of a transmitter. FIG. 10 is a sequence diagram illustrating an operation of the receiving apparatus according to the second embodiment. FIG. 10 is a sequence diagram illustrating an operation of the receiving apparatus according to the second embodiment. FIG. 9 is a block diagram of a receiving apparatus according to a third embodiment. FIG. 6 is a block diagram of an information acquisition unit of a receiving apparatus according to Embodiment 3. 10 is a flowchart illustrating the operation of the receiving apparatus according to the third embodiment. 10 is a flowchart illustrating the operation of the receiving apparatus according to the third embodiment. The figure which shows the information which the non-volatile memory | storage part of the receiver of Example 3 memorize | stores. The figure which shows the information which the non-volatile memory | storage part of the receiver of Example 3 memorize | stores.

Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a block diagram showing a communication system 1 of the present embodiment.

The communication system 1 includes a transmission device 100 that distributes content and a reception device 120 that receives and reproduces the content distributed from the transmission device 100 via the network 130.

The transmission device 100 transmits the content as a packet to the reception device 120, and each time the packet is transmitted, the transmission device 100 calculates a reproduction time predicted to be required for the reception device 120 to reproduce the unreproduced content. When the reproduction time predicted to be required for reproducing the unreproduced content exceeds a certain time, the power saving state is entered. In addition, the transmission device 100 sets the power saving state maintenance time (time for maintaining the power saving state) and the power saving state calculated based on the reproduction time predicted to be required to reproduce all the unreproduced content. It is a device that maintains and stops packet transmission. In addition, every time a reception device 120 receives a packet from the transmission device 100, the reception device 120 calculates a reproduction time predicted to be required for the reception device 120 itself to reproduce unreproduced content, and the time exceeds a certain time. Device that shifts to a power saving state and maintains a power saving state and a power saving state that are calculated based on a reproduction time that is expected to be taken to reproduce unplayed content, and stops packet reception. It is. The receiving device 120 that has stopped receiving the packet continues the content reproduction operation stored in the receiving device 120. When the transmitter 100 and the receiver 120 do not perform communication, the transmitter 100 and the receiver 120 shift to the power saving state, and thus the power consumption of the communication system 1 as a whole can be reduced. The power saving state maintenance time is a time calculated so that the receiving apparatus 120 can maintain content reproduction even when transmission / reception of packets is stopped during the period.

In the first embodiment, a description will be given of a transmission device 100 capable of transitioning to a power saving state in the communication system 1.

The large-capacity storage unit 108 of the transmission device 100 stores content to be distributed to the reception device 120.

The reception processing unit 103 receives a content request command from the receiving device 120 via the interface 106. When receiving the content request command, the reception processing unit 103 makes a content acquisition request to the application processing unit 101.

The application processing unit 101 processes a content providing application. The content providing application reads the content related to the content acquisition request requested from the receiving device 120 from the large-capacity storage unit 108 and stores it in the memory 107. In addition, it instructs the transmission processing unit 102 described later to transmit the content. In addition, the application processing unit 101 reads the reproduction time information (for example, the bit rate of the content) of the content read by the content providing application, and transmits the reproduction time information to the reproduction time calculation unit 104 described later.

The transmission processing unit 102 performs a transmission process such as generating a packet corresponding to the content stored in the memory 107. In addition, the transmission processing unit 102 notifies the reproduction time calculation unit 104 described later of the data size of the content included in the generated packet.

The interface 106 transmits the packet generated by the transmission processing unit 102 to the receiving device 120 via the network 130. The interface 106 includes an I / F control unit 110 and a port 111.

The reproduction time calculation unit 104 uses the data size of the content included in the packet notified from the transmission processing unit 102 and the reproduction time information (for example, the bit rate of the content) of the content read by the content providing application of the application processing unit 101. The playback time that is expected to be required for playing back all the content that is received by the receiving device 120 from the transmitting device 100 and has not been played back is calculated. Then, the playback time calculation unit 104 determines whether or not to cause the transmission apparatus 100 to transition to the power saving state based on the playback time (hereinafter referred to as state transition determination processing) and determines to transition to the power saving state. In this case, the power saving state maintenance time is calculated (hereinafter referred to as a power saving state maintenance time calculation process).

When the operation mode control unit 105 is instructed to shift to the power saving state as a result of the state transition determination process of the reproduction time calculating unit 104, the operation mode control unit 105 sets the transmission device 100 to the power saving state (first power saving state or Second power saving state). Here, the power saving state is a state in which power consumption is less than that in a state where normal communication is performed. There are several states that consume less power, such as turning off the power of each component, lowering the voltage, and stopping the clock. As the power saving state, which state is taken may be changed depending on each component. Further, depending on the reproduction time, which state is taken as the power saving state may be changed. For example, when the power saving state maintenance time calculated by the playback time calculation unit 104 is greater than a predetermined value, the power is turned off, and the playback time is smaller than the predetermined value, and the playback time satisfies the condition for transitioning to the power saving state For this reason, the voltage may be reduced.

The bus 109 connects the application processing unit 101, the transmission processing unit 102, the reception processing unit 103, the reproduction time calculation unit 104, the operation mode control unit 105, the interface 106, the memory 107, and the large capacity storage unit 108.

