JP4600698B2 - Stream reproducing apparatus and program thereof - Google Patents

Description

  The present invention relates to a stream playback device that plays back a data stream that is streamed via a network.

  Recently, as represented by terrestrial digital broadcasting, a system for receiving and reproducing an encoded data stream stream-distributed from a broadcasting facility by a receiving device in a general household has been provided. Terrestrial digital broadcasting realizes wireless streaming distribution.

  On the other hand, a real-time streaming distribution technique via a network such as the Internet is also disclosed. In streaming delivery via a network, a so-called delay fluctuation (jitter) occurs in which the arrival rate of packets constituting a data stream becomes unstable. If the delay fluctuation occurs and the arrival of the packet is delayed while the receiving apparatus is reproducing the data stream, the data stream buffered in the receiving apparatus may be exhausted. At this time, the content being reproduced is interrupted.

  In order to prevent such interruption of the content being reproduced, there are methods of using a sample rate converter or changing a frequency division / multiplication ratio of a PLL (phase synchronization circuit). However, since these methods change the playback rate of the content, the playback sound changes audibly. In particular, when a plurality of different songs are continuously streamed, it is not preferable that the playback sound changes.

  In addition, by setting the buffer reference value to be relatively large, the possibility that the data stream in the buffer is exhausted can be reduced. However, if the buffer reference value is set to a relatively large value, there arises a new problem that it takes time to start reproduction of the first content of the data stream.

JP-A-10-285170 JP-A-2005-167414

  One object of the present invention is to provide a stream playback device capable of quickly starting playback of the first content when a data stream in which a plurality of contents are connected is stream-played.

  Another object of the present invention is to provide a stream reproducing apparatus that prevents a reproduction from being interrupted in the middle of each content when a data stream in which a plurality of contents are connected is reproduced.

  A stream reproducing apparatus according to a preferred embodiment of the present invention includes a receiving unit that receives a data stream in which a plurality of contents are concatenated, a classifying unit that classifies the received data stream for each content, and each of the classified Playback means for sequentially playing back content, buffer means for receiving and temporarily holding the received data stream, and outputting to the playback means when the data amount of the data stream exceeds a reference value; and For content other than the first content in the data stream, the reference value is set to a first reference value, and for the first content in the data stream, the reference value is set to a second reference value that is smaller than the first reference value. Reference value setting means for setting.

  For the first content, the reference value of the buffer means is set to a second reference value that is smaller than the first reference value. Accordingly, it is possible to shorten the time until the first content of the data stream is started to be played, and to start playback quickly. On the other hand, since the reference value of the buffer means is set to the first reference value for the content other than the first content, the possibility of interruption during the reproduction of the content other than the first content is lower than in the case of the first content. can do.

  Preferably, the apparatus further comprises detection means for detecting a data amount of the data stream held in the buffer means, and when the first content is being reproduced, the data stream held in the buffer means When it is detected that the data amount is 0, the reference value setting means sets the reference value to the first reference value.

  The reason why the amount of data held in the buffer means at the time of reproduction of the first content is zero is that the amount of data supplied to the buffer means is smaller than the amount of data output from the buffer means to the reproduction means. For this reason, if the first content is continuously reproduced while the reference value of the buffer means remains the second reference value, the data amount of the buffer means may be exhausted again. However, in this example, the reference value of the buffer means is set to the first reference value when the amount of data held in the buffer means becomes zero even before moving to the second content. Can solve this problem.

  According to another preferred embodiment of the present invention, there is provided a stream reproducing apparatus that receives a data stream in which a plurality of contents are concatenated, a classifying unit that classifies the received data stream for each content, and the classifying unit. Playback means for sequentially playing back each content, buffer means for receiving and temporarily holding the received data stream, and outputting to the playback means when the data amount of the data stream exceeds a reference value; Detecting means for detecting the data amount of the data stream held in the buffer means, and initially setting the reference value to a second reference value smaller than the first reference value and holding the data in the buffer means The reference value is set to the first reference value when it is detected that the data amount of the data stream is zero. And a value setting means.

  Initially, the reference value of the buffer means is set to the second reference value. Accordingly, it is possible to shorten the time until the first content of the data stream is started to be played, and to start playback quickly. Here, the amount of data held in the buffer means becomes zero because the amount of data supplied to the buffer means is smaller than the amount of data output from the buffer means to the reproducing means. For this reason, if the content continues to be played with the reference value of the buffer means kept at the second reference value, the data amount of the buffer means may be exhausted again. However, in this example, this problem can be solved by setting the reference value of the buffer means to the first reference value when the amount of data held in the buffer means becomes zero.

  Preferably, detecting means for detecting the data amount of the data stream held in the buffer means, and adjusting means for adjusting the interval at which the reproducing means reproduces each content based on the detection result of the detecting means. Each content in the data stream includes a plurality of frames, and the buffer means includes a plurality of buffers for receiving or outputting the plurality of frames in accordance with designation of the adjusting means, and the sorting means Determines whether the receiving means has received the first frame of each content, and the adjustment means outputs a frame of the plurality of buffers when the receiving means has received the first frame of the content. First determination means for determining whether or not the data amount of the buffer in the buffer is less than a predetermined lower limit; When the amount of data in the buffer that is outputting is less than the lower limit value, another buffer different from the buffer that is outputting the data is designated as a receiving buffer that receives the first frame of the content and frames received thereafter. Receiving designation means, and when the data amount of the buffer receiving the frame among the plurality of buffers exceeds the reference value or the lower limit value, the buffer receiving the data is changed to the reproduction means. Output designating means for designating the output buffer to sequentially output.

  When the data amount of the buffer that is outputting the frame is less than the lower limit value, the data amount received by the stream reproduction device is smaller than the data amount to be reproduced. Therefore, the stream playback device inputs the first frame of the next content and the subsequent frames to another buffer different from the buffer that is outputting the current frame. Then, no frame is output until the data amount of the buffer that receives and holds the frames after the first frame of the next content exceeds the reference value or the lower limit value. With the above configuration, the adjustment time is inserted after the content reproduction is completed until the next content is reproduced. By inserting the adjustment time, it is possible to prevent content from being interrupted during reproduction due to data depletion.

  Preferably, when the receiving unit receives the first frame of the content, the adjusting unit determines whether the data amount of the buffer that is outputting the frame exceeds a predetermined upper limit value that is larger than the lower limit value. Second receiving means for determining, wherein when the amount of data exceeds the upper limit value, the receiving specifying means specifies another buffer different from the buffer that is outputting the frame as the receiving buffer. The adjusting means further includes an erasing means for erasing a frame held in another buffer different from the buffer designated as the output buffer when the output instruction means designates the output buffer.

  When the data amount of the buffer that is outputting the frame exceeds the upper limit value, the data amount received by the stream reproduction device is larger than the data amount to be reproduced. Since the next content is reproduced after deleting the last data of the currently reproduced content by the erasing unit, the buffer unit can be prevented from overflowing. Further, since the end portion of the content is often silent or no video, even if it is deleted, the user feels uncomfortable.

  According to another preferred embodiment of the present invention, there is provided a stream reproducing apparatus, receiving means for receiving a data stream in which a plurality of contents including a plurality of frames are concatenated, and classifying the received data stream for each of the contents, Sorting means for determining whether the receiving means has received the first frame of each content, playback means for sequentially playing back each sorted content, and receiving and temporarily holding the received data stream. A plurality of buffers to be output to the reproducing means when the data amount of the data stream exceeds a reference value; a detecting means for detecting the data amount of the data stream held in the buffer; and the receiving means Is receiving a frame of the plurality of buffers when receiving the first frame of the content. First judging means for judging whether or not the data amount of the buffer is less than a lower limit value; and when the data amount of the buffer that is outputting the frame is judged to be less than the lower limit value, the plurality of buffers A reference value setting means for setting the reference value by adding a predetermined increment to the data amount of the buffer receiving the frame, and determining that the data amount of the buffer outputting the frame is less than the lower limit value A receiving designation means for designating another buffer different from the buffer that is outputting the data as a receiving buffer for receiving the first frame of the content and a frame received after that; a frame of the plurality of buffers; When the amount of data in the buffer that is receiving the data exceeds the reference value, the buffer that is receiving the data And an output specifying means for specifying the output buffer sequentially outputs the.

