Content generating device, receiving device, and program

Abstract

To recognize a change of a generation parameter during streaming content reproduction.SOLUTION: A content generation device 2 comprises: a media segment generation section 23 which generates a media segment in accordance with a generation parameter to be used for generating a segment of a video content; an initialization segment generation section 24 which generates a new initialization segment including information required for decoding the media segment in accordance with the change of the generation parameter; a manifest generation section 25 which generates a manifest file including segment correspondence information indicating a corresponding initialization segment for each media segment; and a content transmission section 26 which transmits the media segment, the initialization segment and the manifest file.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a content generating device, a receiving device, and a program. [Background technology]

[0002] In recent years, the mainstream streaming video distribution method on the Internet is to use HTTP protocol for streaming distribution by general-purpose web servers. One example of such a streaming distribution method (adaptive streaming) using HTTP protocol is the international standard MPEG-DASH (ISO / IEC23009-1).

[0003] In MPEG-DASH, a Web server is provided with initialization segments, media segments, and a manifest file describing their URLs and video content attributes. Media segments are segments obtained by dividing a stream of video content encoded with one or more qualities (parameters such as screen size and bit rate) into files of several to several tens of seconds each. Initialization segments include metadata required for presenting the segments, such as generation parameters related to encoding and encryption. A receiving device selects a quality at the appropriate time from the manifest file, taking into consideration the screen size of the receiving device and the state of the network bandwidth of the transmission path, and receives the segments one after another, splicing them into one video content and playing it back (for example, see Non-Patent Document 1).

[0004] In addition to the quality switching mentioned above, other possible methods for providing video streaming services include multi-view video and multilingual audio distribution, broadcast-like program distribution according to a schedule, etc. MPEG-DASH defines a method for describing manifests that enable such services.

[0005] Figure 7 shows a conceptual diagram of a manifest file in the MPD (Media Presentation Description) format of MPEG-DASH. The MPD format has a hierarchical structure in the order of Period, AdaptationSet, and Representation. A Period indicates a section into which content is divided in the time direction, and the example in Figure 7 shows that Periods with a media duration of 300 seconds are linked together. A Period consists of one or more AdaptationSets.

[0006] An AdaptationSet indicates information about media components (video, audio, text, etc.) and can include multiple components with different expressions (video from different angles, audio in different languages, etc.) in the same media format. In the example in Figure 7, there are two videos (mimeType=video / mp4) and one audio (mimeType=audio / mp4). The information about each media component included in an AdaptationSet is indicated by Representation.

[0007] Representation describes information about segments (Initialization Segment, Media Segment) which are the actual data that composes the media element. Initialization Segment indicates an initialization segment, and Media Segment indicates a media segment. In the example of Fig. 7, the file name of the media segment has a sequence number ($Number$) that is incremented for each segment length (duration = 5s).

[0008] By using such a manifest file, it is possible to sequentially receive the segments (initialization segments and media segments) that form the media component (Adaptation Set) selected in the Period, and by reselecting the media component, it is possible to switch to receiving segments that form a different media component and display a different video.

[0009] In addition, non-patent document 2 discloses a method for realizing adaptive streaming by preparing a common initialization segment that includes the generation parameters of all Representations included in one AdaptationSet, and simply inserting the common initialization segment at the beginning within the AdaptationSet, without having to insert an initialization segment every time the Representation is switched.

[0010] Furthermore, Patent Document 1 discloses a method for suppressing changes in image quality before and after switching streams by generating a delivery stream by replacing part of the stream after switching with a stream generated using pictures before and after switching to a stream with a different bit rate as reference images. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2015-19329 A [Non-patent literature]

[0012] [Non-Patent Document 1] “Next-generation video distribution technology "MPEG-DASH" technical overview and trends in standardization and related technologies”, Journal of the Institute of Image Information and Television Engineers, Vol.67, No.2, 2013, pp.109-115 [Non-Patent Document 2] “Digital Video Broadcasting (DVB); MPEG-DASH Profile for Transport of ISO BMFF Based DVB Services over IP Based Networks - DVB Document A168”, [online], October 2019, [Retrieved February 22, 2021], Internet<URL:https: / / dvb.org / wp-content / uploads / 2019 / 12 / a168_dvb_mpeg-dash_oct_2019.pdf> Summary of the Invention [Problem to be solved by the invention]

[0013] Fig. 8 is a diagram showing the concept of a buffer in a receiving device. When switching to a stream (representation) with different generation parameters, the receiving device inserts an initialization segment of the switched-to representation immediately before inserting a media segment belonging to the switched-to representation into the buffer, as shown in Fig. 8. This makes it possible to properly notify the decoder behind the buffer of the generation parameters of the subsequent media segment, thereby realizing seamless adaptive streaming. Note that in Fig. 8, each media segment of each quality level is composed of three blocks, and one block corresponds to one representation.

