JP5397301B2 - Content playback apparatus and content playback method - Google Patents

Description

  Embodiments of the present invention relate to playback of content files.

  2. Description of the Related Art In recent years, content distribution systems that allow content playback apparatuses to download content files from content servers via a network have been operated. The content file is stored and distributed in a predetermined file format (for example, MP4).

  The content reproduction apparatus that can use such a content distribution system includes various devices such as a mobile phone, a personal computer, a TV receiver, a video recorder, and a video game machine. There are various hardware resources that can be used by these content reproduction apparatuses. Some devices have a storage capacity capable of storing a large-capacity content file, and some devices do not.

  There has been proposed a function of reproducing content data that can be reproduced (already downloaded) of the content file while downloading the content file in the background. According to such a function, it is possible to sequentially discard the reproduced content data, so that even a content reproduction device having a small storage capacity can be reproduced while downloading a large-capacity content file.

JP 2008-46944 A

  When the content reproduction apparatus is a multifunctional device such as a mobile phone, an interruption process such as an incoming call may occur during the reproduction of the content file. When the interruption process occurs, the reproduction of the content file is interrupted, and the reproduction of the content file is resumed after the interruption process is completed. In addition, the user may wish to interrupt the playback of the content file.

  However, when reproducing a content file in a format (for example, MP4) on the assumption that the entire file can always be referred to, consistency of the content file cannot be maintained if the reproduced content data is discarded. Therefore, in order to resume reproduction, not only unreproduced content data but also data from the beginning of the content file to the beginning of the unreproduced content data is required. Although it is possible to resume the reproduction of the content file by re-downloading the content file from the beginning, the delay and communication cost associated with this re-downloading are not preferable. In addition, it is possible to resume playback by storing all downloaded content data in the storage unit, but it is not preferable to load the storage process, compress the storage area, and the amount of content data is stored in the storage unit. If the storage capacity is exceeded, storage is impossible. In addition, the content distribution source may desire to impose restrictions on the number of times the content is reproduced, the reproducible time, etc. (for example, restricting the content reproduction to one time). If the reproduction of the content is limited to one time, even if the reproduced content data is stored in the storage unit, it can only be used to maintain the consistency of the content file.

  Therefore, an object of the embodiment of the present invention is to provide a content reproduction apparatus capable of reducing the amount of data stored in a storage unit in order to resume reproduction of a content file.

  The content reproduction apparatus according to the embodiment includes a buffer and a downloader that receives content data included in the content file and buffers the content data in the buffer. The content playback apparatus includes a first backup unit that stores content data indicating the top metadata in the content file in a storage unit, and a playback unit that plays back the content data in the buffering order of the buffers. The content playback apparatus includes a second backup unit that stores, in a storage unit, unplayed content data buffered in a buffer and information indicating a playback resume point when playback of the content file is interrupted. . When the reproduction of the content file is resumed, the content reproduction apparatus sequentially buffers the content data indicating the top metadata, the data for instructing skipping of the analysis up to the reproduction resume point, and the unreproduced content data. A restart processing unit for ringing is included.

The functional block diagram which shows the content reproduction apparatus which concerns on one Embodiment. The block diagram which shows the hardware constitutions of the content reproduction apparatus which concerns on one Embodiment. The block diagram which shows a content delivery system. The block diagram which shows the software structure of the content reproduction apparatus which concerns on one Embodiment. The figure which shows the structure of a content file. Explanatory drawing of the reproduction | regeneration restart process which the content reproduction apparatus which concerns on one Embodiment performs. The figure which shows the data for maintaining the integrity of a file when reproduction | regeneration is restarted. Explanatory drawing of a reproduction | regeneration resumption point. The flowchart which shows the content reproduction process which the content reproduction apparatus which concerns on one Embodiment performs.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(One embodiment)
As shown in FIG. 1, a content playback apparatus according to an embodiment of the present invention includes a downloader 101, a buffer 102, a first backup unit 103, a storage unit 104, a playback unit 105, a second backup unit 106, and a restart process. Part 107. Each functional block in FIG. 1 will be described later together with a hardware configuration and a software configuration of the content reproduction apparatus according to the present embodiment.

