JP2007013705A - Simultaneous playback system, information processing apparatus, midway participation method, and midway participation program - Google Patents

Abstract

【Task】
Share data among multiple terminals so that they can participate and play back simultaneously during the simultaneous playback process.
[Solution]
In the present invention, when the PDA 2, the mobile phone 3 and the digital camera 4 are connected to the network, and the PDA 2 transmits content data in response to a request from each player terminal and performs simultaneous playback processing, the PDA 2 participates in the simultaneous playback processing halfway. The notebook PC 5 obtains a reproduction time stamp TSa indicating the elapsed time since the start of reproduction of the content data from the PDA 2, and uses the content data with reference to the reproduction time stamp TSa corresponding to the delay time required for data communication with the PDA 2. The playback start time TI is determined, the content data after the playback start time TI is requested to the PDA 2, and the playback start time TI acquired from the PDA 2 in response to a request from the notebook PC 5 Content data at the timing of the playback start time TI It was to be raw.
[Selection] Figure 3

Description

  The present invention relates to a simultaneous playback system, an information processing apparatus, a midway participation method, and a midway participation program. For example, when an ad hoc network is formed between a plurality of mobile terminals and content data is played back simultaneously, Therefore, the present invention is suitable when applied to simultaneous reproduction.

  2. Description of the Related Art Conventionally, a wireless communication environment called a so-called ad hoc network in which a plurality of portable terminals existing in the same space can form a local network and perform wireless communication with each other is increasing. Between groups formed by this type of ad hoc network, for example, it is required to simultaneously reproduce communication tools such as AV contents that require real-time performance.

  In this ad hoc network, when a plurality of mobile terminals are playing back simultaneously, another mobile terminal may participate from the middle. In such a case, the mobile terminal that participates midway needs to acquire the same part of AV content as the mobile terminal that is playing simultaneously.

Incidentally, in a method such as multicast streaming or unicast streaming, the transmitting terminal transmits the same part of the AV content to each mobile terminal at a uniform transmission speed, and the transmitted AV content is sequentially reproduced by sequentially reproducing it. can do. In such a simultaneous playback system, when there is a mobile terminal that wants to participate in the middle, this transmission terminal transmits the AV content uniformly to the mobile terminal that participates in the middle and plays it back, so that it can be played from the middle part at the same time. (For example, refer to Patent Document 1).
JP 2003-235027 A

  By the way, in the midway participation method of such a configuration, as shown in FIG. 13, the transmission terminal 50 transmits the same part of the AV contents 51 and 52 to the portable terminals A and B being simultaneously reproduced at a uniform transmission rate. In the portable terminals A and B, the common AV content is received at the common reception point and reproduced at the same reproduction point. Accordingly, the mobile terminal C participating in the middle receives the AV content 53 from the same reception point as the mobile terminals A and B, and after waiting for a while, starts playback at the same playback point as the mobile terminals A and B. It was possible to reproduce.

  On the other hand, as shown in FIG. 14, in the ad hoc network, each mobile terminal A ′ and B ′ actively requests data transmission of AV content from the transmission terminal 60 and acquires the AV content individually. May be performed. In this case, there is HTTP (Hypertext Transfer Protocol, RFC2616) used in version 1 of DLNA HN (Digital Living Network Alliance, Home networked Device), for example, mobile terminals A ′ and B ′ on the receiving side. The HTTP client transmits an HTTP GET request as a data transmission request to the HTTP server serving as the transmission terminal 60, and as a result, the AV contents 61 and 62 are transmitted from the transmission terminal 60.

  Therefore, in this download method, the reception points of the mobile terminals A ′ and B ′ at a certain point in time are not uniform, and the mobile terminal C ′ tries to join the simultaneous reproduction group (mobile terminals A ′ and B ′) halfway. There is a problem in that it is impossible to know at which reception point the AV content 63 should be received, and it is not possible to participate in the simultaneous playback process.

  The present invention has been made in consideration of the above points, and during a simultaneous playback process between a plurality of mobile terminals, another mobile terminal trying to participate in the middle can execute the simultaneous playback process from the middle part of the content. The present invention intends to propose a simultaneous playback system, an information processing apparatus, a midway participation method, and a midway participation program that can participate in simultaneous playback.

  In order to solve such a problem, in the simultaneous playback system of the present invention, the sender terminal and one or more player terminals are network-connected, the sender terminal transmits content data in response to a request from each player terminal, A simultaneous playback system in which another player terminal participates in the simultaneous playback process while the player terminal performs simultaneous playback of content data. The other player terminal plays content data from each player terminal or sender terminal. The playback elapsed time information indicating the elapsed time after the start is acquired, the content data playback start time is determined based on the elapsed time information according to the delay time required for data communication with the sender terminal, and the sender terminal Requesting content data after the playback start time, the sender terminal In response to a request from a participating terminal, content data after the playback start time is transmitted to another player terminal, and the other player terminals receive the content data after the playback start time and play the content data after the playback start time. Played at the start time.

  Thus, in the simultaneous playback system of the present invention, other player terminals determine the content data after the playback start time supplied from the sender terminal while each player terminal is simultaneously playing the content data supplied from the sender terminal. By reproducing at the timing of the reproduction start time, the same content data as that being simultaneously reproduced by each player terminal can be reproduced simultaneously from the middle.

