JP2014112280A - Video group reconfiguration/summarizing device, video group reconfiguration/summarizing method, and video group reconfiguration/summarizing program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reconfigure a video group to a video section group for each subject, without using any prior knowledge.SOLUTION: A step for dividing text data with time intervals into one or more segments along a time-axis and allocating each a topic corresponding to a keyword in each segment to the respective segment and a step for combining segments adjoining temporally based on a similarity of the topic are repeated. After the steps are repeated, each segment is clustered for each topic allocated to the segment.

Description

  The present invention relates to a technique for reconstructing a video group and summarizing the reconstructed video.

  There is no end to the increase in video content, and a huge amount of new video is generated every day and distributed through broadcast networks and networks. An image is a medium having a time axis.

  For this reason, it takes a lot of labor and time to grasp the tendency from a huge group of video contents and to find a scene that contains useful information, which itself is attractive.

  Therefore, there is a need for a mechanism for assisting effective viewing of video content by organizing an enormous amount of video content in an easy-to-understand manner or extracting so-called “highlight” scenes.

  There are many different configurations for video, but one of the typical video configurations is video composed of multiple topics. For example, a news video broadcast on television is an example.

  In many cases, various topics such as politics, economy, international, performing arts, and sports are dealt with in one news program broadcasted by terrestrial broadcasting or satellite broadcasting. There is generally no clear rule for the order and video length in which each topic is handled in the program because it is strongly influenced by the latest information and events at the time of the program broadcast.

  A lecture video is also an example of a video composed of a plurality of topics. For example, when a lecture video about a specific subject is considered, if a field such as “calculus” and “vector” in mathematics is considered as a topic, it can be said that the lecture video is a video composed of a plurality of topics.

  Furthermore, a parliamentary video showing the state of the Diet, prefectural assembly, and city council is an example of a video composed of multiple topics. For example, if an agenda such as “Budget for the current fiscal year” or “Revision of the ordinance” is regarded as a topic, it is clear that the Congress video is a video composed of a plurality of topics.

  When there are a plurality of videos composed of a plurality of topics, represented by these examples, the video group is handled in the video group as one method for efficiently viewing these video groups. A method of reconstructing based on a topic and generating a video for each topic or its digest video is conceivable.

  This will be specifically described by taking as an example “a group of news videos broadcast by a plurality of broadcasting stations during a certain week”. Now, it is assumed that only a video section of a topic related to politics that is handled in a news video group for one week is extracted and can be viewed. By viewing this video segment group in chronological order, it is possible to easily grasp the political flow during the week.

  Also, by viewing only important video sections from videos reconstructed for each topic, it becomes possible to view and understand the political flow in a shorter time. Furthermore, for example, by using a viewing method that considers time and channel viewpoints, such as viewing and comparing videos related to the same topic broadcasted at the same time or on the same day by a plurality of broadcasting stations, for example, the same topic It is possible to easily and clearly grasp the difference in opinions between channels.

  As described above, it is considered that the video group can be viewed more efficiently by reconstructing the video group for each topic and allowing viewing of each topic or summary video.

  As a technique for generating a summary video for efficiently viewing a video group in a short time, Patent Document 1 describes (1) suitability for user requirements, (2) semantic completeness, and (3) appearance. A technique for generating one summary video from a video group in consideration of completeness, (4) ease of viewing, and (5) time length is disclosed.

  In addition, in order to reconstruct a video group including videos composed of multiple topics for each topic and further summarize, it is possible to detect topic switching in each video, and each video section obtained as a result Need to be assigned.

  Hereinafter, the detection of video topic switching is also referred to as topic segmentation. Technologies related to topic segmentation are disclosed in Patent Literature 2 and Non-Patent Literature 1.

JP 2012-19305 A Japanese Patent Laying-Open No. 2005-167452

Katsuhito Bessho, “Topic Segmentation Based on the Intracluster Fluctuation Minimal Algorithm”, Natural Language Processing Society / Natural Language Processing Study Group, Research Report, Natural Language Processing 154-25, March 7, 2003, p.177-183

  However, in the technique of Patent Document 1, although information on orderly viewing of videos is taken into consideration, topic information included in each video section is not necessarily reflected. Therefore, for example, a summary video in which video sections of different topics are inserted between the same topic, such as “political topic → sports topic → political topic”, is often generated, and is always easy to understand. Is not always output.

