JP2010028455A - Data structure, playback apparatus and method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the situation where playback is halted in the middle of streaming according to a Play List based on the Blue-ray Disc-Read Only Memory (BD-ROM) standards. <P>SOLUTION: In PI (Play Item) #(k+1)((k) is an integral value from 0 to 6), "1000k.clpi" of 2 Mbps (Angle-1) refers to "1000k.m2ts" encoded with 2 Mbps. "2000k.clpi" of 1 Mbps (Angle-2) refers to "2000k.m2ts" encoded with 1 Mbps. "3000k.clpi" of 0.5 Mbps (Angle-3) refers to "3000k.m2ts" encoded with 0.5 Mbps. Firstly, "1000k.m2ts" encoded with 2 Mbps is downloaded. Thereafter, when it is determined that a network velocity is decelerated before PI#4, the object to be downloaded is switched to "3000k.m2ts" of lower bit rate. The present invention may be applicable to a playback apparatus compliant to the BD-ROM standards. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a data structure, a playback apparatus and method, and a program, and in particular, can avoid a situation where playback stops during streaming according to a PlayList according to the BD-ROM (Blu-ray Disc-Read Only Memory) standard. The present invention relates to a data structure, a playback apparatus and method, and a program.

  In recent years, a Blu-ray Disc standard has been proposed as a standard for a disc-type recording medium that can be removed from a recording / reproducing apparatus.

  As a derivation standard of Blu-ray Disc, there is a movement to develop a reproduction-only recording medium in which data such as movies and music are recorded in advance. As a read-only optical disc for recording data such as movies and music, a DVD (Digital Versatile Disc) has already been widely used. On the other hand, a playback-only optical disc based on the Blu-ray Disc standard can record high-definition video for 2 hours or more with high image quality while taking advantage of the large capacity and high transfer speed of Blu-ray Disc. This is a significant difference from existing DVDs.

  Such a standard for a reproduction-only recording medium in Blu-ray Disc is generally called a BD-ROM (Blu-ray Disc-Read Only Memory) standard.

By using the Virtual Package defined in the BD-ROM standard, the following Clip AV stream file playback method can be realized. That is, another Clip AV stream file associated with the disc is downloaded via the network and recorded in the local storage. A PlayList in which the Clip AV stream file recorded on the disc and the Clip AV stream file recorded on the local storage are associated is created as a Virtual Package. Each Clip AV stream file is reproduced according to the PlayList in this Virtual Package (see Patent Document 1). By using such Virtual Package technology, playback while downloading, that is, so-called streaming becomes possible. Hereinafter, such a reproduction method is referred to as a conventional streaming method.
JP 2005-159589 A

  However, in the conventional streaming method, when a clip AV stream file is played while being downloaded, the network bandwidth may fluctuate during this time. In such a case, if the clip AV stream file to be played back catches up with the clip AV stream to be downloaded, a situation occurs in which playback stops.

  The present invention has been made in view of such a situation, and makes it possible to avoid a situation in which playback is stopped during streaming in accordance with a PlayList according to the BD-ROM standard.

  The data structure of one aspect of the present invention is a multi-angle type PlayItem defined by the BD-ROM (Blu-ray Disc-Read Only Memory) standard, and instead of a plurality of angles of a Clip AV stream file, Refer to Clip AV stream files with multiple bit rates that are obtained as a result of encoding the same material at multiple bit rates, and that are downloaded over the network. The data structure of the PlayList includes one or more PlayItems.

  In the data structure of one aspect of the present invention, the PlayList includes one or more PlayItems as follows. In other words, in the multi-angle type PlayItem defined in the BD-ROM (Blu-ray Disc-Read Only Memory) standard, the same material is used at multiple bit rates instead of multiple-angle Clip AV stream files. Reference is made to Clip AV stream files of a plurality of bit rates to be downloaded via the network, which are obtained as a result of encoding.

  A playback device according to an aspect of the present invention is a multi-angle type PlayItem defined by the BD-ROM (Blu-ray Disc-Read Only Memory) standard, and instead of a plurality of angles of a Clip AV stream file, Play a PlayList containing one or more PlayItems that refer to Clip AV stream files of multiple bit rates to be downloaded via the network, obtained as a result of encoding the same material at multiple bit rates. The playback control means monitors the speed of the network, and determines that the speed has become below a certain level, and uses the PlayItem angle switching control to determine the clip to be downloaded. The AV stream file is switched to a Clip AV stream file having a lower bit rate than before.

  The apparatus further comprises storage means for storing the Clip AV stream file downloaded under the control of the playback control means, wherein the playback control means is configured to control the network speed based on the storage amount of the Clip AV stream file in the storage means. It is determined whether or not is below a certain level.

  When the playback control means determines that the speed has become below a certain level, for the PlayItem to be downloaded next, in addition to the clip AV stream file of the bit rate after switching, the clip of the bit rate before switching Control to download AV stream file.

  The reproduction control means further prohibits the angle switching by the user.

