JP4838191B2 - File reproduction device, file reproduction method, program for executing file reproduction, and recording medium recording the program - Google Patents

Description

  The present invention relates to a file playback apparatus that plays back moving images and the like using an MP4 file format and the like, and in particular, efficiently manages memory when playing back a plurality of media data (image data, audio data, text data, etc.). The present invention relates to a file playback apparatus, a file playback method, a program for executing file playback, and a recording medium on which the program is recorded.

  In recent years, moving images such as television broadcast programs have been displayed not only on television devices but also on mobile phones and mobile terminals. A standard for reproduction and display is defined for moving image data. One of them is the ISO Base Media File Format (MP / MP 14 ISO 14 IEC 496 part 14 MP), which is the ISO Base Media File Format 14 MP 14 (14 MP part 14), which is defined by ISO (International Organization for Standardization) / IEC (International Electrotechnical Commission). is there. The MP4 file format of ISO Base Media File Format and its extension is a file format for storing compressed video data based on Apple's Quick Time format, and various types of moving images (for example, MPEG-4, MPEG- 4 AVC / H.264), audio in various formats (eg, AAC, HE-AAC, AMR, PCM), still images (eg, PNG, JPEG, GIF, Bitmap), telop text, etc. Multiple storage is possible. Hereinafter, for the sake of explanation, a file created in the MP4 file format is referred to as an MP4 file. In the following description, the MP4 file format is used as a reference, but the ISO Base Media File Format, 3GPP (Third Generation Partnership Project) file format, 3GPP2 (Third Generation Partner Format), etc. Needless to say, the technology described in this patent also applies to similar formats.

  The MP4 file format has an object-oriented data structure, and each object is called a box. In addition, the box has a nested structure in which the box further has a box as a child element.

As shown in FIG. 8, in the simplest MP4 file 100, a movie data box (mdat102) in which compressed video and audio data are stored, and the size, playback time, and random access of those data are stored. Are composed of a movie box (moov101) for managing metadata such as file offset position information.
For simplicity, the boxes other than the boxes necessary for the description are omitted, but it is needless to say that the file 100 has boxes such as ftyp.
FIG. 8 shows that the moov 101 and the mdat 102 exist in the same file. However, in the MP4 file format, these two boxes are allowed to exist in different files.

  The moov 101 is composed of an overall declaration box (mvhd103) arranged in the header, a video track management information box (trak 104), and an audio track management information box (trak 105). In the traks 104 and 105, various management information is stored in units of boxes.

  The MP4 file 100 using only the moov 101 and the mdat 102 described above cannot be played back unless both the moov 101 and the mdat 102 are prepared. For example, in order to play back an MP4 file existing on a network, for example, the file must be played after waiting for the file download to be completed, which is unsuitable for applications such as streaming. Basically, the longer the total movie playback time is, the larger the size of the management information moov 101 becomes. Therefore, in an embedded device where the amount of memory that can be used is limited, all of the management information of the long-time movie is stored in the real memory. There was a problem that could not be deployed.

  Movie fragments are sometimes used to solve these problems. ISO / IEC 14496 part 12 discloses a technique for fragmenting media data and management information and distributing management information collectively recorded with moov to a plurality of moof (Movie Fragment Box). However, since the management information is distributed, the processing for referring to the management information may be complicated as compared with the case where the management information is recorded only in moov. Patent Document 1 described later discloses a method that enables access equivalent to a moov-only file by re-deploying all moof fragmented management information into a moov. It was not possible to solve the problem with the devices that use limited memory.

  As shown in FIG. 9, in the fragmented file 110, the data portion that has been bundled is divided into arbitrary sizes to be mdats 112, 114, and 116, and the management information portions corresponding thereto are also divided. Going to moov 111 and moof 113 and 115, the corresponding management information part and data part are alternately arranged so that the entire movie can be played back before completion of acquisition. As a reference for division, a case where the size of the management information part or data part on the file is used as a reference, a reproduction time of data managed by the management information part, or the like can be considered.

  In the MP4 file format, mofh121, traf122, and 123, which are the divided management information, are stored in the moofs 113 and 115. mfhd 121 is a box for a declaration unit in units of fragments, traf 122 is a box for management information of a video track, and traf 123 is a box for management information of an audio track.

Corresponding data parts (mdat 112, 114, 116) are managed by the management information stored in the moov 111 and the moof 113, 115.
Hereinafter, for the sake of explanation, a set of a management information part (moov, moof) and a data part (mdat) to be paired will be called a fragment. For example, as shown in FIG. 9, a combination of moof 115 and mdat 116 is a fragment 117.