  Further, the techniques of Patent Literature 2 and Non-Patent Literature 1 require prior knowledge such as a learning corpus. Especially in the case of a video such as a news program that requires immediacy, words that are uttered or displayed in subtitles in the program are often not included in the existing corpus, so prior knowledge should be updated each time. There is a problem that the time cost is high.

  The present invention has been made in view of the above circumstances, and an object thereof is to reconstruct a video group into video section groups for each topic without using any prior knowledge.

  The video group reconstruction / summarization device according to claim 1, wherein the video group reconstruction / summarization device reconstructs a video group composed of videos to which text data with a time interval is added, and summarizes the video. A segment initialization unit that reads text data with a time interval from the data storage unit and divides the text data into one or more segments along the time axis, and a process of assigning topics according to keywords in each segment to each segment, A topic assignment / segment update unit that repeats the process of combining temporally adjacent segments based on the similarity of the topic, and a segment that clusters the repeated segments for each topic assigned to the segment Group clustering means and the weight of the keyword for the topic An important video segment extracting means for extracting an important video segment from video segments corresponding to the segments in the clustered topic based on the degree, and at least one of the video segment of each cluster and the important video segment of each cluster. And a video output means for outputting a video based on the above.

  According to the present invention, text data with a time section is divided into one or more segments along the time axis, and a topic according to a keyword in each segment is assigned to each segment and the similarity between the topics. And repeating the process of combining temporally adjacent segments, and clustering the repeated segments for each topic assigned to the segment, so that the video group can be grouped for each topic without using any prior knowledge. It can be reconfigured into video segments.

  The video group reconstruction / summarization apparatus according to claim 2 is the video group reconstruction / summarization apparatus according to claim 1, wherein the topic assignment / segment update unit is configured to perform segmentation based on a frequency of use of a keyword included in the segment. A segment feature amount calculation process for calculating the feature amount, a topic assignment process for assigning a topic vector based on the feature amount to the segment, and a similarity between segments calculated using the topic vector is equal to or greater than a threshold value The gist is to repeat the segment combining process for combining adjacent segments until a predetermined end condition is satisfied.

  The video group reconstruction / summarization device according to claim 3 is the video group reconstruction / summarization device according to claim 1 or 2, wherein the segment initialization unit has an information amount per segment larger than a threshold value, The gist is to divide the text data with a time section so that the segment does not span a plurality of topics.

  5. The video group reconstruction / summarization apparatus according to claim 4 is the video group reconstruction / summarization apparatus according to claim 2, wherein the topic assignment / segment update means is a feature quantity of a segment preceding and / or following in time. The gist is that the segment feature amount calculation process is further executed using the above.

  6. The video group reconstruction / summarization method according to claim 5, wherein the video group reconstruction / summarization method reconstructs a video group composed of videos to which text data with a time interval is added, and summarizes the video. The segment initialization step of reading out the text data with time section from the data storage means and dividing it into one or more segments along the time axis, and assigning topics corresponding to the keywords in each segment to each segment, respectively A topic assignment / segment update step that repeats the process and a process of combining temporally adjacent segments based on the similarity of the topic, and each repeated segment is assigned to each topic assigned to the segment. Segment group clustering step for clustering and the corresponding cluster An important video segment extraction step for extracting an important video segment from video segments corresponding to segments in the clustered topic based on the importance of the keyword with respect to the video; and the video segment of each cluster and the importance of each cluster And a video output step of outputting a video based on at least one of the video sections.

  According to the present invention, text data with a time section is divided into one or more segments along the time axis, and a topic according to a keyword in each segment is assigned to each segment and the similarity between the topics. And repeating the process of combining temporally adjacent segments, and clustering the repeated segments for each topic assigned to the segment, so that the video group can be grouped for each topic without using any prior knowledge. It can be reconfigured into video segments.

  The video group reconstruction / summarization method according to claim 6 is the video group reconstruction / summarization method according to claim 5, wherein the topic assignment / segment update step is performed based on a frequency of use of a keyword included in the segment. A segment feature amount calculation process for calculating the feature amount, a topic assignment process for assigning a topic vector based on the feature amount to the segment, and a similarity between segments calculated using the topic vector is equal to or greater than a threshold value The gist is to repeat the segment combining process for combining adjacent segments until a predetermined end condition is satisfied.

  The video group reconstruction / summarization method according to claim 7 is the video group reconstruction / summarization method according to claim 5 or 6, wherein the segment initialization step has an information amount per segment larger than a threshold value. The gist is to divide the text data with a time section so that the segment does not span a plurality of topics.