  In this case, each time a new reception buffer is specified, the reference value is increased according to the amount of data held by the previous reception buffer. That is, when the amount of data in the buffer is large, the amount of increase in the reference value is high, and when the amount of data in the buffer is small, the amount of increase in the reference value is low. If the amount of data in the buffer is large, even if the reference value is increased, the amount of data in the buffer is also large. Therefore, the time when there is no data in the output buffer before the amount of data in the new receiving buffer reaches the reference value can be shortened. Therefore, when a new receiving buffer is designated as the output buffer and content is reproduced, it is possible to prevent a time during which the content is not reproduced from being inserted for a long time.

  In a preferred embodiment, when the receiving means receives the first frame of the content, it is determined whether or not the data amount of the buffer that is outputting the frame exceeds an upper limit value that is larger than the lower limit value. And when the data amount is determined to exceed the upper limit value, the reference value setting unit is configured to increase the data amount of the buffer that is receiving frames among the plurality of buffers by a predetermined increase amount. Is added to set the reference value, and when it is determined that the amount of data exceeds the upper limit value, the reception specifying means receives another buffer different from the buffer that is outputting the frame. Specify in the buffer.

  In a preferred embodiment, the reference value setting means determines whether the current reference value is larger than the lower limit value, and if the current reference value is larger than the lower limit value, When the reference value is maintained and the current reference value is equal to or lower than the lower limit value, the reference value is obtained by adding a predetermined increase amount to the data amount of the buffer receiving the frame among the plurality of buffers. Set.

  In this case, when the reference value becomes larger than the lower limit value, the increase of the reference value can be stopped, and the reference value can be prevented from increasing forever.

  For the first content, the reference value of the buffer means is set to a second reference value that is smaller than the first reference value. Accordingly, it is possible to shorten the time until the first content of the data stream is started to be played, and to start playback quickly. On the other hand, since the reference value of the buffer means is set to the first reference value for the content other than the first content, the possibility of interruption during the reproduction of the content other than the first content is lower than in the case of the first content. can do.

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.

[First Embodiment]
[overall structure]
Referring to FIG. 1, the streaming system according to the present embodiment includes a stream playback device 1 and a streaming server 2. For example, the streaming server 2 is installed in a broadcasting facility and is managed by a company that operates a music distribution service. On the other hand, the stream reproduction apparatus 1 is installed in the home of a user who has contracted to use a music distribution service, for example.

  The streaming server 2 includes a hard disk drive (HDD) 21, a data stream generation unit 22, and a distribution unit 23.

  The HDD 21 stores a plurality of content files. In the present embodiment, the content file is described as a music file. The content may be a song or a video. It may also include video and audio.

  Each music file stored in the HDD 21 is an encoded file such as MPEG2, MPEG4, or MP3. Hereinafter, the encoded music file is referred to as an encoded music file. The encoded music file is composed of a plurality of frames. Each frame in the encoded music file includes time management information (hereinafter referred to as a time stamp) indicating when the frame should be reproduced. For example, the time stamp indicates the playback time of the frame in the encoded music file. When receiving the encoded music file from the streaming server 2, the stream playback device 1 sequentially decodes and outputs the frames based on the time stamps of the frames in the encoded music file. That is, the stream reproduction device 1 sequentially reproduces the frames based on the time stamp.

  The data stream generation unit 22 in the streaming server 2 extracts a plurality of encoded music files from the HDD 21 and creates a data stream by concatenating the extracted encoded music files. FIG. 2 shows an example of the data stream generated by the data stream generation unit 22. As shown in FIG. 2, the data stream DS is configured by connecting a plurality of encoded music files MF. Each encoded music file MF includes a plurality of frames FR. Hereinafter, among the plurality of frames FR, the leading frame FR is referred to as a leading frame.

  The distribution unit 23 distributes the generated data stream in a streaming manner. As described above, when the streaming server 2 is installed in a broadcast station, the broadcast station accepts a song request from the user of the stream playback device 1. Then, the requested plurality of music files are extracted from the HDD 21, and a data stream is created by the data stream generation unit 22. The created data stream is streamed to the stream playback device 1 via the network 3.

  The stream playback device 1 is connected to the streaming server 2 via the network 3. As described above, the stream reproduction device 1 is installed in a user's home, for example. The stream playback device 1 receives a data stream that is streamed from the streaming server 2 and plays back the stream. Specifically, the stream playback device 1 temporarily holds the distributed data stream in a buffer (buffering), reads the held data stream, and continuously plays the encoded music files constituting the data stream. To decode and output.

  Further, the stream playback device 1 adjusts the playback interval (song interval) of the music file to be played back so that the buffered data stream does not run out or the buffer does not overflow (overflow).

  With reference to FIG. 3, the stream reproduction device 1 includes a reception unit 10, a reception buffer 11, a sorting unit 12, a detection unit 13, an adjustment unit 17, and a reproduction unit 18.

  The receiving unit 10 receives a data stream that is stream-distributed from the streaming server 2. More specifically, a plurality of frames constituting the data stream are sequentially received. The reception buffer 11 receives the received data stream from the reception unit 10 and temporarily holds it. That is, the reception buffer 11 buffers the received data stream. Then, the reception buffer 11 sequentially outputs a plurality of frames in the held data stream to the reproduction unit 18 via the sorting unit 12.

  The playback unit 18 includes a decoder 14, a decode buffer 15, and a data editing unit 16. The decoder 14 includes a first decoder 141 and a second decoder 142. The first decoder 141 and the second decoder 142 decode the encoded music file.

  The sorting unit 12 sorts a plurality of frames continuously output from the reception buffer 11 for each encoded music file. Specifically, the sorting unit 12 reads a time stamp in the frame. Then, the first frame of the encoded music file is specified based on the read time stamp. In short, the sorting unit 12 sorts the content by specifying the first frame of each content among the frames output continuously from the reception buffer 11.

  Further, when the sorting unit 12 specifies the first frame of the encoded music file, the sorting unit 12 changes the output destination decoder from the first frame. For example, when the sorting unit 12 specifies the first frame of a new encoded music file while outputting the frame output from the reception buffer 11 to the first decoder 141, the sorting unit 12 The output destination is switched from the first decoder 141 to the second decoder 142. Then, the specified first frame and frames buffered in the reception buffer 11 after the first frame are sequentially output to the second decoder 142. In short, the sorting unit 12 switches the output destination decoder for each encoded music file.

  The decode buffer 15 in the reproduction unit 18 includes a first decode buffer 151 and a second decode buffer 152. The first decoding buffer 151 buffers the music file decoded by the first decoder 141. The second decoding buffer 152 buffers the music file decoded by the second decoder 142.

  The first and second decode buffers sequentially output buffered music files. Specifically, after the first decode buffer 151 outputs the music file, the second decode buffer 152 outputs the music file. The timing of outputting the music file is determined by the adjusting unit 17.

  The detection unit 13 detects the data amount of the data stream (a plurality of frames) buffered in the reception buffer 11 every predetermined period.

  The adjustment unit 17 adjusts the interval between the song files output from the reproduction unit 18 based on the detection result of the detection unit 13. Specifically, the adjustment unit 17 compares the data amount detected by the detection unit 13 (hereinafter referred to as a detected data amount) with the reference data amount Vref1. Here, the reference data amount Vref is an ideal data amount that does not cause the music to be reproduced to be interrupted during reproduction or to overflow the reception buffer 11 (overflow) during normal reproduction.

  When the detected data amount is less than the reference data amount Vref1, the data amount that the stream reproducing device 1 reproduces is larger than the data amount that the stream reproducing device 1 receives from the streaming server 2. Hereinafter, this state is referred to as “reception data insufficient state”. In this case, the adjustment unit 17 adjusts the interval between the reproduced songs. Specifically, the adjustment unit 17 determines the adjustment time based on the difference between the detected data amount and the reference data amount Vref. Then, the data editing unit 16 is instructed to provide a space between the determined adjustment times.

  The data editing unit 16 adjusts the music file output interval (between songs) based on the instruction from the adjusting unit 17. Specifically, after the output of the music file is completed, silence data for the determined adjustment time is generated and output. Then, after outputting the silence data for the adjustment time, the next music file is output. In short, when the reception data is in a low state, the reception buffer 11 is prevented from being depleted by providing a wide space between songs. For this reason, it is possible to prevent the sound from being cut out due to the frame being exhausted in the middle of the music being reproduced.

