JP2013121029A - Content reproduction system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To approximately match reproduction start time of content data at each receiver without requiring any complex processing.SOLUTION: A transmitter calculates time difference information which represents a time difference between a reference time and a transmission time of packet to a receiver, and adds the time difference information in a packet header. A receiver calculates a reproduction delay time by subtracting the time difference information from a predetermined delay time. Although a common value is used for the predetermined delay time at each receiver in general, a predetermined delay time can be set according to a time error on reproduction processing time at each receiver. The receiver waits packet reproduction, until the reproduction delay time elapses after the time of packet reception. The receiver starts the packet reproduction, only if the reproduction delay time has elapsed after the time of packet reception.

Description

  The present invention relates to a content reproduction system including a transmission device and a reception device.

  There has been proposed a content reproduction system in which the same content data is simultaneously reproduced at approximately the same time by each receiving device by transmitting the same content data at approximately the same time to a plurality of receiving devices via a network from the transmitting device. Yes. This system is sometimes referred to as party mode. Here, when UDP is used as the communication protocol and unicast is used, the transmitting device transmits content data packets in order to each receiving device. That is, a certain packet A is transmitted to the receiving device X1, then the same packet A is transmitted to the receiving device X2, and then the same packet A is transmitted to the receiving device X3. Thereafter, the next packet B is transmitted to the receiving device X1, then the same packet B is transmitted to the receiving device X2, and then the same packet B is transmitted to the receiving device X3. In this way, the time at which the same content data packet is transmitted to each receiving device is slightly different, and as a result, the time at which each receiving device receives and reproduces the same content data packet is slightly different. Therefore, if the packet received by each receiving apparatus is reproduced as it is, the reproduction position of the content data reproduced by each receiving apparatus will be shifted. To solve this problem, synchronize the clock between the transmitting device and each receiving device, include a time stamp in the transmitted packet, and each receiving device reproduces the same packet at the same time according to the time stamp Thus, a technique for synchronizing content reproduction has been proposed. However, according to this technique, the clock synchronization processing and the communication protocol become very complicated.

US2007 / 0038999

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a content reproduction system that can substantially match the reproduction start times of the content data of the respective receiving devices without requiring complicated processing. Is to provide.

  A content reproduction system according to a preferred embodiment of the present invention includes a transmission device and a plurality of reception devices that can be connected to the transmission device via a network. A transmission unit that transmits content data at the same reproduction position of the same content, a time difference information calculation unit that calculates time difference information that is a difference between a reference time and a transmission time at which the content data is transmitted to the receiving device, and a transmission A time difference information adding unit that adds the calculated time difference information to the content data to be received, and each receiving device reproduces the received content data with a receiving unit that receives the content data from the transmitting device The playback unit, the reception time specifying unit that specifies the reception time when the content data is received, and the received content data from the predetermined delay time A reproduction delay time calculation unit that subtracts the added time difference information and calculates a reproduction delay time, and waits for the reproduction of the content data until the reproduction delay time elapses from the reception time. A reproduction control unit that causes the reproduction unit to reproduce the content data when a reproduction delay time has elapsed.

  The transmission device calculates time difference information that is the difference between the reference time and the transmission time at which the content data is transmitted to the reception device, and adds the time difference information to the content data (although not particularly limited, for example, a packet). The receiving device subtracts the time difference information from the predetermined delay time to calculate the reproduction delay time. The predetermined delay time is generally a value common to the respective receiving apparatuses, but can be appropriately set according to an error in time required for reproduction processing of each receiving apparatus. The reception device waits for the content data to be reproduced until the reproduction delay time elapses from the reception time. The receiving device starts playing the content data only when the playback delay time has elapsed from the reception time. Therefore, even when the time at which the transmitting device transmits the same content data to each receiving device is different, the same content can be started to be reproduced at approximately the same time by adjusting the reproduction delay time in each receiving device. .

  In a preferred embodiment, the transmission device further includes an identification information adding unit that adds identification information to content data to be transmitted, and an identification information changing unit that changes the identification information when a predetermined condition is satisfied. An identification information change determination unit for determining whether or not the identification information added to the received content data is changed from the identification information added to the previous content data received by the receiving device; In addition, when it is determined that the identification information has been changed, the reproduction control unit waits for reproduction of the content data until the reproduction delay time elapses from the reception time, and the reproduction delay from the reception time. When the time has elapsed, the content data is reproduced by the reproduction unit.