  Furthermore, in the information processing apparatus of the present invention, the sender terminal and one or more player terminals are network-connected, the sender terminal transmits content data in response to a request from each player terminal, and each player terminal transmits the content data. An information processing apparatus that participates in the simultaneous playback process halfway during the simultaneous playback process, and that obtains playback elapsed time information indicating elapsed time since the start of playback of the content data from each player terminal or sender terminal; Reproduction start time determining means for determining the reproduction start time of the content data based on the elapsed time information according to the delay time required for data communication with the sender terminal, and content data after the reproduction start time to the sender terminal Transmission means for transmitting the request signal and playback start time supplied from the sender terminal Receiving means for receiving content data of the descending and the like and a reproducing means for reproducing the content data after the reproduction start time in the timing of the playback start time.

  Thus, in the information processing apparatus of the present invention, the information processing apparatus determines the content data after the reproduction start time supplied from the sender terminal while each player terminal simultaneously reproduces the content data supplied from the sender terminal. By reproducing at the timing of the reproduction start time, the same content data as that being simultaneously reproduced by each player terminal can be reproduced simultaneously from the middle.

  Furthermore, in the halfway participation method of the present invention, the sender terminal and one or more player terminals are network-connected, the sender terminal transmits content data in response to a request from each player terminal, and each player terminal Is an intermediate participation method in which other player terminals participate in the simultaneous reproduction process in the middle, and the elapsed time information indicating the elapsed time since the start of reproduction of the content data from each player terminal or sender terminal An acquisition step of acquiring content, a playback start time determination step of determining a playback start time of content data based on elapsed time information according to a delay time required for data communication with the sender terminal, and playback start for the sender terminal A transmission step of transmitting a request signal for content data after the time; A receiving step of receiving content data of the reproduction start time after supplied from sender terminal, and to and a reproduction step of reproducing the content data after the reproduction start time in the timing of the playback start time.

  Thus, in the halfway participation method of the present invention, the playback start time supplied from the sender terminal at the timing of the playback start time determined by the information processing apparatus while each player terminal simultaneously plays the content data supplied from the sender terminal. By reproducing the subsequent content data, it is possible to simultaneously reproduce the same content data as that being simultaneously reproduced by each player terminal from the middle.

  Further, in the halfway participation program of the present invention, the sender terminal and one or more player terminals are network-connected, the sender terminal transmits content data in response to a request from each player terminal, and each player terminal To obtain the elapsed playback time information indicating the elapsed time since the start of playback of the content data from each player terminal or sender terminal to other player terminals participating in the simultaneous playback process. A playback start time determining step for determining a playback start time of content data based on elapsed time information according to a delay time required for data communication with the sender terminal, and content after the playback start time for the sender terminal A transmission step for transmitting a data request signal, and a sender A receiving step of receiving content data of the reproduction start time after supplied from the terminal and so as to execute a reproducing step of reproducing the content data after the reproduction start time in the timing of the playback start time.

  Thereby, in the midway participation program of the present invention, the information processing apparatus determines the content data after the reproduction start time supplied from the sender terminal while each player terminal simultaneously reproduces the content data supplied from the sender terminal. By reproducing at the timing of the reproduction start time, the same content data as that being simultaneously reproduced by each player terminal can be reproduced simultaneously from the middle.

  According to the present invention, while each player terminal simultaneously plays the content data supplied from the sender terminal, the playback start time determined by other player terminals for the content data after the playback start time supplied from the sender terminal. By playing at this timing, it is possible to simultaneously play the same content data as that being played simultaneously by each player terminal from the middle, thus realizing a simultaneous playback system capable of participating in the simultaneous playback processing halfway.

  According to the present invention, the content data after the reproduction start time supplied from the sender terminal is reproduced at the reproduction start time determined by the information processing apparatus while each player terminal simultaneously reproduces the content data supplied from the sender terminal. By playing at the timing, it is possible to simultaneously play the same content data as each player terminal is playing at the same time from the middle, and thus an information processing apparatus that can participate in the simultaneous playing process halfway, a halfway participation method, a halfway Participation program can be realized.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Simultaneous Playback System (1-1) Overall Configuration In FIG. 1, 1 indicates the simultaneous playback system as a whole. In this simultaneous playback system 1, a PDA (Personal Digital Assistant) 2, a mobile phone 3 and a digital camera 4 have wireless communication functions such as IEEE (Institute of Electrical and Electronics Engineers) 802.11g and Bluetooth (registered trademark). The ad hoc network 7 is constructed by connecting to each other via the wireless communication function.

  Furthermore, in the simultaneous reproduction system 1, the above-described PDA 2 and mobile phone are connected to the above-described ad hoc network 7 via the wireless communication function of a notebook personal computer (hereinafter referred to as a notebook PC) 5 that is a midway participating terminal. 3 and the digital camera 4 are connected to the ad hoc network 7 by wireless connection.

  Here, in the ad hoc network 7, each of the PDA 2, the mobile phone 3, and the digital camera 4 individually owns the moving image content as content data, and the moving image content is shared within the group that constructs the ad hoc network 7. Ring. At this time, one mobile terminal becomes a controller terminal, and the sender terminal that owns the video content to be distributed transmits the video content to another player terminal in accordance with an instruction from the controller terminal. All of the telephone 3 and the digital camera 4 can play the moving image content simultaneously as player terminals.

  In this case, the PDA 2 that is the controller terminal gives an instruction to cause the mobile phone 3 and the digital camera 4 that are other player terminals to perform simultaneous playback processing of the moving image content. The cellular phone 3 and the digital camera 4 are adapted to simultaneously reproduce the moving image content between the PDA 2, the cellular phone 3 and the digital camera 4 in accordance with a command from the PDA 2 which is a controller terminal.

  In the ad hoc network 7, not the moving image content as the content data to be data shared, but also various other content data such as an audio file, a text file, a still image data file, or a game program are targeted for data sharing. can do.