  On the other hand, when the detected data amount is larger than the reference data amount Vref1, the data amount received by the stream reproducing device 1 from the streaming server 2 is larger than the data amount reproduced by the stream reproducing device 1. This state is called “reception data excessive state”. In this case, the adjustment unit 17 determines the frame deletion amount based on the difference between the detected data amount and the reference data amount Vref1. Then, the playback unit 18 is instructed to delete the frames corresponding to the frame deletion amount determined from the beginning or end of the music file buffered in each of the decode buffers 151 and 152 and play the music.

  Based on the instruction from the adjustment unit 17, the data editing unit 16 outputs the music file by excluding frames corresponding to the frame deletion amount from the beginning or end of each music file. In short, when there is an excessive amount of received data, the reception buffer 11 is prevented from overflowing by reproducing the music file excluding the first or last frame. Many of the first and last frames of the music file are silent data. Therefore, even if the first or last frame is removed, it is difficult for the user to feel uncomfortable.

  Each of the above-described configurations 10 to 18 is realized by the hardware configuration illustrated in FIG. The stream playback device 1 includes a CPU 101, a memory 102, a hard disk drive (HDD) 103, and a communication unit 104, which are connected to each other via a bus 105. For example, the stream playback program stored in the HDD 103 is read into the memory 102, and the read music playback program is executed by the CPU 101, whereby the components 10 to 18 of the stream playback device 1 are realized.

[Operation]
Hereinafter, the operation of the stream playback device 1 will be described in detail with reference to a flowchart.

  The operation of the stream playback device 1 is roughly divided into the following three. The first is an operation (sorting operation) in which the sorting unit 12 sorts the frames continuously received by the receiving unit 10 for each music file. The second operation is an operation (adjustment instruction operation) in which the adjustment unit 17 instructs adjustment between music pieces of the reproduced music piece or deletion of a part of the reproduced music piece based on the data amount of the reception buffer 11. The third is an operation (playback operation) in which the playback unit 18 plays back a song in response to an instruction from the adjustment unit 17. Hereinafter, the sorting operation, the adjustment instruction operation, and the reproduction operation will be described.

[Category operation]
Referring to FIG. 5, the sorting unit 12 in the stream playback device 1 receives the frame FR (n) from the reception buffer 11 (S1). The reception buffer 11 outputs the frame FR (n) in the order of frames received from the reception unit 10. Subsequently, the sorting unit 12 reads the time stamp T (n) included in the frame FR (n) (S2). Then, based on the read time stamp T (n), it is determined whether or not the frame FR (n) received in step S1 is the first frame of a new encoded music file (S3). Generally, the time stamp of the first frame of a music file is the initial value “0”. Therefore, the sorting unit 12 can specify the first frame of the music file by referring to the time stamp.

  In general, when the playback time of a frame is added to the time stamp of a certain frame, the time stamp of the next frame is obtained. In other words, the time stamps gradually increase from the beginning in the frames in the same music file. The difference between the time stamps of consecutive frames is within a predetermined numerical range. On the other hand, the difference between the time stamp of the last frame of one song and the time stamp of the first frame of the next song is much larger than the time stamp difference of consecutive frames in the same song file. Therefore, the difference between the time stamp of the frame FR (n) and the time stamp of the frame FR (n−1) is calculated, and when the calculated difference is larger than a predetermined value, the frame FR (n) is set as the first frame. You may judge.

  As a result of the determination in step S3, if the frame FR (n) is not the first frame (NO in S3), the frame FR (n) belongs to the same music file as the frame that has passed through the sorting unit 12 previously. Therefore, the sorting unit 12 outputs the frame FR (n) to a designated decoder (hereinafter referred to as a designated decoder). Identification information (designated decoder information) of the designated decoder is stored in the memory 102. The sorting unit 12 identifies the designated decoder based on the designated decoder information, and outputs the frame FR (n) to the identified designated decoder (S5). Hereinafter, the description will be continued assuming that the designated decoder is the first decoder 141.

  If the result of determination in step S3 is that the frame FR (n) is the first frame of a new song file (YES in S3), the sorting unit 12 switches the designated decoder from the first decoder 141 to the second decoder 142 ( S4). Specifically, the sorting unit 12 changes the designated decoder information from the identification information of the first decoder 141 to the identification information of the second decoder 142. Then, based on the changed designated decoder information, the first frame FR (n) is output to the second decoder 142 (S5).

  Through the above steps, the sorting unit 12 sorts the data stream received by the stream playback device 1 into a plurality of encoded music files. Further, the sorting unit 12 outputs a certain encoded music file and a new encoded music file received next to the encoded music file to different decoders 141 and 142, respectively. Each of the decoders 141 and 142 decodes the encoded music file, and stores the decoded music file in separate decoding buffers (151 and 152).

[Adjustment instruction operation]
Based on the amount of data held in the reception buffer 11, the adjustment unit 17 instructs adjustment of the music pieces of the reproduction music piece or instructs the deletion of the first or last frame of the reproduction music piece.

  Referring to FIG. 6, adjustment unit 17 performs an adjustment instruction operation every predetermined time ΔT (S11). When the predetermined time ΔT has elapsed (YES in S11), the adjustment unit 17 requests the data amount held in the reception buffer 11 from the detection unit 13 (S12). The detection unit 13 receives the request from the adjustment unit 17 and detects the data amount of the reception buffer 11. Then, the adjustment unit 17 is notified of the detected data amount (detected data amount) Vdet.

  The adjusting unit 17 acquires the detected data amount Vdet (S13). Subsequently, the adjusting unit 17 obtains a difference ΔV between the detected data amount Vdet and the reference data amount Vref1 based on Expression (1) (S14).

ΔV = Vdet−Vref1 (1)
The reference data amount Vref1 is stored in the memory 102 in advance.

  The adjustment unit 17 further calculates the adjustment time ΔADJ represented by the equation (2) using the difference ΔV calculated in step S14 (S15).

ΔADJ = ΔV (bit) / compression bit rate (bps) / number of song files played back (2)
Here, the “number of music file playbacks” is the number of music files played back within a predetermined period ΔT. For example, when the predetermined period ΔT is 60 minutes and the average reproduction time of the music file is 4 minutes, the music file reproduction number is set to “15”. The number of music file reproductions may be stored in the memory 102 in advance. Alternatively, the adjusting unit 17 may count the number of music files actually reproduced within a predetermined period ΔT. Alternatively, the adjustment time ΔADJ may be obtained by multiplying the value obtained by Expression (2) by one or more coefficient α. The calculated adjustment time ΔADJ is stored in the memory 102.

  Subsequently, the adjustment unit 17 determines whether or not the adjustment time ΔADJ calculated in step S15 is greater than 0 (S16 and S17). When the adjustment time ΔADJ is smaller than 0 (YES in S16), the adjustment unit 17 instructs the data editing unit 16 to insert silence data for the adjustment time ΔADJ between songs (S18). Specifically, the instruction information stored in the memory 102 is set to an instruction indicating insertion (hereinafter referred to as an insertion instruction). When the adjustment time ΔADJ is smaller than 0, the detected data amount Vdet is smaller than the reference data amount Vref1. That is, the stream reproduction device 1 is in a state where received data is insufficient. Therefore, the adjustment unit 17 provides a space between the reproduced songs so that the currently played song is not interrupted.

  On the other hand, if the adjustment time ΔADJ is greater than 0 (NO in S16, YES in S17), the adjustment unit 17 instructs the data editing unit 16 to output the reproduction music piece with the adjustment time ΔADJ removed. (S19). Specifically, the instruction information stored in the memory 102 is set to an instruction indicating deletion (hereinafter referred to as a deletion instruction). When the adjustment time ΔADJ is larger than 0, the detected data amount Vdet is larger than the reference data amount Vref1. That is, the stream reproduction device 1 is in a reception data excessive state. Therefore, the adjustment unit 17 suppresses the overflow of the reception buffer 11 by reproducing the music except for the head or tail frame. When the adjustment time ΔADJ is 0 (NO in S16 and S17), the data amount of the reception buffer is the same as the reference data amount Vref1, and is an ideal data amount. Therefore, the adjustment unit 17 sets the instruction information in the memory 102 to an instruction (hereinafter referred to as normal reproduction instruction) indicating that the music file is reproduced as it is.

[Playback operation]
The reproduction unit 18 reproduces the music according to the instruction from the adjustment unit 17.

