JP7327953B2 - Video distribution device, video distribution method and program - Google Patents

Description

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

In recent years, distribution systems using IP (Internet Protocol) networks have been increasing. Such distribution systems include systems for distributing the conditions of ski resorts and zoos, and systems for monitoring stores and buildings.

Adaptive Bitrate Streaming technology using HTTP (Hyper Text Transfer Protocol) is becoming popular in video services. Adaptive Bitrate Streaming technology includes DASH (Dynamic Adaptive Streaming over HTTP) and HLS (HTTP Live Streaming). DASH is a technique standardized by MPEG (Moving Picture Experts Group). HLS is a standardized technology led by Apple.

In general DASH distribution, a distribution server divides a plurality of moving image data with different resolutions and bit rates into moving image files called segments of several seconds. On the other hand, the client acquires an MPD (Media Presentation Description) file describing overall information of the moving image from the distribution server, refers to the file, and selects a moving image stream with appropriate resolution and bit rate. Then, the client downloads and reproduces moving image data of the MPEG2 TS stream or MP4 file in units of segments according to the description of the MPD.

Patent Document 1 discloses a method of storing a plurality of video streams and transmitting the stored video when switching streams, thereby reducing the waiting time for starting playback when switching streams, and switching streams at any time. disclosed. In Patent Document 2, in a system for synchronously distributing a plurality of video streams having different bandwidths, a video stream to be reproduced is buffered by FIFO (first in, first out), and the communication speed and loss of the network are detected and streamed. is disclosed.

Japanese Patent Application Laid-Open No. 2004-349743 Japanese Patent Application Laid-Open No. 2003-348548

In general, devices capable of simultaneously generating multiple video streams generate each video stream independently. Therefore, intra-frame-encoded frames (hereinafter referred to as I-frames) are not necessarily generated at the same timing.

In live distribution using Adaptive Bitrate Streaming technology, video streams can be switched according to network bandwidth and the like. However, if it is attempted to switch video streams in a situation where I-frame generation timing is different, it is not always possible to form a segment starting from an I-frame. That is, there is a problem that the client receiving the distributed video data cannot reproduce it continuously.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and it is an object of the present invention to distribute moving image streams that can be continuously reproduced even when moving image streams are switched.

Accordingly, the present invention provides a moving picture distribution apparatus comprising: moving picture generating means for generating a plurality of moving picture data based on a photographed image; and a transmitting means for transmitting the segment generated by the segment generating means, wherein the segment generating means transmits the moving image of the segment that has already been transmitted from the client device to the client device When receiving a request to acquire a segment of video data of a type different from that of the data , includes intra-frame-encoded frames before the segment related to the acquisition request up to the last frame of the segment related to the acquisition request generating a first segment , setting a display time of a frame preceding the segment related to the acquisition request to a time shorter than a display time of a frame included in the segment related to the acquisition request, and , transmitting the first segment .

According to the present invention, it is possible to deliver continuously reproducible moving image streams even when moving image streams are switched.

1 is an overall configuration diagram of a video distribution system; FIG. 3 is a hardware configuration diagram of a camera server device; FIG. 3 is a functional configuration diagram of a camera server device; FIG. 4 is a configuration diagram of distribution data; FIG. FIG. 4 is a relationship diagram between a video stream and segments; It is a figure which shows an example of the data structure of a segment. FIG. 10 is a sequence diagram showing moving image distribution processing; 9 is a flowchart showing distribution management processing;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is an overall configuration diagram of a video distribution system according to this embodiment. The video distribution system has a camera server device 100 and a client device 120 . The camera server device 100 is an example of a video distribution device. The camera server device 100 and client device 120 are interconnected via a network 140 . The camera server device 100 includes a camera, and distributes captured images (moving images) obtained by the camera via the network 140 . The camera server device 100 of the present embodiment generates a plurality of moving images of different types by DASH distribution, and transmits the moving images of the type corresponding to the display performance and communication band of the client device 120 to the client device 120 in segment units. Here, the multiple moving images of different types include multiple moving images having different resolutions, bit rates, and frame rates. A segment is a file of moving image data divided (segmented) into predetermined division units. In other words, a segment is a moving image file containing part of the data in the time axis direction of the moving image. The client device 120 displays the video received from the camera server device 100 .