  For all content data (for example, packets), when the reproduction of the content data is waited until the reproduction delay time elapses from the reception time and the reproduction of the content data is started when the reproduction delay time elapses, the content data reproduction is interrupted. It can happen. In the present embodiment, only when the identification information is changed, the reproduction of the content data is waited until the reproduction delay time elapses from the reception time, and the process of starting the reproduction of the content data is executed when the reproduction delay time elapses. Therefore, for example, if the identification information is changed to a silent portion when the content data is audio, it is possible to eliminate the effect of interruption of the reproduction of the content data.

  In a preferred embodiment, the transmission device calculates a transmission time difference that is a difference between an actual transmission time when the transmission unit actually transmits content data to the reception device and the transmission time. And a transmission time difference adding unit for adding the calculated transmission time difference to the next content data, and the receiving device uses the transmission time difference added to the next content data to A reproduction delay time correction unit for correcting the reproduction delay time of the content data.

  Depending on the processing load of the transmission device, there is a difference in the time from when the time difference information is added to the content data until the transmission unit actually transmits the content data to the reception device. In this case, each receiving device may not be able to start reproducing the content data at substantially the same time. Therefore, in this embodiment, the transmission device calculates a transmission time difference that is a difference between the actual transmission time when the transmission unit actually transmits the content data to the reception device and the transmission time, and adds the transmission time difference to the next content data. . The receiving apparatus corrects the reproduction delay time of the previous content data using the transmission time difference added to the next content data. Accordingly, each receiving apparatus can start reproducing the same content data at approximately the same time more reliably.

  An operation program of a transmission device according to a preferred embodiment of the present invention includes: a transmission step of sequentially transmitting content data at the same reproduction position of the same content to each reception device; a reference time; and a content to the reception device. A time difference information calculating step for calculating time difference information, which is a difference from a transmission time for transmitting data, and a time difference information adding step for adding the calculated time difference information to the content data to be transmitted. To run.

  An operation program of a receiving device according to a preferred embodiment of the present invention includes a receiving step for receiving content data from the transmitting device, a reproducing step for playing back the received content data, and a receiving time for specifying a receiving time when the content data is received. A reproduction step for calculating a reproduction delay time by subtracting the time difference information added to the received content data from a specific step; a reproduction delay time from the reception time; Until the reproduction delay time elapses from the reception time, and a reproduction control step for causing the reproduction unit to reproduce the content data is executed by the computer of the reception apparatus.

  It is possible to provide a content reproduction system that can synchronize the reproduction start times of the contents of the receiving apparatuses without requiring complicated processing.

It is a block diagram which shows the content reproduction system of this invention. It is a block diagram which shows a transmitter. It is a block diagram which shows a receiver. It is a sequence diagram which shows the process with a transmitter and a receiver. It is a flowchart which shows the process of a transmitter. It is a flowchart which shows the process of a transmitter. It is a flowchart which shows the process of a receiver. It is a flowchart which shows the process of a receiver. It is a flowchart which shows the process of a transmitter. It is a flowchart which shows the process of a receiver.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to these embodiments.

  FIG. 1 is a block diagram showing a content reproduction system. The content reproduction system includes a transmission device 100, a plurality of reception devices 200 (200A, 200B, 200C, etc.), and a server 300, which can be connected to each other via an arbitrary network such as the Internet or a LAN. . The server 300 stores a plurality of contents in a storage medium such as an HDD. The content is a general term for music (music) data, video (image) data, and the like, but in this example, it is music data. That is, one piece of music is called one content. Content data refers to each partial data of one content, and is typically a packet.

  The transmission device 100 receives content from the server 300, packetizes the received content, and sequentially transmits the content to each reception device 200 using unicast. That is, transmitting apparatus 100 transmits packet A1 to receiving apparatus 200A, then transmits packet A2 to receiving apparatus 200B, then transmits packet A3 to receiving apparatus 200C, and then receives packet B1. Transmit to apparatus 200A, then transmit packet B2 to receiver apparatus 200B, and then transmit packet B3 to receiver apparatus 200C. Here, the packets A1, A2, and A3 all include the same content data, but the contents of the headers are different. Similarly, the packets B1, B2, and B3 all include the same content data, but the header contents are different.

