JP2020129734A - Content generation device, reception device, and program - Google Patents

Abstract

To reduce the buffering delay in a seek operation during streaming reproduction.SOLUTION: A content generation device 2 includes a segmented stream generation unit 24 that generates a plurality of segmented streams by dividing an encoded stream of a video content into segments at different timings, a manifest generation unit 25 that generates a manifest file in which a stream identifier that identifies the segmented streams and a reproduction time and the URL of the segment are described, and a content transmission unit 26 that supplies the manifest file and the segment to a distribution server.SELECTED DRAWING: Figure 2

Description

The present invention relates to a content generation device, a reception device, and a program.

In streaming video distribution on the Internet these days, there is a transition from a streaming distribution method using a dedicated server and a dedicated protocol to a method using a general-purpose Web server to perform streaming distribution using the HTTP protocol. It has become the mainstream in distribution. As such a streaming delivery method (adaptive streaming) based on the HTTP protocol, an original technology by an IT vendor is widespread, and MPEG-DASH (ISO/IEC23009-1) which is an international standard intended to unify these streaming methods. ) Was formulated.

The basic concept of both technologies is the same, and the web server stores files of several to several tens of seconds each of which is an encoded stream obtained by encoding moving image content with one or more qualities (screen size and bit rate). A manifest file that describes the attributes and URLs of those moving image contents is prepared. The receiving device selects the timely quality from the manifest file in consideration of the screen size of the receiving device, the state of the network bandwidth of the transmission path, and the like, receives the segments one after another, and connects them to one moving image content to reproduce. (See, for example, Non-Patent Document 1).

FIG. 7 shows an example of adaptive streaming. In FIG. 7, an image is encoded with a plurality of qualities, and a segment divided into seconds is generated for each quality. In this example, the encoder splits the video into low quality segments 1-4, medium quality segments 1'-4', and high quality segments 1"-4". In the manifest file, the URLs of the segments and the attribute information such as the bit rate and the image size for each quality are registered. The segment and manifest file are supplied to the web server.

The receiving device receives the manifest file from the Web server, grasps the bit rate and the configuration of the segment from the manifest file (step A), and based on the screen size of the receiving device and the status of the network reception bandwidth, the quality is segmented. Is selected and received by the HTTP protocol (step B). Then, the received segments are connected and reproduced in order according to the manifest file (step C). By repeating the processing of steps B and C in this manner, a series of contents can be received and the reproduction can be continued.

In the receiving device, an HTML5 browser, which has been widely used in many devices, can be used to construct a viewing environment compatible with multiple devices (PC, TV receiver, tablet device, etc.).

However, in the past, the video element (video tag), which is a function for playing a moving image in the HTML5 browser, could only refer to a media file as a source. Therefore, in order to realize such adaptive streaming viewing, A separate browser plugin had to be installed. Therefore, it was difficult to build a viewing environment that can be shared by all browsers. Under such circumstances, W3C, an international non-profit organization that is promoting the standardization of technologies used on the Web, has been developed as a function for realizing the viewing of adaptive streaming using HTML5 browser video elements and JavaScript (registered trademark). , MSE (Media Source Extensions) are being standardized (see Non-Patent Document 2, for example).

The use of MSE allows a video element to reference a buffer as a source. Since the segment received by JavaScript can be inserted into the buffer, various adaptive streaming viewing can be realized by the HTML5 video element and JavaScript.

Here, the buffer model of the MSE will be described with reference to FIG. FIG. 8 is a diagram showing an example of the MSE buffer model. The buffer (SourceBuffer) manages the segment in association with the segment start time and the playback duration. In FIG. 8, blocks with diagonal lines indicate segments. The segment start time, which is the playback start time of each segment, is 0 seconds and the playback duration is 5 seconds, and the segment start time is 5 seconds and the playback duration is 5 seconds. Seconds, and three segments having a segment start time of 15 seconds and a reproduction duration of 5 seconds are inserted in the buffer. At this time, the buffering range (buffered attribute) of the buffer is 0 to 10 seconds and 15 to 20 seconds.