Here, abbreviations of the MP4 file format will be described below.
・ Ftyp: File Type Box
・ Moov: Movie Box
・ Mdat: Movie Data Box
・ Mvhd: Movie Header Box
・ Trak: Track Box
・ Moof: Movie Fragment Box
・ Mfhd: Movie Fragment Header Box
・ Traf: Track Fragment Box

  In the MP4 file format, when multiple types of media data such as video (image) data, audio (voice) data, text (character) data, still image data, etc. are multiplexed, each of these media data is managed in units of tracks. To do. Accordingly, a track is a data stream composed of a single type of media data. Each data stream is a collection of samples. Here, the sample refers to the minimum unit of information for constructing data. A management information box, for example, trak in moov and traf in moof corresponds to a management information (track management information) box for managing this track. In one fragment, one track management information is basically assigned to one media data, but a plurality of track management information may be assigned to one medium for management.

  FIG. 10 is an explanatory diagram showing a media management method for traf. FIG. 10A shows a case where the data part is managed by one traf, and FIG. 10B shows a case where the data part is managed by a plurality of traf. Assume that data 133, 134, 135, 145, 146, and 147 managed by the mdats 132 and 144 are data of the same medium (for example, audio). In FIG. 10A, the media data of mdat 132 is managed by the management information of moof 130. In other words, the management information of the traf 131 in the moof 130 manages data for a total of 15 seconds including 0 to 8 seconds of data 133, 8 to 10 seconds of data 134, and 10 to 15 seconds of data 135. In FIG. 10B, the same media data 145 such that the traf 141 of the moof 140 manages the 0-8 second data 145, the traf 142 manages the 8-10 second data 146, and the traf 143 manages the 10-15 second data 147. 146, 147 are managed by three traf.

  The following is a general example of accessing a fragmented file using moof. For example, as shown in FIG. 11, if samples A to D exist in the order of playback time in the moof and the playback start time of sample A is N, there is a request for sample management information at time (N + 40). In this case, it cannot be immediately indicated that “the management information of which number of moof corresponds to the sample management information at time (N + 40)”. Since the information itself of each sample managed by the moof does not have an absolute time, the sample corresponding to the time (N + 40) is the continuous display time (duration) of each sample (samples A to D). This is because there is no choice but to multiply and calculate. In order to solve this problem, an mfra box (movie fragment random access box) in which information that assists random access such as “what management information of which moof is at time X” is recorded in the standard. However, the mfra box is optional and not present in all files. In addition, even if an mfra box exists, information about all samples is not recorded, so in most cases, sequential access is performed based on randomly accessible information registered in the mfra box. You will get the information of the target sample.

  In FIG. 11, when the samples A to D are accessed in order from the top and the display times are integrated, the display time of the samples A to C is 30 and the display time of the samples A to D is 60. Therefore, it can be seen that the corresponding sample at time (N + 40) is sample D.

Therefore, in order to obtain information on the target sample, it is necessary to refer to all the samples until the target sample management information is reached by performing sequential access from the reference sample whose absolute time information is known. Yes.
JP 2005-117534 A

Memory management in an actual MP4 file analysis library (hereinafter referred to as a library) will be described below.
In the library, one moov management memory and one moof management memory are prepared. Here, there are a plurality of moofs depending on the file. In this case, only an appropriate moof for managing the necessary data is expanded on the memory, and the library does not have a plurality of moof storage memories. .
By using this method, even if the number of fragments becomes enormous, the amount of memory used can be suppressed. Therefore, it is possible to deal with applications such as for embedded use in which the amount of memory is limited.

  As described above, it is assumed that moof is referred to while appropriate expansion is performed in a timely manner. However, in a file in which a plurality of media are multiplexed, all of the moof information currently expanded on the memory is replaced with the next moof information. If this happens, a large overhead may be required.

This will be described in detail with reference to FIG.
For simplicity, the boxes other than those necessary for the description are omitted, but it goes without saying that the file 250 has boxes such as ftyp.
The file 250 is composed of moov 251, moof 253, 255..., Mdat 252, 254, 256. There are a moov storage memory 261 and a moof storage memory 262 as MP4 file analysis libraries 260 from the management information.

In the moov storage memory 261, management information of the moov 251 is stored. The moof storage memory 262 stores any one of the management information of moof 253 and 255 as needed. Although not explicitly shown in FIG. 12, each moof includes mfhd 121, video track and audio track management information traf 122, 123, etc., as shown at 120 in FIG. They are expanded in the moof storage memory 262.
For example, it is assumed that the video track management information and the audio track management information in the moof 253 are now expanded on the memory 262. Here, it is assumed that both the video track management information and the audio track management information of the moof 253 manage information of samples to be reproduced from time T to time T + α. At this time, it is assumed that the management information of the video data and the management information of the audio data are sequentially requested for 10 samples each from the samples to be reproduced at time T.
Here, it is assumed that each track information in each moof 253 has only 8 samples of management information, and if the management information does not exist in the moof 253 currently expanded in the memory 262, the following information It is assumed that the moof 255 is expanded on the memory 262.