  Referring to FIG. 7, the data editing unit 16 in the playback unit 18 identifies a decoding buffer (hereinafter referred to as an output buffer) from which the decoded music file is read out of the two decoding buffers 151 and 152. Here, the description will be continued assuming that the output buffer is the first decode buffer 151. The data editing unit 16 reads the decoded music file from the first decoding buffer 151 (S31). Information about the output buffer (output buffer information) is stored in the memory 102. When the output buffer is the first decode buffer 151, the output buffer information indicates the first decode buffer 151.

  When all the frames of the music file have been read from the first decode buffer 151 (YES in S32), the data editing unit 16 switches the output buffer from the first decode buffer 151 to the second decode buffer 152 (S33). As a result, the data editing unit 16 is ready to output the next music file. At this time, the output buffer information in the memory 102 is changed to the second decode buffer 152.

  Subsequently, the data editing unit 16 reads the instruction information from the memory 102 (S34). When the instruction information is an insertion instruction (YES in S35), the data editing unit 16 generates and outputs silence data having a length corresponding to the adjustment time ΔADJ (S36). After outputting the silent data, the data editing unit 16 returns to step S31, reads out the music file from the output buffer (the second decoding buffer 152 newly designated in step S33), and outputs the music file. In short, silence data for adjustment time ADJ is inserted between songs. As a result, the playback unit 18 starts playback of the next song file after the adjustment time ΔADJ has elapsed since the playback of the song file has been completed.

  On the other hand, if the instruction information read in step S34 is a deletion instruction (NO in S35, YES in S37), among the music files in the output buffer (here, the second decode buffer 152), a plurality of adjustment times ΔADJ from the beginning. A plurality of frames corresponding to the adjustment time ΔADJ from the frame or the end are specified (S38). Then, when returning to step S31 and reading the music file, the portion excluding the frame specified in step S38 is read and output (S31). Thereby, the reproducing unit 18 reproduces the music file by excluding a part at the beginning or the end of the music file. In many cases, the beginning part and the end part of a music file are silent parts. Therefore, the user can listen without feeling uncomfortable even if the frame is reproduced without the head portion or the tail portion. Moreover, it is possible to suppress the overflow of the reception buffer 11.

  When the instruction information is a normal reproduction instruction (NO in S35 and S37), the data editing unit 16 inserts silence data or selects a plurality of frames for the adjustment time ΔADJ from the beginning or end of the music file. Without specifying, the music file is read from the output decoder and output to the outside (S31).

  As described above, the stream reproduction device 1 detects the data amount of the reception buffer 11 for each predetermined period, and based on the difference between the detected data amount Vdet and the reference data amount Vref1, whether the reception data is in the insufficient state or the reception data is in the excessive state. Judging. Then, when the received data is insufficient, the playback music is prevented from being interrupted by inserting an adjustment time between the music. On the other hand, when the received data is in an excessive state, the reception buffer 11 is prevented from overflowing by reproducing a part of the beginning or end frame of each song.

  In Steps S16 and S17 in FIG. 6, the adjustment unit 17 determines the instruction content based on whether or not the adjustment time ΔADJ is greater than zero. However, for example, when the adjustment time ΔADJ is within a predetermined range including 0, the adjustment unit 17 may use the instruction information as a normal reproduction instruction. In short, as long as the detected data amount Vdet is within a predetermined range from the reference data amount Vref1, it is not necessary to instruct the insertion of the silent time and the deletion of the frame.

[Second Embodiment]
In the first embodiment, the stream reproduction device 1 includes two decoders (first decoder 141 and second decoder) and two decode buffers (first decode buffer 151 and second decode buffer 152). When the processing capability of the decoder is high, there may be one decoder and one decoding buffer.

  Referring to FIG. 8, the stream reproduction device 20 according to the second embodiment includes one decoder 143 and one decode buffer 153. Other configurations are the same as those of the stream playback device 1.

  As in the first embodiment, the stream playback device 20 performs a sorting operation, an adjustment instruction operation, and a playback operation. Among these, the adjustment instruction operation is the same as in the first embodiment. Further, the reproduction operation executes steps excluding step S33 in FIG. Hereinafter, the sorting operation will be described.

[Category operation]
Referring to FIG. 9, the sorting unit 12 sorts the data stream output from the reception buffer 11 for each encoded music file, as in the first embodiment. However, the stream reproduction device 20 has only one decoder and decode buffer (decoder 143 and decode buffer 153). Therefore, the sorting unit 12 stops outputting the frame of the new encoded music file until the decoding buffer 153 completes the output of the music file. In short, the sorting unit 12 outputs a new encoded music file to the decoder 143 every time the decode buffer 153 completes the output of the music file. This prevents a plurality of song file frames from being mixed in the decode buffer 153.

  Referring to FIG. 9, the operations from step S1 to S3 are the same as those in FIG. When the sorting unit 12 receives the first frame of a new encoded music file (YES in S3), the sorting unit 12 stops outputting the frame (S7). Then, after outputting all the frames of the music file held in the decode buffer 153 (YES in S8), the output of the frame data stopped in step S7 is started (S6). The adjustment unit 17 monitors whether or not the decode buffer 153 has finished outputting all frames. Then, when the decode buffer 153 has finished outputting all the frames, the adjustment unit 17 outputs an output completion notification to the sorting unit 12. When receiving the output completion notification (YES in S8), the sorting unit 12 starts outputting the frame (S6). With the above operation, the sorting unit 12 can sort each music file.

[Third Embodiment]
Referring to FIG. 10, the stream reproduction device 30 according to the third embodiment includes a receiving unit 31, a sorting unit 32, a first buffer 33, a second buffer 34, a detecting unit 35, and an adjusting unit 36. And a decoder 37.

  In the present embodiment, two buffers 33 and 34 are arranged. The detection unit 35 obtains the data amount accumulated in the first buffer 33 and the second buffer 34 and stores the obtained data amount in the memory 102.

  Based on the amount of data stored in the memory 102, the adjustment unit 36 outputs a data output to the buffer (hereinafter referred to as a reception buffer) that receives the frame output from the sorting unit 32 and the decoder 37. Specifies the original buffer (hereinafter referred to as output buffer).

  The adjustment unit 36 includes a control unit 361, a reception designation unit 362, and an output designation unit 363. The control unit 361 determines whether the data amounts of the first buffer 33 and the second buffer 34 detected by the detection unit 35 are larger than a predetermined reference value, and based on the determination result, the reception designation unit 362 and the output An instruction is output to the designation unit 363.

  The reception designation unit 362 designates a buffer (reception buffer) that is a reception destination of the frame received by the reception unit 31 among the first and second buffers 33 and 34. The output designating unit 363 designates a buffer (output buffer) that outputs a frame to the decoder 37 among the first and second buffers 33 and 34.

[Operation]
The sorting unit 32 in the stream reproducing device 30 sorts the data stream received from the receiving unit 31 for each music file (sorting operation). The detection unit 35 detects the data amount of the first and second buffers 33 and 34. The adjustment unit 36 specifies a reception buffer that receives and holds the frame output from the sorting unit 32 based on the detected data amount. Further, an output buffer for outputting a frame to the decoder 37 is designated based on the detected data amount. At this time, the adjustment unit 36 designates a reception and output buffer so that the music file decoded by the decoder and output to the outside is not interrupted in the middle of the music (adjustment operation).

  The operation of the above-described stream reproduction device 30 will be described using a schematic diagram. Referring to FIG. 11, adjustment unit 36 first designates first buffer 33 as a reception buffer. Therefore, the frame output from the sorting unit 32 is input to the first buffer 33 and held. The amount of data in the first buffer 33 is detected by the detection unit 35. When the detected data amount of the first buffer 33 exceeds the reference value Vref2, the adjustment unit 36 designates the first buffer 33 as an output buffer. As a result, the first buffer 33 sequentially outputs the held frames to the decoder 37 (see FIG. 11).

[Operation of stream playback device when reception data is too low]
When the sorting unit 32 receives the first frame of the new encoded music file, the adjustment unit 36 checks the data amount of the first buffer 33. At this time, as shown in FIG. 12, it is assumed that the data amount of the first buffer 33 is less than the lower limit value Vmin. At this time, the adjustment unit 36 switches the reception buffer from the first buffer 33 to the second buffer 34. That is, the second buffer 34 is designated as a new receiving buffer.