  The PDA 2 creates a simultaneous reproduction data list based on a reproduction data list that is a list of moving image contents owned by each player terminal. Here, the simultaneous reproduction data list is configured by information such as the name of the moving image content, the sender terminal that transmits the moving image content, and the master terminal that serves as a clock reference.

  Accordingly, the PDA 2 transmits the moving image content from the sender terminal to each player terminal in a state where the clock of each player terminal is synchronized with the master terminal based on the simultaneous reproduction data list. Then, the PDA 2 can execute the simultaneous reproduction process by transmitting a simultaneous reproduction start request to each player terminal and reproducing the transmitted moving image content all at once.

(1-2) Midway Participation Next, in this simultaneous playback system 1, when each player terminal of the ad hoc network 7 is playing back video content at the same time, the notebook PC 5 that is a midway participation terminal simultaneously plays the video content. A case will be described in which participation in the reproduction process is performed halfway and the simultaneous reproduction process is started from the middle part of the moving image content.

  In this case, as shown in FIG. 2, the PDA 2 as the controller terminal transmits moving image content to the mobile phone 3 and the digital camera 4 as a sender terminal. Here, as shown in FIG. 3, at time T0, the PDA 2 starts to reproduce the moving image content. Although the cellular phone 3 and the digital camera 4 are omitted in FIG. 3, the reproduction is started at the same timing as the PDA 2. Each player terminal has a playback timer (not shown), and counts the elapsed time from the start of playback by setting the playback start time (time T0) of the moving image content to zero.

  Then, the notebook PC 5 (FIG. 2), which is an intermediate participation terminal, generates an intermediate participation request JR that is a request to participate in the simultaneous reproduction process, and transmits it to the controller terminal. Here, since the notebook PC 5 does not recognize which player terminal is the controller terminal, the notebook PC 5 transmits the midway participation request JR to the PDA 2, the mobile phone 3, and the digital camera 4.

  The PDA 2 that is the controller terminal returns a mid-participation preparation request OR, which is a request to prepare for mid-participation in response to the mid-participation request JR, to the notebook PC 5. As a result, the PDA 2 can make the notebook PC 5 recognize that the PDA 2 that is the transmission source of the midway participation preparation request OR is a controller terminal. In contrast, the mobile phone 3 and the digital camera 4 do not respond to the midway participation request JR.

  Here, the midway participation preparation request OR includes information on the sender terminal that is transmitting the currently played video content and master clock information for clock synchronization correction. It recognizes that the sender terminal is PDA2.

  Then, the notebook PC 5 corrects its own clock based on the master clock information and synchronizes with the master terminal. As a result, the notebook PC 5 can synchronize its clock with the master terminal and each player terminal, and can match the reproduction timing of the moving image content with each player terminal.

  At time T1 (FIG. 3), the notebook PC 5 transmits a playback time stamp request PR for requesting the PDA 2 to transmit a playback time stamp TSa representing the current playback portion of the moving image content, and the time T1 is played back. Temporarily stored as the transmission time TCs of the time stamp request PR.

  When the PDA 2 receives the reproduction time stamp request PR transmitted from the notebook PC 5 at the time T 1 at the time T 2, the PDA 2 temporarily stores the time T 2 as the reception time TAr. Then, the PDA 2 uses a playback timer count value corresponding to the playback time TAs corresponding to the playback time TAs at the moment when playback starts in the next structural unit (frame or field, etc.) in the currently played video content, and a playback time stamp indicating playback elapsed time information. Calculated as TSa.

  Further, the PDA 2 calculates the stay time Sa until the message is returned in response to the reproduction time stamp request PR from the notebook PC 5. Then, the PDA 2 transmits the reproduction time stamp TSa and the stay time Sa to the notebook PC 5 at the time T3 of the reproduction time TAs.

  When the notebook PC 5 receives the reproduction time stamp TSa and the stay time Sa transmitted from the PDA 2 at the time T3 at the time T4, the one-way propagation delay which is a time required for data communication with the PDA 2 with the time T4 as the reception time TCr. The time Lc is calculated according to the following formula.

  Lc = (TCr-TCs-Sa) / 2 (1)

  In this case, the notebook PC 5 uses the time obtained by subtracting the transmission time TCs and the stay time Sa from the reception time TCr as a delay time required for round-trip transmission / reception, and divides this by 2 to obtain a one-way propagation delay time Lc.

  Then, the notebook PC 5 sets the playback time stamp TSc of the playback timer indicating its own playback time when playing back the moving image content based on the one-way propagation delay time Lc and the reception time TCr of the playback time stamp TSa. Specifically, the notebook PC 5 calculates its own reproduction time stamp TSc according to the following equation using the reception time TCr when the reproduction time stamp TSa of the PDA 2 is received.

  TSc = TSr + Lc (2)

  As a result, the notebook PC 5 adds the one-way propagation delay time Lc to the reproduction stamp TS to obtain the same reproduction time stamp TSc as other player terminals.

  Then, the notebook PC 5 reproduces the actual reproduction start point based on the reproduction preparation time Dc that is the processing time required from when the video content is received until the reproduction process is started and the one-way propagation delay time Lc. The start time TI is determined by calculating based on this reproduction timer.

  Specifically, as shown in FIG. 4, the notebook PC 5 first calculates a reproduction start processing time PS that represents a time from the data request time PBs to the PDA 2 to the reproduction start time TI according to the following equation.

  PS = 2 × Lc + Dc (3)

  In this case, the notebook PC 5 doubles the previously calculated one-way propagation delay time Lc to calculate the response time required for the round-trip communication with the PDA 2, and further adds the reproduction preparation time Dc. Thereby, the notebook PC 5 can calculate the reproduction start processing time PS that is at least necessary before the reproduction is started.