At this time, the library 260 takes the following procedure in order to output management information for 10 samples of the data track necessary for reproducing the moving image.
1. Management information for video data is requested for 10 samples.
2. Eight samples of video data management information are obtained from the video traf of the moof 253 expanded in the memory 262.
3. Since the management information for two samples is insufficient for the requested 10 samples, the next management information moof 255 is expanded in the memory 262.
4). Management information for the remaining two samples of video data can be obtained, and management information for ten samples can be obtained.
5). 10 samples of audio data management information are requested.
6). Since it is moof255 currently expanded in the memory 262, the moof253 is expanded again in the memory 262.
7). 8 samples of audio data management information are obtained from the audio traf of the moof 253 expanded in the memory 262.
8). Since the management information for two samples is insufficient for the requested 10 samples, the next management information moof 255 is expanded in the memory 262.
9. Management information for the remaining two samples of video data can be obtained, and management information for ten samples can be obtained.

  As shown here, when the next moof is expanded in the memory 262, if all the moof is expanded, management information that has not yet been referenced (which will be necessary) will be overwritten. A memory expansion operation is required (in the above example, memory expansion is performed in 3, 6 and 8).

  In addition, when video is compressed by an inter-frame predictive encoding method such as the MPEG (Moving Picture Experts Group) method, each sample can be decoded by one sample (generally a key). Depending on the information of other samples (called samples), there are samples that can be decoded for the first time. For this reason, it is not always possible to decode a sample at a specified time alone, and it is necessary to start decoding from a key sample closest to the specified time in order to reproduce such a video.

The key sample that is closest to the specified time is generally a key sample that exists immediately before or after the specified time, and in order to know which sample is the closest, obtain both pieces of information. It is necessary to compare.
In order to obtain key sample information immediately before and after the specified time in a fragmented MP4 file, it is necessary to perform sequential access as described above, and it is necessary to replace management information in a timely manner. .

  However, if the key sample immediately before the specified time is required, and there is no information on the previous key sample in the management information currently expanded in the memory, all samples are returned to the previous moof. It was necessary to sequentially access the information about and acquire key sample management information immediately before the specified time.

  In view of such circumstances, the present invention efficiently manages memory for file reading and the like when reproducing image information consisting of a plurality of media data (image data, audio data, text data, still image data, etc.). An object of the present invention is to provide a file reproducing apparatus, a file reproducing method, a program for executing file reproduction, and a recording medium on which the program is recorded, which can suppress reproduction overhead and can be reproduced with a small memory capacity.

The present invention comprises a fragment-unit actual data group composed of tracks that are data streams of a single type of media data, and a fragment-unit management information group composed of track management information for managing one track. In a file playback device for playing back a file,
If there is no management information storage means for storing only one track management information including management information necessary for each track, reproduction means for reproducing actual data, and management information necessary for reproduction is not in the management information storage means, Only one track management information including management information is stored in the management information storage means , management information necessary for reproduction is acquired from the track management information stored in the management information storage means, and according to the acquired management information Control means for causing the reproduction means to reproduce the actual data.
Here, for example, in the MP4 file format, the actual data group corresponds to the “mdat” box, the track management information corresponds to the “trak” or “traf” box, and the management information group corresponds to “moov” or “moof”. Corresponds to the box. The track management information includes a case where information of one medium (track) is associated with a plurality of pieces of track management information as shown in FIG. 10B in one fragment, and as shown in FIG. In some cases, one track management information is associated with one medium (track).

The present invention also provides a fragment-unit actual data group composed of tracks that are data streams of a single type of media data, and a fragment-unit management information group composed of track management information for managing one track. In a file playback device for playing a file with
Management information storage means for storing the track management information, reproduction means for reproducing actual data, key sample management information storage means for holding key sample management information, and management information storage means for storing the track management information If there is no management information necessary for reproduction, the management information is stored in the management information storage means , and the management information necessary for reproduction is obtained from the track management information stored in the management information storage means. The actual data is reproduced according to the management information, and the key sample management information at the end of the reproduction time in the track management information is keyed in case the management information of the key sample immediately before the designated time is necessary for reproduction at the designated time. And control means for storing and holding in the sample management information storage means.

Here, the file may be in an MP4 file format format.