As a method of providing a streaming service for moving images, in addition to the adaptive streaming described above, multi-view video/multilingual audio distribution, program distribution according to organization such as broadcasting, and the like can be considered. In MPEG-DASH, a description method of a manifest file that enables such a service is defined.

FIG. 9 shows a conceptual diagram of a manifest file in MPD (Media Presentation Description) format of MPEG-DASH. The MPD format has a hierarchical structure in the order of Period, AdaptationSet, and Representation. Period indicates one section obtained by dividing the manifest file in the time direction, and in the example of FIG. 9, it is shown that Periods having a content length (duration) of 300 seconds are connected. Period is composed of one or more AdaptationSets.

The AdaptationSet indicates information of media components (video, audio, text, etc.), and can include a plurality of components different in expression (video of another angle, audio of another language, etc.) in the same media format. In the example of FIG. 9, there are two videos (mimeType=video/mp4) and one audio (mimeType=audio/mp4). Information of each media component included in the Adaptation Set is indicated by Representation.

In the Representation, information on segments (Initialization Segment, Media Segment) that are the actual data that configures the media element is described. Initialization Segment is initialization information such as encoding parameters, and Media Segment is a segment. In the example of FIG. 9, the file name has the sequence number ($Number$) incremented for each segment length (duration=5s).

With such a manifest file, the segments (Initialization Segment, Media Segment in FIG. 9) forming the media component (AdaptationSet) selected in Period can be sequentially received, and the media component can be selected. By fixing it, it becomes possible to switch to reception of a segment forming another media component and display another video.

JP, 2008-098569, A

"Next-Generation Video Delivery Technology "MPEG-DASH" Technology Outline and Standardization/Related Technology Trends", Journal of Image Information Media, Vol.67, No.2, 2013, p.109-115 W3C, “Media Source Extensions W3C Candidate Recommendation 17 November 2016”, [December 28, 2018 search], Internet <URL:http://www.w3.org/TR/media-source/>

Here, generally, in streaming viewing, the reception band constantly fluctuates according to the congestion state of the network, and therefore a desired scene (hereinafter referred to as “new reproduction time”) is skipped at the start of reproduction or a seek operation. At this time, the viewing stability is improved by receiving data up to several seconds ahead of the new playback time, inserting it into the buffer, and playing it back. On the other hand, if the time (buffering delay) until the data amount (buffer specified value) necessary for starting the reproduction is received is long, the start of the reproduction is delayed and the user's quality of experience is deteriorated. At this time, depending on the relationship between the new reproduction time and the segment length, there is a problem that the buffering delay increases due to the reception of useless data.

FIG. 10: is a figure explaining the said subject. In this example, the segment length is set to 5 seconds based on FIG. 10A shows the buffer state when the new playback time by the seek operation is 110 seconds, and FIG. 10B shows the new playback time by the seek operation. The buffer state is shown for 114 seconds. In FIG. 10A, the buffer specified value is reached by receiving two segments of 110 seconds to 115 seconds and 115 seconds to 120 seconds. On the other hand, in FIG. 10B, the buffer prescribed value is not reached unless three segments of 110 seconds to 115 seconds, 115 seconds to 120 seconds, and 120 seconds to 125 seconds are received. The data of 110 seconds to 114 seconds in FIG. 10B is not used for reproduction and includes such useless data, so that it takes time to receive the data and the buffering delay increases.

As a method for reducing useless data reception, it is conceivable to shorten the segment length to, for example, about 1 second, but the number of requests for the segment increases correspondingly, so that the load on the distribution server and the receiving device increases. was there.

Further, in Patent Document 1, in a content distribution system having a first distribution server that distributes content data that is not shaped and a second distribution server that distributes content data that is shaped, a buffer prescribed value A method is disclosed in which data is received at high speed from the first distribution server until the minute data is received to speed up the reproduction start after the seek operation.