Next, a method in which the playback time calculation unit 104 calculates the playback time will be specifically described. The reproduction time calculation unit 104 manages the information shown in FIG. That is, the playback time calculation unit 104 plays back all the content calculated from the communication ID for identifying the communication being executed, the transmitted cumulative size that is the cumulative data size of the transmitted content, and the transmitted cumulative size. The accumulated reproduction time that has been predicted to be required to be received, the accumulation size that has been confirmed to be received, which is the accumulation of the data size of the response that has been confirmed to be received from the receiving apparatus 120 by the reception processing unit 103, and the accumulation that has been confirmed to have been received. It manages the reception confirmed cumulative playback time, communication characteristics, elapsed time from the start of communication, and playback time information for playing back all the content calculated from the size. Here, for example, the communication ID is the IP address and port number of the receiving device 120 and the IP address and port number of the transmitting device 100. The reproduction time information is, for example, a content bit rate. Note that the playback time information is not limited to the bit rate of the content, and may be information that can predict the playback time of the content from the data size of the content. For example, the playback time itself may be used. The transmitted cumulative size is updated by adding the data size of the transmitted content each time the transmission processing unit 102 generates a packet from the content and transmits the packet via the interface 106. The reception confirmed cumulative size is updated by adding the reception confirmed size every time the reception processing unit 103 receives a reception confirmation response. The transmitted cumulative playback time can be calculated from the transmitted cumulative size and playback time information. Also, the reception confirmed cumulative reproduction time can be calculated from the reception confirmed cumulative size and the reproduction time information. The communication characteristics are round trip time (RTT) and transmission rate of the network 130. The communication characteristics are specified by using information (for example, information included in a TCP time stamp option or RTP header) obtained in communication performed by the application processing unit 101, the transmission processing unit 102, and the reception processing unit 103. be able to. The elapsed time is the time after the communication specified by the communication ID is started. The time from the start of communication is, for example, the time from when the TCP connection is established. Note that the time from the start of communication is not limited to this, and may be the time from when the first transmission request with content is generated. The reproduction time calculation unit 104 holds a timer (not shown), and the elapsed time is counted by the timer.

Next, the state transition determination process and the power saving state maintenance time calculation process performed by the reproduction time calculation unit 104 will be described.

First, state transition determination processing and power saving state maintenance time calculation processing are performed, and components (transmission processing unit 102, application processing unit 101, large capacity storage unit 108) related only to packet transmission are set to the power saving state (first saving state). A method for determining whether or not to enter the power state will be described.

The state transition determination process determines that the transmission apparatus 100 transitions to the power saving state when the following equation (1) is satisfied, and determines that the state does not transition to the power saving state when the condition is not satisfied.

Ls (t) −P (t)> m + S (1)
Here, t is the time when the state transition determination process is performed.

Here, each symbol in Equation (1) has the following meaning.

Ls (t): transmitted cumulative playback time at time t (seconds)
P (t): Estimated reproduction position at time t (seconds)
m: Minimum duration of power saving state (seconds)
S: Minimum buffer amount expected for receiving apparatus 120 (seconds)
Here, P (t) (estimated reproduction position at time t) is an estimate of the time that indicates how far the reception device 120 has reproduced the content sent from the transmission device 100 to the reception device 120. . For example, P (t) can be expressed as P (t) = (AR / 2), where A (t) is the elapsed time and R is RTT. Note that P (t) is not limited to the above-described formula. For example, when information indicating that fast-forwarding or rewinding is sent from the receiving device 120, the value reflects the information.

S (minimum buffer amount expected for the receiving device 120) is the time that the receiving device 120 expects to be buffered at least for the purpose of preventing the content reproduction of the receiving device 120 from being stopped.

In addition, m (the minimum duration of the power saving state) is the shortest time that the power saving state should be maintained at least in order to reduce power consumption when the transmission apparatus 100 is shifted to the power saving state. .

It should be noted that S (minimum buffer amount expected for the receiving apparatus 120) and m (minimum duration of power saving state) are stored in a memory (not shown) of the reproduction time calculation unit 104.

Expression (1) indicates that in the state transition determination process, content that has already been transmitted from the transmission device 100 to the reception device 120 and that has not been reproduced by the reception device 120 (Ls (t) -P (t)) is received. Exceeding the sum (m + S) of the minimum buffer amount expected by the device 120 and the shortest duration of the power saving state is a condition for transitioning to the power saving state. When transitioning to the power saving state, if the condition of the expression (1) is satisfied, the content buffer amount (S) for preventing the content reception apparatus 120 from stopping the content reproduction is kept to a minimum, and the power transmission apparatus 100 is made power efficient. By switching to the state, it is possible to secure time (m) for maintaining power saving for effectively achieving power saving.

Further, the power saving state maintaining time T1 is calculated by the following mathematical formula by the power saving state maintaining time calculating process.

T1 = Ls (t) −P (t) −S (2)
Expression (2) is content that has been transmitted from the transmission device 100 to the reception device 120, and the reception device 120 reproduces content from content that has not been reproduced by the reception device 120 ((Ls (t) -P (t)). This is a value obtained by subtracting the content buffer amount (S) to prevent the content from being stopped, and therefore, if the condition of equation (2) is satisfied, the content reproduction of the receiving device 120 is not stopped and the power consumption is effectively reduced. can do.

Next, state transition determination processing and power saving state maintenance time calculation processing are performed, and the components (interface 106, reception processing unit 103) for receiving the reception confirmation response are set to the power saving state (second power saving state). A method of determining whether or not to do will be described.

The state transition determination process determines that the transmission apparatus 100 transitions to the power saving state when the following equation (3) is satisfied, and determines that the state does not transition to the power saving state when the condition is not satisfied.

La (t ′) − P (t ′)> m + S (3)
Here, t ′ is the time when the state transition determination process is performed. Let t ′> t.

Also, La (t ′): the cumulative playback time (seconds) at which reception has been confirmed at time t ′.

Further, the power saving state maintaining time T2 is calculated by the following mathematical formula by the power saving state maintaining time calculating process.

T2 = La (t ′) − P (t ′) − S (4)
Here, when t + T1> t ′ + T2, the duration during which the components related to transmission only (transmission processing unit 102, application processing unit 101, and large-capacity storage unit 108) are in the power saving state is set to T2.

Next, an operation method of the transmission apparatus 100 will be described. In the following operation, a protocol (for example, TCP) with a reception confirmation response is used as a protocol for transmitting content as a packet. 3 and 4 are sequence diagrams illustrating an operation method of the transmission apparatus 100. FIG.