The present invention also provides a fragment-unit actual data group composed of tracks that are data streams of a single type of media data, and a fragment-unit management information group composed of track management information for managing one track. In a file reproduction method for reproducing a file comprising: management information storage means for storing only one track management information including management information necessary for each track; and reproduction means for reproducing actual data,
If the management information required for reproduction is not in the management information storage means , the step of storing only one track management information including the management information in the management information storage means; A step of obtaining from the track management information stored in a storage means; and a step of causing the reproduction means to reproduce the actual data in accordance with the obtained management information.

The present invention also provides a fragment-unit actual data group composed of tracks that are data streams of a single type of media data, and a fragment-unit management information group composed of track management information for managing one track. A file reproduction method for reproducing a file comprising: management information storage means for storing the track management information, reproduction means for reproducing actual data, and key sample management information storage means for holding key sample management information In
If the management information storage unit management information necessary for reproducing and storing the track management information including the management information in the management information storage means, the playback management information storage means for storing the track management information without necessary management information and storing the management information into the management information storage means, and obtaining from the track management information stored in the management information storage unit management information necessary for reproducing, acquires The key data management of the last reproduction time in the track management information is prepared in case the management information of the key sample immediately before the designated time is necessary for reproducing the actual data according to the management information and the reproduction at the designated time. Storing the information in the key sample management information storage means and holding the information.

  The present invention may be a program for causing a computer to execute the file reproduction method, or may be a recording medium on which the program is recorded.

  According to the present invention, the management information necessary for reproduction is acquired by storing the track management information in the management information storage means, and the actual data is reproduced by the reproduction means in accordance with the acquired management information. The storage capacity of the management information storage means can be reduced compared to the means for expanding the management information, and the amount of data written to the management information storage means compared to replacing the management information group in fragment units with the management information storage means Therefore, the processing load can be reduced.

  Also, as described with reference to FIG. 10B, when one track is managed by a plurality of track management information, only one track management information is stored in the management information storage means. Further, there is an advantage that the capacity of the management information storage means can be reduced.

  Furthermore, the information holding means holds the key sample management information at the end of the playback time in the track management information in preparation for the case where the management information of the key sample immediately before the specified time is required for playback at the specified time. Even if it is deleted from the management information storage means for the next reproduction process, in order to obtain a key sample immediately before the designated time, there is no need to store the track management information in the management information storage means again, It is only necessary to read from the information holding means, and the processing load can be reduced.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a moving image recording / reproducing apparatus which is an example of a file reproducing apparatus according to the present invention. This moving image recording / reproducing apparatus includes a recording medium 11, a media access unit 12, an operation unit 13, a system control microcomputer 14, a management information memory controller 15, a management information memory unit 16, a data memory controller 17, and a data The memory unit 18, the demultiplexer 19, the video decoding unit 20, and the audio decoding unit 21 are configured. The reproduction means for reproducing the media data file stored in the recording medium 11 includes a data memory controller 17, a data memory unit 18, a demultiplexer 19, a video decoding unit 20, and an audio decoding unit 21. .
This moving image recording / playback apparatus handles video data and audio data as media data, but can also handle other media data such as text data and still images.

The recording medium 11 is a recording medium that stores a moving image in the MP4 file format or the like, and is a writable disc such as DVD, HD-DVD (High Definition DVD), BD (Blue-ray Disk), SD card, or memory stick. Or a flash memory such as HD (Hard Disk).
The media access unit 12 is a device that writes and reads data on the recording medium 11.
This moving image recording / reproducing apparatus reads out and reproduces a moving image file on a recording medium. However, the moving image data file may be obtained and reproduced by net distribution such as the Internet.

The operation unit 13 receives user operations (play, stop, seek, etc.) and is a switch button arranged on the remote control or the main body.
The system control microcomputer 14 is a microcomputer that controls the operation of the entire apparatus, and controls the operation of each unit in accordance with a user operation. The system control microcomputer 14 reproduces the moving image recorded on the recording medium 11 and provides it to the user. The system control microcomputer 14 has a built-in cache memory 23 and stores data (information) necessary for processing. The cache memory 23 includes a cache A23a, a cache B23b, a cache C23c, and a cache D23d, which are data storage areas. Here, the cache memory is built in the system control microcomputer 14, but may be provided outside the system control microcomputer 14.

The memory controller 15 develops and holds the management information read from the recording medium 11 by the media access unit 12 in the memory unit 16 in an easy-to-use form during reproduction. The management information developed in the memory unit 16 is referred to during control by the system control microcomputer 14.
Based on an instruction from the system control microcomputer 14, the memory controller 17 reads the information of the data part from the recording medium 11 by the media access part 12, expands it in the memory part 18, and holds it.