  When the data amount is less than the lower limit value Vmin, the amount of data to be reproduced is larger than the amount of data received by the stream reproduction device 30. That is, the stream reproducing device 30 is in a state where the received data is insufficient. In this case, if the frames are continuously buffered in the first buffer 33, the frames to be output to the decoder 37 are depleted in the middle of the reproduced music. Therefore, the music output from the stream playback device 30 is cut off in the middle of the music. In order to prevent such sound interruption of the reproduced music, the adjustment unit 36 switches the reception buffer.

  While the frames of the new music file are being buffered in the second buffer 34, all the frames held in the first buffer 33 are output to the decoder 37 as shown in FIG. At this time, the output of the music file for one music is completed.

  The adjustment unit 36 further checks the data amount of the second buffer 34 every predetermined period, and determines whether or not the data amount of the second buffer 34 exceeds the reference value Vref2. The adjustment unit 36 does not output a frame from the second buffer 34 until the data amount exceeds the reference value Vref2. While the adjustment unit 36 does not output a frame from the second buffer 34, the decoder 37 does not perform the decoding process. Therefore, during this time, the stream playback device 30 is in a silent state.

  As shown in FIG. 14, when the data amount of the second buffer 34 exceeds the reference value Vref2, the adjustment unit 36 designates the second buffer 34 as an output buffer. The second buffer 34 designated as the output buffer outputs the frame to the decoder 37. At this time, the stream playback device 30 plays back a new song. In short, when the stream playback device 30 is in a state where the received data is insufficient, a silent adjustment time is inserted after the playback of the music is completed until the next music is played back. By providing an adjustment time between songs, it is possible to prevent playback songs from being interrupted during playback.

[Operation of stream playback device when receiving data is excessive]
The operation of the stream playback device 30 when the received data is excessive is as follows. Assume that the sorting unit 32 receives the first frame of a new song while the first buffer 33 is receiving a frame and outputting the frame to the decoder 37. At this time, the adjustment unit 36 checks the data amount of the first buffer 33. As a result of the confirmation, as shown in FIG. 15, when the data amount exceeds the upper limit value Vmax, the adjustment unit 36 designates the second buffer 34 as a reception buffer. That is, the reception buffer is switched from the first buffer 33 to the second buffer 34. As a result, the second buffer 34 receives and holds the first frame and subsequent frames.

  Subsequently, the adjustment unit 36 monitors the data amount of the second buffer 34 that is a reception buffer. As shown in FIG. 16, when the data amount of the second buffer 34 exceeds the reference value Vref2, the adjustment unit 36 designates the second buffer 34 as an output buffer. As a result, as shown in FIG. 17, the second buffer 34 sequentially outputs the held frames to the decoder 37. Further, when the second buffer 34 is designated as the output buffer, the adjustment unit 36 deletes data remaining in the other buffer (first buffer 33). For example, as shown in FIG. 16, when the data amount of the second buffer 34 exceeds the reference value Vref, it is assumed that data still remains in the first buffer 33. In this case, the adjustment unit 36 designates the second buffer 34 as an output buffer and deletes data remaining in the first buffer 33 (see FIG. 17). Therefore, the data at the end of the music file stored in the first buffer 33 is not output but is cut. In this case, playback is cut at the end of the song, but the end of the song is often silent. Therefore, it is possible to suppress a sense of incongruity given to the user rather than a sound interruption occurring during the reproduction music.

  As described above, the stream reproduction device 30 compares the data amounts of the two buffers 33 and 34 with predetermined reference values (Vmax, Vref2, Vmin). Based on the comparison result, the reception buffer and the output buffer are designated. As a result, the stream playback device 30 inserts an adjustment time between songs when the received data is in a low state, and suppresses breaks in the sound during playback. Further, when the received data is excessive, the end data of the music file is deleted to prevent the sound from being cut off during the playback music. Hereinafter, details of the operation of the stream playback device 30 will be described with reference to a flowchart.

[Category operation]
Referring to FIG. 18, the operations in steps S1 to S3 are the same as those in FIG. That is, the sorting unit 32 reads the time stamp T (n) from the frame FR (n), and specifies the first frame of the new music file based on the time stamp T (n). Thereby, the data stream can be classified for each music file.

  When the sorting unit 32 determines that the frame received by the receiving unit 31 is the first frame (YES in S3), the sorting unit 32 outputs a sorting notification to the adjusting unit 36 (S9).

[Adjustment operation]
The adjustment unit 36 receives a designation of receiving buffer every time receiving a classification notification from the sorting unit 32, and an output specifying operation of judging designation of an output buffer every time the data amount of the receiving buffer exceeds the reference value Vref2. And execute. Hereinafter, the reception specifying operation and the output specifying operation will be described.

[Receive designation operation]
Each time the adjustment unit 36 receives a classification notification from the classification unit 32, the adjustment unit 36 performs a reception designation operation. Referring to FIG. 19, when receiving the segment notification (YES in S61), the control unit 361 in the adjustment unit 36 reads the data amount of the output buffer that is outputting the current frame to the decoder 37 (S62). Information for specifying the output buffer (output buffer specifying information) is stored in the memory 102. When the output buffer is the first buffer 33, the output buffer specifying information indicates the first buffer 33. The amount of data in each of the buffers 33 and 34 is detected every predetermined period by the detection unit 35 and stored in the memory 102. When the control unit 361 receives the classification notification, the control unit 361 specifies the output buffer based on the output buffer specifying information, and reads the data amount of the specified output buffer from the memory 102. Hereinafter, description will be made assuming that the output buffer is the first buffer 33. When the adjustment unit 36 receives the division notification, the buffer designated as the output buffer normally receives the frame from the division unit 32. That is, the buffer specified as the output buffer is also specified as the reception buffer at the same time. Therefore, the first buffer 33 receives and holds the frame, and outputs the frame to the decoder 37.

  The control unit 361 determines whether or not the data amount of the first buffer 33 read in step S62 is within a predetermined range (S63 and S64).

  If the result of determination in step S63 is that the amount of data is less than the lower limit value Vmin (YES in S63), the stream playback device 30 is in a state of insufficient received data. Therefore, the adjustment unit 36 switches the reception buffer (S65, see FIG. 12). Specifically, the control unit 361 changes the reception buffer specifying information stored in the memory 102 to the second buffer 34. Then, the reception designation unit 362 is instructed to output the frame received from the sorting unit 32 to the second buffer 34. In response to the instruction from the control unit 361, the reception designation unit 362 outputs the first frame of the new music file and the frames received by the receiving unit 31 thereafter to the second buffer 34. As a result, the second buffer 34 buffers the frame of the new music file as a receiving buffer.

  On the other hand, when the data amount of the first buffer 33 read in step S62 exceeds the upper limit value Vmax (NO in S63, YES in S64), the stream reproducing device 30 is in a reception data excessive state. Therefore, the adjustment unit 36 switches the reception buffer (S65), and outputs the first frame and subsequent frames to the second buffer 34 (S66).

  In short, the adjustment unit 36 switches the reception buffer when the stream reproducing device 30 determines that the received data is in an insufficient state or an excessively received data state.

[Output specification operation]
Next, the output designation operation of the adjustment unit 36 will be described. Referring to FIG. 20, adjustment unit 36 performs an output designation operation every predetermined period. First, the control unit 361 in the adjustment unit 36 specifies the reception buffer using the reception buffer specifying information (S71). The description will be continued assuming that the specified receiving buffer is the second buffer 34.

  The control unit 361 reads the data amount of the second buffer 34 that is a receiving buffer (S72). Then, it is determined whether or not the read data amount is larger than the reference value Vref2 (S73). If the data amount is smaller than the reference value Vref2 (NO in S73), the adjustment unit 36 ends the output specifying operation. That is, in this case, the output buffer is not switched.

  On the other hand, as a result of the determination in step S73, when the data amount exceeds the reference value Vref2 (YES in S73), the control unit 361 examines designation of the output buffer (S74 to S76).

  First, the control unit 361 identifies the current output buffer (S74). The stream reproducing device 30 stores information for specifying an output buffer (hereinafter referred to as output buffer specifying information) in the memory 102 as well as the receiving buffer specifying information. The control unit 361 reads the output buffer specifying information from the memory 102 and specifies the output buffer.