When the transmission device 100 receives the content acquisition request from the reception device 120, the content acquisition request is stored in the memory 107 and processed by the reception processing unit 103 (S701 to S707). When the reception processing of the content acquisition request is completed by the reception processing unit 103, the content acquisition request is notified to the application processing unit 101 (S708).

The content providing application of the application processing unit 101 reads the content corresponding to the content acquisition request from the large-capacity storage unit 108 and stores the read content in the memory 107 (S709 to S711). Next, the content providing application instructs the transmission processing unit 102 to transmit the content (S712). The content providing application notifies the reproduction time calculation unit 104 of the reproduction time information (content bit rate) of the read content. The transmission processing unit 102 instructed to transmit reads the content from the memory 107, generates a packet including the content, and transmits the packet via the interface 106 (S713 to S718).

Next, the transmission processing unit 102 notifies the reproduction time calculation unit 104 of the data size of the transmitted content (S719). The reproduction time calculation unit 104 also updates the data size of the transmitted content (accumulated transmitted size) from the notified data size of the content. Based on the updated transmitted cumulative size and the content playback time information (content bit rate) read by the content providing application, the playback time calculation unit 104 plays back the entire content (transmitted cumulative playback time). ) Is calculated (S720 to S721). The reproduction time calculation unit 104 performs state transition determination processing, and determines whether or not to cause the transmission apparatus 100 to transition to the power saving state (S722). In addition, the reproduction time calculation unit 104 performs a power saving state maintenance time calculation process, and calculates a time during which the power saving state is maintained. When the reproduction time calculation processing unit 104 determines that the state transition determination process causes transition, the components (transmission processing unit 102, application processing unit 101, large-capacity storage unit 108) related only to packet transmission are set to the power saving state. An instruction is issued to the operation mode control unit 105 to make a transition (S723). The operation mode control unit 105 sets the components related only to packet transmission (the transmission processing unit 102, the application processing unit 101, and the large-capacity storage unit 108) to the power saving state (S724).

Next, the reception processing unit 103 of the transmission device 100 receives a reception confirmation response from the reception device 120 via the interface 106 (S801 to S807). The reception confirmation response is information including the reception confirmation size of the content received by the reception device 120. Next, the reception processing unit 103 notifies the reproduction time calculation unit 104 of the reception confirmed size (S808).

When the reception confirmed size is notified from the reception processing unit 103, the reproduction time calculating unit 104 updates the received confirmed accumulated size and reproduces the reproduction time predicted to be required to reproduce all the content of that size ( (Acknowledged cumulative playback time) is updated (S809 to S810). Then, the reproduction time calculation unit 104 performs state transition determination processing, and determines whether or not to cause the transmission apparatus 100 to transition to the second power saving state (S811). In addition, the reproduction time calculation unit 104 performs a power saving state maintenance time calculation process, and calculates a time during which the power saving state is maintained. When the reproduction time calculation unit 104 determines to shift to the power saving state in the state transition determination process, the operation mode control unit 105 is configured to receive the reception confirmation response (interface 106, reception processing unit 103). Is notified to enter the power saving state (S812).

When the operation mode control unit 105 receives the above-described instruction from the reproduction time calculation unit 104, the operation mode control unit 105 causes the components (interface 106, reception processing unit 103) related to reception of the reception confirmation response to transition to the power saving state (S813).

Next, when the power saving state maintenance time has elapsed, the operation mode control unit 105 causes each component (transmission processing unit 102, large capacity storage unit 108, application processing unit 101, interface) in the power saving state of the transmission device 100. 106, the reception processing unit 103) issues an instruction to return to the operating state (S814 to S816). The transmission device 100 in which each component returns to the operation state resumes the transmission process (S817 to S819).

According to the present embodiment, in the communication system 1 in which content is distributed from the transmission device 100 to the reception device 120, when a predetermined condition is satisfied in the state transition determination process, the components of the transmission device 100 are set in the power saving state. Therefore, the power consumption of the transmission device 100 can be reduced. In addition, the transmission device 100 stops the content reproduction of the reception device 120 in order to determine the power saving maintenance time so as not to stop the content reproduction of the reception device 120 in the power saving state maintenance time calculation process. The power consumption of the transmission apparatus 100 can be reduced without causing it to occur.

According to the present embodiment, among the constituent elements of the transmitting apparatus 100, constituent elements (transmission processing unit 102, large-capacity storage unit 108, application processing unit 101) related only to packet transmission processing and reception of reception confirmation responses The timing at which the components (interface 106, reception processing unit 103) related to the power saving state are set to different timings. As a result, it is possible to keep the components related only to packet transmission in a longer power saving state. Therefore, a power saving effect can be achieved effectively.

In the operation of the present embodiment, a description has been given assuming that a protocol (for example, TCP) with a reception confirmation response is used as a protocol for transmitting content as a packet. good. In this case, in step S724, the transmission apparatus 100 sets elements related to the reception process of the reception confirmation response (interface 106, reception processing unit 103) to a power saving state together with elements related only to the transmission process, and performs steps S801 to S813. It is not necessary to perform the operation.

In addition, although the transmission processing unit 102 and the reception processing unit 103 are shown as different components from the application processing unit 101, the configuration of the transmission apparatus 100 according to the present embodiment is realized as software executed on the same processor. Also good. Further, the operation mode control unit 105 may be realized in the interface 106.