The demultiplexer 19 divides the data obtained by multiplexing the plurality of media output from the memory controller 17 into elementary streams. However, in the MP4 file format, if the sample management information can be acquired, the target sample can be directly designated by the system control microcomputer 14, and data in a state where a plurality of media are multiplexed is not read out. Therefore, it simply serves as a switch that switches the output destination depending on which media sample the read sample is.
The video decoding unit 20 / audio decoding unit 21 decodes each video / audio elementary stream whose transmission destination is switched by the demultiplexer 19 into a reproducible state, and outputs each decoded data.

Next, a case where a fragmented MP4 file as shown in FIG. 2 is reproduced using this moving image recording / reproducing apparatus will be described.
As shown in FIG. 2, the file 30 of the image data of the MP4 file stored in the recording medium 11 includes a file type box (ftyp 31) for storing file header information and a management information group for storing sample management information in fragment units. And mdat34, 38, 42, and 44, which are real data groups storing media data in fragment units corresponding thereto. Fragment 45 is composed of moov32 and mdat34, fragment 46 is composed of moof35 and mdat38, fragment 47 is composed of moof39 and mdat42, and fragment 48 is composed of moof43 and mdat44.

  In moov32, mvex (movie extends box) 33 exists. The mvex 33 notifies that the MP4 file is a fragmented MP4 file, and stores the default value of sample management information such as duration and size information used in each fragment and the playback time of the entire file. Is done. In the moofs 35, 39, 43, there are traf 36, 40,... which are track management information boxes for storing video management information, and traf 37, 41,..., which are track management information boxes for storing audio management information. In this example, it is assumed that management information for eight samples of a video data track and an audio data track is stored in each traf.

  Although video data and audio data are handled as media data, it goes without saying that other media data such as text data and still images may be included. For the sake of simplicity, boxes other than those necessary are omitted in the drawing, but it is needless to say that the MP4 file 30 has essential boxes such as mvhd, mfhd, and trak.

<First Embodiment>
Next, the file playback operation of the moving image recording / playback apparatus will be described. FIGS. 3 and 4 are flowcharts showing the first embodiment when playing back a file format.

First, it is assumed that management information of a video track and an audio track is alternately requested for each of a plurality of samples when performing reproduction processing. The system control microcomputer 14 issues a sample management information acquisition request (for example, traf36 of moof35) necessary for predetermined reproduction (step S1). Then, it is confirmed whether or not the track management information of the trof 36 of the moof 35 is stored in the management information memory unit 16 via the memory controller 15 (step S2). If the management information necessary for reproduction is not stored in the management information memory unit 16, the process proceeds to step S3, and the information stored in the management information memory unit 16 must be updated.
Now, it is assumed that traf 36 is stored in the track management information storage area 53 of the video track and traf 37 is stored in the track management information storage area 54 of the audio track, and the management information of the video track and the audio track is alternately requested for every 10 samples. Shall be.

First, sample management information for a video track is acquired.
At this time, as described above, what is stored in the traf storage area 53 of the moof storage memory 52 in the management information memory unit 16 is the management information of the traf 36 necessary for reproduction. The management information stored in the traf 36 is for 8 samples of the video data track. The system control microcomputer 14 reads the management information from the traf storage area 53 of the management information memory unit 16 via the memory controller 15 and stores it in the cache A 23a of the cache memory 23 (step S4). Furthermore, the system control microcomputer 14 confirms whether all necessary management information has been acquired (step S5). Since the requested 10 samples do not have enough sample management information for two samples, the process returns to step S1, The video track management information traf40 of moof39 is requested. It is confirmed whether or not the traf storage area 53 of the moof storage memory 52 of the management memory unit 16 has a traf 40 (step S2). When it is confirmed that it does not exist, the management information is updated in step S3.

Next, management information update processing in the management information memory will be described with reference to FIG.
Here, a case where the management information of the traf 36 is updated to the management information of the traf 40 will be described, but the same processing is performed for other management information.

  First, the system control microcomputer 14 seeks to the head position of the target moof 39 stored in the storage medium 11 by the media access unit 12 (step S11).

Here, the target moof refers to a moof including a traf that manages sample management information to be referred to next to the sample management information that was referred to when the update process is required.
Consider a case where, as shown in FIG. 2 used for explanation, information of one track is managed by one track management information (traf) in one fragment. At this time, sample management information is displayed in the order of display. . . , Traf36, traf40,. . . Is stored.

  When the traf 36 is expanded in the traf storage area 53 at the time when the update process is required, the traf for managing the sample management information to be referred to next is the traf 40, and the target moof is the moof 39 including the traf 40. Become.

  On the other hand, as shown in FIG. 10B, a case is considered in which information of one track is managed by a plurality of track management information in one fragment. At this time, sample management information is displayed in the order of display. . . traf141, traf142, traf143. . . Is stored.