[0014] However, in the MPEG-DASH standard, information on only one initialization segment could be described in one Representation, as shown in Fig. 7. Therefore, if the generation parameters of the initialization segment described in one Representation were changed while the receiving device was playing back that Representation, the receiving device was unable to recognize the contents and timing of the change.

[0015] Furthermore, even if the technology described in Non-Patent Document 2 is used, the receiving device cannot recognize a change in generation parameters during playback of the Representation. Furthermore, the technology described in Patent Document 1 is not necessarily applicable to changes in generation parameters such as changes in resolution or encryption key.

[0016] In consideration of the above circumstances, the object of the present invention is to provide a content generation device, a receiving device, and a program that enable stable streaming to be continued by enabling the receiving device to recognize changes to generation parameters during playback of streaming content. [Means for solving the problem]

[0017] In order to solve the above problem, a content generation device in one embodiment is a content generation device that generates segments of video content and a manifest file, and includes a media segment generation unit that generates media segments according to generation parameters used to generate segments of video content, an initialization segment generation unit that generates new initialization segments including information necessary to decode the media segments in accordance with changes to the generation parameters, a manifest generation unit that generates a manifest file including segment correspondence information indicating the corresponding initialization segment for each media segment, and a content transmission unit that transmits the media segments, the initialization segments, and the manifest file.

[0018] Furthermore, in one embodiment, the segment correspondence information may be information for identifying a file name of a media segment and a file name of an initialization segment corresponding to the media segment.

[0019] Furthermore, in one embodiment, the manifest generation unit may generate a manifest file in which information on multiple initialization segments is described within one Representation by adding the segment correspondence relationship information to a manifest file conforming to an MPD (Media Presentation Description) format.

[0020] In addition, in order to solve the above problem, a receiving device of one embodiment is a receiving device that receives initialization segments, media segments, and a manifest file of video content, and is equipped with a manifest acquisition unit that acquires a manifest file in which segment correspondence information indicating a corresponding initialization segment for each media segment is described, and generates a segment URL list that corresponds the playback time of the media segment with the initialization segment and the URL of the media segment, a buffer control unit that extracts the URL of the media segment and the URL of the initialization segment corresponding to the media segment based on the playback time that is updated as the media segment is played and the segment URL list, and a segment acquisition unit that acquires the media segment based on the URL of the media segment, and acquires the initialization segment based on the URL of the initialization segment.

[0021] In order to solve the above problem, a program according to one embodiment causes a computer to function as the content generation device.

[0022] In order to solve the above problem, a program according to one embodiment causes a computer to function as the receiving device. Effect of the Invention

[0023] According to the present invention, a receiving device can recognize changes in generation parameters during playback of streaming content and can play the content continuously. Therefore, it is possible to dynamically change the generation parameters of a stream being distributed in accordance with fluctuations in the network bandwidth and the operational requirements of a service provider. [Brief description of the drawings]

[0024] [Figure 1] 1 is a diagram showing an outline of a content distribution system including a receiving device and a content generating device according to an embodiment of the present invention. [Diagram 2] 1 is a block diagram showing an example of the configuration of a content generating device according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram showing an example of a manifest file in MPD format generated by a content generation device according to an embodiment of the present invention. [Figure 4] 4 is a flowchart illustrating a content generating method of the content generating device according to an embodiment of the present invention. [Diagram 5] 1 is a block diagram showing an example of the configuration of a receiving device according to an embodiment of the present invention; [Figure 6] 5 is a flowchart showing a segment acquisition control method of a receiving device according to an embodiment of the present invention. [Figure 7] FIG. 1 is a diagram illustrating the concept of a conventional manifest file. [Figure 8] FIG. 1 is a diagram illustrating the concept of a buffer in a conventional receiving device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the embodiment described below, as an example, the manifest file is in the MPD format of MPEG-DASH (ISO / IEC23009-1).

[0026] 1 shows an overview of a content distribution system including a receiving device and a content generating device according to an embodiment of the present invention. The content distribution system is a system that distributes video content, which is composed of a plurality of segments and a manifest file, for each segment. A receiving device 1 and a distribution server 3 are connected via the Internet. A content generating device 2 and a distribution server 3 may be connected by a dedicated local network, or may be connected via the Internet.