However, the technology disclosed in Patent Document 1 is not necessarily applicable to content providers when performing content delivery using a CDN (Content Delivery Network) service provided by the delivery providers.

An object of the present invention made in view of such circumstances is to provide a content generation device, a reception device, and a program capable of reducing a buffering delay at the time of a seek operation during streaming reproduction.

In order to solve the above problems, a content generation device according to the present invention is a content generation device that generates a segment of a video content and a manifest file, and divides an encoded stream of the video content into segments at different timings. A segmented stream generation unit that generates a segmented stream, a manifest generation unit that generates a manifest file that describes, for each of the plurality of segmented streams, a stream identifier that identifies the segmented stream, a segment playback time, and a URL. A content transmission unit that supplies the manifest file and the segment to a distribution server.

Further, in order to solve the above problems, a receiving device according to the present invention is a receiving device that receives a manifest file regarding a plurality of segmented streams obtained by dividing an encoded stream into segments at different timings, and a segment from a distribution server. In the manifest file, a stream identifier for identifying a segmented stream, a playback time of a segment, and a URL are described. The received manifest file is analyzed, and the playback time of the segment for each stream identifier and When a manifest acquisition unit that generates a segment URL list in which URLs are associated, a playback control unit that extracts a new playback time that is the playback time after a seek when a seek operation is performed, and a seek operation is performed Based on the new playback time, determine the segment URL list corresponding to the segmented stream that requires the minimum number of segments to be stored in the buffer before starting playback, and obtain the segment URL list from the segment URL list. A buffer control unit for extracting the URL of the segment and a segment acquisition unit for acquiring the segment from the distribution server based on the URL of the segment determined by the buffer control unit.

In order to solve the above problems, the program according to the present invention causes a computer to function as the content generation device.

In order to solve the above problems, the program according to the present invention causes a computer to function as the receiving device.

According to the present invention, at the time of a seek operation during streaming reproduction, it is possible to reduce the number of segments to be acquired before the data necessary for reproduction start is stored in the buffer. Therefore, it is possible to shorten the waiting time until the start of reproduction. Further, since the chances of acquiring useless segments are reduced, the utilization efficiency of the network is improved and stable viewing is possible.

It is a figure which shows the outline of the content distribution system provided with the receiver and content generator which concern on one Embodiment of this invention. It is a block diagram which shows the structural example of the content production|generation apparatus which concerns on one Embodiment of this invention. It is a figure which shows the specific example of the segment produced|generated by the content production apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the manifest file of MPD format produced|generated by the content production|generation apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the structural example of the receiver which concerns on one Embodiment of this invention. 9 is a flowchart showing a segment acquisition control method during a seek operation of the receiving device according to an embodiment of the present invention. It is a figure which shows an example of the conventional adaptive streaming. It is a figure which shows an example of the buffer model of the conventional MSE. It is a figure which shows the concept of the conventional manifest file. It is a figure explaining the conventional subject.

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

FIG. 1 shows an outline of a content distribution system including a receiving device and a content generating device according to an embodiment of the present invention. The receiving device 1 and the distribution server 3 are connected via the Internet. The content generation device 2 and the distribution server 3 may be connected via a dedicated local network or may be connected via the Internet.

The receiving device 1 receives the segment of the moving image content and the manifest file from the distribution server 3 and performs streaming reproduction.

The content generation device 2 generates a segment of the moving image content and a manifest file, and supplies the segment and the manifest file to the distribution server 3.

The distribution server 3 is a server that distributes the manifest file and the segment to the reception device 1, and can be, for example, a general Web server.

(Content generation device)
Next, details of the content generation device 2 will be described. FIG. 2 is a block diagram showing a configuration example of the content generation device 2. The content generation device 2 illustrated in FIG. 2 includes a material video output unit 21, an encoding unit 22, a segmentation timing control unit 23, a segmented stream generation unit 24, a manifest generation unit 25, a content transmission unit 26, and And a communication I/F 27. The segmented stream generation unit 24 includes n (n≧2) number of segmented units 24-1 to 24-n.