Although only one camera server device 100 is shown in FIG. 1 for simplification of explanation, the video distribution system may have a plurality of camera server devices 100 . That is, a plurality of camera server devices 100 may distribute moving images to one client device 120 . As another example, one camera server device 100 may distribute moving images to a plurality of client devices 120 .

The network 140 is composed of a plurality of routers, switches, cables, etc. that satisfy communication standards such as Ethernet (registered trademark). It should be noted that the network 140 may have any communication standard, scale, or configuration as long as communication between devices can be performed without hindrance. Therefore, it is applicable from the Internet to LAN (Local Area Network).

FIG. 2 is a hardware configuration diagram of the camera server device 100. As shown in FIG. The camera server device 100 has a CPU 201 , a primary storage device 202 , a secondary storage device 203 , an image capture I/F 204 , an image sensor 205 and a network I/F 206 . The CPU 201 , primary storage device 202 , secondary storage device 203 , image capture I/F 204 and network I/F 206 are interconnected via an internal bus 207 .

The CPU 201 controls the entire camera server device 100 . The primary storage device 202 is a writable high-speed storage device represented by a RAM, loaded with an OS, various programs, and various data, and is also used as a work area for the OS and various programs. The secondary storage device 203 is a non-volatile storage device represented by flash memory, HDD, SD card, etc., and is used as a permanent storage area for the OS, various programs, and various data, as well as various short-term data. It is also used as a storage area for

An image sensor 205 consisting of a CCD or CMOS is connected to the image capture I/F 204 . The image capture I/F 204 converts/compresses image data acquired from the image sensor 205 into a predetermined format, and transfers the converted/compressed image data to the primary storage device 202 . A network I/F 206 is an I/F for connecting to the network 140 described above, and is responsible for communication with the client device 120 and the like via a communication medium such as Ethernet.

FIG. 3 is a functional configuration diagram of the camera server device 100. As shown in FIG. The camera server device 100 has an imaging processing section 301 , a distribution management section 302 and a communication processing section 303 . Note that these functions are realized by the CPU 201 executing various programs including the OS. The imaging processing unit 301 acquires frames generated by the image sensor 205 via the image capture I/F 204 . Then, the imaging processing unit 301 performs encoding processing on the acquired frames. Further, the imaging processing unit 301 stores the encoded frames in the primary storage device 202 together with moving image meta information necessary for moving image reproduction such as SPS (Sequence Parameter Set) and PPS (Picture Parameter Set).

The distribution management unit 302 controls processing for distributing frames stored in the primary storage device 202 to the client device 120 by DASH distribution. The distribution management unit 302 generates a plurality of different types of frames from the frames stored in the primary storage device 202 . Specifically, the distribution management unit 302 generates multiple frames with different resolutions. Furthermore, the distribution management unit 302 creates initialization segment information and segment information based on the moving image meta information and frames stored in the primary storage device 202 . Here, the initialization segment information is information necessary for reproducing the moving image stream. The segment information is information necessary for reproducing each segment included in the frame. The segment information includes one or more frames included in the segment and the header portion of the segment. A communication processing unit 303 controls communication with an external device. The communication processing unit 303 transmits the segment information to the client device 120 under the control of the delivery management unit 302, for example.

FIG. 4 is a configuration diagram of distribution data used for DASH distribution. At the top of the distribution data, there is an MPD file 400 that bundles moving image information. The MPD file 400 defines resolution, encoding information, and segment information as moving image stream information. Note that the moving image stream may be singular or plural. In this embodiment, the MPD file 400 defines three video streams (video stream 1, video stream 2, and video stream 3) with different resolutions.

