JP7319340B2 - Distribution server, distribution method and program - Google Patents

Description

The present invention relates to a distribution server, distribution method and program.

In recent years, cameras capable of capturing omnidirectional 360-degree video up, down, left, and right are known, and the video captured by such a camera is a panoramic video (or "panorama video", "360-degree panoramic video", " VR (Virtual Reality) video", "VR video", etc.).

Also, for example, a video distribution server streams a panoramic video to a terminal so that the panoramic video can be viewed on the terminal. However, in many cases, panoramic video requires a large amount of data to be distributed. On the other hand, the range displayed on the terminal (hereinafter also referred to as "field of view") is distributed with normal image quality, and the range not displayed on the terminal is distributed with low image quality. Techniques for reducing the amount of data are known (see Patent Document 1, for example).

Also, HLS (HTTP Live Streaming) is known as a protocol for a video distribution server to perform streaming distribution of video to terminals (clients). HLS divides the video and audio captured by the camera into multiple segment files in MPEG-2 TS (Transport Stream) format and stores them in the video distribution server. Create a playlist file that records such as, and install it in a predetermined place. By acquiring the playlist file from the video distribution server, the client can acquire and reproduce a desired segment file.

JP 2016-15705 A

Here, for example, in concerts, sports competitions, etc., a plurality of cameras are installed at a plurality of points, respectively, and panorama images are captured by each of the plurality of cameras. At this time, it is common for the user to be able to switch between the panorama images taken by each of the plurality of cameras and display them on the terminal.

However, when panoramic video is distributed by HLS, each time the panoramic video displayed on the terminal is switched (that is, each time the camera for the panoramic video displayed on the terminal is switched), a playlist file corresponding to the camera after switching is acquired. There is a need to. For this reason, a delay may occur in playback of the panoramic video.

The embodiments of the present invention have been made in view of the above points, and it is an object of the present invention to prevent the occurrence of playback delay due to switching of panorama images shot by a plurality of cameras.

In order to achieve the above object, a distribution server according to an embodiment of the present invention is a distribution server for distributing panoramic video captured by each of a plurality of cameras by HTTP Live Streaming to a client, wherein the panoramic video distribution request from the client, a first video distribution means for distributing a playlist for reproducing the panoramic video and the panoramic video to the client; and second video distribution means for distributing the panoramic video to be played back to the client.

It is possible to prevent the occurrence of playback delay due to switching of panorama images shot by a plurality of cameras.

FIG. 4 is a diagram for explaining an example of a panorama video; FIG. FIG. 4 is a diagram for explaining HLS; FIG. 4 is a diagram for explaining an example of panoramic video distribution by HLS; FIG. 10 is a diagram for explaining an example of panorama video distribution when switching between cameras when a plurality of cameras are present; It is a figure showing an example of the whole composition of the video distribution system concerning this embodiment. 1 is a diagram (1) for explaining an example of a data configuration of video content; FIG. FIG. 2 is a diagram (part 2) for explaining an example of the data configuration of video content; FIG. 5 is a sequence diagram showing an example of panorama video distribution processing according to the embodiment; FIG. 10 is a sequence diagram showing an example of communication processing related to playlist acquisition according to the present embodiment;

Hereinafter, embodiments of the present invention (hereinafter also referred to as "present embodiments") will be described. In this embodiment, a video distribution system 1 capable of preventing the occurrence of playback delay due to switching of panorama video captured by a plurality of cameras will be described.

<Explanation of prior art>
First, the related art and the like necessary for explaining the video distribution system 1 according to the present embodiment will be explained.

(Panorama image)
As described above, a panoramic video is also called a “panorama video,” a “360-degree panoramic video,” a “VR video,” a “VR video,” and the like. A panorama image is represented by an omnidirectional projection sphere, for example, as shown in FIG. In a panoramic image represented by an omnidirectional projection sphere, the center of the omnidirectional projection sphere is taken as the observation position, and the range captured by the pseudo camera at this observation position at a predetermined angle of view is the field of view (that is, the terminal range). A panoramic image represented by an omnidirectional projection sphere can be represented by an equirectangular projection with a vertical angle θ of 0 to π and a horizontal angle φ of 0 to 2π. At this time, for example, in the technology described in Patent Document 1 above, the partial area data including the viewing range of the panorama image represented by the equirectangular projection is a "high-resolution tile", and the entire panorama image is compressed data. are delivered to the terminal as "low resolution tiles". In other words, the partial area including the viewing range is delivered to the terminal as a high-bitrate high-resolution tile, and the entire panoramic video is delivered to the terminal as a low-bitrate low-resolution tile with a reduced bitrate.