  The reproduction method and program according to one aspect of the present invention correspond to the reproduction apparatus according to one aspect of the present invention described above.

  In the playback apparatus, method, and program of one aspect of the present invention, a multi-angle type PlayItem defined by a BD-ROM (Blu-ray Disc-Read Only Memory) standard, and a clip AV stream having a plurality of angles. A clip AV stream file with multiple bit rates obtained as a result of encoding the same material at multiple bit rates instead of file, and multiple bit rate clips to be downloaded over the network Playback of a PlayList that includes one or more PlayItems that refer to an AV stream file is controlled as follows. When the speed of the network is monitored and it is determined that the speed has become below a certain level, a clip AV stream file to be downloaded is used as a clip AV stream file to be downloaded by using the angle switching control of the PlayItem. Switch to Clip AV stream file.

  According to the present invention, it is possible to avoid a situation in which playback is stopped during streaming according to a PlayList based on the BD-ROM standard.

  First, in order to facilitate understanding of the present invention, some conventional techniques on which the present invention is based will be described.

  First, a multi-angle type PlayList will be described with reference to FIG. 1 and FIG.

  In the example of FIG. 1, there is one multi-angle type PlayList, and there is also one PlayItem. Also, it is assumed that there are three angles Angle # 1, Angle # 2, and Angle # 3 in the multi-angle playback time section.

  For example, PlayItem has three pieces of information. The first information is information (instruction information) of the reference destination of the AV stream used in multi-angle playback. For example, in the case of the example in FIG. 1, the instruction information that refers to Clip AV stream 1, Clip AV stream 2, and Clip AV stream 3 is the first information. That is, the instruction information (pointer) refers to information indicating the reference destination. The second information is an in point (IN_time) and an out point (OUT_time) representing a time section of multi-angle playback. In the case of the example in FIG. 1, IN_time = T1 and OUT_time = T4. The third information is the time of the entry point indicating the angle switching point in the multi-angle playback time section, and is T2 and T3 in the example of FIG.

  As described above, a multi-angle type PlayItem is associated with a plurality of Clip AV streams. Therefore, when a PlayItem is being played, an AV stream to be played (example of FIG. 1) is detected by a user operation or navigation (a Java (registered trademark) application executed in a Java (registered trademark) application execution environment described later). In this case, switching between Clip AV stream 1, Clip AV stream 2, and Clip AV stream 3) is possible.

  As shown in FIG. 2, each Clip AV stream is associated with a Clip Information file having an EP_map. EP_map is address information (SPN: Source packet Number) at which the decoding of the stream in the Clip AV stream file is to be started when an access point in the Clip AV stream is designated by a time stamp (PTS: Presentation Time Stamp). Help me find).

  Specifically, each video stream data in the stream data A1, B1, and C1 starts from a Closed GOP starting from a Sequence header. Each display start time stamp is the same at T1, and each display period is the same at (T1-T2). The Closed GOP is a GOP that is closed within one section (for example, the playback sections a1, b1, and c1), and is encoded so as to be completed within the section. Of course, as long as it is encoded so as to be completed within each section, that is, between one section (for example, playback section a1) and another section (for example, playback section b1), If there is no prediction relationship, it may not be a GOP.

  As for AV stream data A2, B2, and C2, each video stream data starts from a Closed GOP starting from Sequence header, and each display start time stamp is the same at T2, and each display period is also ( T2-T3) are the same.

  Furthermore, for the AV stream data A3, B3, and C3, each video stream data starts from a Closed GOP starting from the Sequence header, each display start time stamp is the same at T3, and each display period is also ( T3-T4) are the same. In all the video stream data of AV stream data A1, B1, C1, A2, B2, C2, A3, B3, and C3, the picture displayed at the beginning of the Closed GOP is an I picture.

  The audio stream data in the AV stream data A1, B1, and C1 is the same, the audio stream data in the AV stream data A2, B2, and C2 is also the same, and the AV stream The audio stream data in the data A3, B3, and C3 is also the same.

  The AV stream data A1, B1, and C1 include a video packet and an audio packet. Each head packet is a video packet, and its payload starts with an I picture starting from a Sequence header and a GOP header. Each head packet of the AV stream data A2, B2, and C2 is also a video packet, and its payload starts with an I picture starting from a Sequence header and a GOP header. Each head packet of AV stream data A3, B3, and C3 is also a video packet, and its payload starts with an I picture starting from a Sequence header and a GOP header.

  Note that each of the AV stream data A1, B1, and C1 may start from PAT (Program Association Table) and PMT (Program Map Table), and the subsequent elementary stream packet may be a video packet.

  The Clip Information file has an EP_map that is a map that describes the correspondence between the time stamp of the entry point in the Clip and the source packet number at which decoding of the stream is to start in the Clip AV stream file. The source packet number is a number that is incremented by 1 in the order of the source packets in the Clip AV stream file, and the top source packet number of the file is set to zero.