A moving image stream 1 is a moving image file with the highest resolution. When the video stream 1 is distributed, the amount of data downloaded by the client device 120 is large, but high-quality video can be reproduced. A moving image stream 3 is a moving image file with the smallest resolution. A video stream 2 is a video file with medium resolution. The moving picture stream 2 has a smaller data amount than the moving picture stream 1 and a larger data amount than the moving picture stream 3 . In this embodiment, the imaging processing unit 301 generates a plurality of moving image streams of different types, but the types and number are not limited to those in the embodiment. The type of video stream may be determined according to the frame rate, bit rate, and the like.

FIG. 5 is a diagram showing the relationship between video streams 1 to 3 and segments. Here, for ease of understanding, it is assumed that 3 frames are generated per second and 3 frames are 1 segment. The imaging processing unit 301 generates continuous frames 500 to 508 as the moving image stream 1 . Of these frames, frames 500, 503 and 506 are I frames. Other frames 501, 502, 504, 505, 507 and 508 are P frames. Here, the I frame is a frame having video information necessary to construct a video, and is an example of an intra-frame encoded frame. A P frame is a frame having video information of the difference from the previous image. Similarly, the imaging processing unit 301 generates frames 510 to 518 as moving image stream 2 and frames 520 to 528 as moving image stream 3 .

Each segment contains three frames. That is, the first segment (segment 1) of video stream 1 includes frames 500-502, the following segment 2 includes frames 503-505, and the following segment 3 includes frames 506-508. is Similarly, segment 1 of video stream 2 includes frames 510-512, segment 2 includes frames 513-515, and segment 3 includes frames 516-518. The video stream 3 is also the same. Note that in the present embodiment, the moving image information of the difference is the P frame, but it may be the B frame.

A segment indicates a frame included in a certain time period of a moving image stream, and the client device 120 can acquire moving image data of a desired stream by specifying a moving image stream number and a segment number.

In the present embodiment, the processing of the camera server device 100 will be described by taking as an example a case where the client device 120 requests switching of video streams in the order of segment 1 of video stream 1, segment 2 of video stream 2, and segment 3 of video stream 3. explain.

First, when transmitting segment 1 of video stream 1 , the camera server device 100 segments frames 500 , 501 , and 502 and transmits them to the client device 120 because the leading frame 500 of segment 1 is an I frame.

Next, the camera server device 100 transmits segment 2 of video stream 2 . However, since the first frame 513 of segment 2 of video stream 2 is not an I frame, the client device 120 cannot reproduce the first frame 513 even if it is transmitted as it is. Therefore, the camera server device 100 segments the I frame 511 before the first frame 513 to the final frame 515 of the segment 2 and transmits the segments to the client device 120 . At this time, since the client device 120 has already received and displayed the frames 501 and 502 at the same times as the frames 511 and 512, there is no need to display the frames 511 and 512. FIG. Therefore, the camera server device 100 sets the display times of the frames 511 and 512 to zero in the segment header. The data configuration of the segment data will be detailed later with reference to FIG.

Furthermore, the camera server device 100 transmits segment 3 of video stream 3 . However, the first frame 526 of segment 3 of video stream 3 is not an I frame. Therefore, the camera server device 100 segments from the I frame 525 before the frame 526 to the last frame 528 of the segment 3 and transmits them to the client device 120 . In this case as well, since the client device 120 has already transmitted the frame 515 to the client device 120, the display time of the frame 525 is set to zero in the segment header.

In this way, the segment immediately after the camera server device 100 switches the video stream includes the video data starting from the I frame, and if the display overlaps, the display time is set to zero and the video stream is distributed. This allows the client device 120 to switch streams at arbitrary timing. Furthermore, the client device 120 performs decoding processing for duplicately distributed video data but does not need to perform display processing, so that video can be reproduced without interruptions or skips.

FIG. 6 is a diagram showing an example of the data structure of the segment 551. As shown in FIG. In this embodiment, the segment data shall be MP4 file format data. At the beginning of the segment data, there are BOX styp 600 indicating the segment and BOX sidx 601 indicating the order of the segment. Then there is a BOX moof 602 indicating the beginning of the fragment. BOX moof 602 contains BOX trun 603 . BOX trun 603 stores the display time of the frame included in the fragment. The BOX trun 603 contains the number of frames sample_count included in the fragment and the display time sample_duration of each frame. The example of FIG. 6 indicates that the number of frames sample_count is 5, the display time of the first two frames is zero, and the display time of the following three frames is the display time n calculated from the frame rate. For example, in the case of 30 fps, a number representing 33 ms is set. Finally there is a BOX mdat 604 containing video data.