As a result, it is possible to reduce the amount of data required for distribution of panoramic video, and it is possible to view high-quality video within the viewing range, and the video is not interrupted even when the viewing range is moved. can be made viewable. It should be noted that compression means reduction in image size.

In the video distribution system 1 according to the present embodiment as well, the technology described in Patent Document 1 is used to distribute high-resolution tiles and low-resolution tiles to a terminal (client). A video shall be played.

(HLS)
As described above, HLS is a protocol for a distribution server to perform streaming distribution of video to a client. For example, as shown in FIG. 2, a video signal output from a camera is encoded to create encoded video, and the distribution server divides this encoded video into a plurality of segment files and generates a playlist file. Install (store) in a specified location. Note that the segment file is a file in the ".ts" format (that is, MPEG-2 transport stream format), and the playlist file is a file in the ".m3u8" format. As an example, FIG. 2 shows a case where the encoded video is divided into 'TS-00.ts' to 'TS-NN.ts'.

At this time, in HLS, the client can acquire and reproduce a desired segment file by acquiring a playlist file from the distribution server.

(Panorama video distribution by HLS)
When a panorama video is distributed by HLS, the distribution server stores low-resolution tiles and high-resolution tiles for each of a plurality of predetermined viewing ranges as segment files for each predetermined time unit _tc . For example, as shown in FIG. 3, a low resolution tile LT per _tc , a high resolution tile HT1 per _tc in the first viewing range, a high resolution tile HT2 per _tc in the second viewing range, a third high-resolution tiles HT3 and the like are stored for each _tc in the visual field range of . Here, in the example shown in FIG. 3, the first visual field range is a range whose upper left coordinates are (0, 0), and the second visual field range is a range whose upper left coordinates are (S _x , 0). ), and the third visual field range is a range in which the upper left coordinates of the visual field range are (2S _x , 0). _Sx is a shift amount of a predetermined horizontal angle (x-axis direction).

Note that the shift amount _Sy of the vertical angle (y-axis direction) is also predetermined, and the high-resolution tile is set to p=0, . . . , P, q=0, . It is stored for each range whose upper left coordinates are (p×S _x , q×S _y ). Hereinafter, it is assumed that M=P×Q and high-resolution tiles for each of M viewing ranges are stored for each _tc .

In this way, in the panorama video, low-resolution tiles for each _tc and high-resolution tiles for each _tc in a plurality of predetermined visual field ranges are stored as segment files in the distribution server.

Then, when playing back the panoramic video, the client can acquire the low-resolution tiles and the high-resolution tiles of the desired viewing range by acquiring the playlist from the distribution server. As a result, the client can reproduce the panorama video using the low resolution tiles and the high resolution tiles.

For example, if the client's visual range moves by _Sx in the horizontal angle every _3tc , the client will have LT1 to LT3 and HT1-1 to HT1- for the first _3tc , as shown in FIG. 3 are distributed in order, and during the next _3tc , LT4 to LT6 and HT2-4 to HT2-6 are distributed in order, and further during the next _3tc , LT7 to LT9 and HT3-7 to HT3-9 are distributed. are delivered in order.

Although _tc can be set arbitrarily, it is conceivable to set it to about 0.5 [seconds], for example. S _x and S _y are arbitrarily set according _to the number of pixels of the panorama image. , S _y =50, and so on. As S _x and S _y are larger, the number of high-resolution tiles held by the distribution server can be reduced, but the smoothness when switching the viewing range decreases (that is, the user's viewing quality decreases). On the other hand, as _Sx and _Sy become smaller, the number of high-resolution tiles held by the distribution server increases, but the smoothness when switching the viewing range improves (that is, the user's viewing quality improves).

(Panorama video distribution by HLS when there are multiple cameras)
For example, in concerts, sports competitions, etc., a plurality of cameras are installed at a plurality of points, and panorama images are captured by each of the cameras. At this time, it is common for the client to be able to switchably display the panorama video captured by each of the plurality of cameras.

