JP6053180B2 - Video playback state estimation device, video playback state estimation method, and program - Google Patents

Description

  The present invention relates to a technique for estimating a reproduction state based on packet capture data acquired in a network or at a head end for a progressive download video distribution application.

  With the spread of smartphones and tablet terminals, the progressive download video distribution service has become very popular. In general, progressive download video distribution applications require a certain amount of buffering before playback starts, and can reduce playback quality degradation due to degradation of network conditions, while playback due to degradation of network conditions, etc. When the amount of data stored in the buffer decreases, playback may stop (Non-Patent Document 1).

  Therefore, in recent years, a method (adaptive streaming) in which an application on a server or a client terminal observes a network state and dynamically changes a content bit rate (image quality) in accordance with the change has become widespread. For example, HTTP Live Streaming (HLS) and HTTP Dynamic Streaming (HDS) are typical examples. In July 2012, the international standard MPEG-DASH was established in ISO by integrating these vendor-dependent methods. (Non-patent document 2). The organization of international standards for adaptive streaming is still in progress with regard to its peripheral technologies, and it is thought that the number of applications to be adopted will continue to increase. In fact, in recent years, major progressive download video distribution services have adopted an adaptive streaming system that complies with MPEG / DASH.

  For telecommunications carriers, OTT (abbreviation of Over The Top. Providing content such as video data and audio data without relying on the services of telecommunications carriers.) Understanding this is important from the perspective of both network design and operation.

  With regard to progressive download video distribution services, technologies have been proposed to realize quality estimation of progressive download video services based on capture data acquired in the network or at the headend (Non-Patent Documents 1, 3, Four). In these methods, the received byte amount time series of the terminal is grasped from the packet capture data and input to the playout buffer model to realize the reproduction stop state estimation. By using these techniques, it is possible to estimate the video playback state of each session from given packet capture data. Further, Non-Patent Document 5-7 proposes means for obtaining user experience quality, that is, QoE (Quality of Experience) expression based on application level quality indicators such as the number of times playback is stopped and playback stop time.

  In the progressive download type content distribution, even a single content is often distributed in a plurality of units. Each divided unit is called a chunk, and such a distribution method is called a chunk-type content distribution method. An operation image of chunk type content distribution is shown in FIG. As shown in FIG. 1, a chunk is acquired from the received packet, stored in a playback buffer in units of chunk, and played (decoded).

Daisuke Ikegami, Yasunori Honda, Koji Yamamoto et al .: "Progressive download service stop time estimation method" IEICE Technical Report, vol. 111, no. 278, CQ2011-59, pp. 91-96, November 2011 . ISO / IEC 23009-1: 2012, Information technology-Dynamic adaptive streaming over HTTP (DASH)-Part 1: Media presentation description and segment formats, http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail .htm? csnumber = 57623 Daisuke Ikegami, Yasunori Honda, Koji Yamamoto: "Examination of playback state estimation method for chunked video distribution service", IEICE General Conference, B-11-24, March 2012. Yasutoshi Honda, Daisuke Ikegami, Koji Yamamoto: "Study of video playback state estimation method by Ack observation", IEICE General Conference, B-11-25, March 2012. ITU-T recommendation P.1201.1. Tobias Hobfeld R. Schatz, E. Biersack, Internet Video Delivery in YouTube®: From Traffic Measurements to Quality of Experience, Data Traffic Monitoring and Analysis, Lecture notes in Computer Science 7754 (2013), 264? 301. R. K. P. Mok, Edmond W. W. Chan, and Rocky K. C. Chang, Measuring the Quality of Experience of HTTP Video Streaming, Proc. W-MUST 2011 (2011).

  However, the conventional techniques described in Non-Patent Documents 1, 3, and 4 perform simulation for each very small fixed time unit in the buffer model of the terminal, and estimate the amount of data stored in the buffer at each time. For this reason, the calculation amount at the time of simulation execution has a problem that it is enormous. In addition, the case where the target application supports adaptive streaming is not taken into consideration. For this reason, when applied to an application that supports adaptive streaming, there was a concern of outputting an estimation result that deviated from the actual situation.

  The present invention has been made in view of the above points, and provides a technique for reducing the amount of calculation in estimating the reproduction state of video data in a video distribution method in which video data is distributed to terminals in units of chunks. Objective. Another object of the present invention is to provide a technique that enables estimation of a playback state with a reduced amount of calculation even when there is a transition in image quality during distribution of video data, such as adaptive streaming.