In this embodiment, in the first power saving state, the transmission processing unit 102, the application processing unit 101, and the large-capacity storage unit 108 are set to a power saving state as components related only to packet transmission. In the power saving state 2, the reception processing unit 103 and the interface 106 are put into the power saving state as components related to the reception processing of the reception confirmation response in addition to the components in the power saving state in the first power saving state. It was. However, the components to be in the first power saving state, the second power saving state, and the power saving state are not limited to this. For example, in the first power saving state, the components related only to packet transmission are not set to the power saving state, and the components related only to packet transmission and the reception confirmation response reception processing are not set in the second power saving state. All of the elements may be in a power saving state. Further, when the transmission apparatus 100 has a function of retransmitting the content that has been played once, the content necessary for the retransmission is stored in the memory 107, and the operation of the application processing unit 101 may be unnecessary. In this case, in the first power saving state, the application processing unit 101 and the large-capacity storage unit 108 can be set to the power saving state first, and the transmission processing unit 102 can be changed to the power saving state later.

In this embodiment, the reproduction time information of the content read by the application processing unit 101 is notified to the reproduction time calculation unit 104. However, for example, the application processing unit 101 notifies the playback time calculation unit 104 of the identifier of the content to be transmitted, and the playback time calculation unit 104 is content in the memory 107 or the large-capacity storage unit 108 and corresponds to the content identifier. Content playback time information may be acquired. In addition, the reproduction time information of the content may be acquired in real time according to the transmission process, or may be acquired in advance. Further, the reproduction time information may vary depending on the position of the content. In this case, for example, a value averaged per unit time is used as the reproduction time information, and is handled as a value associated with the position of the content.

In addition, although the transmission apparatus 100 according to the present embodiment is configured to satisfy the condition of Expression (1) or (3) as the condition for transitioning to the power saving state in the state transition determination process, it is not limited thereto. Moreover, although the power saving maintenance time calculated in the power saving state maintenance time calculation processing is a time that satisfies Equation (2) or (4), it is not limited thereto. That is, the condition for transitioning to the power saving state and the power saving maintenance time are the contents transmitted from the transmitting device 100 to the receiving device 120, respectively, and the content not yet played by the receiving device 120 is switched to the power saving state. Any condition that prevents the content reproduction of the receiving device 120 from being stopped when the power saving effect can be achieved and the power saving state is set may be used.

The transmission device 100 according to the present embodiment can also be realized by using a general-purpose computer device as basic hardware. That is, the application processing unit 101, the transmission processing unit 102, the reception processing unit 103, the playback time calculation unit 104, the operation mode control unit 105, the interface 106, the memory 107, the large capacity storage unit 108, and the bus 109 are connected to the above computer device. This can be realized by executing a program on an installed processor. At this time, the transmission device 100 can be realized by executing the above program. At this time, the transmission device 100 may be realized by installing the above program in advance in a computer device, or may be stored in a storage medium such as a CD-ROM or distributed through the network. Thus, this program may be realized by appropriately installing it in a computer device. In addition, the memory 107 and the large-capacity storage unit 108 appropriately use a memory, a hard disk or a storage medium such as a CD-R, a CD-RW, a DVD-RAM, a DVD-R, or the like that is built in or externally attached to the computer device. Can be realized.

Next, the receiving device 120 in the communication system 1 in FIG. 1 will be described.

The memory 122 of the receiving device 120 stores the content received from the transmitting device 100.

The app processing unit 121 processes the content playback application. The content playback application plays back the content stored in the memory 122. In addition, the application processing unit 121 notifies the state control unit 125 described later of the reproduction time information (for example, the bit rate of the content) of the content reproduced by the content reproduction application.

The interface 123 includes a transmission processing unit 126, a reception processing unit 127, a state control unit 125, and a port 128.

The port 128 receives a packet transmitted from the transmission device 100.

The reception processing unit 127 extracts content from the packet received from the transmission device 100 via the port 128. The reception processing unit 127 notifies the state control unit 125 described later of the data size of the content extracted from the received packet.

The transmission processing unit 126 transmits a control command instructing to stop transmission of the content of the transmission processing unit 126 via the port 128 when the receiving device 120 is shifted to the power saving state. The transmission apparatus 100 that has received the control command stops packet transmission. Here, the reception window size is information indicating the data size of content that can be received by the reception device 120.

The state control unit 125 predicts that it takes for the receiving apparatus 120 to play back all the unplayed content from the data size of the content notified from the reception processing unit 127 and the playback time information notified from the application processing unit 121. The playback time to be played is calculated. Then, based on the reproduction time, it is determined whether or not the receiving device 120 is to be shifted to the power saving state (hereinafter referred to as state transition determination processing). The state maintenance time is calculated (hereinafter referred to as a power saving state maintenance time calculation process), and the power saving state maintenance time and the receiving apparatus 120 are set to the power saving state.

The state control unit 125 receives the amount of content received from the transmission device 100 buffered in the memory 122 (used buffer size) and the playback time for playing back all the buffered content (cumulative playback of received content). Time). The state control unit 125 manages the communication ID, the used buffer size, the received content accumulated playback time, the communication characteristics, the elapsed time, and the playback time information, similarly to the playback time calculation unit 104 of the transmission device 100 of the first embodiment. . The communication ID, communication characteristics, elapsed time, and reproduction time information are the same information as the information managed by the reproduction time calculation unit 104 of the transmission device 100 according to the first embodiment.

The bus 124 connects the application processing unit 121, the interface 123, and the memory 122.

Next, an operation method of the receiving device 120 will be described. 5 and 6 are sequence diagrams illustrating an operation method of the reception device 120. FIG.

First, when the reception device 120 receives a packet from the transmission device 100, the reception processing unit 127 extracts the content from the received packet and stores the content in the memory 122. (S901 to S904). Further, the reception processing unit 127 notifies the application processing unit 121 that the content has been received (S905). The reception processing unit 127 also notifies the state control unit 125 of the data size of the content (S906). Next, when notified of the data size of the content received from the reception processing unit 127, the state control unit 125 updates the used buffer size and the received content accumulated reproduction time (S907). Note that the state control unit 125 uses the playback time information of the content when calculating to update the received content cumulative playback time. It is assumed that the reproduction time information of the content is periodically notified to the state control unit 125 by the application processing unit 121. When the content has a variable bit rate, the correspondence between the position and size of the content is notified. (For example, as a correspondence, the playback time from L bytes to M bytes from the beginning is T seconds.)
Next, the state control unit 125 performs a state transition determination process, which will be described later, based on the updated content accumulated reproduction time, and determines whether or not to shift the receiving device 120 to the power saving state (S908).