  The leading packet numbers of AV stream data A1, A2, and A3 are x1, x2, and x3, and the leading packet numbers of AV stream data B1, B2, and B3 are y1, y2, and y3, Furthermore, if the leading packet numbers of the AV stream data C1, C2, and C3 are z1, z2, and z3, the EP_map of each ClipInformation 1, 2, and 3 has the contents shown in FIG.

  In the EP_map of Clip Information 1 of Clip AV stream 1, the payload of the source packet pointed to by numbers x1, x2, and x3 starts from an I picture having a display start time of time stamps T1, T2, and T3.

  In the EP_map of Clip Information 2 of Clip AV stream 2, the payload of the source packet pointed to by numbers y1, y2, and y3 starts from an I picture having a display start time of time stamps T1, T2, and T3.

  In the EP_map of Clip Information 3 of Clip AV stream 3, the payload of the source packet pointed to by numbers z1, z2, and z3 starts from an I picture having a display start time with time stamps T1, T2, and T3.

  Specifically, for example, assume that playback switching to Angle # 3 is performed while Angle # 2 is being played back between T2 and T3. In this case, the playback device refers to the EP_map of Clip Information 3 and plays back the clip AV stream 3 from SPN = z3 at the time T3, that is, playback from the first packet (packet number z3) of the AV stream data C3. Start.

  Next, the Virtual Package defined in BD-ROM format Part3 (AV) will be described.

  As shown in FIG. 3, BD-ROM format Part 3 (AV) defines a method of creating a Virtual Package 13 by connecting a disk 11 and a local storage 12 using a Binding Unit Manifest file. That is, this method is one of the methods for reproducing the Clip AV stream file recorded on the disc 11. Another Clip AV stream file associated with the disk 11 is downloaded via a network, for example, and recorded in the local storage 12. Thereafter, the Clip AV stream file recorded on the disk 11 and the Clip AV stream file recorded on the local storage 12 are associated with each other to create a Virtual Package 13. Each Clip AV stream file is reproduced based on the Virtual Package 13.

  Specifically, it is assumed that the directory structure shown in FIG.

  The root directory includes a directory having a predetermined name, for example, a “BDMV” directory.

  The “BDMV” directory stores a file set with the name “info.bdmv” and a file set with the name “MovieObjects.bdmv”.

  The “BDMV” directory also includes a directory with the name “PLAYLIST” (PLAYLIST directory), a directory with the name “CLIPINF” (CLIPINF directory), and a directory with the name “STREAM” (STREAM). Directory) and the like.

  A PlayList file is stored in the PLAYLIST directory. Each PlayList file is named by adding an extension “.mpls” to a file name consisting of 5 digits as shown in the figure.

  A Clip Information file (see FIG. 2) is stored in the CLIPINF directory. Each Clip Information file is named by adding the extension “.clpi” to a file name consisting of five digits as shown in the figure.

  In the STREAM directory, a Clip AV stream file and a substream file are stored. Each stream file is given a name obtained by adding an extension “.m2ts” to a file name consisting of five digits as shown in the figure.

  Further, it is assumed that the directory structure shown in FIG.

  The root directory stores a directory (xxx-yyy directory) in which the name “xxx-yyy” is set.

  In the xxx-yyy directory, another Clip AV stream file associated with the disk 11 is recorded, for example, another Clip AV stream file downloaded via the network, and various information necessary for the reproduction is recorded. Is done.

  In the xxx-yyy directory, a file with the name “zzzzz.bumf” is stored. This file is the Binding Unit Manifest file defined in the above-described BD-ROM format Part3 (AV).

  In the xxx-yyy directory, a directory (NewData directory) in which the name “New Data” is set is stored. In the NewData directory, files f1 to f3 are stored as information downloaded from a network or the like. The file f3 is a file in which the name “04000.m2ts” is set, and is another Clip AV stream file associated with the disk 11. The file f1 is a file set with the name “22222.mpls”, and is a PlayList file for the file f3. The file f2 is a file in which the name “04000.clpi” is set, and is a Clip Information file for the file f3.

  In this case, the virtual package 13 is constructed by rearranging the files f1 to f3 in the NewData directory on the local storage 12 in the corresponding directory with respect to the directory structure of the disk 11. That is, in the Virtual Package 13, the file f1 is stored in the PLAYLIST directory, the file f2 is stored in the CLIPINF directory, and the file f3 is stored in the STREAM directory.

  By adopting such a technique for playing a PlayList using the Virtual Package 13, an application such as streaming can be realized. That is, this method is the conventional streaming method described in [Background Art].

  For example, it is assumed that a PlayList file and a Clip Information file as shown in FIG. In FIG. 4, “Disk 11 / Local Storage 12” is described because the above-described Virtual Package 13 can be created, and the recording location of the PlayList file and Clip Information file is the same as that in Disk 11 as well. This is because any of 12 is acceptable. This also applies to FIGS. 5 to 10 described later.