  FIG. 2 illustrates a hardware configuration of the content reproduction apparatus according to the present embodiment. The content playback device 30 in FIG. 2 is typically a mobile phone, but is not limited thereto. As shown in FIG. 3, the content reproduction device 30 reproduces reproducible content data while sequentially downloading content data included in a desired content file from the content server 31 via the network 32.

  A CPU (Central Processing Unit) 10 implements the function of the content reproduction apparatus according to the present embodiment by executing a content reproduction program stored in the storage unit 16. The memory 11 is a volatile storage medium that temporarily stores data used by the CPU 10 or the like.

  The input device 12 is a device such as a plurality of key switches (for example, numeric keys) and a touch panel. The input processing unit 13 is a user interface that receives a request from the user via the input device 12.

  The communication unit 14 performs processing necessary for data transmission / reception in accordance with an instruction from the CPU 10. The antenna 15 transmits an RF (Radio Frequency) band signal based on transmission data, or receives an RF band signal that is the basis of reception data. When the content reproduction apparatus performs wired communication, the antenna 15 may be replaced with a terminal for wired communication. The storage unit 16 is a nonvolatile storage medium such as a flash memory or an HDD (Hard Disk Drive). As described above, the storage unit 16 stores a content reproduction program and the like.

  The audio processing unit 17 performs decoding of audio data and other audio processing. The audio output unit 18 is a speaker, for example, and outputs an audio signal from the audio processing unit 17. The video processing unit 19 performs decoding of video data and other video processing. The video output unit 20 is, for example, an LCD (Liquid Crystal Display), an OLED (Organic Light Emitting Diode) display, and the like, and outputs a video signal from the video processing unit 19.

  FIG. 4 illustrates a software configuration of the content reproduction apparatus according to the present embodiment. When the CPU 10 executes the content reproduction program, the reproduction application 110, the downloader 120, the buffer 130, the parser 140, and the decoder 150 are realized.

  The playback application 110 receives input from the user via the input device 12 and the input processing unit 13 and performs processing for starting playback of a desired content file. For example, the playback application 110 instructs the downloader 120 to download a desired content file. In addition, the playback application 110 instructs the operations of the downloader 120, the buffer 130, the parser 140, and the decoder 150. In addition, when an interrupt process such as an incoming call occurs, the playback application 110 performs a process for interrupting the playback of the content file in response to a request from the operating system or the like. The reproduction application 110 performs a process for resuming the reproduction of the content file when the interruption process ends.

  The downloader 120 sequentially downloads content data included in a desired content file from the content server via the communication unit 14 and the antenna 15 via the network. The content data downloaded by the downloader 120 is sequentially buffered in a buffer memory (not shown) by the buffer 130.

  The buffer 130 is software that buffers downloaded content data using a partial storage area of the memory 11. The buffer 130 passes the buffered content data to the parser 140. The buffer 130 notifies the parser 140 of the top file position of the transferred content data and the data size of the transferred content data. The buffer 130 may determine content data to be passed to the parser 140 according to a request from the parser 140, or may autonomously determine content data to be passed to the parser 140.

  The parser 140 analyzes the content data passed from the buffer 130, separates the content data into video data and audio data, and inputs them to the decoder 150. The parser 140 may request the buffer 130 to deliver content data necessary for reproduction.

  The decoder 150 controls the video processing unit 19 and the audio processing unit 17 to decode video data and audio data according to a predetermined encoding method, and outputs the decoded data via the video output unit 20 and the audio output unit 18.

Hereinafter, each functional block in FIG. 1 will be described with reference to the hardware configuration and the software configuration described above.
The downloader 101 has the same or similar function as the downloader 120 of FIG. The downloader 101 sequentially downloads content data included in a desired content file from the content server via the network in accordance with an instruction from the playback application 110 being executed by the CPU 10. The downloader 101 causes the buffer 102 to sequentially buffer the downloaded content data.

  Here, the structure of the content file will be described with reference to FIG. The content file to be reproduced by the content reproduction apparatus according to the present embodiment is in a format (for example, MP4) on the assumption that the entire file can always be referred to. Therefore, if the content data in the content file is partially removed and left-justified, consistency cannot be maintained.