  After specifying the output buffer, the control unit 361 determines whether or not the output buffer is the second buffer 34 that is the same as the receiving buffer (S75). When the output buffer specified in step S74 is the first buffer 33, the output buffer (first buffer 33) is different from the reception buffer (second buffer 34) (NO in S75). Therefore, the control unit 361 switches the output buffer from the first buffer 33 to the second buffer 34 (see S76, FIG. 14 and FIG. 17). In other words, the control unit 361 changes the output buffer specifying information from the first buffer 33 to the second buffer 34, and designates the second buffer 34 as the output buffer.

  The control unit 361 instructs the output designation unit 363 to designate the output buffer as the second buffer 34. The output specifying unit 363 receives the data in the second buffer 34 and outputs it to the decoder 37. As a result, the second buffer 34 outputs the frame to the decoder 37 as an output buffer.

  The control unit 361 further deletes all frames remaining in the buffer that is not the output buffer (here, the first buffer 33) (S77). When the stream reproduction device 30 is in the excessive reception data state, the frame remaining in the first buffer 33 is erased by the operation of step S77 (see FIG. 17).

  As a result of the above operation, when the stream reproduction device 30 is in a state where the received data is insufficient (FIG. 12), the adjusting unit 36 stores the frames stored in the first buffer 33 in the second buffer 34 even after finishing outputting all the frames. The frame is not output to the decoder 37 until the frame is buffered by a predetermined amount (an amount larger than Vref2). During this time, since the decoder 37 does not receive a frame, the decoding process is stopped. As a result, a silent period occurs. The adjusting unit 36 designates the second buffer 34 as an output buffer after the second buffer 34 accumulates a sufficient amount of data (an amount larger than Vref2) so that no interruption of sound occurs in the middle of the reproduced music, The data in the second buffer 34 is output to the decoder 37. In short, when the stream playback device 30 is in a state where the received data is insufficient, the adjusting unit 36 inserts a silent adjustment time between songs, thereby suppressing the occurrence of sound interruption in the middle of the played song.

  If the stream playback device 30 is in a state of excessive reception data, the operation ends in step S77, and the end of the previously output music file is cut and the next music file is output. This prevents the buffer from overflowing. In addition, since the end portion of the music is often silent, it is possible to suppress a sense of discomfort given to the user rather than the occurrence of sound interruption in the middle of the music.

  In the above-described third embodiment, the lower limit value Vmin and the reference value Vref2 are different from each other, but the lower limit value Vmin and the reference value Vref2 may be the same value. More specifically, in step S73 during the output designation operation shown in FIG. 20, the control unit 361 determines whether or not the data amount of the reception buffer exceeds the lower limit value Vmin, and outputs based on the determination result. You may specify a buffer. In short, the lower limit value Vmin and the reference value Vref2 only need to be a reference such that the data amount of the first and second buffers 33 and 34 is a data amount that does not cause interruption of sound during the reproduction of the reproduced music. .

  As the reference value Vref2 approaches the lower limit value Vmin, the number of times of buffer switching (number of designated changes) increases. For this reason, every time reproduction of a song is completed, an adjustment time is inserted between the songs. The greater the difference between the reference value Vref2 and the lower limit value Vmin, the smaller the number of buffer switching. That is, the chance that the music is continuously played increases, and it is possible to prevent the adjustment time from being inserted between the music every time the music is played.

  In the third embodiment, the decoder 37 does not perform the decoding process while the frame is not output from the buffer (that is, during the adjustment time) when the received data is insufficient. Data may be inserted into the decoder 37.

  In the above-described embodiment, the sorting unit discriminates the first frame of the song file using the time stamp, but the sorting unit may sort the song file by other methods. For example, when each frame has metadata including identification information (file ID) unique to a music file, the music file may be classified using the file ID.

[Fourth Embodiment]
This embodiment is a modification of the third embodiment. In the third embodiment, when the first buffer 33 is first designated as the receiving buffer, the first buffer 33 is designated as the output buffer until the detected data amount of the first buffer 33 exceeds the reference value Vref2. Accordingly, no frame is output from the first buffer 33 to the decoder 37. As a result, there is a problem that it takes time until the sound is reproduced from the stream reproducing apparatus. Therefore, in the present embodiment, the control unit 361 sets the reference value of the first buffer 33 (and the second buffer 34 if necessary) for the first content (first music file) to a value that is higher than Vref2. By setting Vref2 ′ to a small value, the first song can be quickly played back. Then, the control unit 361 sets the reference value to Vref2 for content other than the first content (music files after the second music). That is, when the sorting unit 32 receives the first frame of the second song, the control unit 361 changes the reference value of the first buffer 33 and the second buffer 34 to Vref2. Accordingly, it is possible to quickly start reproduction of the first content, and it is possible to more surely prevent buffer depletion for content other than the first content.

[Operation]
The operation of this embodiment will be described below. In addition, description is used about the same process as 3rd Embodiment. Hereinafter, a case where the data amount of the first buffer 33 is less than the lower limit value Vmin when the first frame of the second song is determined by the sorting unit will be described as an example. The same applies to the case between the lower limit value Vmin and the upper limit value Vmax.

[Control processing 1 of buffer reference value]
FIG. 21 shows a reference value setting process for the first buffer 33 (and the second buffer 34) by the control unit 361. The control unit 361 temporarily sets the reference value of the first buffer 33 (and the second buffer 34) to Vref2 (S81). The control unit 361 determines whether or not the holding time reduction mode is set to the on state by a user operation (S82). If the retention time reduction mode is not set to the on state (NO in S82), the process is terminated.

  If the retention time shortening mode is set to ON (YES in S82), the control unit 361 retains and outputs the first music file 33 (and the first buffer 33) as shown in FIG. The reference value of the second buffer 34) is set to Vref2 ′ (S83). Vref2 'is a value smaller than Vref2, and is, for example, a value half that of Vref2. By changing the reference value to Vref2 ′, the time until the data amount of the first music file held in the first buffer 33 exceeds the reference value can be shortened, and audio is output from the decoder 37. Can be shortened. For example, if Vref2 'is 1/2 of Vref2, the time until the sound is output from the decoder 37 can be reduced to about 1/2.

  Subsequently, the control unit 361 monitors whether or not a division notification for the second music file has been received (S84). As shown in FIG. 18, the sorting unit 32 determines the first frame of the second song (YES in S3), and outputs a sorting notification to the control unit 36 (S9). Returning to FIG. 21, when the control unit 361 receives the division notification (YES in S84), the first buffer 33 (and the second buffer 33) holds and outputs the second and subsequent music files as shown in FIG. The reference value of the buffer 34) is changed from Vref2 ′ to Vref2 (S85). Therefore, for the second and subsequent songs, as shown in FIG. 24, after the amount of data held in the first buffer 33 or the second buffer 34 exceeds the reference value Vref2, the first buffer 33 or the second buffer 34 Is output to the decoder 37. As a result, for the second and subsequent songs, it is possible to more reliably prevent the data amount held by the first buffer 33 or the second buffer 34 from being exhausted.

[Buffer reference value control process 2]
As described above, since the buffer reference value is set to Vref2 ′ for the first song, the amount of data held in the first buffer 33 or the second buffer 34 may be exhausted. Accordingly, the control unit 361 changes the reference value of the first buffer 33 or the second buffer 34 from Vref2 ′ to Vref2 even when the amount of data held in the first buffer 33 or the second buffer 34 is exhausted. I am doing so. FIG. 25 shows the processing of the control unit 361 when outputting the data of the first song file to the decoder 37.

  As shown in FIG. 25, the control unit 361 reads the data amount held by the first buffer 33 that is the output buffer of the first music file (S91). Then, the control unit 361 determines whether or not the data amount of the first buffer 33 is 0 (that is, is depleted) (S92). If the data amount is not 0 (NO in S92), the control unit 361 continues the reference value Vref2 'and causes the first buffer 361 to output the frame to the decoder 37 (S93).

  On the other hand, as shown in FIG. 26, if the data amount is 0 (YES in S92), the control unit 361 changes the reference value of the first buffer 33 and the second buffer 34 from Vref2 ′ to Vref2 (S94). . The fact that the data amount of the first buffer 33 becomes 0 means that the received data is too small. Therefore, if playback is continued with the reference value of the first buffer 33 being Vref2 ′, the first song file is played back. There is a possibility that the data amount of the first buffer 33 will be exhausted in the future. However, in this example, by changing the reference value of the first buffer 33 to Vref2, the possibility that the data amount of the first buffer 33 will be exhausted in the future can be reduced.