Hereinafter, a case will be described in which it is determined in the state transition determination process that the receiving device 120 does not transition to the power saving state.

When the content reproduction application of the application processing unit 121 reproduces the content stored in the memory 122, the content stored in the memory 122 is released. The application processing unit 121 notifies the state control unit 125 of the data size of the released content. The state control unit 125 updates the used buffer size and the received content accumulated reproduction time from the data size of the released content (S909). The data size of the released content is subtracted from the used buffer size before notification from the application processing unit 121, and the corresponding received content accumulated reproduction time is updated. Note that when the content reproduction application of the application processing unit 121 reproduces the content stored in the memory 122, the content stored in the memory 122 may not be released. For example, when there is a rewind, the reproduced content may be reproduced again. In this case, the application processing unit 121 notifies the data size of the reproduced content to the state control unit 125, and the state control unit 125 updates the received content accumulated reproduction time based on the data size.

Next, the state control unit 125 performs a state transition determination process, which will be described later, based on the updated content accumulated reproduction time, and determines whether or not to shift the receiving device 120 to the power saving state (S910).

Hereinafter, a case will be described in which it is determined in the state transition determination process in S910 that the receiving apparatus 120 does not transition to the power saving state.

Next, when the receiving device 120 receives the packet from the transmitting device 100 again, the processing similar to S901 to S906 is performed, and the state control unit 125 updates the used buffer size and the received content accumulated playback time, The control unit 125 performs a state transition determination process, which will be described later, based on the updated content cumulative reproduction time, and determines whether or not to shift the receiving device 120 to the power saving state (S911).
Hereinafter, a case will be described in which it is determined in the state transition determination process in S911 that the receiving device 120 is to be shifted to the power saving state.

Next, the state control unit 125 acquires the reception window size transmitted from the transmission processing unit 126 to the transmission device 100 before S911 (S912 to S913), and transmits the reception window size to the transmission device 100 via the transmission processing unit 126. Then, a content transmission stop request is sent (S914 to S916). This transmission stop request can be requested by transmitting an ACK with the reception window size set to zero, for example, when communication using TCP is performed. Here, the reception window size is information indicating the data size of content that can be received by the reception device 120. For example, it is information indicating the free capacity of the memory 122 (capacity in which no content is stored).

From the acquired reception window size, the state control unit 125 calculates the data size of the unreceived content among the content transmitted from the transmission device 100 to the reception device 120 and the expected time until all of the data is received. (S917). The state control unit 125 manages the estimated time with a timer (S918).

Next, when the reception device 120 receives the packet transmitted by the transmission device 100, the processing similar to S901 to S907 is performed, and the state control unit 125 updates the used buffer size and the received content accumulated reproduction time ( S1001 to S1007). Further, the unreceived data size is updated by subtracting the data size of the content received in S1001 to S1007 from the data size of the unreceived content calculated in S917 (S1008). When the unreceived data size becomes 0 as a result of the update of the unreceived data size, the state control unit 125 performs the power saving state maintenance time calculation process from the received content accumulated reproduction time updated in S1007, and saves power. The state maintaining time is calculated, the power saving state maintaining time is set in a timer attached to the state control unit 125, and the receiving apparatus 120 is shifted to the power saving state (S1009 to S1011). For example, the state control unit 125 causes the port 128, the reception processing unit 127, and the transmission processing unit 126 to transition to the power saving state.

In addition, as a result of updating the unreceived data size in S1008, the state control is performed even if the expected time for receiving all the unreceived data calculated in S917 has elapsed before the unreceived data size becomes zero. The unit 125 calculates the power saving state maintenance time from the content cumulative playback time updated in S1007, sets the power saving state maintenance time in a timer attached to the state control unit 125, and then sets the reception device 120 in the power saving state. Transition to.

Even when the receiving device 120 shifts to the power saving state, the content reproduction process of the content reproduction application of the application processing unit 121 is continued. That is, the content playback application of the application processing unit 121 plays back the content stored in the memory 122, and the state control unit 125 updates the used buffer size and the received content cumulative playback time managed by the state control unit 125 ( S1012 to S1013).

When the power saving state maintenance time set in the timer elapses, the state control unit 125 returns the port 128, the reception processing unit 127, and the transmission processing unit 126 that have transitioned to the power saving state to the operating state (S1014 to S1014). S1015). Next, a transmission start request is sent to the transmission apparatus 100 via the transmission processing unit 126 (S1016 to S1018). For example, if the transmission start request is a communication using TCP, an ACK packet having a reception window size other than zero is generated and transmitted.

Next, state transition determination processing (that is, transition to the power saving state) performed by the state control unit 125, an expected time until all unreceived data sizes are received (after determining that transition to the power saving state is performed, not received) (Estimated time until all data is received) and a method of calculating the power saving state maintenance time will be described.

First, the state transition determination process will be described.

In the state transition determination process, the state control unit 125 determines that the state (used buffer size) stored in the memory 122 transitions to the power saving state when the following two conditions are satisfied. 1. The bit rate of the content to be reproduced is smaller than the transmission speed of the network 130 to be used. 2. The received accumulated content playback time updated by the state control unit 125 is longer than the minimum power saving state time.

The above condition 1 can be expressed by equation (5).

Bn> Bc (5)
The above condition 2 can be expressed by equation (6).

Lr (t) + (R × Bn / Bc) −R ≧ m (6)
Here, the symbols in the formulas (5) and (6) have the following meanings.