  Then, the notebook PC 5 (FIG. 3) determines the data request time PBs that is the time for transmitting the data transmission request for transmitting the moving image content, and based on the data request time PBs and the reproduction start processing time PS. Then, the reproduction start time TI of the moving image content is calculated according to the following equation.

  TI = PBs + PS (4)

  In this case, the notebook PC 5 calculates the reproduction start time TI by adding the reproduction start processing time PS to the data request time PBs.

  Then, at the instant of this data request time PBs, which is time T5, the notebook PC 5 receives a data transmission request DR constituted by a TimeSeekRange.dlna.org HTTP header defined by, for example, DLNA (Digital Living Network Alliance) shown in FIG. At the same time, the reproduction start time TI is transmitted to the PDA 2. Note that the data transmission request DR in FIG. 5 indicates a request message for transmitting moving image content from the reproduction start time TI = 100.00 seconds.

  As a result, the notebook PC 5 calculates the reproduction start time TI by adding the minimum reproduction start processing time PS required before the actual reproduction start to the data request time PBs, and the PDA 2 performs the reproduction start time TI. Since the subsequent video content is specified and requested for distribution, preparation for playback start is completed by the playback start time TI, and playback processing of the video content can be started at the timing of the playback start time TI. ing.

  When the PDA 2 receives the data transmission request DR and the reproduction start time TI at time T6, for example, together with the data transmission response DA configured by the TimeSeekRange.dlna.org HTTP header defined by DLNA as shown in FIG. The moving image contents after the reproduction start time TI are sequentially transmitted to the notebook PC 5. Note that the data transmission response DA in FIG. 6 indicates a response message indicating that the moving image content from 100.00 seconds (reproduction start time TI) to 150.00 seconds is transmitted.

  When the notebook PC 5 receives the moving image content after the reproduction start time TI from the PDA 2 at the time T7 (FIG. 4), the notebook PC 5 starts preparation for the reproduction process, and at the time T8 when the reproduction preparation time Dc has elapsed, Play and display video content.

  As a result, in the simultaneous reproduction system 1, by reproducing the video content after the reproduction start time TI acquired by the notebook PC 5 at the time when the reproduction start time TI is reached, the video content being reproduced by each player terminal is obtained. Since the notebook PC 5 can reproduce the moving image content after the reproduction start time TI at the moment when the reproduction start time TI is reached, the notebook PC 5 can simultaneously reproduce the moving image content of the same part as each player terminal.

  Further, the notebook PC 5 calculates the reproduction start time TI based on the reproduction start processing time PS composed of the response time required for the round-trip communication with the PDA 2 required until the reproduction processing and the reproduction preparation time Dc (FIG. 4). ), The preparation for starting the playback process can be completed by the playback start time TI, and the video content distributed from the PDA 2 starts to be played immediately after the minimum time required for the playback process has passed. The player terminal can participate in the simultaneous playback processing performed by the player terminal.

  In this way, the notebook PC 5 sets a playback timer indicating the time from the start of playback by the playback time stamp TSa acquired from the PDA 2, and is necessary for the round-trip communication with the playback preparation time Dc and the PDA 2 with reference to the playback timer. When the playback start time TI corresponding to the response time is determined, the PDA 2 is requested for video content after the playback start time TI. As a result, the notebook PC 5 can receive the content data after the reproduction start time TI by the reproduction start time TI and complete the preparation for reproduction start. Therefore, the notebook PC 5 can complete the preparation for reproduction start at the timing of the reproduction start time TI. The moving image content can be reproduced, and thus the moving image content can be displayed at the same timing as each player terminal.

(2) Circuit configuration of notebook PC 5 Next, the circuit configuration of the PDA 2 that is the controller terminal, the sender terminal and the player terminal, and the notebook PC 5 that is a midway participating terminal will be described. The necessary circuit configuration is common to each portable terminal, and the circuit configuration of the common part will be described.

  As shown in FIG. 7, the notebook PC 5 has a network transmission / reception unit 22, an operation unit 26, a speaker unit 27, an LCD (Liquid Crystal Display), etc. with respect to a control unit 23 having a central processing unit (CPU) configuration for overall control. The display unit 28 is connected.

  The wireless communication interface 21 connected to the network transmission / reception unit 22 performs short-range wireless communication such as IEEE802.11g or Bluetooth (registered trademark) with other portable terminals. Transfer of JR, midway participation preparation request OR, reproduction time stamp request PR, reproduction time stamp TSa, reproduction start time TI, data transmission request DR, data transmission response DA, and moving image content is performed.

  The control unit 23 is configured to execute various processes and a simultaneous reproduction midway participation process procedure described later based on the basic program and the midway participation program read out from the ROM 35 and developed.

  In addition, the control unit 23 is used as a work area that temporarily stores various information such as a decoded moving image content and a transmission / reception time, and a decoder 33 for decoding the encoded moving image content acquired through the wireless communication interface 21. RAM 34 to be used.

  Then, the control unit 23 displays the decoded moving image content on the display unit 28, and similarly outputs audio data from the speaker unit 27, and at the same time according to a user's operation instruction to the operation unit 26 including buttons, a touch panel, and the like. Participation processing during playback is started.

  In addition, the control unit 23 adjusts the reference time for performing simultaneous playback processing between the player terminals to the master clock information, and also manages a playback information timer, a one-way propagation delay time Lc, and playback of the notebook PC 5. And a calculation unit 32 for calculating the time stamp TSc, the reproduction start processing time PS, the reproduction start time TI, the reproduction time stamp TSa of the PDA 2, the stay time Sa, and the like.