  Thereafter, as shown in FIG. 27, the control unit 361 waits for the frame to be output from the first buffer 33 to the decoder 37 until the data amount of the first buffer 33 exceeds the reference value Vref2, and the first buffer 33 When the data amount 33 exceeds the reference value Vref2, a frame is output from the first buffer 33 to the decoder 37 (S95).

  As described above, according to the present embodiment, it is possible to quickly start the reproduction of the first song, and it is possible to prevent the sound from being cut off during the reproduction of the second and subsequent songs.

  In the fourth embodiment, the reference value of the first buffer 33 and the second buffer 34 is set to Vref2 when the first frame of the second music is detected. However, the first frame of the second music is detected. However, the reference values of the first buffer 33 and the second buffer 34 may be maintained at Vref2 ′. Then, the reference value of the first buffer 33 and the second buffer 34 may be set to Vref2 only when the data amount of the first buffer 33 and the second buffer 34 becomes 0 by the processing of FIG. . That is, as long as the first buffer 33 and the second buffer 34 are not exhausted, the reference values of the first buffer 33 and the second buffer 34 may be maintained at Vref2 '.

  Further, the above fourth embodiment may be applied to the first embodiment and the second embodiment. That is, the fourth embodiment can be applied to a case where there is one buffer.

[Fifth Embodiment]
This embodiment is a modification of the fourth embodiment. In the fourth embodiment, the reference value is set to Vref2 ′ smaller than Vref2 for the first content, and the reference value is set to Vref2 for content other than the first content. In this case, Vref2 ′ is used. When the difference between Vref and Vref is large, silence may be inserted for a long time before the reproduction of the second music file is started. In order to solve this problem, in this example, when the classification notification is received and the reception buffer is switched, a predetermined increase amount (for example, data amount for 2 seconds) is added to the data amount held in the buffer, A new reference value Vref2 is set. As a result, the difference between the new reference value Vref2 and the amount of data held in the buffer is always a predetermined increase amount, so that it is possible to prevent silence from being inserted for a long time between songs.

  28 to 33 are schematic diagrams showing the operation of this example, and FIGS. 34 and 35 are flowcharts showing the operation of this example. First, as shown in FIGS. 28 and 34, the control unit 361 sets the output buffer to a buffer different from the reception buffer (S101). For example, the receiving buffer is set in the first buffer 33 and the output buffer is set in the second buffer 34. Next, the control unit 361 sets the reference value Vref2 of the first buffer 33 and the second buffer 34 to the data amount of the first buffer 33 that is the receiving buffer (here, it is 0 because no data is held yet). It is calculated and set by adding a predetermined increase amount (data amount for 2 seconds) (S102). Then, frame reception is started from the sorting unit 32 to the first buffer 33 which is a reception buffer (S103).

  As shown in FIG. 35, frame reception from the sorting unit 32 to the first buffer 33 that is a receiving buffer is continued (S111), and the control unit 361 determines whether or not a sorting notification is received from the sorting unit 32 ( S112). If no classification notification is received (NO in S112), frame reception to the reception buffer is continued (S117). The control unit 361 determines whether or not the output buffer and the reception buffer are different (S118). Here, the receiving buffer is the first buffer 33 and the output buffer is the second buffer 34 (YES in S118). The control unit 361 determines whether or not the data amount of the first buffer 33 that is a receiving buffer is equal to or greater than the reference value Vref2 (S119). In FIG. 29, the data amount of the first buffer 33 is equal to or greater than the reference value Vref2. Therefore (YES in S119), the output buffer is switched to the same buffer as the receiving buffer (S120). That is, the output buffer is switched to the first buffer 33. Accordingly, frame output from the first buffer 33 is started and playback is started.

  When the sorting unit 32 receives the first frame of the second song and receives a sorting notification from the sorting unit 32 (YES in S112), the control unit 361 has the data amount of the first buffer 33, which is a receiving buffer, less than the lower limit value Vmin. Or whether the upper limit value Vmax is exceeded (S113). In FIG. 30, the amount of data in the first buffer 33, which is a receiving buffer, is less than the lower limit value Vmin (YES in S113). Therefore, the control unit 361 determines whether or not the reference value Vref2 is larger than the lower limit value Vmin and smaller than the upper limit value Vmax (S114). Here, the reference value Vref2 is smaller than the lower limit value Vmin (NO in S114). As shown in FIG. 30, the control unit 361 adds a predetermined increase amount (data amount for 2 seconds) to the data amount of the first buffer 33, which is a reception buffer, and sets a new reference value Vref2 (S115). . That is, when data for 5 seconds is held in the first buffer 33, the reference value Vref2 is set to 5 + 2 = 7 seconds. Since the previous reference value is for 2 seconds, the reference value Vref2 is increased by 5 seconds. Thus, the greatest feature of this example is that the increase amount of the reference value Vref2 changes each time according to the data amount of the buffer. Then, the control unit 361 switches the reception buffer to a buffer different from the output buffer (S116). That is, the reception buffer is switched to the second buffer 34 as shown in FIG.

  Then, as shown in FIG. 31, the frame is received by the second buffer 34, which is a receiving buffer (S117), and when the data amount of the second buffer 34 becomes equal to or greater than the reference value Vref2 (YES in S119), as shown in FIG. The output buffer is switched to the second buffer 34 which is the same buffer as the receiving buffer (S120), and reproduction is started from the second buffer 34. At this time, if data remains in the first buffer 33, which is the original output buffer, the data is deleted and the first buffer 33 is emptied (S121).

  Subsequently, a classification notification is received from the classification unit 32 in the state of FIG. 32 (YES in S112). The amount of data in the second buffer 34 is less than the lower limit value Vmin (YES in S113), and the reference value Vref2 is smaller than the lower limit value Vmin (NO in S114). Therefore, as shown in FIG. 32, the control unit 361 adds a predetermined increase amount (data amount for 2 seconds) to the data amount of the second buffer 34 to set a new reference value Vref2 (S115). For example, if the data amount of the second buffer 34 is 7 seconds, the reference value Vref2 is set to 9 seconds. That is, since the previous reference value Vref2ga is 7 seconds, the increase amount of the reference value Vref2 is 2 seconds. Then, the reception buffer is switched to the first buffer 33 which is a buffer different from the output buffer (S116), and the first buffer 33 is made to receive the frame (S117). Thereafter, as shown in FIG. 33, when the data amount of the first buffer 33 becomes equal to or larger than the reference value Vref2, the output buffer is switched to the first buffer 33, and reproduction is started from the first buffer 33.

  If the reference value Vref2 is larger than the lower limit value Vmin and smaller than the upper limit value Vmax in S114, the process of S115 is skipped and the process proceeds to S116. That is, when the reference value Vref2 is larger than the lower limit value Vmin and smaller than the upper limit value Vmax, the increase of the reference value Vref2 is finished at that time. As a result, in the steady state, the reference value Vref2 is set to a value between the lower limit value Vmin and the upper limit value Vmax. Further, instead of the determination in S114, it may be determined only whether the reference value Vref2 is larger than the lower limit value Vmin.

  If the data amount in the receiving buffer is not less than the lower limit value Vmin and not more than the upper limit value Vmax in S113, the processing of S114 to S116 is skipped and the process proceeds to S117. That is, the increase of the reference value Vref2 is executed when the reception buffer is switched. Even when the classification notification is received from the classification unit 32, the reference value Vref2 is not increased if the reception buffer is not switched.

  When the new reference value Vref2 calculated in S115 exceeds the upper limit value Vmax, the reference value Vref2 may be set to a value slightly smaller than Vmax. This is because the steady-state reference value Vref2 is set between the lower limit values Vmin and Vmax, and NO is determined in S114 to prevent the reference value Vref2 from continuously increasing.

  As described above, according to the present embodiment, since the reference value Vref2 is increased stepwise according to the data amount of the receiving buffer, silence can be prevented from being inserted for a long time when the output buffer is changed (that is, between songs). can do. In other words, if the amount of increase in the reference value is increased, it takes time until the new receive buffer data amount reaches the reference value. However, the amount of data in the receive buffer (that is, the output buffer) is large and the output buffer data is lost. When the time is long, silence is not inserted for a long time when data is output from a new receiving buffer. Similarly, if the amount of data in the receiving buffer (that is, the output buffer) is small, the data in the output buffer will be lost immediately. However, by reducing the increase in the reference value, the data amount in the new receiving buffer becomes the reference value. The time to reach is shortened, and no silence is inserted for a long time when data is output from a new receiving buffer.