  Here, it is assumed that the clip AV stream file to be reproduced is not recorded on the disc 11. That is, when PlayList playback starts, Clip AV stream files referred to by the respective PlayItems are sequentially downloaded to the local storage 12 and sequentially played back.

  In FIG. 4 and subsequent figures, the Clip AV stream file is indicated by a dotted line, that is, a file having a name with an extension “.m2ts” added to a file name consisting of five digits is indicated by a dotted line. This means that the Clip AV stream file indicated by the dotted line has not been downloaded yet.

  Hereinafter, a Clip AV stream file having a name obtained by adding an extension “.m2ts” to a file name consisting of five digits is simply expressed using the name. Further, the entire Clip AV stream file having a name obtained by adding the extension “.m2ts” to a file name consisting of five digits is collectively referred to as an m2ts file.

  For example, in the example of FIG. 5, “10000.m2ts” to “10003.m2ts” have been downloaded, and “10004.m2ts” to “10006.m2ts” have not yet been downloaded. That is, “10004.m2ts” is the Clip AV stream file to be downloaded next.

  The conventional streaming method has been described above with reference to FIGS. 4 and 5.

  By the way, during reproduction according to the conventional streaming method, that is, during reproduction of a PlayList as in the examples of FIGS. 4 and 5, the network bandwidth may fluctuate. That is, the network speed may decrease. In such a case, as shown in FIG. 5, when the clip AV stream file to be played back catches up with the clip AV stream file to be downloaded (“10004.m2ts” in the example of FIG. 5), a situation where playback stops Will occur.

  Accordingly, the present inventors have invented a technique of dynamically changing the bit rate of the Clip AV stream file to be downloaded in order to avoid such a situation. Hereinafter, this method is referred to as a download stream bit rate variable method.

  However, in order to realize the download stream bit rate variable method, it is necessary to consider the following assumptions.

  That is, there is a precondition that all the Clip Information files referred to by the PlayList must be prepared in advance before playing the PlayList. This is a prerequisite that arises in order to be able to store the EP_map in advance in the memory of the playback device. This assumption can also be understood as the assumption that the time stamp-address correspondence of the Clip AV stream file (m2ts file) is fixed by the predetermined EP_map before playing the PlayList. .

  Therefore, under such preconditions, when a PlayList according to the conventional streaming method, that is, a PlayList as in the examples of FIGS. 4 and 5 is adopted, once playback is started, the clip to be downloaded is downloaded. The bit rate of AV stream file cannot be changed. This is because the predetermined time stamp-address relationship of EP_map cannot be applied to a Clip AV stream file whose bit rate is lowered. That is, if the bit rate of the Clip AV stream file to be downloaded is changed, normal reproduction cannot be performed.

  In summary, under the premise, when the PlayList according to the conventional streaming method, that is, the PlayList as in the examples of FIGS. 4 and 5 is adopted, the download stream bit rate variable method cannot be realized.

  Accordingly, the present inventors have invented the following streaming method (hereinafter referred to as the streaming method of the present invention) that can realize the download stream bit rate variable method.

  That is, in the streaming method of the present invention, the PlayList includes one or more PlayItems using a multi-angle type structure. However, the concept of multi-bit rate is adopted instead of the concept of multi-angle. That is, under the conventional multi-angle concept, PlayItem refers to Clip AV stream files of various angles. On the other hand, under the concept of multi-bit rate, PlayItem refers to Clip AV stream files of various bit rates. Here, Clip AV stream files of various bit rates mean files obtained as a result of encoding the same video material at different bit rates (image quality). That is, conventionally, the concept of angle selection is adopted, whereas the streaming technique of the present invention adopts the concept of bit rate selection.

  Specifically, for example, in the streaming method of the present invention, reproduction by a PlayList as shown in FIG. 6 is possible.

  In FIG. 6, the video material itself of the Clip AV stream file reproduced with PI (Play Item) # (k + 1) (k is an integer value of 0 to 6) is obtained by the conventional streaming method shown in FIGS. Suppose that it is identical to the video material adopted. Further, in the conventional streaming methods of FIGS. 4 and 5, it is assumed that the bit rate is fixed at 2 Mbps. In this case, in PI # (k + 1) of FIG. 6, “1000k.clpi” of 2 Mbps (Angle-1) is “1000k.m2ts” (this file itself is only k = 0 to 3 in FIG. 6). Is shown). “1000k.m2ts” is a Clip AV stream file obtained as a result of encoding the same video material as in the examples of FIGS. 4 and 5 at the same bit rate (= 2 Mbps).

  Further, “2000k.clpi” of 1 Mbps (Angle-2) in PI # (k + 1) of FIG. 6 refers to “2000k.m2ts” (this file itself is not shown in FIG. 6). . Therefore, “2000k.m2ts” is a Clip AV stream file obtained as a result of encoding the same video material as “1000k.m2ts” at a bit rate (= 1 Mbps) different from “1000k.m2ts”.