The material video output unit 21 outputs the content to be generated to the encoding unit 22 from the material video input from the outside or the material video stored in advance.

The encoding unit 22 converts the material video signal input from the material video output unit 21 into the H.264 format, for example. H.264|MPEG-4 AVC (Advanced Video Coding), H.264. 265|MPEG-H It is encoded by an existing encoding method such as HEVC (High Efficiency Video Coding). Then, the encoding unit 22 outputs the encoded stream to each of the segmentation units 24-1 to 24-n of the segmented stream generation unit 24.

The segmentation timing control unit 23 outputs segmentation timing information indicating the start position and segment length of each segment to each of the segmentation units 24-1 to 24-n of the segmented stream generation unit 24. Here, it is assumed that the segmenting timing information output to each segmenting unit 24-1 to 24-n is different. Therefore, the timings of segment breaks are different.

Each of the segmenting units 24-1 to 24-n uses the encoded stream input from the encoding unit 22 according to the segmenting timing information input from the segmenting timing control unit 23, for example, ISO-BMFF (ISO-Base Media). Generate a segmented stream that is a stream of segments by segmenting in the File Format) format. That is, the segmented stream generation unit 24 divides the coded stream input from the encoding unit 22 into segments at different timings to generate a plurality of segmented streams. Then, the segmentation units 24-1 to 24-n output the segmented streams to the manifest generation unit 25, respectively.

The manifest generation unit 25 inputs the segments input from the plurality of segmentation units 24 and generates one manifest file in the MPD format of MPEG-DASH, for example. The manifest file describes at least the stream identifier that identifies the segmented stream, the playback time of the segment, and the URL. Then, the manifest generation unit 25 outputs the manifest file and the segment to the content transmission unit 26. The manifest file may be generated by a method of sequentially updating each time a segment is input, or may be performed after inputting all the segments.

The content transmission unit 26 transmits the manifest file and the segment input from the manifest generation unit 25 to the distribution server 3 via the communication I/F 27.

Here, a specific example of the content generated by the content generation device 2 according to the present invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing a specific example of the segments generated by the segmenting unit 24. In FIG. 3, the encoded stream having a content length of 30 seconds generated by the encoding unit 22 is divided into three segmenting units 24 (segmenting unit 24-1, segmenting unit 24-2, and segmenting unit 24-3). ), the segmented stream 1, the segmented stream 2, and the segmented stream 3 are generated.

The segmented stream 1 is a stream segmented from the beginning with a segment length of 3 seconds. The segmented stream 2 has a segment length of 0 seconds to 1 second of 1 second, a segment length of 1 second to 28 seconds of 3 seconds, and a segment length of 28 seconds to 30 seconds of 2 seconds. Is. The segmented stream 3 is a stream segmented with a segment length of 0 to 2 seconds being 2 seconds, a segment length of 2 seconds to 29 seconds being 3 seconds, and a segment length of 29 seconds to 30 seconds being 1 second. ..

FIG. 4 is a diagram showing an example (excerpt) of an MPD format manifest file generated based on the segmented stream 1, the segmented stream 2, and the segmented stream 3 of FIG. 3. In the example shown in FIG. 4, there is one Period whose content length information (duration) is 30 seconds, and there are three AdaptationSets with the same media format (mimeType=“video/mp4”) in the Period (id= "Mod3_0", id="Mod3_1", id="Mod3_2"), and one Representation exists in each AdaptationSet. Hereinafter, the id of the AdaptationSet will be referred to as the “stream identifier”.