According to an embodiment of the present invention, in a video distribution method for distributing video data from a distribution server to a terminal in units of chunks, a video playback state estimation device for estimating a playback state of video data in a terminal,
For the target chunk that arrived at a certain time, the number of regenerated chunks at the arrival time of the chunk before the target chunk is played back from the arrival time of the chunk immediately before the target chunk to the arrival time of the target chunk. Calculating means for calculating the number of provisionally played chunks by adding the estimated number of played chunks estimated to have been played,
There is provided a video playback state estimation device comprising estimation means for estimating a playback state by comparing the number of provisionally played chunks and the cumulative number of received chunks up to the chunk immediately before the target chunk.

  According to the embodiment of the present invention, it is possible to reduce the amount of calculation in the video data reproduction state estimation in the video distribution method in which the video data is distributed to the terminal in units of chunks as compared with the conventional technique.

  According to the embodiment of the present invention, by adopting a configuration using an image quality transition table or the like, the amount of calculation is reduced even when there is a transition in image quality during distribution of video data, such as adaptive streaming. It is possible to perform reproduction state estimation.

It is a figure which shows the operation | movement image of chunk type | mold delivery. 1 is a configuration diagram of a video playback state estimation device 10 according to an embodiment of the present invention. It is a figure which shows the example of a chunk image quality level mapping table. It is a figure which shows the example of an image quality transition table. 5 is a flowchart for explaining the operation of the video reproduction state estimation device 10. It is a figure which shows the image of the chunk discard operation | movement at the time of image quality transition. It is a figure which shows the estimated value by the video reproduction state estimation apparatus 10 concerning this Embodiment, and the observation value by visual observation.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiment described below is only an example, and the embodiment to which the present invention is applied is not limited to the following embodiment. For example, in this embodiment, the progressive download video distribution service is targeted, but the application destination of the present invention is not limited to this, and the present invention can also be applied to other types of content distribution services.

(Device configuration)
FIG. 2 is a functional configuration diagram of the video reproduction state estimation device 10 according to the embodiment of the present invention. As shown in FIG. 2, the video playback state estimation apparatus 10 according to the present embodiment includes a capture data analysis unit 1 that analyzes capture data, a chunk time series analysis unit 2 that analyzes the time series of chunks, and a playback state in a terminal A reproduction state estimation unit 3 for estimating.

  In this embodiment, a packet of video data distributed from the distribution server to the terminal is captured outside the video reproduction state estimation device 10, and the captured data is input as packet capture data. The reproduction state estimation device 10 may include a function of capturing a packet. Further, each functional unit of the video reproduction state estimation device 10 may physically operate in a separate casing.

  The video reproduction state estimation apparatus 10 according to the present embodiment can be realized by causing, for example, one or a plurality of computers to execute a program describing the processing contents described in the present embodiment. That is, the function of the video playback state estimation device 10 executes a program corresponding to the processing executed by the video playback state estimation device 10 using hardware resources such as a CPU, a memory, and a hard disk built in the computer. This can be realized by doing so. Further, the program can be recorded on a computer-readable recording medium (portable memory or the like), stored, or distributed. It is also possible to provide the program through a network such as the Internet or electronic mail.

  The outline of each functional unit in the video reproduction state estimation device 10 according to the present embodiment having the above-described configuration is as follows.

<Capture data analysis unit 1>
The capture data analysis unit 1 extracts the arrival time and chunk length information (eg, byte amount) of the chunk included in the estimation target video flow from the input packet capture data, and outputs it as a chunk time series. The chunk time-series data (arrival time, chunk length) can be held in a storage unit such as a memory as a two-dimensional array corresponding to the chunk number, for example.

  The method for estimating the arrival time of a chunk from the packet capture data (time when the downloading of the chunk is completed) is not limited to a specific method. For example, the method using the response timing of the HTTP GET message, the header information of the TCP packet is used. There are methods.

<Chunk time series analysis unit 2>
The chunk time series analysis unit 2 receives the chunk time series data acquired by the capture data analysis unit 1 and the chunk image quality level mapping table, determines the image quality level to which each chunk belongs, and outputs the chunk image quality time series. . The chunk image quality time series is data in which image quality is added to each chunk in the above-described chunk time series data.