  Similarly, in PI # (k + 1) of FIG. 6, “3000k.clpi” of 0.5 Mbps (Angle-3) is “3000k.m2ts” (this file itself is only k = 3 to 6 in FIG. 6). Is shown). Therefore, “3000k.m2ts” means a clip obtained as a result of encoding the same video material as “1000k.m2ts” at a bit rate (= 1 Mbps) different from “1000k.m2ts” and “2000k.m2ts”. AV stream file.

  Thus, the PlayItem employed in the streaming method of the present invention employs a conventional multi-angle type structure, such as PI # (k + 1) in FIG. However, the PlayItem employed in the streaming method of the present invention does not refer to Clip AV stream files of various angles as in the prior art, such as PI # (k + 1) in FIG. Refer to Clip AV stream file for rate. Hereinafter, the PlayItem employed in the streaming method of the present invention is hereinafter referred to as a PlayItem having a multi-bit rate structure of the present invention in order to clearly distinguish it from the conventional PlayItem.

  In the conventional PlayItem having a multi-angle type structure, it is possible to switch the angle to be reproduced. In the PlayItem having the multi-bit rate structure of the present invention, it is possible to switch the bit rate to be reproduced by using this “angle switching”.

  It is assumed that the bit rate switching control of the playback target is performed by a Java (registered trademark) application executed on the playback device side Java (registered trademark) application execution environment (see FIG. 11 described later). That is, the Java (registered trademark) application monitors the network bandwidth (speed) by monitoring the buffer amount of the downloaded Clip AV stream file (buffer amount of the local storage 12). If the Java (registered trademark) application determines that the bandwidth of the network has become narrower than a certain value (the speed has become less than a certain value), it switches the download target to a Clip AV stream file with a low bit rate.

  However, the issuance timing of the bit rate switching command (conventional angle switching command corresponding to selectAngle () in FIG. 6) by the Java (registered trademark) application and the actual bit rate switching operation by the playback device The timing (corresponding to the conventional angle switching operation) is not simultaneous. That is, the latter timing is delayed. Therefore, in the AV steam file playback section in the vicinity of switching the bit rate, the Clip AV stream file of the bit rate before switching (corresponding to the conventional original angle) and the bit rate after switching (corresponding to the conventional destination angle) Overlap of downloads is required. For example, in the example of FIG. 6, PI # 4 corresponds to an AV steam file playback section in the vicinity of switching the bit rate. Therefore, “10003.m2ts” of 2 Mbps and “30003.m2ts” of 0.5 Mbps are downloaded and accumulated in the local storage 12 of the playback device.

  In the conventional multi-angle type PlayItem, the user is allowed to perform “angle switching” operation, whereas in the multi-bit rate structure PlayItem of the present invention, the user can switch the bit rate. Operation (“angle switching” operation from the user's perspective) is prohibited. As described above, the purpose of the streaming method of the present invention is that when the network bandwidth is narrowed, the clip AV stream file to be played back catches up with the clip AV stream file to be downloaded and stops playing. Is to avoid. Therefore, if the operation of “switching the bit rate” by the user is permitted, the bit rate is changed regardless of the bandwidth of the network, and this will be lost.

  Further, a detailed example of the streaming method of the present invention will be described below with reference to FIGS.

  FIG. 7 shows a state before starting playback of the PlayList by the streaming method of the present invention.

  Before playing the PlayList, as shown in FIG. 7, it is assumed that the PlayList file and Clip Information files referenced by the PlayList are all in advance.

  In addition, it is assumed that a Java (registered trademark) application for controlling playback of the PlayList exists in the disk 11 or the local storage 12. The Java (registered trademark) application is executed by a CPU (Central Processing Unit) of the playback device. That is, the CPU executing the Java (registered trademark) application is the Java (registered trademark) application execution environment.

As the structure of PlayItem, the multi-bit rate structure of the present invention is adopted. That is, PlayItem refers to Clip AV stream files of various bit rates. Clip AV stream files of various bit rates are files obtained as a result of encoding the same video material at various bit rates (image quality) as described above. The conventional Clip AV stream file referred to by “Angle-1” is a 2 Mbps Clip AV stream file. The conventional Clip AV stream file referred to by “Angle-2” is a 1 Mbps Clip AV stream file.
A conventional “Angle-3” clip is a 0.5 Mbps Clip AV stream file.

  In addition, the PlayList file is specified to prohibit the user from performing a bit rate switching operation (the conventional “angle switching” operation).

  The Java (registered trademark) application checks the speed of the network prior to playing this PlayList. The Java (registered trademark) application determines the bit rate of the Clip AV stream file to be downloaded based on the network speed by a predetermined method. That is, the Java (registered trademark) application checks the network speed before reproduction to determine which bit rate (= angle) of the Clip AV stream file is to be reproduced.

  It is assumed that the bit rate of the Clip AV streams file is sufficiently small compared to the network speed. This premise is a premise for the purpose of making it possible to sufficiently increase the data storage amount (download speed) in the local storage 12 rather than the stream playback speed (reproduction data consumption amount).