[0027] The receiving device 1 receives segments of video content (initialization segments and media segments) and a manifest file from the distribution server 3, and performs streaming playback.

[0028] The content generator 2 generates segments of video content and a manifest file, and provides them to the distribution server 3.

[0029] The distribution server 3 is a server that distributes the manifest file and segments of the URL designated by the receiving device 1 to the receiving device 1, and may be, for example, a general web server.

[0030] (Content generation device) Next, a description will be given of the details of the content generation device 2. Fig. 2 is a block diagram showing an example of the configuration of the content generation device 2. The content generation device 2 shown in Fig. 2 includes a raw video output unit 21, a generation parameter change unit 22, a media segment generation unit 23, an initialization segment generation unit 24, a manifest generation unit 25, a content transmission unit 26, and a communication I / F 27.

[0031] The raw video output unit 21 outputs to the media segment generation unit 23 content to be generated from raw video input from an external source or from raw video stored in advance.

[0032] The generation parameter modification unit 22 sets or modifies the generation parameters, and outputs the generation parameters to the media segment generation unit 23 and the initialization segment generation unit 24. The generation parameters are parameters used to generate segments of video content, and include media encoding parameters (resolution, bit rate, etc.) and encryption parameters for content protection. The generation parameters may be set or modified by a user via an input interface. Furthermore, the generation parameter modification unit 22 outputs a parameter change trigger indicating the timing at which the generation parameters are changed to the initialization segment generation unit 24.

[0033] The media segment generation unit 23 generates a media segment in accordance with the generation parameters. The media segment generation unit 23 includes an encoding unit 231 and a segmentation unit 232.

[0034] The encoding unit 231 encodes the raw video signal input from the raw video output unit 21 using an existing encoding method or encrypts it using an existing encryption method in accordance with the generation parameters input from the generation parameter change unit 22. Examples of the existing encoding method include H.264|MPEG-4 AVC (Advanced Video Coding), H.265|MPEG-H HEVC (High Efficiency Video Coding), etc. Examples of the existing encryption method include AES (Advanced Encryption Standard), etc. Then, the encoding unit 231 outputs the encoded stream to the segmentation unit 232. Note that audio can also be processed in the same way as video.

[0035] The segmentation unit 232 segments the encoded stream input from the encoding unit 231, for example, in ISO-BMFF (ISO-Base Media File Format) format, to generate media segments including media information. Then, the segmentation unit 232 outputs the generated media segments to the manifest generation unit 25.

[0036] The initialization segment generation unit 24 inputs the generation parameters and the parameter change trigger from the generation parameter change unit 22. Then, the initialization segment generation unit 24 generates a new initialization segment including information required to decode the media segment in accordance with the change in the generation parameters. For example, the initialization segment generation unit 24 segments in ISO-BMFF (ISO-Base Media File Format) format and generates an initialization segment including the generation parameters. Then, the initialization segment generation unit 24 outputs the generated initialization segment to the manifest generation unit 25.

[0037] The manifest generation unit 25 inputs the media segments from the segmentation unit 232 and the initialization segments from the initialization segment generation unit 24. Then, the manifest generation unit 25 generates a manifest file including segment correspondence relationship information. The segment correspondence relationship information is information indicating the corresponding initialization segment for each media segment. For example, the manifest generation unit 25 adds the segment correspondence relationship information to a manifest file that complies with the conventional MPD format of MPEG-DASH. Then, the manifest generation unit 25 outputs the initialization segments, the media segments, and the manifest file to the content transmission unit 26. The manifest file may be generated by a method of sequentially updating the manifest file every time a segment is input, or may be generated after all segments are input.

[0038] The content sending unit 26 sends the initialization segment, the media segment, and the manifest file input from the manifest generating unit 25 to the distribution server 3 via the communication I / F 27.

[0039] Here, a specific example of content generated by the content generation device 2 will be described with reference to Fig. 3. Fig. 3 shows an example (excerpt) of a manifest file in MPD format to which segment correspondence relationship information has been added, where the segment correspondence relationship information is information for identifying the file name of a media segment and the file name of an initialization segment corresponding to the media segment.

[0040] Figure 3 shows a manifest file in which the content duration is 32 seconds, the segment length is 2 seconds, and the generation parameters are changed every 8 seconds from the start of encoding. In this example, there is one Period with content duration information (duration) of 32 seconds, the Period has one AdaptationSet whose media format is video (mimeType="video / mp4"), and the AdaptationSet has one Representation.