  The content file includes media data that is video or audio data, and metadata indicating information necessary for reproducing the media data (content file structure, playback time of each frame, and the like). That is, the content data is media data or metadata.

  Media data is divided into a plurality of pieces in the content file, and divided metadata is assigned to each of the divided media data. A combination of the divided metadata and the divided media data is generally called a fragment. The metadata in the fragment indicates information necessary for reproducing the media data in the same fragment (such as the reproduction time of each frame included in the media data). Information (content file structure, etc.) necessary for starting playback of the content file is arranged before the fragment as part of the head metadata. The head metadata also includes information (such as the playback time of each frame included in the head media data) necessary for playing back the head media data. The fragment is arranged subsequent to the head metadata and the head media data. The head metadata may be placed before the head media data, or may be placed after the head media data. For example, if the content file is in the MP4 format, the top metadata corresponds to a combination of a plurality of boxes such as a moov box, and the metadata in the fragment corresponds to a moof box.

  The buffer 102 has the same or similar function as the buffer 130 of FIG. The buffer 102 uses the partial storage area of the memory 11 as a buffer memory to buffer downloaded content data. The buffer 102 passes the buffered content data to the playback unit 105.

  The first backup unit 103 copies the content data indicating the head metadata and stores it in the storage unit 104. The first backup unit 103 is realized by the reproduction application 110, the buffer 130, or the parser 140 shown in FIG. If the playback time of the head media data is about 15 seconds, the size of the head metadata is about several kbytes. Note that if the timing of saving the top metadata in the storage unit 103 is set before the start of the content file playback, the storage process can be executed without imposing a load on the content file playback process.

  The storage unit 104 is a nonvolatile storage medium corresponding to the storage unit 16 of FIG. The playback unit 105 has the same or similar function as the combination of the parser 140 and the decoder 150 of FIG. The playback unit 105 plays back the content file based on the content data passed from the buffer 102.

  When the reproduction of the content file is interrupted, the second backup unit 106 stores the unreproduced content data buffered by the buffer 102 and information indicating the reproduction resume point in the storage unit 104. Information indicating the reproduction restart point will be described later. The second backup unit 106 is realized by the reproduction application 110, the buffer 130, or the parser 140 shown in FIG.

  When the reproduction of the content file is resumed, the resume processing unit 107 saves the top metadata saved in the storage unit 104, data instructing skipping of the analysis up to the reproduction resume point, and the storage unit 104. Read unplayed content data. Each read data is sequentially buffered by the buffer 102. Note that data for instructing skipping of the analysis up to the playback restart point will be described later. The restart processing unit 107 is realized by the playback application 110 or the buffer 130 of FIG.

  Hereinafter, the reproduction restart process performed by the content reproduction apparatus according to the present embodiment will be described with reference to FIG. As described above, the content file has a format (for example, MP4) on the assumption that the entire file can always be referred to. Therefore, if the content data in the content file is partially removed and left-justified, consistency cannot be maintained.

  Since the start metadata includes information necessary for starting the reproduction of the content file, it is necessary for restarting the reproduction of the content file. The first metadata is stored in the storage unit 104 by the first backup unit 103. The head metadata stored in the storage unit 104 is used when replaying is resumed. Depending on the structure of the content file, the top metadata may refer to the top media data (for example, to display the top frame image). In such a case, the first backup unit 103 stores the top media data together with the top metadata in the storage unit 104, and both the stored top media data and top metadata are used when resuming playback. The

  The reproduced content data is replaced with data for maintaining file consistency when reproduction is resumed. The data for maintaining the consistency includes data instructing skipping of the analysis up to the reproduction restart point. Data instructing skipping of the analysis up to the playback restart point corresponds to, for example, a skip box or free box in MP4. FIG. 7 shows an example of the data structure for maintaining file consistency when resuming playback. Information indicating the amount of data to be skipped is stored in the size field (4 bytes) in FIG. For example, information indicating the data amount from the end of the top metadata (or a reference destination from the playback unit 105) to the top of the unreproduced content data is stored in the size field. Also, information indicating the type of this data is stored in the type field (4 bytes) in FIG. Since the playback unit 105 (parser 140) is normally designed to skip the analysis up to the playback resume point according to the data instructing skipping, the buffer 102 uses the information stored in the size field and the type field as the playback unit 105. You can maintain the integrity of the content file just by passing to. Even if the buffer 102 requests the reproduced content data from the reproduction unit 105, the consistency of the content file can be maintained by generating and passing dummy data corresponding to the requested data amount.