  For example, as shown in FIG. 3, the chunk image quality level mapping table associates a predetermined image quality level (eg, high, medium, low) with a chunk length (described as a chunk length basic area in FIG. 3). It is a table. That is, since the longer chunk length is estimated to be high image quality, the image quality for each chunk is estimated using such a mapping table. For example, from the mapping table in FIG. 3, it is estimated that the image quality of a chunk having a chunk length of 2 MB is 1 (high image quality).

  Also, the chunk time series analysis unit 2 checks whether the image quality has changed from the previous chunk for each chunk based on the chunk image quality time series, and for the chunk where the image quality transition has occurred, the arrival time of the chunk The image quality and the cumulative number of received chunks at that time are accumulated in the image quality transition table. The image quality transition table is table data stored in storage means in the video reproduction state estimation device 10. FIG. 4 shows an example of the image quality transition table. A method of using the image quality transition table will be described later.

<Playback state estimation unit 3>
The playback state estimation unit 3 performs playback on the terminal based on the playback time length per chunk for each image quality input from the outside, the chunk image quality time series data output from the chunk time series analysis unit 2, and the image quality transition table. The state is estimated including the image quality level at the time of reproduction. That is, it is possible to estimate which chunk of image quality is being played back if playback is in progress at a certain time, playback is stopped, or playback is in progress. The playback state estimation unit 3 outputs a playback state estimation result in which playback states including image quality are recorded in time series.

(Operation of video playback state estimation device 10)
Next, the operation of the video playback state estimation device 10 having the above configuration will be described in detail. FIG. 5 is a flowchart showing the operation of the video reproduction state estimation device 10.

  As an operation in the video reproduction state estimation device 10 according to the present embodiment, the chunk data obtained by the capture data analysis unit 1 each time the arrival of the chunk (chunk download completion) is identified from the input packet capture data. Image quality determination and reproduction state estimation may be performed based on (arrival time, chunk length), or time series data of all chunks is obtained from the packet capture data by the capture data analysis unit 1 and stored in the storage means. The image quality determination and the reproduction state estimation may be performed by reading out chunk data (arrival time, chunk length) from the storage unit in the order of arrival of the chunks. Although there is no essential difference between the two, in the present embodiment, the former is assumed.

  In the flowchart of FIG. 5, in step 0, the capture data analysis unit 1 performs a process for identifying a chunk. When the arrival of the chunk is detected in step 1, the chunk is detected after step 1 shown in FIG. Processing according to the procedure is performed. Thereafter, the procedure is repeatedly executed for each arrival time of the chunk.

  In the following, a basic reproduction state estimation process when there is no chunk image quality transition will be described first, followed by a process when there is an image quality transition. The process when there is no image quality transition corresponds to the process when reaching step 5 or step 8 in the flowchart of FIG. The process when there is an image quality transition corresponds to the process when reaching step 9 in the flowchart of FIG. The description along the flowchart of FIG. 5 will be given in the description of the processing when there is an image quality transition.

<Basic playback state estimation processing when there is no image quality transition of chunks>
First, the first and second chunks will be described in order to explain the processing details.

  For the chunk at the first arrival time, the cumulative number of received chunks at that time is recorded as “1”. Here, recording the cumulative number of received chunks means storing the cumulative number of received chunks in a variable (specifically, i). The number of accumulated received chunks in i is stored each time a chunk arrives.

  Now assume that the second chunk has arrived. The reproduction state estimation unit 3 estimates the reproduction state at this time as follows.

First, the playback state estimation unit 3 adds the value calculated by the following equation (1) to the number of played back chunks at the time of arrival of the first chunk (in this example, 0 because it is the first), The number of provisionally reclaimed chunks at (2 chunk arrival time) is calculated.
{(Second chunk arrival time)-(First chunk arrival time)}
/ (Reproduction time per chunk of the first chunk) ... (1)
Since playback may stop before the second chunk arrives, the value (positive real value) obtained by the above equation (1) may be larger than the number of played chunks. A value obtained by adding the number of regenerated chunks when the first chunk arrives to the value of equation (1) is referred to as “temporarily regenerated chunk number”.