At this time, when a panorama video is distributed by HLS, the distribution server stores a playlist and a segment file for each camera. For example, as shown in FIG. 4, when there are N cameras from camera 1 to camera N, the distribution server stores a panorama image captured by camera 1 (that is, an encoded video signal of camera 1) camera 1 content showing a panoramic video), camera 2 content showing a panoramic video shot by camera 2, . . . , camera N content showing a panoramic video shot by camera N are stored. That is, the distribution server stores, for each camera, a playlist and a segment file for playing back the panorama video captured by this camera.

Therefore, as shown in FIG. 4, when playing back the panorama video captured by camera 1, the client acquires the playlist for the camera 1 content and uses the low resolution tiles (LT: Low -resolution Tile) and the High-resolution Tile (HT) of the camera 1 content. Similarly, when playing back panoramic video captured by camera N, the client acquires a playlist for camera N content, and stores the low resolution tiles of camera N content and the high resolution tiles of camera N content. get.

In other words, the client needs to acquire the playlist file corresponding to this camera each time the camera for the panorama video to be reproduced is switched. For this reason, the client needs to communicate with the distribution server each time the camera for the panoramic video to be played back is switched, which may cause a delay in playback of the panoramic video.

Therefore, in the video distribution system 1 according to the present embodiment, which will be described later, by eliminating the communication (communication for acquiring the playlist) when switching the camera of the panoramic video to be played back on the client, the panoramic video can be played back. Prevent delays from occurring.

<Overall Configuration of Video Distribution System 1>
The overall configuration of the video distribution system 1 according to this embodiment will be described with reference to FIG. FIG. 5 is a diagram showing an example of the overall configuration of the video distribution system 1 according to this embodiment.

As shown in FIG. 5, the video distribution system 1 according to this embodiment includes a distribution server 10, a client 20, a plurality of cameras 30, and an encoding device 40. FIG. The camera 30 and the encoding device 40, the encoding device 40 and the distribution server 10, and the distribution server 10 and the client 20 are communicably connected via an arbitrary communication network.

The distribution server 10 is a computer or computer system that distributes panoramic video to the client 20 by HLS. At this time, the distribution server 10 distributes to the client 20 the panorama video shot by the camera 30 desired by the client 20 among the panorama videos shot by the plurality of cameras 30 .

The client 20 is a computer that receives (obtains) panoramic video from the distribution server 10 by HLS and reproduces this panoramic video. The client 20 can select one or more cameras 30 from a plurality of cameras 30 and reproduce the panoramic video of the selected camera 30 (that is, the client 20 can switch the camera 30 of the panoramic video to be reproduced). be able to.).

As the client 20, for example, a PC (personal computer), a smart phone, a tablet terminal, a head mounted display (HMD), a wearable device, a game machine, etc. can be used.

The camera 30 is an imaging device installed at a predetermined point or position. Therefore, the plurality of cameras 30 are installed at a plurality of spots or positions. In the following description, the total number of cameras 30 is defined as N (where N is an integer equal to or greater than 2), and when each of the plurality of cameras 30 is distinguished, it will be referred to as “camera 30 ₁ ”, “camera 30 ₂ ”, . , “camera 30 _N ” and the like.

The encoding device 40 is a computer that encodes the video signal of the camera 30 to create an encoded video. The encoded video created by the encoding device 40 is transmitted to the distribution server 10 .

Here, the distribution server 10 according to this embodiment has a distribution processing unit 110 and a storage unit 120 . The distribution processing unit 110 is realized by processing that one or more programs installed in the distribution server 10 cause a processor such as a CPU (Central Processing Unit) to execute. Also, the storage unit 120 can be implemented using an auxiliary storage device such as a HDD (Hard Disk Drive) or an SSD (Solid State Drive). Note that the storage unit 120 may be implemented using a storage device or the like connected to the distribution server 10 via a communication network.

The distribution processing unit 110 distributes the contents of the corresponding camera 30 (that is, the low-resolution tile and the high-resolution tile) to the client 20 in response to a request from the client 20 .

The storage unit 120 stores image content showing panoramic images captured by the plurality of cameras 30 . Here, the video content includes a playlist common to the content of all the cameras 30 and the content of each camera 30 (that is, “camera 1 content”, “camera 2 content”, . . . , “camera N content”). ) and are included. Also, the content of each camera 30 includes, as segment files, low-resolution tiles for each _tc and high-resolution tiles for each _tc in a plurality of predetermined viewing ranges. Note that, where n=1, _.