[0041] Here, a method for identifying a media segment that includes a certain playback time and the file name of an initialization segment that corresponds to the media segment will be described.

[0042] The start value on the second line of Figure 3 indicates that the start time of the Period is 0. The timescale value on the fourth line of Figure 3 indicates that the timescale (the number of ticks per second) of the AdaptationSet is 1000.

[0043] The value of media on line 13 of Figure 3 indicates that the base name of the media segment file is s1_$Time$.mp4, and the value obtained by replacing $Time$ with the timestamp value of the media segment is the file name. The value of initialization indicates that the base name of the initialization segment file is s1_init_$Index$.mp4, and the value obtained by replacing $Index$ with the identifier of the initialization segment is the file name.

[0044] Moreover, the SegmentTimeline shown in lines 5 to 10 of FIG. 3 indicates the relationship between the playback start time of each segment, the segment length, and the identifier of the corresponding initialization segment. In S, t indicates the playback start time, d indicates the segment length, i indicates the identifier of the initialization segment, and r indicates the number of consecutive segments with the same i and d. That is, S in line 6 indicates that the start time is 0 (t=0), the segment length is 2 seconds (d / timescale), the index of the initialization segment is 0, and the same i and d continue for three segments. Therefore, the file names of the segments are s1_0.mp4, s1_2000.mp4, s1_4000.mp4, and s1_6000.mp4 for the media segments with start times of 0 seconds, 2 seconds, 4 seconds, and 6 seconds, and the file names of the corresponding initialization segments are s1_init_0.mp4. 5, the media segments with start times of 8, 10, 12, and 14 seconds are s1_8000.mp4, s1_10000.mp4, s1_12000.mp4, and s1_14000.mp4, and the corresponding initialization segment is s1_init_1.mp4. In this way, it is possible to identify the file name of a media segment that includes a certain playback time and the file name of the initialization segment that corresponds to that media segment.

[0045] In the example of Fig. 3, lines 5 to 10 and 13 are segment correspondence relationship information. Here, i is an identifier not defined in conventional standards, and $Index$ is a variable not defined in conventional standards. In this way, the manifest generation unit 25 can generate a manifest file in which information on a plurality of initialization segments is described in one Representation by adding segment correspondence relationship information to a manifest file conforming to the MPD format. In the example of Fig. 3, information on four initialization segments with i=0 to 3 is described for the Representation with id=1.

[0046] (How content is generated) Next, a content generating method according to the present invention will be described with reference to the flow chart of FIG.

[0047] In step S001, the generation parameter change unit 22 checks whether or not there are any initial settings for the generation parameters if encoding has not yet started, and checks whether or not there are any changes to the generation parameters if encoding has started. If there are any initial settings or changes to the generation parameters (step S001-YES), the process proceeds to step S002, and if there are no initial settings or changes to the generation parameters (step S001-NO), the process proceeds to step S004.

[0048] In step S002, generation parameter change unit 22 sets the set or changed generation parameters as new generation parameters.

[0049] In step S003, the initialization segment generating unit 24 generates an initialization segment based on new generation parameters.

[0050] In step S004, the encoding unit 231 continues encoding using the previously set parameters.

[0051] In step S005, the segmentation unit 232 generates media segments segmented at predetermined intervals.

[0052] In step S006, manifest generation unit 25 associates an initialization segment for each generation parameter with a media segment generated by each generation parameter.

[0053] In step S007, the manifest file is updated by the manifest generation unit 25. Then, the content transmission unit 26 and the communication I / F 27 transmit the initialization segment, the media segment, and the manifest file.

[0054] In step S008, it is confirmed whether the encoding has reached the end of the content or an instruction to end the encoding has been given. If the encoding has reached the end of the content or an instruction to end the encoding has been given (step S008-YES), the process ends. If the encoding has not reached the end of the content and there has been no instruction to end the encoding (step S008-NO), the process continues.

[0055] A computer can be suitably used to function as the above-mentioned content generation device 2, and such a computer can be realized by storing in a storage unit of the computer a program describing the processing contents for realizing each function of the content generation device 2, and having the processor of the computer read and execute this program. Note that this program can be recorded on a computer-readable recording medium.

[0056] (Receiving device) Next, a description will be given of the details of the receiving device 1. Fig. 5 is a block diagram showing an example of the configuration of the receiving device 1. The receiving device 1 shown in Fig. 5 includes a communication I / F 10, a manifest acquisition unit 11, a segment list storage unit 12, a segment acquisition unit 13, a buffer 14, a buffer control unit 15, a playback control unit 16, a playback control user I / F 17, a playback unit 18, and a display unit 19.

