JP2012014038A - Content reproduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a content reproduction device that hardly causes sound interruption during content reproduction.SOLUTION: A content reception section 22 receives a content 5 consisting of a plurality of packets 50. A buffer 231 stores the packets 50 included in the content received by the content reception section 22 in order. An initial packet number determination section 241 determines the number of initial packets indicative of the number of packets 50 which should be stored in the buffer 231 before the content 5 beings to be reproduced according to a reproduction time of the content 5 included in some starting packets of the packets 50 stored in the buffer 231. A packet readout section 242 reads the packets 50 out of the buffer 231 after the number of packets 50 stored in the buffer 231 reaches the number of initial packets determined by the initial packet number determination section 241. A reproduction section 25 reproduces the content 5 based upon the packets 50 read out by the packet readout section 242.

Description

  The present invention relates to a content reproduction apparatus, and more particularly to a content reproduction apparatus that reproduces content by a streaming method.

  Japanese Laid-Open Patent Publication No. 11-215182 (Patent Document 1) discloses voice packet transmission / reception that absorbs delay fluctuations and reproduces voice without changing the processing contents of a network relay node, thereby reducing the discard rate of voice packets. An apparatus is disclosed. When the voice packet transmitting / receiving apparatus receives a voice packet at the beginning of a voiced section, the voice packet transmitting / receiving apparatus accumulates the voice packet in a fluctuation absorbing buffer in which a threshold is set. When the voice packet transmitting / receiving apparatus accumulates the voice packet by the initial accumulation amount, it transmits the voice data. The voice packet transmitting / receiving apparatus discards data up to the initial accumulated amount when the accumulated amount of packets exceeds a threshold and a predetermined time elapses. The information storage unit stores the number of data discards and the number of underflow occurrences of the fluctuation absorbing buffer. The voice packet transmitting / receiving apparatus determines the initial accumulation amount of the next sound section based on the number of data discards and the number of underflow occurrences of the fluctuation absorbing buffer.

  In Japanese Patent Laid-Open No. 2006-50488 (Patent Document 2), it is possible to appropriately adjust the initial accumulation amount of the jitter buffer, and to control the fixed delay added to the received packet by the jitter buffer appropriately. There has been disclosed a communication terminal device that can be used. The communication terminal device includes a buffer threshold value setting unit and a buffer control unit. The buffer threshold setting unit calculates the jitter amount in the period from the packet received in the past certain period, and updates the initial accumulation amount of the jitter buffer based on the calculated jitter amount. The buffer control unit changes the packet output speed from the jitter buffer based on the accumulated amount of the jitter buffer.

Japanese Patent Laid-Open No. 11-215182 JP 2006-50488 A JP 2002-271391 A

  However, since all of the above devices are applied to Internet telephones or the like, priority is given to real-time characteristics so that the delay of voice does not become too large. Therefore, when the network traffic increases, sound interruption occurs.

  An object of the present invention is to provide a content reproduction apparatus in which sound interruption is unlikely to occur during content reproduction.

Means and effects for solving the problems

  A content reproduction apparatus according to the present invention includes a content reception unit, a buffer, an initial packet number determination unit, a packet reading unit, and a reproduction unit. The content receiving unit receives content composed of a plurality of packets. The buffer sequentially stores packets included in the content received by the content receiving unit. The initial packet number determining unit determines the number of packets to be stored in the buffer before starting the content playback according to the playback time of the content included in a part of the first packet among the packets stored in the buffer. Determine the number of initial packets to show. The packet reading unit reads packets from the buffer after the number of packets stored in the buffer reaches the initial packet number determined by the initial packet number determining unit. The reproduction unit reproduces the content based on the packet read by the packet reading unit. Here, the content is, for example, music, video, or audio. The playback time is, for example, the remaining playback time required for playback of a portion of one content that has not yet been played, and the total playback time required for playback of all of the content.

  According to the present invention, the initial number of packets is determined according to the reproduction time, and after the number of packets stored in the buffer reaches the determined initial number of packets, the packets are read from the buffer. Therefore, sound interruption is unlikely to occur during content playback.

  Preferably, the playback time is the remaining playback time of the content. The initial packet number determining unit refers to a table including a plurality of remaining playback times and a plurality of initial packet numbers corresponding to the plurality of remaining playback times, and corresponds to the remaining playback time of the content included in a part of the first packet. Select the initial number of packets to perform.