In this way, the storage unit 120 _of the distribution server 10 according to the present embodiment stores a common playlist for camera n contents of the cameras 30 _n (n=1, . . . , N) and 1, . . . , N) of camera n contents (low resolution tiles and high resolution tiles) are stored. For this reason, once the client 20 has acquired the playlist, even if the camera 30 is switched, the client 20 does not need to acquire the playlist again, and communication for acquiring the playlist can be reduced. The details of the data configuration of the video content will be described later.

Further, the client 20 according to this embodiment has a viewing processing unit 210 . The viewing processing unit 210 is implemented by processing that one or more programs installed in the client 20 cause a processor such as a CPU to execute.

The viewing processing unit 210 transmits various requests (for example, video distribution requests, etc.) to the distribution server 10, and receives content (low-resolution tiles and high-resolution tiles) of the corresponding camera 30 from the distribution server 10. Then, the panorama video is reproduced by the content.

Note that the overall configuration of the video distribution system 1 shown in FIG. 1 is an example, and other configurations may be used. For example, the encoding device 40 may be integrated with the distribution server 10 . In this case, the video signal is encoded by the distribution server 10 .

<Data structure of video content>
Next, the data configuration of video content stored in the storage unit 120 of the distribution server 10 according to this embodiment will be described.

(Example 1)
A data structure of video content in Example 1 will be described with reference to FIG. FIG. 6 is a diagram (part 1) for explaining an example of the data configuration of video content.

As shown in FIG. 6, in Example 1, a playlist (which is also expressed as "Content.m3u8"), a Conf folder, and a Media folder are arranged directly under the content folder. Also, in the Conf folder, a metadata list (also referred to as "Play.ini") and layout information (also referred to as "Rendering.ini") are arranged.

On the other hand, in the Media folder, each folder (0 folder, 1 folder, 2 folder, . . . , 2M+1 folder), .

Here, i ₌ 0 , . Specifically, for example, in the 0 folder, high-resolution tiles for every _tc in the first field-of-view range of the camera _30-1 are arranged. In the example shown in FIG. 6, the high resolution tile "0.ts" during the first _tc , the high resolution tile "1.ts" during the next _tc , and the high resolution tile "1.ts" during the next _tc "2.ts" and the like are arranged. Similarly, one folder contains high-resolution tiles for every t _c in the second field of view of camera ₃₀₂ .

On the other hand, with i=M, the M(n-1)+M+n-1 folder contains low-resolution tiles for every t _c of camera 30 _n . Specifically, for example, in the M folder, low-resolution tiles for each _tc of the camera _30-1 are arranged. In the example shown in FIG. 6, the low resolution tile "0.ts" during the first _tc , the low resolution tile "1.ts" during the next _tc , and the low resolution tile "2.ts" during the next _tc . ts” and the like are arranged. The M(n−1)+M+n−1 folder also contains a playlist for media (also referred to as “LT.m3u8”).

Thus, in the video content in the first embodiment, content for each camera 30 is stored in the Media folder.

Note that Content. In order to distinguish the playlist represented by m3u8 from the playlist for media, hereinafter also referred to as "playlist for content", the playlist for content includes, for example, communication session information, segment file transmission Required information etc. are described.

On the other hand, the playlist for media (LT.m3u8) is also referred to as "playlist for media". The media playlist describes, for example, the length (playback time) of each segment file.

The metadata list also describes information on codecs, information on the size of each tile, information on the number of cameras 30, and the like. More specifically, the metadata list describes information on the number of cameras 30, information on the codec for each camera 30, information on the size of tiles for each camera 30, and the like.

Further, the layout information describes information about the layout of the high-resolution tiles (that is, information about the coordinates of the viewing range for each high-resolution tile). More specifically, the arrangement information describes information regarding the arrangement of high-resolution tiles for each camera 30, and the like.

(Example 2)
A data structure of video content in Example 2 will be described with reference to FIG. FIG. 7 is a diagram (part 2) for explaining an example of the data configuration of video content.

As shown in FIG. 7, in the second embodiment, a content playlist, a Conf folder, and a Media folder for each camera 30 (that is, Media_1 folder, Media_2 folder, . . . , Media_N folder) are directly under the content folder. are placed. As in the first embodiment, the Conf folder contains a metadata list and location information.