  For example, it is assumed that the highest bit rate that can be selected is selected as the bit rate in the initial state among the bit rates that are equal to or less than half the speed of the network. For example, when the network speed is 4 Mbps or higher, 2 Mbps (Angle-1) is determined as the initial bit rate in the examples of FIGS.

  FIG. 8 shows a state immediately after playback of the PlayList by the streaming method of the present invention.

  The Java (registered trademark) application downloads “10000.m2ts” of 2 Mbps of PI # 1 as the first Clip AV stream file.

  Note that the Java (registered trademark) application does not start playing the PlayList at least until the first Clip AV stream file is downloaded. In the present embodiment, for example, when the first Clip AV stream file (“10000.m2ts” in the example of FIG. 8) is downloaded, PlayList playback is started.

  The Java (registered trademark) application monitors the network speed, and when the network speed is equal to or higher than a certain level, sequentially downloads the Clip AV stream file having the initial bit rate.

  In other words, in the example of FIG. 8, when 2 Mbps “10000.m2ts” of PI # 1 is downloaded, 2 Mbps “10001.m2ts” of PI # 2 is downloaded. After that, 2Mbps “10002.m2ts” of PI # 3 and 2Mbps “10003.m2ts” of PI # 4 are downloaded sequentially in that order.

  Here, when the network speed is N times the bit rate of the Clip AV stream file, the storage speed of the Clip AV stream file downloaded via the network in the local storage 12 is N of the playback speed of the Clip AV stream file. Double. Therefore, when the reproduction of the first Clip AV stream file is completed, it is expected that N clip AV stream files to be reproduced from the next time are accumulated in the local storage 12.

  For example, if N = 4, in the example of FIG. 8, the network speed is 8 Mbps (= 2 Mbps × 4), and the playback speed of “10000.m2ts” of PI # 1 that is the first Clip AV stream file is 2 Mbps. Become. In this case, at the end of playback of “10000.m2ts”, N = 4 Clip AV stream files transmitted via the network at 8 Mbps should have been downloaded. That is, PI # 2 2Mbps "10001.m2ts", PI # 3 2Mbps "10002.m2ts", PI # 4 2Mbps "10003.m2ts", and PI # 5 2Mbps "10004.m2ts" A total of four Clip AV stream files should be stored in the local storage 12.

  Therefore, when playback of the clip AV stream file of PI # (k + 1) is completed, the clip AV stream file of PI # (k + 2) to PI # (K + 1 + N) to be played back after the next Is at least stored in the local storage 12 as a steady state. That is, a state where at least N Clip AV stream files are accumulated in the local storage 12 is a steady state.

  For example, when N = 4, when playback of the clip AV stream file of PI # (k + 1) ends, at least the clip AV stream file of PI # (k + 2) to PI # (K + 5) is local The state that is at least accumulated in the storage 12 is a steady state. That is, a state where N = 4 or more Clip AV stream files are accumulated in the local storage 12 is a steady state.

  Specifically, for example, when k = 0, at the end of playback of PI # 1 “10000.m2ts”, PI # 2 2Mbps “10001.m2ts”, PI # 3 2Mbps “10002.m2ts” ”, PI # 4 2 Mbps“ 10003.m2ts ”and PI # 5 2 Mbps“ 10004.m2ts ”, a total of four clip AV stream files are stored in the local storage 12 in a steady state. It is.

  Such a steady state should be maintained as long as the network speed is maintained. However, when the network speed decreases, it becomes difficult to maintain a steady state.

  Therefore, for example, the Java (registered trademark) application compares the number of Clip AV stream files stored in the local storage 12 (hereinafter referred to as the stored number) with a threshold (for example, N / 2), Whether or not the network speed is reduced can be determined. That is, when the accumulated number exceeds the threshold, it is determined that the network speed has not decreased. On the other hand, when the accumulated number is equal to or less than the threshold value, it is determined that the network speed is decreasing.

  When it is determined that the network speed has decreased, the Java (registered trademark) application switches the Clip AV stream file to be downloaded next to the Clip AV stream file having a lower bit rate than the current one. Note that the switching method itself is not particularly limited.

  Specifically, for example, N = 4 and threshold = (N / 2) = 2. In this case, at the end of playback of PI # 1 “10000.m2ts”, PI # 2 2Mbps “10001.m2ts”, PI # 3 2Mbps “10002.m2ts”, and PI # 4 2Mbps Assume that a total of three (> threshold 2) Clip AV stream files of “10003.m2ts” are stored in the local storage 12 at least. In this case, since the accumulated number 3> the threshold value 2, it is determined that the network speed has not decreased. Therefore, the bit rate is not switched, and then 2 Mbps “10004.m2ts” of PI # 5 is downloaded.