Here, a method of identifying the file name of the segment including a certain reproduction time will be described. From the start value in the second line of FIG. 4, the start time of Period is 0. From the timescale value on the 10th line in FIG. 4, the timescale (the number of scales per second) of the AdaptationSet with id=“Mod3_1” is 1000. From the value of startNumber on the 10th line in FIG. 4, the start number of the segment is 1. From the value of media on the 10th line in FIG. 4, the standard value of the segment file name is s2_$Number$.mp4, and the value obtained by replacing $Number$ with the sequence number of the segment becomes the file name.

Further, the Segment Timeline shown on the 11th to 15th lines indicates the relationship between the reproduction start time of each segment of the segmented stream 2 shown in FIG. 3 and the segment length. In S, t is the reproduction start time, d is the segment length, and r is the same number of times d is continued. That is, S in the 12th row indicates that the start time is 0 (t=0) and the segment length is 1 second (d/timescale). S in the 13th row indicates that the start time is 1 second (t/timescale), the segment length is 3 seconds, and that eight segments with the same segment length follow. S in the 14th line represents a segment having a start time of 28 seconds and a segment length of 2 seconds. The segment number is incremented by this information. According to this, for example, the sequence number of the segment including the reproduction time of 8 seconds is 4, and the file name thereof is "s2_4.mp4". In this way, it becomes possible to specify the file name of the segment including a certain reproduction time.

It should be noted that a computer can be preferably used for causing the above-described content generation device 2 to function, and such a computer stores a program describing the processing content for realizing each function of the content generation device 2 in the storage unit of the computer. It can be realized by storing it in the computer and reading and executing this program by the CPU of the computer. Note that this program can be recorded in a computer-readable recording medium.

(Receiver)
Next, details of the receiving device 1 will be described. FIG. 5 is a block diagram showing a configuration example of the receiving device 1. The reception device 1 illustrated 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 reproduction control unit 16, A reproduction control user I/F 17, a reproduction unit 18, and a display unit 19 are provided.

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 received manifest file, generates a segment URL list that associates the segment reproduction time and the URL for each stream identifier, and stores the segment URL list in the segment list storage unit 12.

The segment acquisition unit 13 inputs the URL of the segment to be acquired from the buffer control unit 15, and requests the distribution server 3 via the communication I/F 10 for a request including the URL of the input segment. 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 the segment to the buffer control unit 15.

The buffer 14 stores the segment input from the buffer control unit 15 in association with the segment reproduction start time and segment reproduction duration (segment length). Then, the buffer 14 outputs the information of the segment reproduction time and the reproduction continuation time of all the currently stored segments to the buffer control unit 15.

Further, the buffer 14 sequentially outputs the segments of the reproduction time requested by the reproducing unit 18 to the reproducing unit 18.

When the reproduction control user I/F 17 inputs a reproduction start/stop command, the reproduction control unit 16 instructs the reproduction unit 18 to start/stop reproduction.

Further, when the reproduction control user I/F 17 inputs a seek command to the new reproduction time, the reproduction control unit 16 outputs the new reproduction time information to the buffer control unit 15, and the buffer control unit 15 exceeds the buffer specified value. When the notification indicating that is input, the reproduction unit 18 is instructed to change the reproduction time to the new reproduction time. As the buffer stipulated value, an arbitrary value may be set in the receiving device 1, or a set value described in the manifest file (for example, the value of minBufferTime shown in FIG. 4) may be used.

Further, the reproduction control unit 16 outputs the current reproduction state (reproducing or stopped) and the reproduction time information input from the reproduction unit 18 to the buffer control unit 15 and the reproduction control user I/F 17.

The reproduction control user I/F 17 is a function of controlling reproduction by a user's operation. A playback start/stop button, a button that enables a seek operation to a desired playback time, and the like are provided. The time may be displayed graphically. For example, at the bottom of the playback screen, display the content as a horizontal bar with the left end as the left end and the end time as the right end, arrange the knob-shaped operation part so that it overlaps with it, and move the knob-shaped operation part as playback progresses. By moving from the left end to the right end, it is possible to grasp at a glance which part of the entire reproduction time is currently being reproduced. Further, the seek operation to a desired reproduction time may be performed by changing the knob-shaped operation portion.