Bn: Transmission speed of the network 130 (bps)
Bc: Content bit rate (bps)
R: RTT of network 130 (seconds)
Lr (t): Reproducible time of received content data at time t (Received accumulated content playback time) (seconds)
Next, a description will be given of a method in which the state control unit 125 calculates an estimated time until all unreceived data is received from the reception window size after determining that the state control unit 125 makes a transition to the power saving state.

Here, the reception window size of the reception window transmitted by the receiving apparatus 120 most recently at time t (time determined to transition to the power saving state) is W bytes, and the transmission is performed after the window has been transmitted and before time t. When the data size of the content received from the device 100 is M bytes, the expected time for receiving all the unreceived data can be expressed by the following equation (7).

8 × (WM) / Bn (7)
The state control unit 125 can acquire the reception window size W by acquiring the reception window from the transmission processing unit 126. The data size M bytes of content received from the transmission device 100 before time t is calculated by associating information managed as a used buffer size by the state control unit 125 with the time when the reception window size is transmitted. can do. Further, the data size M bytes of the content received from the transmission device 100 before the time t may be calculated using the reception window size and the number of received bytes notified in accordance with the reception window size.

Next, a method for calculating the power saving state maintenance time will be described.

The condition of the power saving state maintaining time T3 can be expressed by the following formulas (8) and (9).

T3 = Lr (t ′) − R (8)
T3 ≧ m (9)
Here, t ′ (> t) is a time for transition to the power saving state.

Note that the power saving state maintaining time T3 can be designed to be calculated at time t. In that case, a timer may be added to the state control unit 125, and both the expected time until all the unreceived data described above are received and the power saving state maintaining time may be set.

According to the present embodiment, in the communication system 1 in which content is distributed from the transmission device 100 to the reception device 120, when a predetermined condition is satisfied in the state transition determination process, the constituent elements of the reception device 120 are set to the power saving state. Therefore, the power consumption of the receiving apparatus 120 can be reduced. In addition, the reception device 120 stops the reproduction of the content of the reception device 120 in order to determine the power saving maintenance time that does not stop the reproduction of the content of the reception device 120 in the power saving state maintenance time calculation process. The power consumption of the transmission apparatus 100 can be reduced without causing it to occur.

In the receiving apparatus 120 of the present embodiment, the transmission processing unit 126, the reception processing unit 127, and the state control unit 125 are provided in the interface 123. However, the transmission processing unit 126, the reception processing unit 127, and the state control unit 125 are each an interface. 123 may not be provided.

In this embodiment, when the power saving state is set, among the components of the receiving device 120, the port 128, the transmission processing unit 126, and the reception processing unit 127 are set to the power saving state. However, the components to be in the power saving state are not limited to these. Some of these components may be put into a power saving state, or may be put into a power saving state together with other components.

In addition, although the transmission apparatus 100 according to the present embodiment is configured to satisfy the conditions of Expressions (5) and (6) as the condition for transitioning to the power saving state in the state transition determination process, it is not limited thereto. Moreover, although the power saving maintenance time calculated in the power saving state maintenance time calculation processing is a time that satisfies Expressions (8) and (9), it is not limited thereto. That is, the conditions for transitioning to the power saving state and the power saving maintenance time can be achieved when the content that has not been played back by the receiving device 120 stored in the receiving device 120 is switched to the power saving state. What is necessary is just a condition that prevents the content reproduction of the receiving device 120 from being stopped when the power state is set.

Note that the receiving device 120 according to the present embodiment can also be realized by using a general-purpose computer device as basic hardware. That is, the application processing unit 121, the interface 123 (the transmission processing unit 126, the reception processing unit 127, the state control unit 125, the port 128), the memory 122, and the bus 124 execute a program to the processor mounted on the computer device. Can be realized. At this time, the receiving device 120 can be realized by executing the above-described program. At this time, the receiving device 120 may be realized by installing the above program in a computer device in advance, or may be stored in a storage medium such as a CD-ROM or distributed through the network. Thus, this program may be realized by appropriately installing it in a computer device. The memory 122 can be realized by appropriately using a memory built in or externally attached to the computer device, a hard disk, or a storage medium such as a CD-R, CD-RW, DVD-RAM, or DVD-R. it can.

The receiving device 300 according to the third embodiment is a device that acquires an IP address from a DHCP server in synchronization with the timing of transition from the power saving state to the operating state.

The receiving device 300 of the third embodiment is different from the configuration of the receiving device 120 of the second embodiment in the configuration of the interface 301. That is, as illustrated in FIG. 7, the interface 301 further includes an information acquisition unit 302 in addition to the configuration of the interface of the receiving device 120 of the second embodiment.

As shown in FIG. 8, the information acquisition unit 302 includes a DHCP processing unit 401, a lease period calculation unit 402, a storage unit 403, a nonvolatile storage unit 404, and a real-time clock (described as RTC 405 in the figure. , RTC405) and a bus 406.

The DHCP processing unit 401 acquires an IP address from the DHCP server via the port 128. Further, the DHCP processing unit 401 calculates a lease period for the IP address.

The storage unit 403 is a working memory that is used by the DHCP processing unit 401.

The nonvolatile storage unit 404 stores the IP address acquired by the DHCP processing unit 401, the lease period corresponding to the IP address, and the execution interval of the process in which the receiving apparatus 300 transitions from the power saving state to the operating state.

The lease period calculation unit 402 calculates a lease period and a renewal period synchronized with the execution interval from the lease period stored in the nonvolatile storage unit 404 and the execution interval.

RTC 405 manages the time when the device operates.

The bus 124 connects the DHCP processing unit 401, the storage unit 403, the nonvolatile storage unit 404, the lease period calculation unit 402, and the RTC 405.

The operation method of the receiving apparatus 300 will be described. 9 and 10 are flowcharts showing the operation of the receiving apparatus 300. FIG.