FIG. 7 is a sequence diagram showing moving image distribution processing. The moving image distribution processing is processing in which the camera server device 100 distributes moving images to the client device 120 . A case in which video streams 1, 2, and 3 shown in FIG. 5 are to be distributed will be described as an example.

In S<b>701 , the client device 120 transmits an MPD file acquisition request to the camera server device 100 . Upon receiving the MPD file acquisition request in S701, the distribution management unit 302 of the camera server apparatus 100 instructs the imaging processing unit 301 to start generating a distributable moving image stream in S702. Next, in S<b>703 , the distribution management unit 302 creates an MPD file describing the moving image stream information and sends it back to the client device 120 .

Note that in this figure, it is assumed that the imaging processing unit 301 has already started video generation of the video streams 2 and 3 for reasons such as video distribution to another client device or recording. Assume that there is Furthermore, in moving image streams 2 and 3, it is assumed that the next generated video is a P frame. Video distribution to another client and recording processing are omitted.

Upon receiving the acquisition request, the imaging processing unit 301 also generates frame 1 of moving image streams 1, 2, and 3, ie, frames 500, 510, and 520 (I, P, and P frames). This process is an example of a moving image generation process. When the frame is generated, the imaging processing unit 301 notifies the distribution management unit 302 that frame 1 has been generated in S704. For the convenience of explanation, it is assumed that the frames of all three streams are notified together, but if the frame generated first is a P frame, the generation of the frame is not notified and is skipped until the I frame is generated. I don't mind.

Next, in S<b>705 , the distribution management unit 302 creates an initialization segment from the SPS/PPS data attached to the I frame of the moving picture stream 1 . In this example, the SPS/PPS data is attached to the I frame, but the SPS/PPS data may be notified to the distribution management unit 302 regardless of the type such as the I/P/B frame. After that, it is assumed that the distribution management unit 302 creates an initialization segment when receiving the first I frame of each stream.

On the other hand, upon receiving the MPD file in S706, the client device 120 selects a video stream to be received based on its own CPU power, display resolution, network bandwidth, and the like. The client device 120 then transmits to the camera server device 100 an acquisition request for an initialization segment containing information necessary for reproduction. In this example, it is assumed that client device 120 has selected video stream 1 . Next, in S707, the distribution management unit 302 transmits the initialization segment created in S705 as a response.

In the camera server device 100, the imaging processing unit 301 generates frame 2 of each of the moving image streams 1, 2, and 3, that is, frames 501, 511, and 521 (P, I, P frames), and advances the process to S708. In S708, the imaging processing unit 301 notifies the distribution management unit 302 that frame 2 has been generated. Similarly, in S709, the imaging processing unit 301 notifies that frame 3 generated next, that is, frames 502, 512, and 522 (P, P, and I frames) has also been generated. Next, in S710, the distribution management unit 302 creates segment 1 for three streams from frames 1, 2, and 3, and buffers until a segment acquisition request is received. This process is an example of the segment generation process. In S<b>711 , the client device 120 transmits a request to acquire segment 1 of video stream 1 . Next, in S712, the distribution management unit 302 of the camera server device 100 transmits the segment generated in S710 as a response. In the example of FIG. 5, segment 550 is transmitted.

Similarly, the imaging processing unit 301 sequentially generates three video stream frames (frames 4, 5, and 6) (S713, S714, and S717), and the distribution management unit 302 generates the next frame when the three frames are complete. segment is created (S718). Frame 4 notified in S713 are frames 503, 513, and 523 (I, P, P frames). Frame 5 notified in S714 are frames 504, 514, and 524 (P, I, P frames). Frame 6 notified in S717 is frames 505, 515, and 525 (P, P, I frames).