When the reproduction unit 18 inputs a reproduction command including the reproduction start time from the reproduction control unit 16, the reproduction unit 18 sequentially inputs the segments from the buffer based on the reproduction start time, and the input segment is a segment media format (video, audio, text, etc.). ), and outputs to the display unit 19, and also outputs reproduction time information, which is information of the reproduction time updated at the time of reproduction, to the reproduction control unit 16.

In addition, when the reproduction unit 18 inputs a stop command from the reproduction control unit 16, the reproduction unit 18 stops the reproduction.

The display unit 19 displays the decoded media data input from the reproduction unit 18 according to the format of the media.

The buffer control unit 15 determines the URL of the acquisition target segment from the reproduction time information input from the reproduction control unit 16 and the segment URL list corresponding to the acquisition target stream identifier representing the acquisition target segmented stream, and acquires the segment acquisition. It is output to the unit 13. Further, when the segment is input from the segment acquisition unit 13, the buffer control unit 15 outputs the segment to the buffer 14.

When the new reproduction time information is input from the reproduction control unit 16, the buffer control unit 15 determines the minimum number of segments to be stored in the buffer 14 before starting reproduction based on the new reproduction time. The stream identifier of the encoded stream is extracted as the acquisition target stream identifier from the segment list storage unit 12. That is, the buffer control unit 15 determines the segment URL list corresponding to the acquisition target stream identifier. Then, the buffer control unit 15 extracts the URL of the acquisition target segment from the segment URL list and outputs it to the segment acquisition unit 13. Details of the control during the seek operation will be described below.

It should be noted that a computer can be preferably used to function as the above-described receiving device 1, and such a computer stores a program describing the processing content for realizing each function of the receiving device 1 in the storage unit of the computer. Moreover, it can be realized by reading and executing this program by the CPU of the computer. Note that this program can be recorded in a computer-readable recording medium.

(Segment acquisition control method during seek operation)
Next, a segment acquisition control method at the time of a seek operation of the receiving device 1 will be described with reference to the flowchart of FIG. The flowchart shown in FIG. 6 starts from a state in which the manifest acquisition unit 11 has already acquired a manifest file from the distribution server 3 and created a segment URL list in which segment playback times and URLs are associated with each stream identifier. And Also, in anticipation that the reception band will always fluctuate depending on the congestion status of the network, starting from the new reproduction time, a segment with a preset buffer specified value (for example, 3 seconds) or more is inserted into the buffer 14 and then reproduced. Shall be started.

Further, the buffer 14 has a range from the start time to the end time of the Period described in the MPD, and stores the segment in association with the information of the reproduction start time and the reproduction continuation time. A range in which the content segment is inserted in the buffer 14 is referred to as a buffered segment range.

First, when a seek operation is executed by the playback control user I/F 17 (step S001), the playback control unit 16 extracts a new playback time that is the playback time after the seek (step S002), and outputs it to the buffer control unit 15. To do.

Subsequently, the buffer control unit 15 resets the acquisition target stream identifier representing the segmented stream that is currently the acquisition target (step S003), and the range from the new reproduction time in the buffer 14 to the preset buffer specified value or more. Check whether there is a corresponding segment up to.

If the above segment does not exist in the buffer 14 (step S004-NO), the buffer control unit 15 determines the number of segments that need to be stored in the buffer 14 before starting reproduction (by the time when the buffer prescribed value is reached). The stream identifier of the segmented stream that minimizes the number of segments that need to be acquired) is extracted and set as the acquisition target stream identifier (step S005). If the buffered segment range includes a segment corresponding to the new playback time, the segmented stream that minimizes the number of segments that need to be acquired from the end of the buffered segment range to the buffer specified value The identifier is extracted (step S005).