  On the other hand, for example, as shown in FIG. 9, at the end of playback of PI # 1 “10000.m2ts”, PI # 2 2 Mbps “10001.m2ts” and PI # 3 2 Mbps “10002” It is assumed that a total of two (= threshold 2) Clip AV stream files “.m2ts” are stored in the local storage 12. In this case, since the accumulated number 2 = threshold value 2, it is determined that the network speed is decreasing. Therefore, as shown in FIG. 10, the Java (registered trademark) application switches the bit rate (= conventional) so that the clip AV stream file of the next PI # 4 to be downloaded has a low bit rate. Control of “angle switching”). For example, in the example of FIG. 10, switching is performed so that a Clip AV stream file having a bit rate (= Angle-3) of 0.5 Mbps is downloaded.

  As a result, in the example of FIG. 10, PI # 4 0.5 Mbps “30003.m2ts”, PI # 5 0.5 Mbps “30004.m2ts”, and PI # 6 0.5 Mbps “30005.m2ts” , PI # 7 0.5Mbps "30006.m2ts" will be downloaded sequentially in that order.

  However, as described above, the issuance timing of the bit rate switching command (conventional angle switching command corresponding to selectAngle () in FIG. 10) by the Java (registered trademark) application and the actual bit by the playback device The timing of the rate switching operation (corresponding to the conventional angle switching operation) is not simultaneous. That is, the latter timing is delayed. Therefore, in PI # 4 near the bit rate switching, the 2Mbps “10003.m2ts” before switching and the 0.5Mbps “30003.m2ts” after switching are overlapped and downloaded, and the local storage 12 of the playback device 12 Accumulated in.

  Note that the Java (registered trademark) application continues to monitor the network speed (accumulated amount of the local storage 12 and the like).

  For example, if the network speed further decreases and the playback catches up with the download, the playback temporarily stops.

  Conversely, for example, when it is determined that the network speed has increased, the Clip AV stream file to be downloaded next is switched to one having a higher bit rate than the current one.

  Note that the switching method itself is not particularly limited. However, for safety reasons, it is preferable to switch to a bit rate that is one step higher than the current level. In this case, for example, in the example of FIG. 10, switching from 0.5 Mbps (Angle-3) to 1 Mbps (Angle-2) is performed. In this case as well, in the AV steam file playback section in the vicinity of switching the bit rate, the bit rate before switching (corresponding to the conventional original angle) and the bit rate after switching (corresponding to the conventional destination angle) Clip AV stream file downloads may be overlapped.

  The streaming method of the present invention has been described above with reference to FIGS. FIG. 11 shows a configuration example of a playback apparatus capable of playback according to the streaming method of the present invention. That is, FIG. 11 shows a configuration example of an embodiment of a playback apparatus to which the present invention is applied.

  The playback device 21 in the example of FIG. 11 includes a disk drive 41, a local storage 12, a network interface 42, a memory 45, a Java (registered trademark) application execution environment 44, and an AV decoder 46.

  The disk drive 41, the local storage 12, the network interface 42, the memory 45, and the Java (registered trademark) application execution environment 44 are connected to each other by a bus 43. The AV decoder 46 is connected to the bus 43 and the Java (registered trademark) application execution environment 44.

  Explaining in order, before playing a PlayList, the PlayList file and Clip Information files referenced by the PlayList are all on the disc 11 or the local storage 12. In addition, a Java (registered trademark) application for controlling the playback of this PlayList exists in the disk 11 or the local storage 12. These PlayList file, Clip Information file, and Java (registered trademark) application are stored in the memory 45.

  The Java (registered trademark) application executed in the Java (registered trademark) application execution environment 44 checks the speed of the network 33 by controlling the network interface 42 before playing the PlayList. The Java (registered trademark) application determines which bit rate (= angle) is to be reproduced as an initial state based on the investigation result.

  The Java (registered trademark) application controls the network interface 42 to communicate with the server 22 via the network 33. That is, the server 22 stores Clip AV stream files of various bit rates to be downloaded. Therefore, the Java (registered trademark) application downloads the Clip AV stream file having the bit rate determined as the initial state from the server 22 and stores it in the local storage 12.

  The Java (registered trademark) application determines whether there is a decrease in the network speed by examining the storage amount of the local storage 12.

  When it is determined that the network speed has decreased, the Java (registered trademark) application executes the conventional “angle switching control” to switch the clip AV stream file to be downloaded to one with a reduced bit rate. That is, the Java (registered trademark) application notifies the server 22 of switching of download. Upon receiving the notification, the server 22 transmits a Clip AV stream file with a low bit rate. The Java (registered trademark) application downloads a Clip AV stream file having a low bit rate and stores it in the local storage 12.

  Even when it is determined that the network speed has increased, the Java (registered trademark) application performs basically the same operation as when the network speed has been decreased, so that a Clip AV stream with a high bit rate is obtained. The file can be downloaded and stored in the local storage 12.

  During this time, the Java (registered trademark) application controls the AV decoder 46 to reproduce the PlayList. That is, the AV decoder 46 reads out the Clip AV stream file to be reproduced next from the local storage 12 according to the PlayList, and performs a decoding process. Thereby, a video signal and an audio signal are obtained and output to an external monitor or the like.