  Thus, in the simultaneous playback system 1, the PDA 2 that is the controller terminal and the sender terminal and the notebook PC 5 that is the midway participating terminal basically have the common circuit configuration shown in FIG. Since the mobile phone 3 and the digital camera 4 that have the same circuit configuration also have the common circuit configuration, any player terminal can join the ad hoc network 7 that is playing simultaneously as a halfway participation terminal. .

(3) Simultaneous Replay Participation Process Procedure Next, a simultaneous replay participation process procedure in the simultaneous replay system 1 will be described. As shown in FIG. 8, in the simultaneous reproduction system 1, an exchange according to the following processing sequence is performed between the PDA 2 that is the controller terminal and the sender terminal and the notebook PC 5 that is the midway participating terminal.

  In step SP1, the notebook PC 5 that is a halfway participation terminal transmits a halfway participation request JR to the PDA2 that is the controller terminal in response to a user operation, and requests halfway participation in the simultaneous reproduction process for the video content being reproduced. Thereafter, the process proceeds to the next step SP2.

  At this time, in step SP11, the PDA2 which is the controller terminal responds to the reception of the midway participation request JR, and receives a midway participation preparation request including master clock information for clock synchronization correction and sender terminal information of the video content currently being played back. OR is transmitted to the notebook PC 5 to request preparation for executing the simultaneous reproduction participation process, and the process proceeds to the next step SP12.

  As a result, the PDA 2 can make the notebook PC 5 recognize that the current sender terminal is the PDA 2.

  At this time, when receiving the midway participation preparation request OR in step SP2, the notebook PC 5 performs clock correction using the master clock information, and proceeds to the next step SP3.

  In step SP3, the notebook PC 5 transmits a playback time stamp request PR to the PDA 2 that is the sender terminal at the timing of the time point T1 (FIG. 3), and the playback timer counts the playback time from the playback start (time point T0). When the value is requested as the reproduction time stamp TSa of PDA2, the process proceeds to the next step SP4.

  At this time, in step SP12, when the PDA 2 receives the reproduction time stamp request PR at the timing of the time point T2 (FIG. 3), the PDA 2 at the time point T3, which is the moment when the reproduction starts in a predetermined structural unit in the moving image content to be reproduced next. At this time, the value of the reproduction timer at this moment is transmitted to the notebook PC 5 as a reproduction time stamp TSa. At the same time, when the PDA 2 transmits the stay time Sa representing the stay time from the time point T2 at which the playback time stamp request PR is received to the time point T3 at which the playback time stamp TSa is transmitted to the notebook PC 5, the process proceeds to the next step SP13 (FIG. 8). Move.

  At this time, when the reproduction time stamp TSa and the stay time Sa are supplied at the timing of time T4 (FIG. 3), the notebook PC 5 receives the reception time TCr at this time and the transmission time TCs at step SP3 (FIG. 8). Based on the stay time Sa, the one-way propagation delay time Lc required for one-way transmission / reception with the PDA 2 is calculated by the equation (1).

  Further, the notebook PC 5 calculates the reproduction time stamp TSc of the notebook PC 5 by the equation (2) based on the one-way propagation delay time Lc and the reproduction time stamp TSa of the PDA 2 at the time T3, and the reproduction indicated by the reproduction time stamp TSc. The count value of the timer is set, and the process proceeds to the next step SP5 (FIG. 8).

  As a result, the notebook PC 5 can match the value of the playback timer of the notebook PC 5 with the value of the playback timer of the PDA 2, so that the playback timing of the moving image content can be aligned.

  In step SP5, the notebook PC 5 uses the equation (3) to start playback from the data request time PBs based on the one-way propagation delay time Lc and the playback preparation time Dc (FIG. 3) required for playback processing. The reproduction start processing time PS representing the time is calculated.

  Furthermore, the notebook PC 5 determines the data request time PBs when transmitting the playback start time TI of the moving image content to the PDA 2, and based on the playback start processing time PS and the data request time PBs, starts the playback according to the equation (4). Time TI is determined. Then, the notebook PC 5 transmits the reproduction start time TI and the data transmission request DR (FIG. 5) to the PDA 2 at the instant of the data request time PBs (time T5), and requests video content data after the reproduction start time TI. Thereafter, the process proceeds to the next step SP6 (FIG. 8).

  At this time, in step SP13, when the PDA 2 receives the data transmission request DR and the reproduction start time TI at the timing of the time point T6 (FIG. 3), the PDA 2 transmits the data transmission response DA (FIG. 6) and transmits the moving image content. In addition, the video content from the reproduction start time TI (FIG. 3) is sequentially transmitted to the notebook PC 5, and the process proceeds to the next step SP14 to end the process.

  At this time, in step SP6, the notebook PC 5 sequentially receives the video content after the reproduction start time TI together with the data transmission response DA at the timing of the image reception time PBr at the time T7 (time 7 in FIG. 3). Video content after the reproduction start time TI is received and temporarily stored, and reproduction preparation processing is started.

  The notebook PC 5 matches the playback timing with each player terminal by starting playback from the portion corresponding to the playback start time TI of the moving image content at the playback start time TI (time T8) after the playback preparation time Dc has elapsed. Then, the process proceeds to the next step SP7 (FIG. 8), and the process is terminated.

(4) Operation and Effect In the above configuration, the simultaneous playback system 1 matches the playback time stamp TSa as the playback elapsed time information acquired by the notebook PC 5 from the PDA 2 with its own playback time stamp TSc, and communicates with the PDA 2. When the playback start time TI corresponding to the one-way propagation delay time Lc required is determined, moving picture content after the playback start time TI is requested to the PDA 2. When receiving the moving image content after the reproduction start time TI, the notebook PC 5 reproduces the moving image content after the reproduction start time TI at the timing of the reproduction start time TI.