[0057] The manifest acquisition unit 11 receives a manifest file of a desired program from the distribution server 3 via the communication I / F 10. Then, the manifest acquisition unit 11 analyzes the manifest file in which the segment correspondence relationship information is described, generates a segment URL list in which the playback times of media segments are associated with the URLs of the initialization segment and the media segments, and stores the segment URL list in the segment list storage unit 12.

[0058] The segment acquisition unit 13 inputs the URL of the segment to be acquired from the buffer control unit 15, and sends a request including the URL of the input segment to the distribution server 3 via the communication I / F 10. Then, the segment acquisition unit 13 receives the segment from the distribution server 3 via the communication I / F 10 as a response to the request, and outputs it to the buffer control unit 15.

[0059] The buffer 14 inputs segments from the buffer control unit 15, and stores the media segments in association with the initialization segment and the playback start time and playback duration (segment length) of the media segment. The buffer 14 then outputs information on the segment playback times and playback durations of all currently stored media segments to the buffer control unit 15. The buffer 14 also sequentially outputs segments with playback times requested by the playback unit 18 to the playback unit 18.

[0060] The playback control unit 16 outputs the current playback state (playing, stopped) and current playback time information input from the playback unit 18 to the playback control user I / F 17. Furthermore, when a playback start or stop command is input from the playback control user I / F 17, the playback control unit 16 instructs the playback unit 18 to start or stop playback.

[0061] The playback control user I / F 17 is a function that controls playback by user operation. It may be provided with playback start / stop buttons and buttons that enable a seek operation to a desired playback time, and may graphically display the current playback time based on the start and end times of the content and the playback time information input from the playback control unit 16. For example, the start time of the content may be displayed as a horizontally long bar at the bottom of the playback screen with the left end at the left end and the end time at the right end at the right end, and a knob-shaped operation part may be arranged so as to overlap with it, and the knob-shaped operation part may be moved from the left end to the right end as the playback progresses, so that it is possible to grasp at a glance which part of the entire playback time is currently being played. Also, a seek operation to a desired playback time may be performed by changing the knob-shaped operation part.

[0062] When the playback unit 18 receives a playback command including a playback start time from the playback control unit 16, it sequentially inputs media segments from the buffer 14 based on the playback start time, decodes the media segments using parameters indicated by the initialization segment corresponding to the media segments, and outputs the decoded media segments to the display unit 19. The playback unit 18 also outputs playback time information, which is information on the playback time that is updated as the media segments are played back, to the playback control unit 16. When the playback unit 18 receives a stop command from the playback control unit 16, it stops the playback.

[0063] The display unit 19 displays the decoded media data input from the playback unit 18 in accordance with the format of the media.

[0064] The buffer control unit 15 determines (extracts) the URL of the segment to be acquired from the playback time information and the segment URL list input from the playback control unit 16, and outputs it to the segment acquisition unit 13. In addition, the buffer control unit 15 outputs the segment input from the segment acquisition unit 13 to the buffer 14.

[0065] (Segment acquisition control method) Next, a segment acquisition control method of the receiving device 1 will be described with reference to the flowchart in Fig. 6. The flowchart shown in Fig. 6 starts from a state in which the manifest file has already been acquired from the distribution server 3 by the manifest acquisition unit 11 and a segment URL list has already been created. Also, it is assumed that the buffer 14 has a range from the start time to the end time of the Period described in the MPD, and stores the segments in association with information on the playback start time and the playback duration time. Also, the range in which the content segments are inserted in the buffer 14 is referred to as the buffered segment range.

[0066] In step S101, when any playback start is executed in the playback control user I / F 17, the playback control unit 16 outputs the playback start time to the buffer control unit 15 as the current playback time.

[0067] In step S102, the buffer control unit 15 determines whether or not the current playback time is within the buffered segment range. If it is within the buffered segment range (step S102-YES), the process proceeds to step S103, and if it is not within the buffered segment range (step S102-NO), the process proceeds to step S104.

[0068] In step S103, the buffer control unit 15 extracts, from the segment URL list, the URL of the media segment following the buffered segment range, and the URL of the initialization segment corresponding to that media segment.

[0069] In step S104, the buffer control unit 15 extracts, from the segment URL list, the URL of the media segment including the current start time, and the URL of the initialization segment corresponding to that media segment.