  In this case, the table is referred to, and the initial number of packets corresponding to the remaining playback time of the content is selected. Therefore, the initial number of packets can be easily determined.

  Preferably, the initial packet number determining unit monitors a content identifier included in a part of the packet read by the packet reading unit, and re-determines the initial packet number when the content identifier changes.

  In this case, when the content identifier changes, the initial number of packets is re-determined. Therefore, even if the content changes, it is difficult for sound interruption to occur.

  Preferably, a channel selection unit is further provided. The channel selection unit selects a desired channel from the plurality of channels. The content receiving unit receives the content of the channel selected by the channel selection unit. The initial packet number determination unit monitors the channel selected by the channel selection unit, and re-determines the initial packet number when the channel changes.

  In this case, when the channel changes, the initial number of packets is re-determined. Therefore, even if the channel changes, it is difficult for sound interruption to occur.

It is a block diagram which shows the whole structure of the content reproduction system by embodiment of this invention. It is the schematic which shows the structure of the content by embodiment of this invention. FIG. 3 is a schematic diagram illustrating a configuration of a packet included in the content illustrated in FIG. 2. It is a figure which shows a mode that the receiving interval of a packet fluctuates with progress of time. It is a figure which shows the frequency which the reception interval of each packet arises based on the relationship between the reception interval of a packet and elapsed time shown in FIG. It is a figure which shows time when the probability that a sound interruption will occur is 1% based on the frequency shown in FIG. FIG. 7 is a table created based on the time when the probability shown in FIG. 6 is 1%, and shows the remaining playback time of content and the number of initial packets corresponding to them. It is a flowchart which shows the memory | storage process of the content reproduction apparatus in this Embodiment. It is the schematic which shows a mode that the packet is memorize | stored in the buffer in the memory | storage process shown in FIG. FIG. 9 is a flowchart illustrating a control process of the content reproduction device continued from FIG. 8. It is a flowchart which shows the detail of the initial packet number determination process in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Content playback system configuration]
With reference to FIG. 1, the structure of the content reproduction system according to the present embodiment will be described. The content reproduction system includes content supply apparatuses 1A, 1B, and 1C and a content reproduction apparatus 2. The content reproduction device 2 is connected to the content supply devices 1A, 1B, and 1C via the network 3.

  The content supply devices 1A, 1B, and 1C broadcast content 5. The content 5 is music, video, audio or the like. In the present embodiment, the content 5 is music. FIG. 2 shows the configuration of the content 5. In the present embodiment, one content 5 corresponds to one piece of music. The content 5 is divided into a plurality of packets 50. Each packet includes music data for 0.4 seconds.

  FIG. 3 shows the configuration of each packet 50. Each packet 50 includes a header 51 and a payload 52. The payload 52 includes compressed music data. The header 51 includes information for specifying music data. Specifically, the header 51 includes a packet number, a content identifier, a content playback time, and a total content playback time. The packet number indicates the order in which the payload 52 is reproduced. The content identifier is identification information given to each content. For example, the identifier “100” is assigned to the content A, and the identifier “200” is assigned to the content B. The content playback time is the time that has elapsed since the content 5 started to be played back. The total content playback time is the playback time of the entire content 5. The difference between the total content playback time and the content playback time is the remaining content playback time.

  Referring to FIG. 1 again, the content reproduction apparatus 2 includes a channel selection unit 21, a content reception unit 22, a storage unit 23, a control unit 24, and a reproduction unit 25. Although not shown in the figure, the content playback apparatus 2 also includes a display unit, an operation unit, and the like.

  The channel selection unit 21 selects a desired channel from among a plurality of channels. Channels are assigned to the content supply apparatuses 1A, 1B, and 1C, respectively. In this example, the content reproduction apparatuses 1A, 1B, and 1C correspond to 1 channel, 2 channels, and 3 channels, respectively.

  The content receiver 22 receives the content 5 broadcast from the content supply device corresponding to the selected channel.

  The storage unit 23 is an HDD (Hard Disk Drive), a semiconductor memory, or the like. The storage unit 23 includes a buffer 231 and a table 232. The buffer 231 is a FIFO (First in First out) buffer, a ring buffer, or the like. In this example, the buffer is a FIFO buffer. The buffer 231 stores the packets 50 received by the content receiving unit 22 in order. The table 232 is created in advance and stored in the storage unit 23. Details of the table 232 will be described later.