  As a result, the notebook PC 5 plays the video content supplied from the PDA 2 at the moment when the video content being played back by each player terminal reaches the playback start time TI. As a result, the timing coincides with each player terminal. The same moving image content can be played in the state.

  Further, the notebook PC 5 can request the moving image content after the reproduction start time TI from the PDA 2 by determining the reproduction start time TI, and can acquire the moving image content from the PDA 2. Even in the simultaneous playback processing mode of the download method that requests data, it is possible to participate on the way.

  At this time, the notebook PC 5 calculates the reproduction start time TI in a state where the reproduction timer of the notebook PC 5 and the reproduction timer of each player terminal are synchronized, and the PDA 2 receives the moving image content after the reproduction start time TI, and this reproduction start By starting playback at the instant of time TI, the time point of the video content playback start time TI on the notebook PC 5 can be synchronized with the time point of the video content playback start time TI on each player terminal. The simultaneous reproduction process can be executed accurately.

  Further, since the notebook PC 5 is configured to determine the playback start time TI corresponding to the one-way propagation delay time Lc of the data communication, it can receive the video content and start playback before the playback start time TI. The moving image content after the reproduction start time TI can be reproduced at the timing of the start time TI.

  Furthermore, since the notebook PC 5 determines the playback start time TI by adding only the playback preparation time Dc in addition to the one-way propagation delay time Lc described above, the video content is surely acquired by the playback start time TI, In addition, since the reproduction process can be started after the reproduction preparation of the moving image content is completed, a wasteful waiting time can be eliminated and the simultaneous reproduction process can be started quickly.

  Further, since the notebook PC 5 receives the moving image content after the reproduction start time TI and starts reproduction at the timing of the reproduction start time TI, the portion of the moving image content not subjected to the reproduction process is not acquired wastefully and efficiently. Participate in the simultaneous playback process. Similarly, the PDA 2 does not need to transmit unnecessary video content to the notebook PC 5, so that simultaneous playback processing can be executed efficiently.

  The notebook PC 5 can determine the playback start time TI for starting playback using the one-way propagation delay time Lc used to determine the playback time stamp TSa, so that the playback start time TI is determined. There is no need to acquire special information from the PDA 2, and the time until the playback start time TI is determined is shortened and the simultaneous playback processing is started in a short time as much as possible so that the video content common to the player terminals can be quickly transmitted to the user. Can be provided.

  According to the above configuration, in the simultaneous reproduction system 1, the notebook PC 5 matches the reproduction time stamp TSa of the PDA 2 with the reproduction time stamp TSc of the notebook PC 5 itself, and corresponds to the one-way propagation delay time Lc required for data communication with the PDA 2. The playback start time TI is determined, and at the moment when the video content being simultaneously played by each player terminal reaches the playback start time TI, the video content starting from the playback start time TI is started to be played back, thereby participating later. The notebook PC 5 can simultaneously reproduce the moving image content common with each player terminal.

(5) Other Embodiments In the above-described embodiment, the notebook PC 5 sets the playback start processing time PS, which is the time for actually starting playback after transmitting the data transmission request DR to the PDA 2. Although the case where the calculation is performed by the equation (3) has been described, the present invention is not limited to this, and the reproduction start processing time PS is set to a predetermined time as shown in FIG. 9, for example. Anyway. In this case, the notebook PC 5 determines the reproduction start processing time PS so as to be longer than the time obtained by adding the reproduction preparation time Dc and the round trip one-way propagation delay time Lc. As a result, the notebook PC 5 does not need to accurately calculate the reproduction start processing time PS, so that the processing time required for the calculation can be shortened.

  Similarly, as shown in FIG. 10, the notebook PC 5 uses the one-way propagation delay time Lc, the reproduction preparation time Dc, and the buffer time Bc for buffering the received video content as the reproduction start processing time PS. You may make it calculate with following Formula.

  PS = 2 × Lc + Bc + Dc (5)

  As a result, the notebook PC 5 can perform playback after buffering the received video content in a buffer memory (not shown) in addition to the above-described minimum time required for the start of playback. Thus, even when the reception of the moving image content is temporarily interrupted, the moving image content can be read from the buffer memory and played back, and stable playback processing can be performed.

  In the above-described embodiment, the notebook PC 5 uses the playback timer as the playback time, and the playback process is started from the playback start time TI of the moving image content with reference to the playback timer. However, the present invention is not limited to this. For example, when playing back music data at a fixed rate, a playback data offset counter is used instead of a playback timer, and the data offset when the playback processing is started is zero. You may make it count as a value. In this case, after calculating the relationship between the data amount and the reproduction time by the time information management unit 31, the notebook PC 5 determines a reproduction start data offset value instead of the reproduction start time TI, and determines from the reproduction start data offset value. Request PDA2 for data transmission.

  Further, in the above-described embodiment, the case where the notebook PC 5 uses the TimeSeekRange.dlna.org HTTP header defined by DLNA as the data transmission request DR has been described, but the present invention is not limited to this, For example, as shown in FIG. 11, a Range HTTP header ER defined by HTTP may be used. FIG. 11 shows a request message for requesting the PDA 2 for moving image content from the 20,000,000th byte.

  Further, in the above-described embodiment, the PDA 2 has described the case where the TimeSeekRange.dlna.org HTTP header defined by DLNA is used as the data transmission response DA. However, the present invention is not limited to this, for example, As shown in FIG. 12, a Content-Range HTTP header EA defined by HTTP may be used. FIG. 12 shows a response message indicating that moving image content from the 20,000,000th byte to the 29,999,999th byte is transmitted to the notebook PC 5.