The segments of moving image stream 2 and moving image stream 3 generated in S718 are both segments starting from P frames. If a segment whose first frame is a segment starting with a P frame is transmitted, the client device 120 cannot display the P frame.

In S715, the client device 120 transmits a request to acquire the initialization segment of the new video stream 2 in order to switch from the video stream 1 that has already been transmitted from the camera server device 100 to the video stream 2. FIG. Next, in S716, the distribution management unit 302 of the camera server device 100 transmits the initialization segment of the moving image stream 2 as a response.

Next, in S<b>719 , the client device 120 transmits a request to acquire segment 2 of video stream 2 . However, the beginning of segment 2 held by the distribution management unit 302 is a P frame. Therefore, in S720, the distribution management unit 302 goes back to the immediately preceding I frame, that is, the frame 511, and reconstructs a reconstructed segment 551 including the frame 511 (I frame) to the frame 515. FIG. Next, in S721, the distribution management unit 302 transmits the reconstructed segment as a response.

In this case, the distribution management unit 302 sets the display time of the frames (frames 511 and 512) before the segment reconstructed in S720 to zero. Also, the distribution management unit 302 sets a value calculated from the frame rate for the display time of the frames (frames 513, 514, and 515) of the segment (segment 2) to be transmitted.

In this way, the client device 120 reproduces the moving image while sequentially acquiring segments. The client device 120 counts the amount of segment data in order to measure the network bandwidth, but segments containing frames whose display time is zero are essentially unnecessary data. Therefore, when a segment reconstructed at the time of switching from a previously received video stream is received, the entire segment may be excluded from the count target, or only frames whose display time is zero may be excluded from the count target.

FIG. 8 is a flowchart showing distribution management processing by the distribution management unit 302. As shown in FIG. The distribution management process is started when the camera server device 100 receives an MPD file acquisition request from the client device 120 .

In S801, the distribution management unit 302 instructs the imaging processing unit 301 to start frame generation. This process corresponds to the process of S702 described with reference to FIG. Next, in S<b>802 , the distribution management unit 302 transmits the MPD file to the client device 120 . This process corresponds to the process of S703. Next, in S803, the distribution management unit 302 waits for an event to occur. Next, in S302, when an event occurs, the contents of the event are confirmed. If the content of the event is a frame generation notification event from the imaging processing unit 301 (frame generation notification in S804), the distribution management unit 302 advances the process to S805. If the content of the event is a segment acquisition request event from the client device 120 (segment acquisition request in S804), the distribution management unit 302 advances the process to S810.

In S<b>805 , the distribution management unit 302 determines whether or not the generated frames are generated for the segments. If the frame for the segment has been generated (YES in S805), the distribution management unit 302 advances the process to S806. If the frame for the segment has not been generated (NO in S805), the distribution management unit 302 advances the process to S808. In S806, the distribution management unit 302 generates a segment including the generated frame from the segment number and frame information included in the segment. Next, in S807, the distribution management unit 302 adds the corresponding video stream to the transmission waiting list provided in the primary storage device 202, and then advances the process to S803. Also, in S808, the distribution management unit 302 saves the frame information, and then returns to S803.

In S810, the distribution management unit 302 determines whether the requested segment is stored in the transmission waiting list of the requested stream. If the requested segment is stored (YES in S810), the distribution management unit 302 advances the process to S811. If the requested segment is not stored (NO in S810), distribution management unit 302 advances the process to S819.

In S811, the distribution management unit 302 determines whether the leading frame of the segment is an I frame. If it is an I frame (YES in S811), the distribution management unit 302 advances the process to S812. If the frame is not an I frame (NO in S811), the distribution management unit 302 advances the process to S813. In S812, the distribution management unit 302 transmits the segment to the client device 120, and then advances the process to S803.