For example, in the case of seeking at the position of 5 seconds in the example of FIG. 3 described above, it is necessary to acquire two segments in the segmented stream 1 and the segmented stream 2 in order to achieve the buffer specified value (3 seconds) or more. However, segmented stream 3 only needs to acquire one segment. Therefore, the acquisition target stream identifier is the stream identifier of the segmented stream 3.

Subsequently, the buffer control unit 15 extracts (determines) the URL of the segment corresponding to the new reproduction time from the segment URL list corresponding to the acquisition target stream identifier stored in the segment list storage unit 12 (step S006). .. If the buffered segment range includes a segment corresponding to the new playback time, the buffer control unit 15 determines the URL of the segment following the last segment of the buffered segment range including the new playback time as the acquisition target stream. Extract from the segment URL list corresponding to the identifier.

Subsequently, the segment acquisition unit 13 transmits a request (segment request) including the URL of the extracted segment to the distribution server 3, and acquires a segment from the distribution server 3 as a response to the request (step S007). Then, the segment acquisition unit 13 inserts the received segment into the buffer 14 (step S008).

When the reproduction time has not reached the end time of the content and the stop button is not pressed by the reproduction control user I/F 17 (step S009-NO), the process returns to step S004. On the other hand, when the reproduction time reaches the end time of the content or when the stop button is pressed in the reproduction control user I/F 17 (step S009-YES), the process ends.

If YES in step S004, the current reproduction time is changed to the new reproduction time (step S010), reproduction is started from the reproduction time (step S011), and the process ends.

As described above, when performing a seek operation during streaming reproduction, it is possible to reduce the number of segments acquired until the data necessary for reproduction start is accumulated in the buffer 14. Therefore, it is possible to shorten the waiting time (buffering delay) until the reproduction is started, and the chances of acquiring useless segments are reduced, so that the utilization efficiency of the network is improved and stable viewing is possible.

Although the above embodiments have been described as representative examples, it will be apparent 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 construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims. For example, regarding the constituent blocks or processing steps described in the embodiments, it is possible to combine a plurality of them into one or divide one into a plurality.

1 Receiving Device 2 Content Generating Device 3 Distribution Server 10 Communication I/F
11 manifest acquisition unit 12 segment list storage unit 13 segment acquisition unit 14 buffer 15 buffer control unit 16 reproduction control unit 17 reproduction control user I/F
18 playback unit 19 display unit 21 material video output unit 22 encoding unit 23 segmentation timing control unit 24 segmented stream generation unit 24-1 to 24-n segmentation unit 25 manifest generation unit 26 content transmission unit 27 communication I/F

Claims (4)

A content generation device for generating a segment of a video content and a manifest file,
A segmented stream generation unit that generates a plurality of segmented streams by dividing the encoded stream of the video content into segments at different timings,
A manifest generation unit that generates a manifest file that describes a stream identifier that identifies the segmented stream, a segment reproduction time, and a URL for the plurality of segmented streams,
A content transmission unit that supplies the manifest file and the segment to a distribution server;
A content generation device comprising: A manifest file relating to a plurality of segmented streams obtained by dividing an encoded stream into segments at different timings, and a receiving device for receiving the segments from a distribution server,
In the manifest file, a stream identifier for identifying a segmented stream, a segment playback time and a URL are described.
A manifest acquisition unit that analyzes the received manifest file and generates a segment URL list that associates the playback time and URL of the segment for each stream identifier;
A playback control unit that extracts a new playback time, which is the playback time after the seek, when a seek operation is executed,
When a seek operation is performed, based on the new playback time, determine the segment URL list corresponding to the segmented stream that minimizes the number of segments that need to be stored in the buffer before playback starts, A buffer control unit that extracts the URL of the segment to be acquired from the segment URL list;
A segment acquisition unit that acquires a segment from a distribution server based on the URL of the segment determined by the buffer control unit;
A receiver, comprising: A program for causing a computer to function as the content generation device according to claim 1. A program for causing a computer to function as the receiving device according to claim 2.

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