  When the traf 141 is expanded in the traf storage area 53 at the time when the update process becomes necessary, the traf for managing the sample management information to be referred to next is the traf 142, and the target moof is the moof 140 including the traf 142. Yes (this is the same as the target moof when storing the traf 141, and further the same as the target moof when storing the traf 143).

  Next, the plurality of track management information included in the moof 39 are inspected one by one (step S12). Then, the presence / absence of traf40 as the target track management information is confirmed (step S13). If there is no target track management information, it is confirmed whether all the management information has been inspected (step S14). If all the track management information included in the moof 39 has been inspected, the process ends. If not all are inspected, the process returns to step S12 to continue the inspection.

  If it is confirmed in step S13 that the track management information of traf40 exists, the track management information of traf40 is read (step S15). Then, it is stored in the traf storage area 53 of the management information memory unit 16 via the memory controller 15 (step S16). In this way, the traf storage area 53 of the moof storage memory 52 of the management information memory unit 16 is updated with the new track management information traf40.

  The system control microcomputer 14 acquires management information for the remaining two samples necessary for reproduction from the new management information stored in the management information memory unit 16, and stores it in the cache A 23a of the cache memory 23 (step S4). .

  Next, since management information for 10 samples of audio data has not yet been acquired in step S5, the process returns to step S1, and the system control microcomputer 14 issues a sample management information acquisition request necessary for predetermined reproduction (step S1). ). Then, it is confirmed via the memory controller 15 whether the audio track management information traf37 of the moof 36 is stored in the traf storage area 54 of the management information memory unit 16moof storage memory 52 (step S2). If the management information necessary for reproduction is not stored in the management information memory unit 16, the process proceeds to step S3 and the storage information in the management information memory unit 16 must be updated.

  It is assumed that the traf 37 management information necessary for reproduction is stored at this time. The management information stored in the traf 37 is management information for 8 samples. The system control microcomputer 14 reads the management information from the traf storage area 54 of the management information memory unit 16 via the memory controller 15 and stores it in the cache B 23b of the cache memory 23 (step S4). Further, the system control microcomputer 14 confirms whether all necessary management information has been acquired (step S5). Since there is not enough audio track management information for two samples, the process returns to step S1, and the audio track management information of the moof 39 is returned. Request traf41. It is confirmed whether or not traf 41 exists in the traf storage area 54 of the moof storage memory 52 of the management memory unit 16 (step S2). If it does not exist, the management information is updated in step S3.

Next, management information update processing in the management information memory will be described with reference to FIG.
Here, a case where the management information of the audio traf 37 is updated to the management information of the audio traf 41 will be described, but the same processing is performed with other management information.

  First, the system control microcomputer 14 seeks to the head position of the target moof 39 stored in the storage medium 11 by the media access unit 12 (step S11). Thereafter, the track management information of the moof39 is inspected one by one (step S12), and the presence / absence of the target track management information traf40 is confirmed (step S13). If there is no target track management information, it is confirmed whether all the management information has been inspected (step S14). If all the management information in the moof 39 has been inspected, the process ends. If not all are inspected, the process returns to step S12 to continue the inspection.

  If it is confirmed in step S13 that the audio track management information of traf41 exists, the track management information traf41 is read (step S15). Then, it is stored in the traf storage area 53 of the management information memory unit 16 via the memory controller 15 (step S16). In this way, the management information in the management information memory unit 16 is updated with new track management information.

  The system control microcomputer 14 acquires track management information for the remaining two samples necessary for reproduction from the new management information stored in the management information memory unit 16, and stores it in the cache B 23b of the cache memory 23 (step S4). ).

  In this way, management information for 10 samples of the track is stored in the cache 23, and based on this information, the system control microcomputer 14 reads data from the recording medium 11 via the media access unit 12 and acquires sample data. (Step S6). In this case, the data is mdat 38 and 42. Next, the system control microcomputer 14 develops the acquired sample data in the data memory unit 18 via the memory controller 17 (step S7).

  The memory controller 17 reads the data of mdat 38 and 42 in accordance with a control signal from the system control microcomputer 14, and the demultiplexer 19 sends the video data to the video decoding unit 20 and the audio data to the audio decoding unit 21. 20 and 21 (step S9).

  In the first embodiment, it is described that there is no text data, still image, or the like, but the same processing is performed even if there is such data.

  In this manner, the system control microcomputer 14 obtains management information necessary for reproduction by expanding the traf storing the track management information of each media data one by one in the management information memory unit 16, so The memory capacity may be smaller than when the moof storing the management information of the entire fragmented media data is expanded to moov. Further, since processing can be performed with track management information, the number of times of memory update is reduced and the amount of data input / output to / from the management information memory unit 16 can be reduced as compared with processing with a moof unit. A load can be prevented.