In S813, the distribution management unit 302 determines whether or not the immediately preceding I frame exists in the transmission waiting list. If the immediately preceding I frame exists in the transmission waiting list (YES in S813), the distribution management unit 302 advances the process to S814. If the immediately preceding I frame does not exist in the transmission waiting list (NO in S813), the distribution management unit 302 advances the process to S816. In the example of FIG. 5, one I frame is included in each segment. For example, when three or more P frames are consecutive for one I frame, the I frame is added to the transmission waiting list. May not exist. In addition, the immediately preceding I frame may be deleted from the transmission waiting list because the buffering amount of the transmission waiting list is exceeded.

In S814, the distribution management unit 302 performs the first segment reconstruction processing. Specifically, the distribution management unit 302 reconstructs a segment (first reconstructed segment) including frames from the immediately preceding I frame to the requested segment. Furthermore, in this case, the distribution management unit 302 sets the display time of the frame before the requested segment to zero, and sets the display time of the frame included in the requested segment to a value calculated from the frame rate. do. Note that the display time of the frame before the requested segment may be set to a time shorter than the value calculated from the frame rate, and the value is not limited to zero. Next, in S815, the distribution management unit 302 transmits the reconfigured segments to the client device 120, and then advances the process to S803.

In this way, when the first frame of the segment to be distributed is not an I frame, the distribution management unit 302 reconstructs the segment from the I frame before the first frame to the last frame of the segment to be distributed, Send this. Therefore, the client device 120 can reproduce the segment to be distributed from the first frame without omission. Furthermore, since the display time of the frame before the segment to be distributed is set to zero, after the stream is switched on the client device 120, the frame displayed before the stream switching can be displayed from the frame following the frame. can be done.

In S816, the distribution management unit 302 determines whether an I frame exists within the requested segment. If an I frame exists in the requested segment (YES in S816), distribution management unit 302 advances the process to S817. If there is no I frame in the requested segment (NO in S816), distribution management unit 302 advances the process to S819.

In S817, the distribution management unit 302 performs second reconstruction processing. Specifically, the distribution management unit 302 reconstructs a segment (second reconstructed segment) having the I frame in the requested segment as the head and the final frame in the requested segment as the final frame. Next, in S818, the distribution management unit 302 transmits the reconstructed segments to the client device 120, and then advances the process to S803. Note that the processes of S816, S817, and S818 are processes for discarding part of the moving image data. These processes may be omitted.

In S819, the distribution management unit 302 transmits an error response to the client device 120, and then advances the process to S803. Note that the distribution management unit 302 may wait until the next distributable segment is generated instead of the process of S819.

As described above, the camera server device 100 according to this embodiment reconstructs a segment including an I-frame preceding the segment to be distributed and transmits this to the client device 120 . Therefore, the camera server device 100 can deliver continuously reproducible moving image streams even when moving image streams are switched.

As a first modified example of the embodiment, the distribution management unit 302 may perform the following processing when it is determined as NO in S816. That is, when the period until the first generated I frame after the segment to be distributed is more than a predetermined period in the future, the distribution management unit 302 requests the imaging processing unit 301 to generate an I frame. good. On the other hand, the imaging processing unit 301 generates an I frame at a timing before the next scheduled I frame. Then, the distribution management unit 302 may reconstruct a segment (third reconstructed segment) having the I frame generated by the imaging processing unit 301 as the first frame, and transmit the segment to the client device 120 .
A second modification will be described. In the present embodiment, the moving image distribution processing has been described using the DASH distribution as an example, but the distribution method is not limited to the embodiment. As another example, other adaptive bitrate streaming techniques such as HLS distribution may be used for moving image distribution.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the invention described in the claims.・Changes are possible.

The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

100 camera server device 120 client device 301 imaging processing unit 302 distribution management unit 303 communication management unit