  The header of the packet includes time difference information Tdif between the reference time Tbase and the transmission time Tsend at which the transmission device 100 transmits the packet to each reception device 200. Each receiving apparatus 200 calculates a reproduction delay time Tdelay by subtracting the time difference information Tdif from a predetermined delay time preset for each receiving apparatus 200 in order to determine the time to start reproducing the packet. . Each receiving device 200 waits for reproduction of the packet from the reception time when the packet is received until the reproduction delay time Tdelay elapses, and starts reproduction of the packet when the reproduction delay time Tdelay elapses from the reception time. Thereby, each receiving device 200 can start reproducing the same packet at substantially the same time. Here, the predetermined delay time set in advance for each receiving device 200 is generally set to the same value in each receiving device 200, but the time required for the reproduction processing and the like of the receiving device 200 is set. If they are different, it is necessary to adjust appropriately based on the time. Note that the predetermined delay time may be transmitted from the transmission device 100 to each reception device 200.

  Note that the server 300 does not need to be connected to the transmission apparatus 100 via a network, and may be wired by an audio cable or the like. Further, the transmission device 100 may have the function of the server 300.

  The transmission device 100 may have the function of the reception device 200. That is, the transmission device 100 transmits content data at the same reproduction position of the same content to the transmission device 100 itself in addition to each reception device 200. Similarly to the reception device 200, the transmission device 100 also subtracts the time difference information Tdif from a predetermined delay time set in advance to calculate the reproduction delay time Tdelay. The transmitting apparatus 100 waits for the reproduction of the packet until the reproduction delay time Tdelay elapses from the reception time when the packet is received, and starts reproducing the packet when the reproduction delay time Tdelay elapses from the reception time. As a result, the transmitting apparatus 100 itself can start reproducing the same packet at approximately the same time as each receiving apparatus 200.

  FIG. 2 is a schematic block diagram illustrating the configuration of the transmission apparatus 100 (note that the function of the transmission apparatus 100 as the reception apparatus 200 is described in FIG. 3). The transmission device 100 generally includes a control unit 11, a memory (ROM, RAM, etc.) 12, a network interface 13, a reception buffer 14, a decoder 15, a packetizing unit 16, and a transmission buffer 17.

  The control unit 11 controls each unit of the transmission device 100 based on an operation program of the transmission device 100 stored in the memory 12, and is a microcomputer, a CPU, or the like. The network interface 13 communicates with the server 300 and the receiving device 200 via the network, and transmits and receives data and commands. The reception buffer 14 temporarily stores music data received from the server 300 via the network interface 13 and then supplies the music data to the decoder 15. The decoder 15 decodes the music data, converts it into a PCM data string, and supplies it to the packetizing unit 16. The packetizing unit 16 converts a group of PCM data strings into packets using an arbitrary protocol such as UDP. The packetizing unit 16 temporarily stores the packet in the transmission buffer 17. The control unit 11 takes out the packet from the transmission buffer 17, adds a header including the time difference information Tdif and the session ID, and transmits the packet to each receiving device 200 via the network interface 13.

  FIG. 3 is a block diagram illustrating the configuration of each receiving device 200 (and the function of the transmitting device 100 as a receiving device). The receiving apparatus 200 includes a control unit 21, a memory 22 (ROM, RAM, etc.), a reception processing unit 23, a queue management unit 24, and a reproduction processing unit 25. The control unit 21 controls each unit of the receiving device 200 by executing an operation program of the receiving device 200 stored in the memory 22, and is a microcomputer, a CPU, or the like.

  The reception processing unit 23 receives the music data packet transmitted from the transmission device 100 via the network, and generates a chunk. A chunk is a set of PCM data strings with a header added. The reception processing unit 23 includes a packet reception unit 23A, a packet analysis unit 23B, a chunk generation unit 23C, and a queue operation unit 23D. The packet reception unit 23A receives a packet transmitted from the transmission device 100 via the network, and supplies the packet to the packet analysis unit 23B. The packet receiving unit 23 </ b> A specifies the time when the packet is received as the reception start time, and stores it in the memory 22. The packet analysis unit 23B acquires the time difference information Tdif and the session ID included in the packet header. Further, the packet analysis unit 23B determines whether or not the session ID included in the received packet has been changed. When the session ID has been changed, the packet analysis unit 23B subtracts the time difference information Tdif from the predetermined delay time, thereby reproducing the reproduction delay time. Tdelay is calculated. The chunk generator 23C generates a chunk from the packet and supplies it to the queue manager 24. The queue operation unit 23D controls the generation and deletion of the queue.