With n=1, . . . , N, the contents of camera n are stored in the Media_n folder. That is, ₀ folder, 1 folder, . A high-resolution tile of the field of view is placed. Specifically, for example, in the 0 folder of the Media_1 folder, high-resolution tiles for each _tc in the first visual field range of the camera _30-1 are arranged. In the example shown in FIG. 7, the high resolution tile "0.ts" during the first _tc , the high resolution tile "1.ts" during the next _tc , and the high resolution tile "1.ts" during the next _tc "2.ts" and the like are arranged. Similarly, in one folder of the Media — 1 folder, high-resolution tiles for each _tc in the second field of view range of the camera _30-1 are arranged.

On the other hand, in the M folder of the Media_n folder, low-resolution tiles for each _tc of the camera 30 _n are arranged. Specifically, for example, in the M folder of the Media_1 folder, low-resolution tiles for each _tc of the camera _30-1 are arranged. In the example shown in FIG. 7, the low resolution tile "0.ts" during the first _tc , the low resolution tile "1.ts" during the next _tc , and the low resolution tile "2.ts" during the next _tc . ts” and the like are arranged. The M folder also contains playlists for media.

As described above, in the video content in the second embodiment, the Media folder for each camera 30 is arranged directly under the content folder, and the content of the corresponding camera 30 is stored in each Media folder.

<Panorama video distribution processing>
Next, panorama video distribution processing according to this embodiment will be described with reference to FIG. FIG. 8 is a sequence diagram showing an example of panorama video distribution processing according to this embodiment. In the following description, the camera number is used as information for specifying the camera 30 , and the camera ₃₀₁ with the camera number n=1 is the default camera 30 . It is assumed that when the client 20 reproduces the panoramic video, the default panoramic video of the camera ₃₀₁ is reproduced first.

First, when the viewing processing unit 210 of the client 20 starts reproducing the panorama video, it transmits a video distribution request to the distribution server 10 (step S101). Here, the video distribution request includes the camera number n=1 of the default camera ₃₀₁ . The video distribution request also includes the current time or the time specified by the user. Hereinafter, the current time or the time specified by the user will also be referred to as "playback time". For example, in the case of live distribution, etc., the current time is often included as the playback time, and in the case of on-demand distribution, etc., the time specified by the user is often included as the playback time.

In the present embodiment, the request transmitted in step S101 is referred to as a "video distribution request", but this request may also be referred to as, for example, a "video distribution start request".

Next, the distribution server 10 and the client 20 perform communication processing related to playlist acquisition (that is, processing for transmitting a content playlist, media playlist, etc. from the distribution server 10 to the client 20) (step S102). Thereby, the client 20 can acquire a content playlist, a media playlist, and the like. The details of the communication processing regarding this playlist acquisition will be described later.

Next, the distribution processing unit 110 of the distribution server 10 selects the low-resolution tile corresponding to the playback time and the high-resolution tile corresponding to the playback time in the default visual field range from among the low-resolution tiles and high-resolution tiles of the camera 1 content. are read from the storage unit 120 (step S103). Note that the low-resolution tile and high-resolution tile corresponding to the playback time are, for example, tiles whose playback time is included in the playback time of the low-resolution tile and high-resolution tile.

Then, the distribution processing unit 110 of the distribution server 10 distributes (transmits) the low-resolution tiles and high-resolution tiles read in step S103 to the client 20 (step S104).

Upon receiving the low-resolution tile and high-resolution tile, the viewing processing unit 210 of the client 20 synthesizes these low-resolution tile and high-resolution tile (step S105). That is, the viewing processing unit 210 superimposes the high-resolution tile on the corresponding area of the low-resolution tile based on the arrangement information acquired in step S102 described above, for example. Combine tiles. As a result, a panorama image is created in which the viewing range has a high resolution and the area outside the viewing range has a low resolution.

Then, the viewing processing unit 210 of the client 20 reproduces the panorama video created by synthesizing the low-resolution tiles and the high-resolution tiles in step S105 (step S106). The viewing processing unit 210 reproduces the panorama video according to the codec-related information described in the metadata list, for example.

In subsequent steps S107 to S111, processing when the visual field range of the client 20 is changed while the panorama image of the camera _30n is being reproduced will be described. In the client 20, for example, a gyro sensor or the like detects a change in the line-of-sight direction, and the visual field range is also changed according to the change in the line-of-sight direction. However, the line-of-sight direction is not limited to being detected by a gyro sensor or the like, and the line-of-sight direction may be changed by, for example, operating the touch panel of the client 20 with a user's finger.