  The control unit 24 controls the buffer 231. The control unit 24 includes an initial packet number determining unit 241 and a packet reading unit 242. The initial packet number determination unit 241 refers to the table 232 and determines the initial packet number. The initial number of packets is the number of packets 50 to be stored in the buffer 231 before the reproduction of the content 5 is started. The packet reading unit 242 reads the packet 50 from the buffer 231 after the number of the packets 50 stored in the buffer 231 reaches the initial packet number determined by the initial packet number determining unit 241.

  The reproducing unit 25 is an MP3 decoder or the like. The reproducing unit 25 reproduces the content 5 based on the payload 52 of the packet 50 read by the packet reading unit 242.

[How to create a table]
A method of creating the table 232 will be described with reference to FIGS.

  First, a plurality of packets 50 transmitted from the content supply device are received. At this time, the time (reception interval) required from receiving a packet 50 to receiving the next packet 50 is measured. FIG. 4 is a graph in which the elapsed time is plotted on the horizontal axis and the reception interval of the packet 50 is plotted on the vertical axis. As is apparent from FIG. 4, many reception intervals are 0.4 seconds. However, the reception interval may be longer than 0.4 seconds. This is because jitter occurs in the reception interval.

  Next, based on the measurement result of the reception interval shown in FIG. 4, the frequency at which the reception interval of the packet 50 becomes 0.8 seconds or more is calculated. Similarly, the frequency at which the reception interval of the packet 50 is 1.2 seconds or longer, 1.6 seconds or longer, is calculated. FIG. 5 shows the relationship between the reception interval and the frequency.

  As shown in FIG. 5, the reception interval of the packet 50 becomes 0.8 seconds or more at a frequency of once every hour (3600 seconds). That is, if the packet 50 is received for 36 seconds (= 3600 seconds × 0.01), the probability that the reception interval of the packets 50 is 0.8 seconds or more is 1%. In this way, the time when the probability that the reception interval is 0.8 seconds or more is 1% is determined. Similarly, the time when the probability that the reception interval is 1.2 seconds or longer, 1.6 seconds or longer,... FIG. 6 shows the relationship between the reception interval, the frequency, and the time when the probability is 1%.

  From the above, when the packet 50 is received only for 36 seconds, the reception interval does not exceed 0.8 seconds with a probability of 99%. That is, when the packet reading unit 232 of the content reproduction apparatus 2 starts reading the packet 50 after two packets (0.8 seconds) are stored in the buffer 231, the packet 50 stored in the buffer 231 has a probability of 99%. Does not run out. Therefore, when the remaining content playback time is 36 seconds or less, the initial number of packets is set to 2. Similarly, the initial number of packets is set. FIG. 7 shows the table 232. The table 232 includes a plurality of remaining content playback times and a plurality of initial packet numbers corresponding thereto. In this way, the table 232 is created in advance.

  In this embodiment, the time at which the probability that the reception interval of the packet 50 is 0.8 seconds or more is 1% is determined, but a desired probability may be set. In this case, if the probability is set high, the packet 50 is likely to be depleted while the packet reading unit 242 is reading the packet 50 stored in the buffer 231. However, the waiting time required for the packet reading unit 242 to start reading the packet 50 is shortened. On the other hand, when the probability is set to be low, the packet 50 is unlikely to be depleted while the packet reading unit 242 is reading the packet 50 stored in the buffer 231. However, the waiting time required for the packet reading unit 242 to start reading the packet 50 becomes longer.

  In this embodiment, the table 232 is created in advance, but the present invention is not limited to this. For example, the content reproduction device 2 may automatically create the table 232. In this case, the content playback apparatus 2 may create the table 232 when the content playback apparatus 2 is turned on.

[Operation of content playback device]
The operation of the content reproduction apparatus 2 will be described with reference to FIGS. The operation of the content reproduction apparatus 2 includes a storage process, a control process, and a reproduction process.

[Remember process]
First, the storage process will be described with reference to FIG.

  The channel selection unit 21 selects a desired channel from among a plurality of channels (step S1). Specifically, when the user operates the operation unit, a desired channel is selected. Hereinafter, a case where one channel is selected will be described as an example. The storage unit 23 stores the selected channel (one channel).