  Unreproduced content data is stored in the storage unit 104 by the second backup unit 106. Unreproduced content data stored in the storage unit 104 is also used when resuming reproduction.

  In this way, by replacing the reproduced content data with data instructing skipping, the consistency of the content file can be maintained without saving the reproduced content data. Further, since the top metadata (including the top media data in some cases) can be saved in the storage unit 104 before the start of reproduction and the unreproduced content data is interrupted after the reproduction is interrupted, the saving process does not impose a load on the reproduction process. It will end. Even if the reproduced content data is stored, it is better to use data instructing skipping if the content data is not reproduced. If the reproduced content data is replaced with data instructing skipping, processing delay due to transfer of the content data from the storage unit 104 to the buffer 102 and from the buffer 102 to the reproduction unit 105 can be avoided.

  Hereinafter, the reproduction restart point will be described with reference to FIG. In FIG. 8, the file position indicates the position of the content data (media data and metadata) in the content file, and the reproduction time is the reproduction time given to the content data (media data) arranged at the corresponding file position. Is shown. The interruption point indicates the reproduction time corresponding to the point where the reproduction is interrupted. The reproduction restart point indicates the file position corresponding to the point at which reproduction is resumed. Specifically, the reproduction restart point indicates the head position of the fragment to which the interruption point belongs. That is, when playback is interrupted in the middle of a fragment, playback is resumed from the beginning of this fragment. Therefore, strictly speaking, even reproduced video or audio is reproduced as part of unreproduced content data when resuming reproduction. One of the purposes of resuming playback from the beginning of the fragment is to ensure that unplayed video can be decoded. Frames constituting a video may not be able to be decoded unless a temporally past frame is referred to, and if a reproduced frame is discarded, an unreproduced frame may not be decoded. Note that the information indicating the reproduction restart point saved in the storage unit 104 by the second backup unit 106 may include information indicating the reproduction time corresponding to the file position in addition to the information indicating the file position. By storing information indicating the playback time, the playback time of the content file can be accurately restored when playback is resumed. For example, as shown in FIG. 8, if information indicating the playback time of “01:00:00” is stored, the correct playback time can be counted based on this “01:00:00” when playback is resumed. On the other hand, if the information indicating the playback time is not stored, the playback time of the content file is reset to “00:00:00” or the like when playback is resumed, and the accurate playback time becomes unknown. Note that the information indicating the playback restart point can be acquired by using the function of the parser 140.

Hereinafter, content reproduction processing performed by the content reproduction apparatus according to the present embodiment will be described with reference to FIG.
First, the downloader 101 starts downloading a desired content file (step S201). The content data downloaded by the downloader 101 is sequentially buffered by the buffer 102.

  The first backup unit 103 duplicates the head metadata buffered by the buffer 102 and stores it in the storage unit 104 (step S202). When the predetermined amount of content data is buffered in the buffer 102, the playback unit 105 starts playback of the content file (step S203). When downloading content data via a network, the communication speed may decrease or the communication may be disconnected due to various factors. If the playback process is waited until a predetermined amount of content data is buffered in the buffer, the content file functions as a margin when the communication speed is temporarily reduced or communication is cut off. Playback is difficult to interrupt. Note that, as the margin increases, playback is less likely to be interrupted, but the delay from the start of download to the start of playback increases.

  Interrupt processing occurs during downloading and playback of the content file (step S204). When the interruption process occurs, the downloader 101 interrupts the download of the content file, and the playback unit 105 interrupts the playback of the content file (step S205). The second backup unit 106 stores the unreproduced content data buffered by the buffer 102 and information indicating the reproduction resume point in the storage unit 104 (step S206).