The viewing processing unit 210 of the client 20 transmits line-of-sight direction information indicating the changed line-of-sight direction to the distribution server 10 (step S107). At this time, the viewing processing unit 210 may transmit the reproduction time to the distribution server 10 as well.

When the distribution processing unit 110 of the distribution server 10 receives the line-of-sight direction information, the distribution processing unit 110 selects one of the low-resolution tiles and the high-resolution tiles of the camera n content corresponding to the playback time (that is, the current time or the time specified by the user). The resolution tile and the high resolution tile corresponding to the playback time in the viewing range in the viewing direction indicated by the viewing direction information are read out from the storage unit 120 (step S108). Note that the field of view range is specified as a range photographed by a pseudo camera at the observation position directed in the direction of the line of sight, for example, when a panoramic image is represented by an omnidirectional projection sphere.

Then, the distribution processing unit 110 of the distribution server 10 distributes (transmits) the low-resolution tiles and high-resolution tiles read in step S108 to the client 20 (step S109).

Upon receiving the low-resolution tile and high-resolution tile, the viewing processing unit 210 of the client 20 synthesizes these low-resolution tile and high-resolution tile (step S110) in the same manner as in step S105.

Then, the viewing processing unit 210 of the client 20 reproduces the panorama video created by synthesizing the low-resolution tiles and the high-resolution tiles in step S110 (step S111).

In subsequent steps S112 to S116, processing when the panorama video to be played back on the client 20 is switched (that is, when the camera 30 is switched) will be described. The user of the client 20 can switch the panorama video played on the client 20 by performing a predetermined operation (for example, pressing a camera switching button). As an example, a case of switching to a panorama image captured by camera 30 _k with camera number n=k will be described.

The viewing processing unit 210 of the client 20 transmits a video distribution request to the distribution server 10 when an operation to switch to the panorama video captured by the camera 30 _k with camera number n=k is performed (step S112). Here, the video distribution request includes the camera number n=k. At this time, the viewing processing unit 210 may transmit the reproduction time to the distribution server 10 as well. In the present embodiment, the request transmitted in step S112 is a "video distribution request," but this request may also be called a "camera switching request," a "panoramic video switching request," or the like. good.

The distribution processing unit 110 of the distribution server 10 stores the low-resolution tile corresponding to the reproduction time and the high-resolution tile corresponding to the reproduction time in the default visual field range among the low-resolution tiles and high-resolution tiles of the camera k content. It is read out from the unit 120 (step S113).

Then, the distribution processing unit 110 of the distribution server 10 distributes (transmits) the low-resolution tile and the high-resolution tile read in step S113 to the client 20 (step S114).

Upon receiving the low-resolution tile and high-resolution tile, the viewing processing unit 210 of the client 20 synthesizes these low-resolution tile and high-resolution tile (step S115) in the same manner as in step S105.

Then, the viewing processing unit 210 of the client 20 reproduces the panorama video created by synthesizing the low-resolution tiles and the high-resolution tiles in step S115 (step S116).

As described above, in the video distribution system 1 according to the present embodiment, even when the camera 30 for capturing the panoramic video to be played back on the client 20 is switched, if the playlist is acquired once in step S102, , no need to get the playlist again. Therefore, since it is not necessary to perform the communication processing related to acquiring the playlist again, it is possible to prevent the playback delay of the panorama video.

In this embodiment, the viewing range of the panorama image after switching to the camera 30 _k is assumed to be the default viewing range of the camera 30 _k (step S113 above), but is not limited to this. For example, the coordinates for identifying the visual field range after switching may be the same as the coordinates for identifying the visual field range before switching.

Further, for example, when a certain object (for example, a certain singer in the case of a concert, a certain athlete in the case of sports, etc.) is included in the visual field range before switching, the same object The included range may be set as the visual field range after switching. Accordingly, by switching between the plurality of cameras 30, the user can view the same object photographed from different angles or different positions, for example.