  If (number of provisionally played chunks) ≦ 1 at the second chunk arrival time, the playback state estimation unit 3 determines that the playback is still continuing. Further, when (the number of provisionally played chunks)> 1, it is determined that the playback has already been stopped. In this way, the playback state can be estimated at the second chunk arrival time. Further, since the image quality of the first chunk is determined by the chunk time series analysis unit 2, if it is being reproduced at the second chunk arrival time, it can be estimated which image quality is being reproduced. The reproduction state estimation unit 3 can output such information as a reproduction state estimation result at the second chunk arrival time.

  When it is determined that the playback state has been changed to the playback stop state as described above, the playback state estimation unit 3 calculates the time when the playback state is changed to the playback stop state as follows.

  First, the reproduction state estimation unit 3 calculates the number of temporarily reproduced chunks at the second chunk arrival time based on the equation (1). Then, a value (r1-1) obtained by subtracting the number of regenerated chunks (here, “1”) at the time of arrival of the second chunk from r1 is calculated. Then, an elapsed time dt from the reproduction stop occurrence time to the current time (second chunk arrival time) is calculated by the following equation.

dt = (r1-1) × reproduction time per chunk of the first chunk And reproduction stop occurrence time r2 is estimated by the following formula.

r2 = (current time (second chunk arrival time here))-dt
Therefore, it can be estimated that the time interval [r2, r2 + dt] is the reproduction stop time. When the reproduction state estimation unit 3 is in the reproduction stop state at the second chunk arrival time, the reproduction state estimation unit 3 can output the time interval [r2, r2 + dt] as the reproduction stop time.

  Thereafter, it is possible to estimate and output the reproduction state up to the final chunk arrival time by repeating the same processing for each chunk arrival time. Specifically, the playback state can be estimated and output every time the i-th chunk arrives as follows.

The number of provisionally regenerated chunks at the i-th chunk arrival time is defined as r _i _pre.
r _i _pre = r _i-1 + (arrival _i -arrival _i-1 ) / l _i-1 (2)
Calculated by Here, arrival _i represents the arrival time of the _i- th chunk, and l _i−1 represents the reproduction time per chunk of the (i−1) -th chunk. r _i-1 indicates the number of regenerated chunks at the (i-1) th chunk arrival time. Here, r _i is calculated by r _i = min {i−1, r _i _pre}. That is, the number of regenerated chunks at the i-th chunk arrival time is estimated to be the smaller of i−1 and r _i _pre. This is because the number of regenerated chunks at the i-th chunk arrival time is at most i-1. However, as will be described later, when an image quality transition occurs, the number of reproduced chunks is the cumulative number of received chunks C _i0 when the image quality transition occurs.

The provisionally played chunk count r _i _pre indicates, as a real value, the number of chunks consumed from the start of viewing to the relevant time point when the chunk in the buffer is not depleted when the i-th chunk arrives. In fact, it is assumed that the chunks in the buffer are exhausted, so the following logical judgment is made.

r _i _pre> i-1 (3)
When (3) is FALSE, the reproduction state estimation unit 3 determines that the chunk is not depleted and determines that the state being reproduced is continuing. If (3) is TRUE, it is determined that the chunk is already exhausted, and the exhaustion time (= regeneration stop occurrence time) is calculated by the following equation.

(Playback stop time) = arrival _i- (r _i _pre-(i-1))
× Playing time per chunk of jth chunk (4)
Here, j is the number of the chunk being played at the time. In this case, the playback stop time is estimated from the playback stop occurrence time calculated in (4) to arrival _i . As described above, the reproduction state at each chunk arrival time can be determined.

  The playback state estimation unit 3 may store the playback state estimated at each chunk arrival time in a storage unit, display it on a display, or send it to an external device via a network. The form of output is not limited to a specific form.

<Processing when there is image quality transition>
Next, processing when a chunk image quality transition occurs will be described. Below, it demonstrates along the flowchart of FIG. 5 including the step of image quality transition.

  The capture data analysis unit 1 detects the arrival of the i-th chunk (step 1). The chunk time series analysis unit 2 determines the image quality of the chunk from the chunk length of the chunk obtained by the capture data analysis unit 1, and determines whether the image quality has changed from the image quality of the previous (i-1) th chunk. (Step 2).

  When the chunk image quality transition is confirmed, the chunk time-series analysis unit 2 accumulates the arrival time, image quality, and cumulative number of received chunks at that time in the image quality transition table (step 3).