  The content receiver 22 receives the content 5 from the content supply device 1A corresponding to one channel (step S2).

  The buffer 231 sequentially stores the packets 50 included in the content 5 received by the content receiving unit 22 (step S3). As shown in FIG. 9, the first packet among the packets 50 stored in the buffer 231 is defined as a head packet 50A.

  In the present embodiment, a desired channel is selected, but the present invention is not limited to this. For example, when the content playback apparatus 2 is turned on, the channel selection unit 21 may select the channel that was selected before the power is turned off.

  The channel selector 21 can select a desired channel at any time. Therefore, the user can switch a desired channel. When the channel is switched, the content receiving unit 22 receives the content 5 from the content supply device corresponding to the switched channel.

[Control processing]
Next, the control process will be described with reference to FIG.

  When the packet 50 is stored in the buffer 231, the state of the content reproduction device 2 is set to “buffering” (step S11). “Buffering in progress” means that the packet 50 is accumulated in the buffer 231 and the accumulated packet 50 is not read out.

  The packet reading unit 242 reads the head packet 50A (step S12). When the head packet 50A is read, the packet 50 stored next to the read head packet 50A is the head packet 50A.

  After the process of step S12, the initial packet number determination unit 241 determines the initial packet number (step S13). FIG. 11 shows details of the initial packet number determination process.

  The initial packet number determination unit 241 calculates the remaining content reproduction time from the header 51 of the read first packet 50A (step S131). Specifically, the initial packet number determination unit 241 calculates the remaining content playback time by subtracting the content playback time from the total content playback time included in the header 51.

  The initial packet number determination unit 241 refers to the table 232 shown in FIG. 7 and selects the initial packet number corresponding to the content remaining reproduction time calculated by the process of step S131 (step S132). For example, when the calculated remaining content reproduction time is 120 seconds, the initial packet number determination unit 241 refers to the table 232 and selects three packets as the initial packet number.

  As a result, the initial packet number determination unit 241 can determine the initial packet number simply by calculating the remaining content playback time by referring to the table 232. Therefore, the initial packet number determining unit 241 can easily determine the initial packet number.

  The calculated initial number of packets is stored in the storage unit 23 (step S14). Thereafter, the number of packets 50 stored in the buffer 231 is confirmed (step S15).

  It is determined whether or not the number obtained by adding 1 to the number of packets 50 confirmed in step S15 has reached the initial number of packets stored in step S14 (step S16). The reason why 1 is added to the number of confirmed packets 50 is that one packet has already been read out by the process of step S12.

  When the number obtained by adding 1 to the number of confirmed packets 50 has not reached the stored initial packet number (NO in step S16), the process returns to step S15 again.

  When the number of confirmed packets 50 plus 1 reaches the stored initial packet number (YES in step S16), the state of the content playback device 2 is set to “playing” (step S17). . “Now playing” means that the packet 50 is stored in the buffer 231 and the stored packet 50 is being read. The playback unit 25 plays back the packet 50 read from the buffer 231. Details of the reproducing unit 25 will be described later.

  Thereafter, it is determined whether or not the channel has been switched (step S18). Specifically, the initial packet number determination unit 241 monitors the channel stored in the storage unit 23 and determines whether the channel has changed.

  If the channel has changed (YES in step S18), all the packets 50 stored in the buffer 231 are discarded (step S22), and the state of the content reproduction device 2 is set to “buffering” (step S22). Step S23). Thereafter, the first packet 50A is read (step S12), and the initial packet number determination unit 241 re-determines the initial packet number (step S13).

  If the channel has not changed (NO in step S18), the packet reading unit 242 outputs the payload 52 of the read packet 50 to the reproduction unit 25 (step S19). At this time, the content identifier of the header 51 of the read packet 50 is stored in the storage unit 23.

  The current first packet 50A is read (step S20). This process is the same as the process of step S12.

  It is determined whether or not the content has changed (step S21). Specifically, the initial packet number determination unit 241 monitors the content identifier stored in the storage unit 23. The initial packet number determination unit 241 determines whether or not the monitored content identifier is the same as the content identifier read in step S19.

  If it is determined that the content has not changed (NO in step S21), the process returns to step S18.