When the receiving apparatus 300 starts operation, the DHCP processing unit 401 is initialized. Next, the DHCP processing unit 401 checks whether or not the IP address is stored in the nonvolatile storage unit 404 (S1). If an IP address is stored in the non-volatile storage unit 404, the DHCP processing unit 401 reads the IP address from the non-volatile initial storage unit 403 (S2), and transmits the transmission processing unit 126 and the state via the state control unit 125. The IP address is notified to the reception processing unit 127 (S3). The transmission processing unit 126 and the reception processing unit 127 set the notified IP address, and set a default gateway or the like (S4).

On the other hand, when the IP address is not stored in the nonvolatile storage unit 404, the DHCP processing unit 401 first detects the maximum time that the DHCP server can lease (S5). FIG. 10 shows an operation method for detecting the maximum time that the DHCP server can lease. Specifically, for example, the DHCP processing unit 401 transmits a DHCP DISCOVER message including an initial lease period to the DHCP server (S51, S52). When receiving the DHCP OFFER message including the initial lease period from the DHCP server, the DHCP processing unit 401 stores the DHCP OFFER message in the storage unit 403 and transmits the DHCP DISCOVER message including a lease period longer than the initial lease period ( S53, S54, S55, S56, S52). Next, when a DHCP OFFER message for the DHCP DISCOVER message is received, a DHCP DISCOVER message including a longer lease period is transmitted. In this way, every time a DHCP OFFER message is received, a DHCP DISCOVER message including a lease period longer than the lease period corresponding to the message is transmitted, and when the DHCP OFFER message cannot be received, it is stored in the storage unit 403. By looking at the lease period, the lease period included in the DHCP DISCOVER message corresponding to the last received DHCP OFFER message is determined as the maximum lease period (S57, S58). The DHCP processing unit 401 stores the determined maximum lease period in the nonvolatile storage unit 404.

On the other hand, the DHCP processing unit 401 acquires the execution interval L (execution interval at the timing when the power saving state changes from the power saving state) of the receiving device 300 from the receiving device 300 of the second embodiment, and stores it in the nonvolatile storage unit 404. Here, the execution interval L can be obtained, for example, by the sum of the power saving state maintaining time T3 calculated by the state control unit 125 and the time during which the receiving apparatus 300 is in the operating state. FIG. 11 is a table in which the execution interval L and the next execution time stored in the nonvolatile storage unit 404 are stored in association with each other. Here, the next execution time is the time when the power saving state is switched to the operating state next.

Next, the lease period calculation unit 402 calculates the lease period from the duration L stored in the nonvolatile storage unit 404 and the maximum lease period (S6). The lease period calculation unit 402 calculates a lease period and a renewal period in which the execution interval L is synchronized with the renewal period and the lease period corresponding to the renewal period is the largest. The lease period and renewal period can be calculated using the following formula.

Renewal period T4 = T + L × [{l− (T × m)} / (L × m)] (10)
Lease period T5 = T4 × m (11)
Here, the parameters used in the above equations (10) and (11) are as follows.

Current time (seconds): t
Execution interval (seconds) for transition to the operating state: L
Next, time (seconds) for transition from the power saving state to the operating state: T
Maximum lease period (seconds): l
Factor: m
In the equation (10), the symbol [X] represents a maximum integer equal to or less than X. )
Next, the DHCP processing unit 401 transmits a DHCP DISCOVER message including the lease period calculated by the lease period calculation unit 402 to the DHCP server, and receives a DHCP OFFER message for the message, thereby including the message in the message. The IP address to be acquired is acquired (S7). The DHCP processing unit 401 stores the acquired IP address, the lease period, and the renewal period in the nonvolatile storage unit 404 (S8), and notifies the transmission processing unit 126 and the reception processing unit 127 via the state control unit 125. (S3), an appropriate IP address is set (S4).

FIG. 12 shows an example of the contents of the lease period, the renewal period, and the IP address corresponding to these periods (shown as [Info] in the table of FIG. 12) stored in the nonvolatile storage unit 404. In FIG. 12, the lease term and the renewal term obtained by adding the current time t to the lease term and the renewal term are stored.

When the time reaches the renewal deadline, the lease period calculation unit 402 calculates the lease period and the renewal period again according to the method described above, and the DHCP processing unit 401 acquires the IP address and transmits it via the state control unit 125. The information is notified to the processing unit 126 and the reception processing unit 127, and the IP address is set. By repeating these operations, the IP address, lease period, and renewal period are repeatedly updated.

According to the receiving device 300 of the third embodiment, since the IP address is acquired from the DHCP server at the timing of transition from the power saving state to the operating state, the power consumption of the receiving device 300 can be reduced. That is, when the IP address acquired from the DHCP server is set in the transmission processing unit 126 and the reception processing unit 127, the transmission processing unit 126 and the reception processing unit 127 are in an operating state. Therefore, it is not necessary to make a transition to a separate operation state, so that power consumption can be reduced.

In the present embodiment, the receiving apparatus 300 that acquires an IP address from a DHCP server in synchronization with the timing of transition from the power saving state to the operating state has been described. The receiving apparatus 300 has the above-described functions by including the information acquisition unit 302. However, the device having these functions is not limited to the receiving device 300. For example, by providing the information acquisition unit 302 in the transmission device 100 according to the first embodiment, it is possible to configure the transmission device 100 having a function of acquiring an IP address from the DHCP server as a timing for transition from the power saving state to the operation state. .

In addition, the operation that is the target of the execution interval synchronized with the renewal period is not limited to the timing at which the power saving state is switched to the operation state. For example, when the receiving device 300 has a television broadcast recording function, the interval for acquiring the broadcast program guide may be set as the execution interval. Further, if the receiving apparatus 300 has a function of periodically checking the arrival of electronic mail, it may be synchronized with the interval. Thus, it can synchronize with what knows a period regularly or beforehand.

In addition, although the receiving apparatus 300 according to the third embodiment includes the information acquisition unit 302 inside the interface 301, it may be provided outside the interface 301.