  The queue management unit 24 creates a queue for each session ID, for example, and stores the chunk in the queue. The chunk stored in the queue is output to the reproduction processing unit 25.

  The reproduction processing unit 25 reproduces the chunk read from the queue management unit 24 and outputs an audio signal. The reproduction processing unit 25 generally includes a chunk processing unit 25A and an audio output unit 25B. The chunk processing unit 25A reads a chunk from the queue and extracts a PCM data string from the chunk. The audio output unit 25B temporarily stores the PCM data string from the chunk processing unit 25A in its own buffer (audio output buffer), and then performs audio output.

The operation of the content reproduction system having the above configuration will be described.
FIG. 4 is a sequence diagram illustrating packet transmission and reproduction start times of the transmission device 100 and the reception devices 200A, 200B, and 200C. FIGS. 5 and 6 are flowcharts showing processing of the control unit 11 and the like of the transmission apparatus 100, and FIGS. 7 and 8 are flowcharts showing processing of the control unit 21 and the like of the reception apparatus 200.

  First, with reference to FIG. 5, a process when transmitting the content data packet A to each receiving apparatus 200 will be described. The control unit 11 of the transmission device 100 initializes the index i of the reception device 200 that is the transmission target of the packet A to 0 (S1). The control unit 11 measures the current time as the reference time Tbase and stores it in the memory 12 (S2).

  Here, the reference time Tbase may be the transmission time Tsend to the receiving apparatus 200A that transmits the packet A first. In this case, the time difference information Tdif transmitted to the receiving apparatus 200A is 0.

  The control unit 11 determines whether the index i is less than N (S3). N is the number of receiving apparatuses 200 that should transmit a packet, and is 3 in this example. That is, it is determined whether or not the packet A has been transmitted to all the receiving apparatuses 200. When the transmission of the packet A to all the receiving apparatuses 200 is completed (NO in S3), the process returns to S1 and moves to the transmission process for the next packet B.

  When the packet A has not been transmitted to all the receiving apparatuses 200 yet (YES in S3), the control unit 11 is the time when the packet A is transmitted to the receiving apparatus 200 with the index i. The transmission time Tsend is measured and stored in the memory 12 (S4). Specifically, the transmission time Tsend is a time at which a header is added to the transmission buffer 17 and transmitted to the network interface 13.

  Subsequently, the control unit 11 subtracts the transmission time Tsend from the reference time Tbase to calculate time difference information Tdif (S5). The control unit 11 reads the packet A from the transmission buffer 17 and adds the time difference information Tdif and the session ID to the header of the packet A (S6). The session ID is identification information indicating a group of packets. The control unit 11 transmits the packet A to the receiving device 200 with the index i via the network interface 13 (S7). Thereafter, the index i is incremented (S8), and the process returns to S3. Therefore, the above processing is repeated for all receiving apparatuses 200 to be transmitted, and packet A including time difference information Tdif is transmitted.

  As illustrated in FIG. 4, the time when the packet A is transmitted to the receiving apparatus 200A is Tsend1, and the time difference information Tdif1 included in the header of the packet A transmitted to the receiving apparatus 200A is Tbase-Tsend1. The time when the packet A is transmitted to the receiving apparatus 200B is Tsend2, and the time difference information Tdif2 included in the header of the packet A transmitted to the receiving apparatus 200B is Tbase-Tsend2. The time when the packet A is transmitted to the receiving apparatus 200C is Tsend3, and the time difference information Tdif3 included in the header of the packet A transmitted to the receiving apparatus 200C is Tbase-Tsend3.