  Furthermore, in the above-described embodiment, the notebook PC 5 uses the TimeSeekRange.dlna.org HTTP header as the data transmission response DA and transmits it with the moving image content. However, the present invention is not limited to this. The data transmission response DA and the moving image content may be separately transmitted by different methods, and the moving image content may be included in the data transmission response DA.

  Further, in the above-described embodiment, the notebook PC 5 transmits the midway participation request JR to the PDA 2 that is the controller terminal, and the PDA 2 responding thereto transmits the midway participation preparation request OR. However, the present invention is not limited to this, and the intermediate participation request JR may be transmitted to each player terminal so that one terminal responds and transmits the intermediate participation preparation request OR. At this time, regardless of which terminal responds, each player terminal synchronizes its clock with the master terminal, so that the notebook PC 5 can correct the clock, and the effect does not change.

  Furthermore, in the above-described embodiment, the notebook PC 5 performs clock correction to match the clock with each player terminal, and further, the playback timer matches with each player terminal based on the playback time stamp TSa. As described above, the present invention is not limited to this, and only one of the clock and the reproduction timer may be matched.

  Furthermore, in the above-described embodiment, the case where the notebook PC 5 is represented as the count value of the playback timer indicating the elapsed time from the start of playback as the playback start time TI has been described, but the present invention is not limited thereto, and the notebook PC 5 You may make it designate the time based on the reference | standard clock which PC5 has. In this case, the notebook PC 5 can execute participation in the simultaneous reproduction process by synchronizing each player terminal with the clock of the reference clock in advance.

  Furthermore, in the above-described embodiment, the case where the PDA 2 transmits the stay time Sa together with the reproduction time stamp TSa has been described, but the present invention is not limited to this, and the reception time TAr and the reproduction time together with the reproduction time stamp TSa. The time TAs may be transmitted.

  Further, in the above-described embodiment, the PDA 2 has described the case where the reproduction time stamp TSa and the reproduction processing time Sa are transmitted to the notebook PC 5 in response to the reproduction time stamp request PR. However, the present invention is not limited to this. Instead, the reproduction time stamp TSa and the reproduction processing time Sa may be transmitted together with the reproduction information response which is a message to transmit the reproduction time stamp TSa and the reproduction processing time Sa.

  Furthermore, in the above-described embodiment, the case where the PDA 2 that is the controller terminal is the sender terminal has been described. However, the present invention is not limited to this, and any player terminal may be the controller terminal. The digital camera 4 may be a sender terminal.

  Furthermore, in the above-described embodiment, the case where each player terminal constructs the ad hoc network 7 wirelessly has been described. However, the present invention is not limited to this, and either a wired or wireless system may be used. For example, a network is constructed in a community where each terminal simultaneously plays the same video content at a location separated by a network such as the Internet, and a conversation is performed using another tool such as a mobile phone or chat. May be.

  Furthermore, in the above-described embodiment, the time information management unit 31 as the acquisition unit, the wireless communication interface 16 as the transmission unit and the reception unit, the time information management unit 31 and the calculation unit 32 as the reproduction start time determination unit, In the above description, the decoder 33 serving as the playback unit and the notebook PC 5 serving as the information processing apparatus are configured. However, the present invention is not limited to this, and the acquisition unit configured in other various configurations, the playback start time, and the like. The information processing apparatus may be configured by the determination unit, the reproduction unit, the transmission unit, and the reception unit.

  The simultaneous playback system, information processing apparatus, midway participation method, and midway participation program of the present invention participate, for example, in the middle of communication by simultaneous playback via wired or wireless electronic devices such as an ad hoc network or the Internet. Can be applied to.

It is a basic diagram which shows the whole structure of a simultaneous reproduction | regeneration system. It is an approximate line figure used for explanation of midway participation request transmission. It is a timing chart used for description of midway participation processing. It is a basic diagram with which it uses for description of calculation of the reproduction start time in this Embodiment. It is a basic diagram which shows the data transmission request in this Embodiment. It is a basic diagram which shows the data transmission response in this Embodiment. It is a rough-line block diagram which shows the circuit structure of each terminal. It is a flowchart with which it uses for description of a midway participation process procedure. It is a basic diagram with which it uses for description of calculation (1) of reproduction start time in other embodiments. It is a basic diagram with which it uses for description of calculation (2) of reproduction | regeneration start time in other embodiment. It is a basic diagram which shows the data transmission request in other embodiment. It is a basic diagram which shows the data transmission response in other embodiment. It is a basic diagram with which it uses for description of the midway participation by the conventional multicast streaming. It is a basic diagram with which it uses for description of the midway participation by the conventional download type streaming.

Explanation of symbols

1 ... Data sharing simultaneous playback system, 2 ... PDA, 3 ... Mobile phone, 4 ... Digital camera, 5 ... Notebook PC, 7 ... Simultaneous playback system, 21 ... Wireless communication interface, 22 ... Network transmission / reception unit 23 …… Control unit 26 …… Operation unit 27 …… Speaker unit 28 …… Display unit 31 …… Time information management unit 32 …… Calculation unit 33 …… Decoder 34… RAM, 35 ROM.