  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 above-described stream reproduction device or a recording medium on which the computer program is recorded.

  The present invention can be suitably applied to a stream reproduction device that receives a data stream distributed from a server.

It is a functional block diagram which shows the structure of the streaming system by embodiment of this invention. It is a figure which shows the data structure of the data stream delivered from the streaming server in FIG. It is a functional block diagram which shows the structure of the stream reproduction | regeneration apparatus in FIG. It is a block diagram which shows the hardware constitutions of the stream reproduction | regeneration apparatus in FIG. FIG. 4 is a flowchart showing details of the sorting operation of the stream playback device shown in FIG. 3. FIG. 4 is a flowchart showing details of an adjustment instruction operation of the stream reproduction device shown in FIG. 3. FIG. 4 is a flowchart showing details of a playback operation of the stream playback device shown in FIG. 3. It is a functional block diagram which shows the structure of the stream reproducing | regenerating apparatus by the 2nd Embodiment of this invention. It is a flowchart which shows the detail of the division | segmentation operation | movement of the stream reproduction | regeneration apparatus shown in FIG. It is a functional block diagram which shows the structure of the stream reproducing | regenerating apparatus by the 3rd Embodiment of this invention. It is a schematic diagram which shows operation | movement of the stream reproduction | regeneration apparatus shown in FIG. FIG. 12 is a schematic diagram illustrating the operation of the stream playback device following FIG. 11. FIG. 13 is a schematic diagram illustrating the operation of the stream playback device continued from FIG. 12. FIG. 14 is a schematic diagram illustrating the operation of the stream playback device continued from FIG. 13. FIG. 15 is a schematic diagram illustrating another example of the operation of the stream playback device, which is different from FIGS. 11 to 14. FIG. 16 is a schematic diagram illustrating an operation of the stream reproduction device continued from FIG. 15. FIG. 17 is a schematic diagram illustrating the operation of the stream reproduction device continued from FIG. 16. It is a flowchart which shows the detail of the division | segmentation operation | movement of the stream reproduction | regeneration apparatus shown in FIG. It is a flowchart which shows the detail of the reception designation | designated operation | movement of the stream reproduction | regeneration apparatus shown in FIG. It is a flowchart which shows the detail of the output designation | designated operation | movement of the stream reproduction | regeneration apparatus shown in FIG. It is a flowchart which shows the reference value control operation | movement of the buffer of 4th Embodiment. It is a schematic diagram which shows the other example of operation | movement of the stream reproducing | regenerating apparatus of 4th Embodiment. It is a schematic diagram which shows the other example of operation | movement of the stream reproducing | regenerating apparatus of 4th Embodiment. It is a schematic diagram which shows the other example of operation | movement of the stream reproducing | regenerating apparatus of 4th Embodiment. It is a flowchart which shows the reference value control operation | movement of the buffer of 4th Embodiment. It is a schematic diagram which shows the other example of operation | movement of the stream reproducing | regenerating apparatus of 4th Embodiment. It is a schematic diagram which shows the other example of operation | movement of the stream reproducing | regenerating apparatus of 4th Embodiment. It is a schematic diagram which shows operation | movement of a stream reproducing | regenerating apparatus. FIG. 29 is a schematic diagram illustrating the operation of the stream playback device following FIG. 28. FIG. 30 is a schematic diagram illustrating an operation of the stream reproduction device continued from FIG. 29. FIG. 31 is a schematic diagram illustrating the operation of the stream playback device following FIG. 30. FIG. 32 is a schematic diagram illustrating the operation of the stream playback device following FIG. 31. FIG. 33 is a schematic diagram illustrating the operation of the stream playback device following FIG. 32. It is a flowchart which shows operation | movement of the stream reproducing | regenerating apparatus of 5th Embodiment. It is a flowchart which shows operation | movement of the stream reproducing | regenerating apparatus of 5th Embodiment.

Explanation of symbols

1, 20, 30 Stream playback device 2 Streaming server 10, 31 Reception unit 11 Reception buffer 12, 32 Sorting unit 13, 35 Detection unit 14, 37 Decoder 15 Decoding buffer 16 Data editing unit 17, 36 Adjustment unit 18 Playback unit 22 Data Stream generation unit 23 Distribution unit 33 First buffer 34 Second buffer 102 Memory 361 Control unit 362 Receipt designation unit 363 Output designation unit

Claims (5)

Receiving means for receiving a data stream in which a plurality of contents are concatenated;
Sorting means for sorting the received data stream by content;
Playback means for sequentially playing back each of the divided contents;
Buffer means for receiving and temporarily holding the received data stream, and outputting to the reproducing means when the data amount of the data stream exceeds a reference value;
For the contents other than the first content in the data stream, the reference value is set to the first reference value, and for the first content in the data stream, the reference value is a second reference value that is smaller than the first reference value. a reference value setting means for setting a,
Detecting means for detecting a data amount of the data stream held in the buffer means;
Adjusting means for adjusting an interval at which the reproduction means reproduces each content based on a detection result of the detection means;
Each content in the data stream includes a plurality of frames,
The buffer means includes a plurality of buffers for receiving or outputting the plurality of frames in accordance with designation of the adjusting means;
The classifying means determines whether the receiving means has received the first frame of each content;
When the receiving unit receives the first frame of the content, the adjusting unit determines whether the data amount of the buffer that is outputting the frame among the plurality of buffers is less than a predetermined lower limit value. 1 judging means,
When the amount of data in the buffer that is outputting the frame is less than the lower limit value, another buffer that is different from the buffer that is outputting the data is used as a receiving buffer that receives the first frame of the content and frames received thereafter. The receipt designation means to be specified in
An output buffer for sequentially outputting the frame to the reproducing means when the data amount of the buffer receiving the frame out of the plurality of buffers exceeds the reference value or the lower limit value. A stream reproducing device including output designating means for designating . Receiving means for receiving a data stream in which a plurality of contents including a plurality of frames are concatenated;
Classifying means for classifying the received data stream for each content, and determining whether the receiving means has received the first frame of each content;
Playback means for sequentially playing back each of the divided contents;
A plurality of buffers that receive and temporarily store the received data stream and that output to the playback means when the data amount of the data stream exceeds a reference value;
Detecting means for detecting a data amount of the data stream held in the buffer;
First receiving means for determining whether or not the data amount of a buffer that is outputting a frame among the plurality of buffers is less than a lower limit value when the receiving means receives the first frame of the content;
When it is determined that the data amount of the buffer that is outputting the frame is less than the lower limit value, a predetermined increment is added to the data amount of the buffer that is receiving the frame among the plurality of buffers, and the reference value is obtained. A reference value setting means to be set;
When it is determined that the data amount of the buffer that is outputting the frame is less than the lower limit value, other buffers different from the buffer that is outputting the data are received in the first frame of the content and the frames received thereafter. A receiving specification means for specifying a receiving buffer for receiving,
When the data amount of the buffer receiving the frame among the plurality of buffers exceeds the reference value, the buffer receiving the data is designated as an output buffer for sequentially outputting the frames to the reproducing means. A stream reproduction apparatus comprising: a designation unit; When the receiving means receives the first frame of the content, the apparatus further comprises second determining means for determining whether or not the data amount of the buffer that is outputting the frame exceeds an upper limit value that is larger than the lower limit value. ,
When it is determined that the data amount exceeds the upper limit value, the reference value setting means adds a predetermined increase amount to the data amount of the buffer receiving the frame among the plurality of buffers, and the reference value Set
3. The reception specification unit according to claim 2 , wherein when it is determined that the amount of data exceeds the upper limit value, the reception specifying unit specifies another buffer different from the buffer that is outputting the frame as the reception buffer. Stream playback device. The reference value setting means determines whether or not the current reference value is greater than the lower limit value. If the current reference value is greater than the lower limit value, the current reference value is maintained as it is. And when the current reference value is less than or equal to the lower limit value, the reference value is set by adding a predetermined increment to the data amount of the buffer receiving the frame among the plurality of buffers. 4. The stream playback device according to 2 or 3 . To execute respective means of the stream playback device according to any one of claims 1-4 in a computer, the stream reproduction program.