  FIG. 6 shows a session ID change process of the control unit 11. The control unit 11 determines whether the packet to be transmitted is a packet to be changed to the next song (S11). When the packet is changed to the next song (YES in S11), the control unit 11 changes the session ID (S13). If it is not the packet of the next song (NO in S11), the control unit 11 has received an instruction to stop the reproduction of song data by a user operation, or seek (changes the reproduction position of song data) processing. It is determined whether it is being executed (S12). In the case of YES in S12, the control unit 11 changes the session ID (S13). If NO in S12, the process returns to S11. As described above, the session ID is changed at an arbitrary timing such that the music data becomes silent. As will be described later, since the packet synchronization process is executed when the session ID is changed, the interruption of sound can be prevented by changing the session ID to the silent period.

  As illustrated in FIG. 7, the control unit 21 of the reception device 200 determines whether a packet is received from the transmission device 100 by the packet analysis unit 23A (S21). If received (YES in S21), the packet receiver 23A measures the current time as the packet reception time and stores it in the memory 22 (S22). The packet analysis unit 23B acquires the session ID from the header of the packet in accordance with an instruction from the control unit 21 (S23), and determines whether the session ID is different from the session ID of the previously received packet (that is, whether the session ID has been changed). Judgment is made (S24). If the session ID has not been changed (NO in S24), the chunk generation unit 23C generates a chunk from the packet without supplying the synchronization process, and supplies the chunk to the queue (S25). That is, the reproduction is continued without performing the synchronization process.

  If the session ID has been changed (YES in S24), the chunk generation unit 23C executes the synchronization process without immediately outputting the received packet to the queue (S26).

  The synchronization process is shown in FIG. The packet analysis unit 23B acquires the time difference information Tdif from the header of the packet according to the instruction from the control unit 21 (S31). The packet analysis unit 23B subtracts the time difference information Tdif from the predetermined delay time, calculates the reproduction delay time Tdelay of the packet, and stores it in the memory 22 (S32). The chunk generation unit 23C determines whether or not Tdelay between playback delays has elapsed from the packet reception time according to an instruction from the control unit 21, and waits until Tdelay between playback delays has elapsed from the packet reception time (S33). . When the Tdelay between playback delays has elapsed from the packet reception time (YES in S33), the queue operation unit 23D deletes the queue that has been used so far (S34). If there is a chunk in the queue so far, the queue is deleted for synchronization, and the chunk stored in the deleted queue is deleted and not reproduced. The queue operation unit 23D creates a new queue, and the chunk generation unit 23C generates a chunk from the synchronization target packet and stores it in the newly generated queue (S35). Therefore, when the reproduction delay time Tdelay elapses from the packet reception time, the packet is started to be reproduced.

  As shown in FIG. 4, it is assumed that the time required for the packet transmitted from the transmission device 100 to reach each reception device 200 is the same, the time at which the reception device 200A receives the packet A is Trece1, and the reception device The time at which 200B receives packet A is Tlace2, the time at which receiving apparatus 200C receives packet A is Tlace3, the reproduction delay time of receiving apparatus 200A is Tdelay1, the reproduction delay time of receiving apparatus 200B is Tdelay2, and the receiving apparatus Assuming that the reproduction delay time of 200C is Tdelay3, Trece1 + Tdelay1 = Trece2 + Tdelay2 = Trece3 + Tdelay3, and the receiving apparatuses 200A, 200B, and 200C all start reproducing packet A at the same time.

  In the above embodiment, the synchronization process is performed only on the packet whose session ID is changed. However, the synchronization process may be performed on all packets. However, if synchronization processing is performed in a non-silent section, sound interruption may occur. Therefore, by changing the session ID in the silent section and performing synchronization processing only on the packet whose session ID is changed, Can be prevented.

  Next, another embodiment of the present invention will be described. Depending on the processing load of the transmission apparatus 100, the time from when a packet is transmitted from the transmission buffer 17 to the network interface 13 until when the packet is actually transmitted from the network interface 13 to the reception apparatus 200 may be delayed. is assumed. In this case, even if the transmission time Tsend is measured and the time difference information Tdif is included in the packet and transmitted to the receiving device 200, there is a possibility that a deviation occurs in the packet reproduction start time in each receiving device 200.