  The reproduction state estimation unit 3 determines the reproduction state (reproduction stop or reproduction) of the target chunk using the method described above (step 4). If the reproduction stop state, the process proceeds to step 5. If not, the step 6 Proceed to In step 5, the reproduction state estimation unit 3 estimates the reproduction stop occurrence time by the method as described above, calculates the reproduction stop state period, and performs output.

  In step 6, the reproduction state estimation unit 3 determines whether or not an element of the image quality transition table exists. If the element exists, the process proceeds to step 7, and if the element does not exist, the process proceeds to step 8. Here, in step 8, the reproduction state estimation unit 3 determines that reproduction is in progress (the reproduction state continues) with the current image quality (eg, the image quality after the latest image quality transition), and performs output. Thereafter, the process proceeds to confirmation of the (i + 1) th chunk.

  Step 7, that is, when there is an image quality transition table element, a chunk having a different image quality is stored above a certain image quality chunk in the buffer. This corresponds to a case where image quality transition occurs.

  In step 7, the reproduction state estimation unit 3 first confirms the image quality of the element (chunk) having the minimum arrival time in the image quality transition table. The element with the shortest arrival time is the element that causes the image quality transition earliest among the elements stored in the image quality transition table.

Now, assume that the element is (t _i0 , C _i0 , q _i0 ). This represents (chunk arrival time, cumulative number of received chunks, image quality level) for each element. The image quality q _i0 may be higher or lower than the image quality of the i-th chunk that is the current target chunk. A high case is a case where a transition to high image quality occurs, and a low case is a case where a transition to low image quality occurs.

When the image quality q _i0 is higher than the image quality of the i-th chunk, the playback state estimation unit 3 determines that the image quality transitions when the following conditional expression is TRUE, updates the number of played chunks as C _i0 , and changes the image quality Delete the element in the table (step 9). The estimation result output in step 9 is the image quality during reproduction and the image quality after the image quality transition.
(Number of played chunks at the i-th chunk arrival time)> (C _i0 -rh)
Here, rh is a parameter in transition to high image quality. Further, the number of played chunks at the i-th chunk arrival time is a value calculated as r _i based on i−1 and r _i _pre as described above.

  The meaning of this expression is to check whether or not the number of regenerated chunks at the i-th chunk arrival time has reached a value (threshold value) obtained by subtracting rh from the current cumulative number of received chunks.

Conversely, when there is an element of the image quality transition table at the i-th chunk arrival time and the image quality of the element with the smallest arrival time is lower than the image quality of the i-th chunk, the playback state estimation unit 3 When the conditional expression is TRUE, it is determined that there is an image quality transition, the number of reproduced chunks is updated as C _i0 , and the element in the image quality transition table is deleted (step 9).

(Number of played chunks at the i-th chunk arrival time)> (C _i0 -rl)
Here, rl is a parameter in transition to low image quality. The meaning of this equation is to check whether or not the number of regenerated chunks at the i-th chunk arrival time has reached a value (threshold value) obtained by subtracting rl from the current cumulative received chunk number.

  As described above, subtracting rh and rl from the current cumulative number of received chunks means that at the time of image quality transition, only the rh and rl chunks with the image quality before the transition are deleted and the chunks with the image quality after the transition are played back. means. A processing image at the time of this image quality transition is shown in FIG. The upper part of FIG. 6 shows the transition from high image quality to low image quality. Here, rl = 2 is set, and at the time of transition from high image quality to low image quality, the operation of shifting to low image quality by discarding two high-quality chunks.

  The lower part of FIG. 6 shows the transition from low image quality to high image quality. Here, rh = 1 is set, and at the time of transition from low image quality to high image quality, an operation of discarding one chunk of low image quality and shifting to high image quality is performed.

  As described above, in the present embodiment, instead of transitioning to the next image quality after the completion of reproduction of all the chunks, modeling is performed in which a predetermined number of chunks are discarded and transition is performed. The threshold values are rh and rl.

  As described above, the playback state estimation unit 3 and the chunk time series analysis unit 2 perform processing, so that the playback state at each chunk arrival time can be estimated including the image quality level. By repeating the above processing up to the final arrival chunk, reproduction state estimation including the image quality level is realized until the final chunk arrival time.