[0070] In step S105, the buffer control unit 15 determines whether the URL of the extracted initialization segment is different from the URL of the previously acquired media segment. If they are different (step S105-YES), the process proceeds to step S106, and if they match (step S105-NO), the process proceeds to step S108.

[0071] In step S106, segment acquisition unit 13 transmits a segment request including the URL of the extracted initialization segment to distribution server 3, and receives the initialization segment corresponding to the request.

[0072] In step S 107 , the buffer control unit 15 inserts the received initialization segment into the buffer 14 .

[0073] In step S108, the segment acquisition unit 13 transmits a segment request including the URL of the media segment extracted in step S103 or step S104 to the distribution server 3, and receives the media segment corresponding to the request.

[0074] In step S 109 , the buffer control unit 15 inserts the received media segment into the buffer 14 .

[0075] In step S110, it is confirmed whether the end of the segment URL list has been reached or the stop button has been pressed. If the end of the segment URL list has been reached or the stop button has been pressed (step S110-YES), the process ends. If the end of the segment URL list has not been reached and the stop button has not been pressed (step S110-NO), the process proceeds to step S1111.

[0076] In step S111, the playback unit 18 continues playback, updates the current playback time, and returns the process to step S102.

[0077] A computer can be suitably used to function as the above-mentioned receiving device 1, and such a computer can be realized by storing in a storage unit of the computer a program describing the processing contents for realizing each function of the receiving device 1, and reading and executing this program by a processor of the computer. This program can be recorded on a computer-readable recording medium.

[0078] As described above, the content generator 2 or the program for functioning as the content generator 2 generates a new initialization segment in accordance with the change in the generation parameters and generates a manifest file including the segment correspondence relationship information. The receiving device 1 or the program for functioning as the receiving device 1 can recognize the change in the generation parameters during the playback of the streaming content by acquiring the manifest file in which the segment correspondence relationship information is described, and can continue stable streaming.

[0079] Although the above-mentioned embodiment has been described as a representative example, it is obvious to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited by the above-mentioned embodiment, and various modifications and changes are possible without departing from the scope of the claims. For example, it is possible to combine multiple components or process steps described in the embodiment into one, or to divide one into multiple components. [Explanation of symbols]

[0080] 1. Receiving device 2 Content Generation Device 3. Distribution Server 10 Communication I / F 11 Manifest Acquisition Department 12 Segment list storage section 13 Segment Acquisition Section 14 Buffer 15 Buffer control section 16 Playback control section 17 Playback control user interface 18 Playback Department 19 Display section 21 Video source output section 22 Generation parameter change section 23 Media Segment Generation Unit 24 Initialization segment generation part 25 Manifest Generation Unit 26 Content Transmission Unit 27 Communication I / F 231 Encoding section 232 Segmentation Section

Claims

1. A content generation device that generates video content segments and a manifest file, comprising: a media segment generator for generating media segments in accordance with generation parameters used to generate segments of the video content; an initialization segment generating unit that generates a new initialization segment including information necessary for decoding the media segment in accordance with the change in the generation parameter; a manifest generation unit that generates a manifest file including segment correspondence relationship information indicating the corresponding initialization segment for each of the media segments; a content transmitter that transmits the media segments, the initialization segment, and the manifest file; A content generating device comprising:

2. The content generating device according to claim 1 , wherein the segment correspondence information is information for identifying a file name of a media segment and a file name of an initialization segment corresponding to the media segment.

3. The content generating device according to claim 1 or 2, wherein the manifest generation unit generates a manifest file in which information of multiple initialization segments is described in one Representation by adding the segment correspondence relationship information to a manifest file conforming to an MPD (Media Presentation Description) format.

4. A receiving device for receiving an initialization segment, a media segment, and a manifest file of video content, the receiving device comprising: a manifest acquisition unit that acquires a manifest file in which segment correspondence information indicating a corresponding initialization segment for each media segment is described, and generates a segment URL list in which the playback times of the media segments are associated with the URLs of the initialization segments and the media segments; a buffer control unit that extracts a URL of the media segment and a URL of the initialization segment corresponding to the media segment based on a playback time that is updated along with playback of the media segment and the segment URL list; a segment acquisition unit that acquires the media segment based on the URL of the media segment and acquires the initialization segment based on the URL of the initialization segment; A receiving device comprising:

5. A program for causing a computer to function as the content generating device according to any one of claims 1 to 3.

6. A program for causing a computer to function as the receiving device according to claim 4.

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