  If it is determined that the content has changed (YES in step S21), the state of the content reproduction device 2 is set to “buffering” (step S24). Thereafter, the initial packet number determination unit 241 determines the initial packet number again (step S13).

[Playback processing]
Next, the reproduction process will be described.

  When the payload 52 is output by the process of step S <b> 19, the reproducing unit 25 reproduces the content 5 based on the output payload 52. Specifically, the reproducing unit 25 reproduces the content 5 by decoding the payload 52.

[Effects of the present embodiment]
In the content reproduction apparatus 2 according to the present embodiment, the initial packet number determination unit 241 determines the initial packet number based on the content remaining time and the table 232. The packet reading unit 242 reads the packet 50 stored in the buffer 231 and outputs the payload 52 to the reproducing unit 25 after the number of packets 50 stored in the buffer 231 reaches the initial number of packets. Therefore, sound interruption is unlikely to occur during the reproduction of the content 5.

  Further, when the channel is switched (YES in step S18), the initial packet number determination unit 241 re-determines the initial packet number (step S13). The packet reading unit 242 reads the packet 50 stored in the buffer 231 after the number of packets 50 stored in the buffer 231 has reached the re-determined initial packet number, and outputs the payload 52 to the reproducing unit 25. ing. Therefore, even if the channel is switched, it is difficult for sound interruption to occur.

  In addition, when the content 5 has changed (YES in step S21), the initial packet number determining unit 241 re-determines the initial packet number (step S13). The packet reading unit 242 reads the packet 50 stored in the buffer 231 after the number of packets 50 stored in the buffer 231 has reached the re-determined initial packet number, and outputs the payload 52 to the reproducing unit 25. ing. Therefore, even if the content (song) changes, it is difficult for sound interruption.

[Other embodiments]
In the present embodiment, the initial packet number determination unit 241 calculates the initial packet number based on the remaining content playback time, but the present invention is not limited to this. If the content remaining reproduction time cannot be calculated, the initial packet number determination unit 241 may calculate the initial packet number assuming that the content remaining reproduction time is 5 minutes. In addition, the initial packet number determination unit 241 may regard the total content playback time as the remaining content playback time, and may select the initial packet number corresponding thereto.

  In the present embodiment, the total content playback time is acquired from the header 51 of the packet 50, but is requested from the content playback device 2 to each content supply device via the network 3, and each content is responded to this request. You may acquire from a supply apparatus.

  In the present embodiment, the content playback time is included in the header 51 of the packet 50, but may be included in another part (for example, a footer).

  In this embodiment, a channel is assigned to each content supply device, but a plurality of channels may be assigned to one content supply device.

  While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

2 Content playback device 5 Content 21 Channel selection unit 22 Content reception unit 23 Storage unit 25 Playback unit 50 Packet 51 Header 52 Payload 50A First packet 231 Buffer 232 Table 241 Initial packet number determination unit 242 Packet reading unit

Claims (4)

A content receiver that receives content composed of a plurality of packets;
A buffer for sequentially storing packets included in the content received by the content receiving unit;
An initial packet indicating the number of packets to be stored in the buffer before starting the playback of the content according to the playback time of the content included in a part of the first packet among the packets stored in the buffer An initial packet number determination unit for determining the number;
A packet reading unit that reads packets from the buffer after the number of packets stored in the buffer reaches the initial packet number determined by the initial packet number determination unit;
A content reproduction apparatus comprising: a reproduction unit that reproduces the content based on the packet read by the packet reading unit. The content playback device according to claim 1,
The playback time is the remaining playback time of the content,
The initial packet number determination unit refers to a table including a plurality of remaining playback times and a plurality of initial packet numbers corresponding to the plurality of remaining playback times, and the remaining content of the content included in a part of the first packet A content playback apparatus that selects an initial number of packets corresponding to a playback time. The content playback device according to claim 1 or 2,
The initial packet number determining unit monitors a content identifier included in a part of the packet read by the packet reading unit, and re-determines the initial packet number when the content identifier changes. . The content playback apparatus according to any one of claims 1 to 3, further comprising:
A channel selection unit for selecting a desired channel from a plurality of channels is provided.
The content receiver receives the content of the channel selected by the channel selector;
The content reproduction apparatus, wherein the initial packet number determination unit monitors the channel selected by the channel selection unit and re-determines the initial packet number when the channel changes.

Images