Claims (13)

a moving image generating means for generating a plurality of moving image data based on the captured image;
segment generation means for generating a segment, which is video data for a predetermined time in the video data generated by the video generation means;
a transmitting means for transmitting the segment generated by the segment generating means ;
When receiving from a client device a request to acquire a segment of moving image data of a type different from the moving image data of the segment already transmitted to the client device , the segment generating means generates a frame prior to the segment related to the acquisition request. generating a first segment including the inner-coded frame to the last frame of the segment related to the acquisition request, and displaying the display time of the frame before the segment related to the acquisition request, Set it to a time shorter than the display time of the frames included in the segment,
The moving picture distribution device, wherein the transmission means transmits the first segment . 2. The method according to claim 1 , wherein said segment generating means generates said first segment when the first frame of the segment related to said acquisition request is not an intra-frame encoded frame. The moving picture distribution device described. further comprising storage means for storing the segments generated by the segment generation means;
The segment generation means generates the first 3. The moving picture distribution device according to claim 2, wherein the segments of are generated. When the first frame of the segment related to the acquisition request is not an intra-frame-encoded frame and the storage unit does not store an intra-frame-encoded frame, the segment generation means generates the acquisition request. generating a second segment including from the intra-frame encoded frame included in the segment related to the acquisition request to the last frame of the segment related to the acquisition request,
4. The moving picture distribution apparatus according to claim 3, wherein said transmission means transmits said second segment . The motion picture generation means determines that the first frame of the segment related to the acquisition request is not an intra-frame-encoded frame, the storage means does not store an intra-frame-encoded frame, and generating an intra-coded frame if the segment does not include an intra-coded frame;
5. The moving image distribution apparatus according to claim 4, wherein the segment generating means generates a third segment having the frame that is intra-frame-encoded and generated by the moving image generating means as a leading frame. The motion picture generating means determines that the first frame of the segment related to the acquisition request is not an intra-frame-encoded frame, the storage means does not store an intra-frame-encoded frame, and If the segment does not include an intra-frame-encoded frame, and the period until the first intra-frame-encoded frame generated after the segment related to the acquisition request is equal to or longer than a predetermined period, 6. The moving picture distribution device according to claim 5, wherein an intra-frame encoded frame is generated. The moving picture distribution device according to any one of claims 1 to 6, wherein the segment generating means sets the display time to zero. The moving picture distribution device according to any one of claims 1 to 7, wherein the plurality of moving picture data are data different in at least one of resolution, frame rate, and bit rate. A video distribution system having a video distribution device and a client device,
The video distribution device is
a moving image generating means for generating a plurality of moving image data based on the captured image;
segment generation means for generating a segment, which is video data for a predetermined time in the video data generated by the video generation means;
a transmitting means for transmitting the segment generated by the segment generating means ;
When receiving from a client device a request to acquire a segment of video data of a type different from the video data of the segment already transmitted to the client device , the segment generation means receives a segment within a frame before the segment related to the acquisition request. generating a first segment including the encoded frame to the last frame of the segment related to the acquisition request, and displaying the display time of the frame before the segment related to the acquisition request to the segment related to the acquisition request; set it to a time shorter than the display time of the frames contained in the
The moving image distribution system, wherein the transmission means transmits the first segment . The client device
further comprising calculating means for calculating a network bandwidth based on the received video data;
The calculation means calculates the network bandwidth by excluding a segment received immediately after switching of a segment when a segment of video data different from video data of a segment that has already been received is received. The moving picture delivery system according to claim 9. The client device
further comprising calculating means for calculating a network bandwidth based on the received video data;
10. The moving picture delivery system according to claim 9, wherein said calculating means calculates said network bandwidth excluding frames whose display time is shorter than a predetermined time. A video distribution method executed by a video distribution device,
a moving image generating step of generating a plurality of moving image data based on the captured image;
a segment generation step of generating a segment that is video data for a predetermined time in the video data generated in the video generation step;
a transmitting step of transmitting the segment generated by the segment generating step ;
In the segment generating step, when receiving from a client device a request to acquire a segment of moving picture data of a type different from the moving picture data of the segment already transmitted to the client device , a frame prior to the segment related to the acquisition request is received. generating a first segment including the inner-coded frame to the last frame of the segment related to the acquisition request, and displaying the display time of the frame before the segment related to the acquisition request, Set it to a time shorter than the display time of the frames included in the segment,
The moving image distribution method, wherein in the transmitting step, the first segment is transmitted. A program for causing a computer to function as each means of the moving image distribution apparatus according to any one of claims 1 to 8.

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