Second Embodiment
Next, a key sample acquisition process will be described as a second embodiment.
FIG. 5 is an explanatory diagram showing a data structure related to key sample processing. For the sake of simplicity, the boxes other than those necessary for the description are omitted, but it goes without saying that the file 60 has boxes such as ftyp and moov. FIG. 6 is a flowchart related to key sample processing, and FIG. 7 is a flowchart related to key acquisition processing immediately before a specified time.

  The MP4 file shown in FIG. 5 includes moofs 61 and 63 and mdats 62 and 64 corresponding thereto. Fragment 65 is a combination of moof61 and mdat62, and fragment 66 is a combination of moof63 and mdat64. Although not shown in the moofs 61 and 63, there is a traf which is the track management information of the mdat 62 and 64, and the moving image recording / playback apparatus, as described above, stores the track management information of the traf in the management information memory unit 16. To obtain management information necessary for playback.

  Further, in mdat shown in FIG. 5, it is assumed that samples are stored in order from the top to the bottom. For example, two key samples 67 and 68 exist in mdat 64, time A is between key samples 67 and 68, and time B is before key sample 67 (in the figure, above key sample 67).

  For example, consider processing when seeking at time A and time B. However, it is assumed that the management information of the moof 63 is expanded on the management information memory unit 16.

  When seeking at time A, since the key samples 67 and 68 exist before and after, information about the key samples 67 and 68 can be obtained from the management information in the moof 63 currently expanded on the memory unit 16. Is possible. On the other hand, when seeking at time B, the key sample 67 immediately after the specified time exists, but the immediately preceding key sample does not exist in the current fragment 66. In order to acquire key sample management information before time B, it is necessary to re-deploy the moof 61 on the management information memory unit 16 and search for the last key sample therein.

  Here, if the last key sample management information of the immediately preceding fragment 65 is cached in advance, there is no immediately preceding key sample in the current fragment 66 as in the case of acquiring the preceding and following key samples at time B. However, it is not necessary to go back to the previous fragment 65 and search again.

A reproduction process using key samples in the moving image recording / reproducing apparatus shown in FIG. 1 will be described with reference to FIGS.
First, the system control microcomputer 14 issues a request for acquiring key sample management information (step S21). That is, a reproduction time is designated, and a request for acquiring management information of key samples before and after the reproduction time is issued. The system control microcomputer 14 sequentially refers to the sample management information through the memory controller 15 in order to search for information on the target key sample from the video data developed in the management information memory unit 16. First, it is confirmed whether the sample management information being referred to is for the key sample immediately after the specified time (step S22). If it is not the sample management information of the key sample immediately after the designated time (step S22; No), it is confirmed whether it is the key sample management information (step S23). If the sample management information currently being referenced is that of the key sample (step S23; Yes), the sample management information is stored in the cache C23c as information that may become the key sample information immediately before the specified time ( The process proceeds to step S24) and step S25. If it is not key sample management information (step S23; No), the process proceeds to step S25.

  In step S <b> 25, the system control microcomputer 14 confirms whether the next sample management information is expanded in the management information memory unit 16. If the next sample management information is expanded in the management information memory unit 16 (step S25; Yes), the next sample management information is referred to (step S26), and the process returns to step S22. If the next sample management information is not expanded in the management information memory unit 16 (step S25; No), the key sample management information in the cache C23c is moved to the cache D23d (step S27).

  Then, the management information of the next fragment is read from the moof traf to update the management information memory unit 16 (step S28), and the process proceeds to step S26.

  If the referenced key sample management information is the key sample management information immediately after the specified time (step S22; Yes), the key sample management information immediately after the specified time is acquired (step S29), and the key sample management information immediately before the specified time is also obtained. Obtain (Step S30)

  Regarding the key sample management information acquisition process in step S30, as shown in FIG. 7, first, the system control microcomputer 14 checks whether or not the cache C23c is valid (step S31), and if valid (step S31; Yes). ) The information of the cache C23c is set as the immediately preceding key sample management information (step S32), and the process proceeds to step S36.

  If the cache C23c is not valid (step S31; No), the system control microcomputer 14 checks whether or not the cache D23d is valid (step S33). If valid (step S33; Yes), the previous key Information of the cache D23d is set as sample management information (step S34), and the process proceeds to step S36.

  In step S36, acquisition of key sample management information immediately before the specified time is completed. If the cache D23d is not valid (step S33; No), the key sample management information immediately before the specified time cannot be acquired (step S35).

  In this way, the last key sample management information among the management information developed on the management information memory unit 16 is stored in the cache memory 23. Therefore, even if the next management information is expanded on the management information memory unit 16 and the previous management information is deleted from the management information memory unit 16 while the reproduction process is proceeding, the cache memory unit In 16, the last key sample management information of the deleted management information remains. For this reason, even if there is no key sample management information immediately before the specified time in the management information developed in the management information memory unit 16, the previous key sample management information exists again because the cache memory 23 has the previous key sample. It is not necessary to develop the traf to be managed in the management information memory unit 16, and the processing load is reduced.