<After arrival of all chunks>
Here, a description will be given after all chunks have arrived, that is, after all chunks have been downloaded. Generally, playback continues even after all chunks have been downloaded. Therefore, in the present embodiment, the reproduction state estimation unit 3 determines whether or not the cumulative number of received chunks (that is, the total number of chunks) exceeds the number of reproduced chunks at the final chunk arrival time. In this case, the remaining reproduction time rem_time at the time is estimated by the following equation.

rem_time = {(total number of chunks)-(number of played chunks at the time)}
× (Reproduction time per chunk of the chunk being played at the time)
This equation means that the remaining reproduction time rem_time is estimated on the assumption that each chunk that has been received but not reproduced is reproduced at the reproduction time per chunk of the chunk being reproduced at the final chunk arrival time.

  The reproduction state estimation unit 3 can calculate the time when the reproduction of the final chunk is completed by adding the rem_time to the final chunk arrival time. Thus, the estimation of the playback state at each time is completed.

<Output example>
FIG. 7 shows an output example of the estimation result of the reproduction state by the video reproduction state estimation device 10 according to the present embodiment. In the estimation, the reproduction start threshold is set to 1, the number of image quality levels is set to 5, and rh = 2 and rl = 1. Note that the reproduction start threshold value 1 means that the reproduction of a chunk is started immediately when even one chunk is in the buffer.

  In FIG. 7, the estimation result by the video reproduction state estimation device 10 is indicated by a dotted line, and the visually observed value is indicated by a solid line. Also, 0 in the playback state means stop, and 1 to 5 mean the image quality during playback. However, in the estimation by the video playback state estimation device 10, the number of image quality levels is five, but in visual observation, the image quality is two levels of high image quality and low image quality. The image quality is set to image quality 1. As shown in FIG. 7, it can be seen that the image quality visually observed at each time and the level of the estimated image quality by the video reproduction state estimation device 10 substantially match, and the reproduction state can be estimated with high accuracy.

(Summary of embodiment)
As described above, in the present embodiment, in a video distribution method for distributing video data from a distribution server to a terminal in units of chunks, a video playback state estimation device for estimating a playback state of video data in a terminal, For the target chunk that arrived at a certain time, the number of regenerated chunks at the arrival time of the chunk before the target chunk is played back from the arrival time of the chunk immediately before the target chunk to the arrival time of the target chunk. Calculating means for calculating the number of provisionally regenerated chunks by adding the estimated number of regenerated chunks estimated to have been obtained, the number of provisionally regenerated chunks, and the cumulative number of received chunks up to the chunk before the target chunk. There is provided a video reproduction state estimation device including estimation means for estimating a reproduction state by comparison.

  The calculation means calculates the estimated number of replay chunks by dividing a value obtained by subtracting the arrival time of the chunk immediately before the target chunk from the arrival time of the target chunk by the reproduction time length of the chunk.

  The estimating means determines that the playback is stopped when the number of provisionally played chunks is larger than the cumulative received chunk number, and when the number of provisionally played chunks is not larger than the cumulative received chunk number. It is determined that playback is in progress.

  When it is determined that the reproduction is stopped, the estimation unit multiplies the reproduction time length of the chunk by a value obtained by subtracting the cumulative received chunk number from the provisionally reproduced chunk number, thereby determining the reproduction stop time from the reproduction stop occurrence time. The elapsed time until the arrival time of the target chunk is calculated, and the reproduction stop occurrence time is estimated based on the elapsed time.

  Further, the video reproduction state estimation device has a means for recording the number of accumulated received chunks at the time point in the image quality transition table when a certain chunk arrives and the image quality of the chunk is different from the image quality of the previously arrived chunk. And the estimation means reproduces when the number of reproduced chunks at the arrival time of the target chunk exceeds a threshold obtained by subtracting a predetermined value from the cumulative number of received chunks recorded in the image quality transition table. It is determined that the image quality of the chunk has changed.

  Further, according to the present embodiment, in a video distribution method for distributing video data from a distribution server to a terminal in units of chunks, a video reproduction state estimation method executed by a video reproduction state estimation device that estimates a reproduction state of video data in a terminal. For the target chunk that arrived at a certain time, the arrival time of the target chunk from the arrival time of the chunk immediately before the target chunk is added to the number of regenerated chunks at the arrival time of the chunk immediately before the target chunk. A step of calculating the number of provisionally regenerated chunks by adding the estimated number of regenerated chunks estimated to have been regenerated before, the number of provisionally regenerated chunks, and the cumulative received chunks up to the chunk before the target chunk A video playback state estimation method comprising: an estimation step for estimating a playback state by comparing a number It is.