  Therefore, in this embodiment, the actual transmission time Trsend at which the packet A is actually transmitted from the network interface 13 to the receiving device 200 is measured, and a transmission time error (Trsend−) that is the difference between the actual transmission time Trsend and the transmission time Tsend is measured. Tsend) is calculated and added to the header of the next packet B. When receiving the next packet B, the receiving apparatus 200 acquires a transmission time error (Trsend−Tsend) from the header and corrects the reproduction delay time Tdelay of the previous packet A. Specifically, the corrected reproduction delay time Tdelay 'is obtained by Tdelay- (transmission time error (Trsend-Tsend)). Thereby, each receiving device 200 can synchronize the reproduction time of the packet.

  FIG. 9 is a flowchart showing the processing of the transmission apparatus 100. The same processing as in FIG. First, for example, in the processing when transmitting the packet A to the receiving device 200A, the control unit 11 measures the actual transmission time Trsend1 at which the packet A is actually transmitted from the network interface 13 (S42). The control unit 11 subtracts the transmission time Tsend1 from the measured actual transmission time Trsend1, calculates a transmission time error, and stores it in the memory 12 (S43). This process is also executed in the same way in the transmission process of packet A to the other receiving apparatuses 200B and 200C.

  Subsequently, in the process when transmitting the next packet B of the packet A to the receiving device 200A, the control unit 11 adds the transmission time error of the previous packet A to the header of the next packet B (S41). Therefore, when the next packet B is transmitted, the transmission time error of the previous packet A is transmitted to the receiving apparatus 200A. This process is executed in the same way in the process of transmitting the packet B to the other receiving apparatuses 200B and 200C.

  FIG. 10 is a flowchart showing the reproduction delay time correction process of the receiving apparatus 200. When the packet receiver 23A receives the packet B (YES in S51), the packet analyzer 23B acquires the transmission time error of the previous packet A from the header of the packet B (S52). The chunk generation unit 23C corrects the reproduction delay time Tdelay of the packet A by subtracting the transmission time error of the packet A from the reproduction delay time Tdelay of the packet A stored in the memory 22.

  Through the above processing, the time from when the packet is transmitted from the transmission buffer 17 to the network interface 13 until when the packet is actually transmitted from the network interface 13 to the reception device 200 is reproduced after the reception device 200 side. By subtracting from the delay time Tdelay, it is possible to match the reproduction start times of the packets of the respective receiving apparatuses 200.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment. The present invention may be provided in the form of a computer program for operating the transmission device 100 and the reception device 200 of the present invention or a recording medium recording the computer program.

  The present invention can be suitably applied to a content reproduction system including a transmission device and a reception device.

DESCRIPTION OF SYMBOLS 100 Transmission apparatus 11 Control part 12 Memory 13 Network interface 14 Reception buffer 15 Decoder 16 Packetization part 17 Transmission buffer 200 Reception apparatus 21 Control part 22 Memory 23 Reception processing part 23A Packet reception part 23B Packet analysis part 23C Chunk generation part 23D Queue operation Section 24 Queue management section 24A Queue 25 Playback processing section 25A Chunk processing section 25B Audio output section 300 Server

Claims (7)