  In the present invention, the file reproduction processing described in the above embodiment can be executed by a computer as a program, and further, the program is recorded on a recording medium and read by the computer to execute file reproduction. You can also.

It is a block diagram which shows the moving image recording / reproducing apparatus which is an example of the file reproducing | regenerating apparatus concerning this invention. It is explanatory drawing which shows the storage state of the MP4 file in the memory part 16 for management information. It is a flowchart which shows 1st Embodiment in the case of reproducing | regenerating a file format. It is a flowchart which shows 1st Embodiment in the case of reproducing | regenerating a file format. It is explanatory drawing which shows the data structure regarding a key sample process. It is a flowchart regarding a key sample process. It is a flowchart regarding the key acquisition process immediately before the designated time. It is explanatory drawing which shows the structure of MP4 file. It is explanatory drawing which shows the structure of the fragmented MP4 file. It is explanatory drawing which shows the media management of traf, (a) is a case where a data part is managed by one traf, (b) is a case where a data part is managed by several traf. It is explanatory drawing which searches the sample of reproduction | regeneration designated time. It is explanatory drawing which shows the state which stores an MP4 file in an analysis library.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Recording medium 12 Media access part 13 Operation part 14 System control microcomputer 15 Memory controller 16 Management information memory part 17 Memory controller 18 Data memory 19 Demultiplexer 20 Video decoding part 21 Audio decoding part 23 Cache memory 30 File 32 moov
34, 38, 42, 44 mdat
35, 39, 43 moof
45, 46, 47, 48 Fragment 51 moov storage memory 52 moof storage memory

Claims (7)

Plays a file with a fragment-unit actual data group composed of tracks that are data streams of a single type of media data and a fragment-unit management information group composed of track management information for managing one track In the file playback device to
Management information storage means for storing only one track management information including necessary management information for each track;
Playback means for playing back actual data;
If there is no management information necessary for reproduction in the management information storage means, only one track management information including the management information is stored in the management information storage means , and management information necessary for reproduction is stored in the management information storage means. Control means for acquiring from the track management information stored in, and causing the reproduction means to reproduce the actual data according to the acquired management information;
A file playback apparatus comprising: Plays a file with a fragment-unit actual data group composed of tracks that are data streams of a single type of media data and a fragment-unit management information group composed of track management information for managing one track In the file playback device to
Management information storage means for storing the track management information;
Playback means for playing back actual data;
Key sample management information storage means for storing key sample management information;
Without management information necessary for reproducing the management information storage means for storing the track management information, stores the management information into the management information storage means, stores management information necessary for reproducing the management information storage means The track management information is obtained from the track management information, the actual data is reproduced according to the obtained management information, and the management information of the key sample immediately before the designated time is necessary for reproduction at the designated time. Control means for storing and holding key sample management information at the end of the reproduction time in the key sample management information storage means;
A file playback apparatus comprising:   3. The file reproduction apparatus according to claim 1, wherein the file is an MP4 file format file. A file comprising a fragment-unit actual data group composed of tracks that are data streams of a single type of media data, and a fragment-unit management information group composed of track management information for managing one track, In a file reproduction method for reproduction by management information storage means for storing only one track management information including necessary management information for each track and reproduction means for reproducing actual data,
If there is no management information necessary for reproduction in the management information storage means , storing only one track management information including the management information in the management information storage means ;
Obtaining management information necessary for reproduction from the track management information stored in the management information storage means;
Causing the reproducing means to reproduce the actual data according to the acquired management information;
A file playback method comprising: A file comprising a fragment-unit actual data group composed of tracks that are data streams of a single type of media data, and a fragment-unit management information group composed of track management information for managing one track, In a file reproduction method for reproduction by management information storage means for storing the track management information, reproduction means for reproducing actual data, and key sample management information storage means for holding key sample management information,
If there is no management information necessary for reproduction in the management information storage means, track management information including the management information is stored in the management information storage means ;
Without management information necessary for reproducing the management information storage means for storing the track management information, storing said management information in said management information storage means,
Obtaining management information necessary for reproduction from the track management information stored in the management information storage means;
Reproducing the actual data according to the acquired management information;
Store and hold key sample management information at the end of the playback time in the track management information in the key sample management information storage means in case the management information of the key sample immediately before the specified time is required for playback at the specified time. Steps to keep
A file playback method comprising:   A program for causing a computer to execute each step of the file reproduction method according to claim 4 or 5.   A recording medium on which the program according to claim 6 is recorded.

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