(Effects of the technology of the embodiment)
In the video reproduction state estimation device 10 according to the present embodiment, the number of reproduced chunks at each chunk arrival time is measured as a continuous value, and this is compared with a value based on the cumulative number of received chunks at each time. Thus, it is possible to estimate the reproduction state.

  That is, in this embodiment, for the progressive download video distribution service, instead of directly estimating the number of chunks in the playback buffer of the terminal in a fine time unit, the number of played chunks as a continuous value for each chunk arrival The calculation method is adopted. As a result, the simulation time is only the chunk arrival time, and the amount of calculation is greatly reduced as compared with the existing estimation method.

  Also, the video playback state estimation device 10 can manage the schedule of the image quality transition time, the post-transition image quality, the chunk time length, etc., even when the target progressive download video distribution service provides adaptive streaming. It is possible to realize reproduction state estimation taking image quality changes into account.

  That is, in the present embodiment, it is possible to estimate the playback state even for an application that supports adaptive streaming by taking into account the change in the image quality of the video being played back and taking into account the buffer threshold at the time of image quality transition.

  As described above, with the technology of the present embodiment, dynamic bit rate distribution based on captured data acquired in the network or at the head end is targeted for a progressive download video distribution application that involves dynamic bit rate change. Can be realized.

  The present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the claims.

10 Video playback state estimation device
1 Capture data analysis unit
2 Chunk time series analysis part
3 Playback state estimation unit

Claims (7)

In a video distribution method for distributing video data from a distribution server to a terminal in units of chunks, a video playback state estimation device for estimating a playback state of video data in a terminal,
For the target chunk that arrived at a certain time, the number of regenerated chunks at the arrival time of the chunk before the target chunk is played back from the arrival time of the chunk immediately before the target chunk to the arrival time of the target chunk. Calculating means for calculating the number of provisionally played chunks by adding the estimated number of played chunks estimated to have been played,
An image reproduction state estimation device comprising: estimation means for estimating a reproduction state by comparing the number of provisionally reproduced chunks and the cumulative number of received chunks up to the chunk immediately before the target chunk. The calculation means calculates the estimated number of playback chunks by dividing a value obtained by subtracting the arrival time of the chunk immediately before the target chunk from the arrival time of the target chunk by the playback time length of the chunk. The video reproduction state estimation device according to claim 1, wherein The estimating means determines that the playback is stopped when the number of provisionally played chunks is larger than the cumulative received chunk number, and when the number of provisionally played chunks is not larger than the cumulative received chunk number. The video reproduction state estimation device according to claim 1, wherein the video reproduction state estimation device determines that the reproduction is in progress. When it is determined that the reproduction is stopped, the estimation unit multiplies the reproduction time length of the chunk by a value obtained by subtracting the cumulative received chunk number from the provisionally reproduced chunk number, thereby determining the reproduction stop time from the reproduction stop occurrence time. The video playback state estimation device according to claim 3, wherein an elapsed time until the arrival time of the target chunk is calculated, and a playback stop occurrence time is estimated based on the elapsed time. The video reproduction state estimation device comprises means for recording the number of received chunks received at the time point in the image quality transition table when the image quality of the chunk is different from the image quality of the previously arrived chunk when a certain chunk arrives,
The estimating means determines the number of chunks to be played when the number of played chunks at the arrival time of the target chunk exceeds a threshold obtained by subtracting a predetermined value from the cumulative number of received chunks recorded in the image quality transition table. The video reproduction state estimation device according to any one of claims 1 to 4, wherein it is determined that the image quality has transitioned. In a video distribution method for distributing video data from a distribution server to a terminal in units of chunks, a video playback state estimation method executed by a video playback state estimation device that estimates a playback state of video data in a terminal,
For the target chunk that arrived at a certain time, the number of regenerated chunks at the arrival time of the chunk before the target chunk is played back from the arrival time of the chunk immediately before the target chunk to the arrival time of the target chunk. A calculation step of calculating the number of provisionally regenerated chunks by adding the estimated number of regenerated chunks estimated to have been played,
A video playback state estimation method comprising: an estimation step of estimating a playback state by comparing the number of provisionally played chunks and the cumulative number of received chunks up to the chunk immediately before the target chunk.   The program for functioning a computer as each means in the image | video reproduction | regeneration state estimation apparatus of any one of Claims 1 thru | or 5.

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