Claims (19)

A sender terminal and one or more player terminals are connected to a network, and the sender terminal transmits content data in response to a request from each player terminal, and each player terminal simultaneously processes the content data. At the same time, a simultaneous playback system for allowing other player terminals to participate in the simultaneous playback process halfway,
The other player terminal obtains reproduction elapsed time information indicating an elapsed time since the start of reproduction of the content data from each player terminal or the sender terminal, and according to a delay time required for data communication with the sender terminal. Determining the playback start time of the content data based on the elapsed time information, requesting the content data after the playback start time to the sender terminal,
The sender terminal transmits content data after the reproduction start time to the other player terminals in response to a request from the midway participating terminal,
The simultaneous reproduction system, wherein the other player terminal receives the content data after the reproduction start time and reproduces the content data after the reproduction start time at the timing of the reproduction start time. A sender terminal and one or more player terminals are connected to a network, and the sender terminal transmits content data in response to a request from each player terminal, and each player terminal simultaneously processes the content data. An information processing apparatus that participates in the simultaneous reproduction process on the way,
Acquisition means for acquiring reproduction elapsed time information indicating an elapsed time since the start of reproduction of the content data from each player terminal or the sender terminal;
Reproduction start time determining means for determining a reproduction start time of the content data based on the elapsed time information according to a delay time required for data communication with the sender terminal;
Transmitting means for transmitting a request signal for the content data after the reproduction start time to the sender terminal;
Receiving means for receiving the content data after the reproduction start time supplied from the sender terminal;
An information processing apparatus comprising: reproducing means for reproducing the content data after the reproduction start time at the timing of the reproduction start time. The transmission means is
By requesting the content data after the playback start time to the sender terminal by sending a data transmission request,
The reproduction start time determining means is
The information processing apparatus according to claim 2, wherein the reproduction start time is determined by adding a predetermined time including the delay time to a transmission time of the data transmission request. The reproduction start time determining means is
The information processing apparatus according to claim 3, wherein the reproduction start time is determined by adding only the delay time and the reproduction preparation time required for preparation for reproduction start to the transmission time of the data transmission request. The reproduction start time determining means is
The playback start time is set by adding the delay time, the playback preparation time required for preparation for starting playback, and the temporary storage time for temporarily storing the content data in the buffer memory to the transmission time of the data transmission request. The information processing apparatus according to claim 3, wherein the information processing apparatus is determined. The acquisition means is
3. The elapsed playback time information acquired from each of the player terminals or the sender terminal is matched with a playback time representing a playback time when the content data is played back by the playback means. Information processing device. The acquisition means is
The information processing apparatus according to claim 2, wherein the player elapsed time or the sender terminal acquires the playback elapsed time information that represents a moment when playback of the constituent unit of the content data is started. The acquisition means is
The processing time from when the player terminal or the sender terminal acquires the request signal for the playback elapsed time information from the information processing apparatus to when the playback elapsed time information is transmitted is received together with the playback elapsed time information. The information processing apparatus according to claim 2. The reproduction start time determining means is
The information processing apparatus according to claim 6, wherein the reproduction start time is determined by calculation based on the reproduction time. The reproduction start time determining means is
The information processing apparatus according to claim 9, wherein the reproduction start time is expressed as a value of the reproduction time. The transmission means is
The information processing apparatus according to claim 3, wherein the data transmission request configured by a TimeSeekRange.dlna.org.HTTP header defined by DLNA (Digital Living Network Alliance) is transmitted. The receiving means is
The information processing apparatus according to claim 2, wherein the content data to which a TimeSeekRange.dlna.org.HTTP header specified by DLNA (Digital Living Network Alliance) is added is received. The acquisition means is
Acquire the data offset value from the head part in the content data together with the playback elapsed time information,
The reproduction start time determining means is
The information processing apparatus according to claim 2, wherein the reproduction start time is determined by calculation based on the data offset value. The reproduction start time determining means is
The information processing apparatus according to claim 13, wherein the reproduction start time is expressed as the data offset value. The transmission means is
The information processing apparatus according to claim 14, wherein the data transmission request is configured using a Range HTTP header defined by HTTP (Hypertext Transfer Protocol). The receiving means is
The information processing apparatus according to claim 15, wherein the content data to which a Content-Range HTTP header defined by HTTP (Hypertext Transfer Protocol) is added is received. The reproducing means is
The information processing apparatus according to claim 2, wherein the reproduction process is started at a timing before the reproduction preparation time required for preparation for starting reproduction from the reproduction start time. A sender terminal and one or more player terminals are connected to a network, and the sender terminal transmits content data in response to a request from each player terminal, and each player terminal simultaneously processes the content data. When the information processing apparatus joins the above simultaneous playback process halfway,
An acquisition step of acquiring reproduction elapsed time information indicating an elapsed time since the start of reproduction of the content data from each player terminal or the sender terminal;
A reproduction start time determining step for determining a reproduction start time of the content data based on the elapsed time information according to a delay time required for data communication with the sender terminal;
A transmission step of transmitting a request signal for the content data after the reproduction start time to the sender terminal;
A receiving step of receiving the content data after the playback start time supplied from the sender terminal;
A halfway participation method comprising: a reproduction step of reproducing the content data after the reproduction start time at the timing of the reproduction start time. A sender terminal and one or more player terminals are connected to a network, and the sender terminal transmits content data in response to a request from each player terminal, and each player terminal simultaneously processes the content data. When the information processing apparatus participates in the simultaneous reproduction process on the way,
An acquisition step of acquiring reproduction elapsed time information indicating an elapsed time since the start of reproduction of the content data from each player terminal or the sender terminal;
A reproduction start time determining step for determining a reproduction start time of the content data based on the elapsed time information according to a delay time required for data communication with the sender terminal;
A transmission step of transmitting a request signal for the content data after the reproduction start time to the sender terminal;
A receiving step of receiving the content data after the playback start time supplied from the sender terminal;
A mid-participation program, comprising: executing a reproduction step of reproducing the content data after the reproduction start time at the timing of the reproduction start time.

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