A transmitter, and a plurality of receivers connectable to the transmitter via a network,
The transmitting device transmits, in order to each receiving device, content data at the same reproduction position of the same content;
A time difference information calculation unit that calculates time difference information that is a difference between a reference time and a transmission time at which content data is transmitted to the receiving device;
A time difference information adding unit for adding the calculated time difference information to the content data to be transmitted;
Each of the receiving devices is
A receiving unit for receiving content data from the transmitting device;
A playback unit for playing back the received content data;
A reception time specifying unit for specifying the reception time when the content data is received;
A reproduction delay time calculating unit for calculating a reproduction delay time by subtracting the time difference information added to the received content data from a predetermined delay time;
A playback control unit that waits for playback of the content data from the reception time until the playback delay time elapses and causes the playback unit to play back the content data when the playback delay time elapses from the reception time; Playback system. The transmitting device is
An identification information adding unit for adding identification information to the content data to be transmitted;
An identification information changing unit that changes the identification information when a predetermined condition is satisfied;
The receiving device is
An identification information change determination unit for determining whether or not the identification information added to the received content data is changed from the identification information added to the content data received immediately before;
When it is determined that the identification information has been changed, the reproduction control unit waits for reproduction of the content data until the reproduction delay time elapses from the reception time, and when the reproduction delay time elapses from the reception time The content reproduction system according to claim 1, wherein the content data is reproduced by the reproduction unit. The transmitting device is
A transmission time difference calculating unit that calculates a transmission time difference that is a difference between the transmission time and the actual transmission time when the transmission unit actually transmits content data to the receiving device;
A transmission time difference adding unit for adding the calculated transmission time difference to the next content data;
The receiving device is
The content reproduction system according to claim 1, further comprising a reproduction delay time correction unit that corrects the reproduction delay time of the previous content data using a transmission time difference added to the next content data. A transmission device, and a plurality of reception devices connectable to the transmission device via a network, each reception device receiving content data from the transmission device, and a reproduction unit reproducing the received content data A reception time specifying unit for specifying the reception time at which the content data is received, and a reproduction delay time for calculating a reproduction delay time by subtracting the time difference information added to the received content data from a predetermined delay time A calculation unit; a reproduction control unit that waits for reproduction of the content data until the reproduction delay time elapses from the reception time, and causes the reproduction unit to reproduce the content data when the reproduction delay time elapses from the reception time; The content transmission system in the transmission device, comprising:
A transmission unit that sequentially transmits content data of the same reproduction position of the same content to each of the receiving devices;
A time difference information calculation unit that calculates time difference information that is a difference between a reference time and a transmission time at which content data is transmitted to the receiving device;
A transmission apparatus comprising: a time difference information adding unit that adds the calculated time difference information to content data to be transmitted. A transmission device, and a plurality of reception devices connectable to the transmission device via a network, wherein the transmission device sequentially transmits content data of the same reproduction position of the same content to each of the reception devices. A transmission unit, a time difference information calculation unit that calculates time difference information that is a difference between a reference time and a transmission time at which the content data is transmitted to the receiving device; and the calculated time difference information in the content data to be transmitted. A receiving device in a content reproduction system having a time difference information adding unit to be added,
A receiving unit for receiving content data from the transmitting device;
A playback unit for playing back the received content data;
A reception time specifying unit for specifying the reception time when the content data is received;
A reproduction delay time calculating unit for calculating a reproduction delay time by subtracting the time difference information added to the received content data from a predetermined delay time;
A reception control unit that waits for reproduction of the content data from the reception time until the reproduction delay time elapses, and causes the reproduction unit to reproduce the content data when the reproduction delay time elapses from the reception time; apparatus. A transmission device, and a plurality of reception devices connectable to the transmission device via a network, each reception device receiving content data from the transmission device, and a reproduction unit reproducing the received content data A reception time specifying unit for specifying the reception time at which the content data is received, and a reproduction delay time for calculating a reproduction delay time by subtracting the time difference information added to the received content data from a predetermined delay time A calculation unit; a reproduction control unit that waits for reproduction of the content data until the reproduction delay time elapses from the reception time, and causes the reproduction unit to reproduce the content data when the reproduction delay time elapses from the reception time; An operation program for the transmission device in the content reproduction system,
A transmission step of sequentially transmitting content data of the same content at the same reproduction position to each of the receiving devices;
A time difference information calculating step for calculating time difference information that is a difference between a reference time and a transmission time for transmitting content data to the receiving device;
An operation program for a transmitting apparatus that causes the transmitting apparatus to execute a time difference information adding step of adding calculated time difference information to content data to be transmitted. A transmission device, and a plurality of reception devices connectable to the transmission device via a network, wherein the transmission device sequentially transmits content data of the same reproduction position of the same content to each of the reception devices. A transmission unit, a time difference information calculation unit that calculates time difference information that is a difference between a reference time and a transmission time at which the content data is transmitted to the receiving device; and the calculated time difference information in the content data to be transmitted. An operation program for the receiving device in a content reproduction system having a time difference information adding unit to be added,
A receiving step of receiving content data from the transmitting device;
A playback step of playing back the received content data;
A reception time specifying step for specifying the reception time when the content data is received;
A reproduction delay time calculating step of calculating a reproduction delay time by subtracting the time difference information added to the received content data from a predetermined delay time;
A reproduction control step of waiting for reproduction of the content data from the reception time until the reproduction delay time elapses, and causing the reproduction unit to reproduce the content data when the reproduction delay time elapses from the reception time; An operation program for the receiving apparatus to be executed by

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