Further, although the receiving device 300 according to the third embodiment uses the IP address as the information acquired from the DHCP server, it can also acquire information other than the IP address. For example, a net mask. That is, the receiving apparatus 300 acquires information necessary for network setting of the transmission processing unit 126 and the reception processing unit 127 from the DHCP server.

Note that the receiving device 300 according to the present embodiment can also be realized by using a general-purpose computer device as basic hardware. That is, the application processing unit 121, interface 123 {transmission processing unit 126, reception processing unit 127, state control unit 125, port 128, information acquisition unit 302 (DHCP processing unit 401, lease period calculation unit 402, storage unit 403, non-volatile The storage unit 404, the RTC 405, the bus 406)}, the memory 122, and the bus 124 can be realized by executing a program on a processor mounted on the computer device. At this time, the receiving apparatus 300 can be realized by executing the above program. At this time, the receiving device 300 may be realized by installing the above program in advance in a computer device, or may be stored in a storage medium such as a CD-ROM or distributed through the network. Thus, this program may be realized by appropriately installing it in a computer device. In addition, the memory 122, the nonvolatile storage unit 404, and the storage unit 403 are a storage medium such as a memory, a hard disk or a CD-R, a CD-RW, a DVD-RAM, and a DVD-R that are built in or externally attached to the computer device. It can be realized by appropriately using the above.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 ... Communication system, 100 ... Transmission apparatus, 101, 121 ... Application processing part, 102, 126 ... Transmission processing part, 103, 127 ... Reception processing part, 104 ... Playback time Calculation unit, 105 ... operation mode control unit, 106, 123, 301 ... interface, 107, 122 ... memory, 108 ... mass storage unit, 109, 124, 406 ... bus, 110 ... I / F control unit, 111, 128 ... port, 120, 300 ... receiving device, 125 ... state control unit, 130 ... network, 302 ... information acquisition unit, 401 .. DHCP processing unit, 402 ... lease period calculation unit, 403 ... storage unit, 404 ... non-volatile storage unit, 405 ... RTC

Claims

A storage unit for storing content to be transmitted to the receiving device;
A transmission processing unit for generating a packet from the content stored in the storage unit;
From the packet generated by the transmission processing unit, a first reproduction time that is expected to be taken for the reception device to reproduce the unreproduced content is calculated, and the first reproduction time and the reception device reproduce the content. A calculation unit for calculating the first power saving maintenance time from the buffer amount for not stopping
A control unit that maintains the first power saving time and the first power saving state that sets the transmission processing unit to a power saving state when the first reproduction time exceeds the first time; A transmission device provided.
An interface for transmitting the packet to the receiving device;
A reception processing unit that receives a reception confirmation response indicating that the reception device has received the packet via the interface;
The calculation unit calculates, based on the reception confirmation response, a second playback time predicted to be required for the receiving device to play back unplayed content, and the second playback time and the receiving device The second power saving maintenance time is calculated from the buffer amount for not stopping the reproduction of
The control unit maintains the second power saving state in which the second power saving maintenance time and the reception processing unit are set in a power saving state when the second reproduction time exceeds the second time. The transmission device according to claim 1.
The first power saving state is a state in which a first component necessary for transmitting the packet to the receiving device among components of the own device is set to a power saving state.
The second power saving state is a state in which a second component for receiving the reception confirmation response from the receiving device among components of the own device is in a power saving state. 2. The transmission device according to 2.
The first component includes the storage unit and the transmission processing unit,
The transmission apparatus according to claim 3, wherein the second component includes the interface and the reception processing unit.
A system comprising the transmission device and the reception device according to claim 4,
The receiving device is:
An interface for receiving packets from the transmitter;
A reception processing unit for extracting content from the received packet;
A storage unit for storing the content extracted by the reception processing unit;
An application processing unit for playing back the content stored in the storage unit;
From the packet received by the reception processing unit, a third reproduction time predicted to be taken for reproducing the content received from the transmitting apparatus and not reproduced by the application processing unit is calculated. And a control unit that makes a transition to a power saving state when the playback time of is longer than the third time.
The receiving device is:
Transmission processing for transmitting information including a receivable data amount to the transmission device, and transmitting a control command for instructing the transmission device to stop packet transmission when the control unit transitions to a power saving state The control unit, when transitioning to a power saving state, the content data that can be transmitted to the receiving device by the transmitting device from information including the amount of data that can be received before the transition. A size is calculated, a time estimated to be taken until all contents of the data size are received is calculated, and the apparatus is shifted to a power saving state after the predicted time has elapsed. 5. The system according to 5.
The control unit of the receiving device determines a second power saving maintenance time from a fourth reproduction time and a round-trip delay time that are predicted to be required for reproducing the unreproduced content at the time when the estimated time has elapsed. The system according to claim 6, wherein the device is maintained in a power saving state for the second power saving maintenance time.
The receiving device is:
A DHCP processing unit for detecting a first lease period of an IP address managed by the DHCP server from the DHCP server via the network;
A second storage unit that stores a first lease period detected by the DHCP processing unit and an execution interval of a process of transitioning from the power saving state of the device to the operation state;
A lease period calculation unit that calculates a second lease period and a renewal period that are synchronized with the execution interval based on the first lease period and the execution interval;
The DHCP processing unit obtains an IP address corresponding to the second lease period calculated by the lease period calculation unit from a DHCP server,
The transmission processing unit and the reception processing unit set an IP address corresponding to the second lease period calculated by the lease period calculation unit,
When the renewal period calculated by the lease period calculation unit has elapsed, the lease period calculation unit synchronizes with the execution interval based on the first lease period and the execution interval stored in the second storage unit again. Calculate the lease period and renewal period,
The DHCP processing unit obtains an IP address corresponding to the second lease period calculated by the lease period calculation unit from a DHCP server,
The system according to claim 7, wherein the transmission processing unit and the reception processing unit set an IP address corresponding to the second lease period calculated by the lease period calculation unit.