  When the interruption process ends (step S207), the restart processing unit 107 performs a process for restarting the reproduction (step S208). Specifically, the restart processing unit 107 reads out the head metadata stored in step S 202 from the storage unit 104, and the head metadata is buffered by the buffer 102. Next, the restart processing unit 107 reads information indicating the playback restart point stored in step S206 from the storage unit 104, and generates data instructing skipping to this playback restart point. This data is buffered by the buffer 102. Next, the restart processing unit 107 reads the unreproduced content data stored in step S206 from the storage unit 104, and the unreproduced content data is buffered by the buffer 102.

  When step S208 is completed, the downloader 101 resumes downloading the content file, and the reproduction unit 105 resumes reproduction after a predetermined amount of content data is buffered by the buffer 102 (step S209).

  As described above, the content reproduction apparatus according to an embodiment of the present invention replaces the reproduced content data with data instructing skipping to the reproduction resume point when the reproduction of the content file is resumed. Therefore, according to the content reproduction apparatus according to the present embodiment, the consistency of the content file can be maintained without storing the reproduced content data. In other words, according to the present embodiment, it is possible to provide a content reproduction apparatus that can reduce the amount of data stored in the storage unit in order to resume reproduction of a content file.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. Further, for example, a configuration in which some components are deleted from all the components shown in the embodiment is also conceivable.

  For example, it is possible to provide a program that realizes the processing of the above-described embodiment by storing it in a computer-readable storage medium. The storage medium may be a computer-readable storage medium such as a magnetic disk, optical disk (CD-ROM, CD-R, DVD, etc.), magneto-optical disk (MO, etc.), semiconductor memory, etc. For example, the storage format may be any form.

  Further, the program for realizing the processing of the above embodiment may be stored on a computer (server) connected to a network such as the Internet and downloaded to the computer (client) via the network.

10 ... CPU
DESCRIPTION OF SYMBOLS 11 ... Memory 12 ... Input device 13 ... Input processing part 14 ... Communication part 15 ... Antenna 16 ... Memory | storage part 17 ... Audio | voice processing part 18 ... Audio | voice output part 19 ... Video processing unit 20 ... Video output unit 30 ... Content playback device 31 ... Content server 32 ... Network 101 ... Downloader 102 ... Buffer 103 ... First backup unit 104 ... Storage unit 105 ... Playback unit 106 ... Second backup unit 107 ... Resumption processing unit 110 ... Playback application 120 ... Downloader 130 ... Buffer 140 ... Parser 150 ···decoder

Claims (5)

A buffer,
A downloader for receiving the content data contained in the content file and buffering it in the buffer;
A first backup unit that stores content data indicating head metadata in the content file in a storage unit;
A playback unit for playing back the content data according to the buffering order of the buffer;
When the reproduction of the content file is interrupted, a second backup unit that stores unreproduced content data buffered in the buffer and information indicating a reproduction restart point in the storage unit,
When the reproduction of the content file is resumed, the content data indicating the top metadata, the data for instructing skipping of the analysis up to the reproduction resume point, and the unreproduced content data are sequentially buffered in the buffer. A content playback device comprising: a restart processing unit.   The content playback apparatus according to claim 1, wherein the first backup unit stores content data indicating the top metadata in the storage unit before the content file is played back.   The content reproduction apparatus according to claim 1, wherein the data instructing skipping of analysis includes information indicating a data amount to be skipped of analysis.   The content playback apparatus according to claim 1, wherein the information indicating the playback restart point includes information indicating a head position of the unplayed content data in the content file and information indicating a playback time corresponding to the head position. . Receiving content data contained in a content file and buffering it in a buffer;
Storing content data indicating head metadata in the content file in a storage unit;
Playing the content data according to the buffering order of the buffers;
When playback of the content file is interrupted, storing unplayed content data buffered in the buffer and information indicating a playback resume point in the storage unit;
When the reproduction of the content file is resumed, the content data indicating the top metadata, the data for instructing skipping of the analysis up to the reproduction resume point, and the unreproduced content data are sequentially buffered in the buffer. And a content playback method.

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