Further, for example, the visual field range to be focused on may be designated in advance for each camera 30 according to the playback time and content of the panorama video. Specifically, for example, when the playback time is between "0:00" and "5:00", when switching to the camera ₃₀₁ , the viewing range is 1, and when switching to the camera ₃₀₂ , the viewing range is 3, and the camera When switching to 30 ₃ , it is conceivable to set the visual field range 2 or the like in advance. Similarly, for example, when the content of the panorama video is "concert", when switching to the camera _30-1 , the viewing range is 2, when switching to the camera _30-2 , the viewing range is 2, and when switching to the camera _30-3 When the content of the panoramic video is "sports", the viewing range is set to 1 when switching to the camera _30-1 , and when switching to the camera _30-2 , the viewing range is set to 1 and the camera 30-2. When switching to ₃ , it is conceivable to set the visual field range to 3 or the like in advance. As a result, it is possible to view the range of field of view specified by the camera 30 after switching according to the playback time and content of the panorama video.

Here, the details of the communication processing regarding the playlist acquisition in step S102 will be described with reference to FIG. FIG. 9 is a sequence diagram showing an example of communication processing regarding playlist acquisition according to the present embodiment.

First, the viewing processing unit 210 of the client 20 transmits a Master Playlist request to the distribution server 10 (step S201). Note that the Master Playlist request is a request for acquiring a content playlist.

Upon receiving the Master Playlist request, the distribution processing unit 110 of the distribution server 10 reads the content playlist from the storage unit 120 (step S202).

Then, the distribution processing unit 110 of the distribution server 10 transmits the content playlist (that is, Content.m3u8) read in step S202 to the client 20 (step S203). Thereby, the client 20 can acquire the content playlist.

Upon receiving the content playlist, the distribution processing unit 110 of the client 20 transmits a Media Playlist request to the distribution server 10 (step S204). Note that the Media Playlist request is a request for acquiring a media playlist or the like.

When the distribution processing unit 110 of the distribution server 10 receives the Media Playlist request, the media playlist (that is, LT.m3u8), the metadata list (that is, Play.ini), the layout information (that is, Rendering.ini ) are read from the storage unit 120 (step S205).

Then, the distribution processing unit 110 of the distribution server 10 transmits the media playlist, the metadata list, and the arrangement information read in step S205 to the client 20 (step S206). Thereby, the client 20 can acquire the media playlist, the metadata list, and the arrangement information.

The invention is not limited to the specifically disclosed embodiments described above, but various modifications, alterations, combinations, etc. are possible without departing from the scope of the claims.

1 video distribution system 10 distribution server 20 client 30 camera 40 encoding device 110 distribution processing unit 120 storage unit 210 viewing processing unit

Claims (7)

A distribution server that distributes panoramic video shot by each of a plurality of cameras to a client by HTTP Live Streaming,
A playlist for playing back the panoramic video by HTTP Live Streaming when a distribution request for the panoramic video is received from the client , the playlist being common to all the panoramic videos captured by each of the plurality of cameras. and a first video distribution means for distributing to the client the playlist of and the panorama video taken by the camera requested in the distribution request ;
and a second video distribution means for distributing a panoramic video to be reproduced after switching to the client when a switching request of the panoramic video to be reproduced is received. The second video distribution means is
2. The distribution server according to claim 1, wherein said playlist is not transmitted to said client. The first video distribution means is
3. The distribution server according to claim 1, wherein a panorama image captured by a camera set as a default among the plurality of cameras is distributed to the client. Each camera has storage means for storing, as a segment file, contents of a panoramic video shot by the camera,
The first video distribution means and the second video distribution means are
4. The distribution server according to any one of claims 1 to 3, wherein the distribution server distributes a segment file of a panorama video to be played back to the client. The segment file includes low-resolution data representing data obtained by compressing a panorama video of a predetermined duration to low resolution, and high-resolution data representing a predetermined image area included in the panorama video of the duration. 5. The distribution server according to claim 4, characterized by: A computer that distributes panoramic images shot by each of multiple cameras to clients by HTTP Live Streaming,
A playlist for playing back the panoramic video by HTTP Live Streaming when a distribution request for the panoramic video is received from the client , the playlist being common to all the panoramic videos captured by each of the plurality of cameras. and a first video distribution procedure for distributing to the client the playlist of and the panoramic video captured by the camera requested in the distribution request ;
and a second video distribution procedure for distributing the panoramic video to be played after switching to the client when a switching request of the panoramic video to be played is received. A program for causing a computer to function as the distribution server according to any one of claims 1 to 5.

Images