  By the way, the series of processes described above can be executed by hardware, but can also be executed by software.

  When a series of processing is executed by software, a program constituting the software executes various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a network or a recording medium into the general-purpose personal computer or the like other than the playback device 21 of FIG.

  As shown in FIG. 11, the recording medium including such a program is distributed to provide a program to the user separately from the apparatus main body, and a magnetic disk (including a floppy disk) on which the program is recorded. An optical disk (including a compact disk-read only memory (CD-ROM), a DVD (Digital Versatile Disk), a disk 11 of FIG. 11 such as a Blu-ray disk), a magneto-optical disk (including an MD (Mini-Disk)), or In addition to a removable medium (package medium) composed of a semiconductor memory or the like, the local storage 12 or the memory 45 in which a program is recorded, a personal computer, etc. provided to the user in a state of being incorporated in the apparatus main body in advance. The hard disk included in

  In the present specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in chronological order according to the order, but is not necessarily performed in chronological order, either in parallel or individually. The process to be executed is also included.

  Further, in the present specification, the system represents the entire apparatus composed of a plurality of processing devices and processing units.

  Note that the playback apparatus of the present invention can switch the output video signal after identifying the display system including the ordinary display.

It is a figure explaining the conventional multi-angle type PlayItem. It is a figure explaining the conventional multi-angle type PlayItem. It is a figure explaining Virtual Package. It is a figure explaining the conventional streaming method. It is a figure explaining the conventional streaming method. It is a figure explaining the outline | summary of the streaming method of this invention. It is a figure explaining the detail of the streaming method of this invention. It is a figure explaining the outline | summary of the streaming method of this invention. It is a figure explaining the outline | summary of the streaming method of this invention. It is a figure explaining the outline | summary of the streaming method of this invention. It is a block diagram which shows the structural example of the reproducing | regenerating apparatus which can reproduce | regenerate according to the streaming method of this invention, ie, the reproducing | regenerating apparatus to which this invention is applied.

Explanation of symbols

  11 disk, 12 local storage, 13 Virtual Package, 21 playback device, 22 server, 33 network, 41 disk drive, 42 network interface, 43 bus, 44 Java (registered trademark) application execution environment, 45 memory, 46 AV decoder

Claims (7)

A multi-angle type PlayItem defined in the BD-ROM (Blu-ray Disc-Read Only Memory) standard,
Instead of multiple-angle Clip AV stream files, refer to multiple-bit-rate Clip AV stream files that are downloaded as a result of encoding the same material at multiple bit rates. A data structure of a PlayList including one or more PlayItems. It is a multi-angle type PlayItem defined by the BD-ROM (Blu-ray Disc-Read Only Memory) standard, and the same material is used at multiple bit rates instead of multiple-angle Clip AV stream files. A playback control means for controlling playback of a PlayList including one or more PlayItems obtained by encoding and referencing Clip AV stream files of a plurality of bit rates to be downloaded via a network;
The reproduction control means includes
When the network speed is monitored and it is determined that the speed has become below a certain level, the clip AV stream file to be downloaded is used as the clip AV stream file to be downloaded by using the angle switching control of the PlayItem. Playback device that switches to AV stream file. A storage means for storing the Clip AV stream file downloaded under the control of the playback control means;
The playback apparatus according to claim 2, wherein the playback control means determines whether or not the speed of the network has become below a certain level based on an accumulation amount of the Clip AV stream file in the storage means. When the playback control means determines that the speed has become below a certain level, for the PlayItem to be downloaded next, in addition to the clip AV stream file of the bit rate after switching, the clip of the bit rate before switching The playback device according to claim 2, wherein the playback is controlled so as to download the AV stream file. The playback apparatus according to claim 2, wherein the playback control means further prohibits the angle switching by a user. It is a multi-angle type PlayItem defined by the BD-ROM (Blu-ray Disc-Read Only Memory) standard, and the same material is used at multiple bit rates instead of multiple-angle Clip AV stream files. A playback device that controls playback of a PlayList that includes one or more PlayItems that refer to Clip AV stream files of a plurality of bit rates to be downloaded via a network obtained as a result of encoding,
When the network speed is monitored and it is determined that the speed has become below a certain level, the clip AV stream file to be downloaded is used as the clip AV stream file to be downloaded by using the angle switching control of the PlayItem. Playback method including the step of switching to AV stream file. It is a multi-angle type PlayItem defined by the BD-ROM (Blu-ray Disc-Read Only Memory) standard, and the same material is used at multiple bit rates instead of multiple-angle Clip AV stream files. A computer that controls playback of a PlayList that includes one or more PlayItems that refer to Clip AV stream files of a plurality of bit rates to be downloaded via a network, obtained as a result of encoding,
When the network speed is monitored and it is determined that the speed has become below a certain level, the clip AV stream file to be downloaded is used as the clip AV stream file to be downloaded by using the angle switching control of the PlayItem. A program that executes control processing including steps to switch to AV stream file.

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