  The video group reconstruction / summarization method according to claim 8 is the video group reconstruction / summarization method according to claim 6, wherein the topic assignment / segment update step includes temporally and / or subsequent segment feature quantities. The gist is that the segment feature amount calculation process is further executed using the above.

  According to a ninth aspect of the present invention, there is provided a video group reconstruction / summarization program that causes a computer to execute the video group reconstruction / summarization method according to any one of the fifth to eighth aspects.

  According to the present invention, a video group can be reconfigured into a video section group for each topic without using any prior knowledge.

It is a figure explaining the outline | summary of the whole process. It is a figure which shows the example of text data with a time interval. It is a figure which shows the functional block structure of an image group reconstruction / summarization apparatus. It is a figure which shows the example of a keyword information management table. It is a figure which shows the example of the segment initialization on the basis of a punctuation mark. It is a figure which shows the example of the segment initialization on the basis of information amount. It is a figure which shows the example of the segment initialization on the basis of the switching of an image | video. It is a figure which shows the example of a segment information management table. It is a figure which shows the processing flow of topic allocation and segment update. It is a figure which shows the example of calculation of a segment feature-value. It is a figure which shows the example of a topic-word importance degree table. It is a figure which shows the example of an update of a segment information update table. It is a figure which shows the clustering example of a segment group. It is a figure which shows the example of a video viewing interface. It is a figure which shows the outline | summary of an effect. It is a figure which shows the example of application with respect to a news video group. It is a figure which shows the example of application with respect to teaching-materials video group (mathematics problem exercise lecture). It is a figure which shows the example of application with respect to an assembly video group.

  The present invention increases the accuracy of topic assignment and topic segmentation by repeating topic assignment processing to subelement groups of text data given to video and combining processing of adjacent elements based on topic similarity. It is characterized by.

  The outline of the processing will be described with reference to FIG. In the present invention, first, the text data group with a time section assigned to each video is divided into appropriate subelement groups. Subsequently, after a keyword and a feature amount are extracted from the text data of each element, a process of assigning a topic to this element group is performed. Then, adjacent subelements are combined based on the assigned topic similarity.

  A topic is assigned to each finally obtained subelement by repeating the topic assignment process and the subelement combination process a plurality of times. Moreover, the importance with respect to the topic of each keyword can be obtained for each topic.

  Then, by clustering element groups based on topics, it is possible to obtain video reconstructed for each topic. In addition, it is possible to obtain a summary video for each topic by determining an important video section using the importance of each keyword for each topic.

  The above-described text data with time section refers to data composed of a text group having a start time and an end time corresponding to one video file as shown in FIG.

  Specifically, for example, subtitles added to the video, closed captions, or text data obtained as a result of voice recognition processing can be used. It is assumed that the input text data and the video are associated with each other on a one-to-one basis, and it is not assumed that there is no video without text data with a time interval or text data with a time interval not associated with a video. Shall.

  Hereinafter, the subelement of the text data with time section is referred to as a segment. A segment is composed of texts of some adjacent time intervals or a part thereof in text data with time intervals.

  Specifically, as shown in FIG. 2, for example, the underlined portion from the first line to the second line is defined as one segment, or the text from the beginning of the text on the fifth line to the punctuation point is defined as a segment. Hereinafter, an embodiment for carrying out the present invention will be described.

[Functions of image group reconstruction / summarization device 1]
FIG. 3 is a diagram showing a functional block configuration of the video group reconstruction / summarization apparatus 1 according to the present embodiment. The video group reconstruction / summarization apparatus 1 includes a data storage unit 11, a segment initialization unit 12, a topic assignment / segment update unit 13, a segment group clustering unit 14, an important video segment extraction unit 15, and a video output unit. 16.

  The data storage unit 11 has a function of storing a video group given as input and managed on a database, and a text data group having a time section corresponding to each of the video group.

  The segment initialization unit 12 reads a text data group with a time section from the data storage unit 11, extracts a keyword from the text data group, and segments to be divided into one or more segments along the time axis It has a function to perform initialization processing.

  The topic assignment / segment update unit 13 assigns a topic corresponding to a keyword in each segment to each segment, and segment combination that combines temporally adjacent segments based on the similarity of the assigned topics It has a function of repeating the processing a predetermined number of times.

  The segment group clustering unit 14 has a function of performing clustering processing for clustering each segment finally obtained by the processing in the topic assignment / segment update unit 13 for each topic assigned to the segment. . Each cluster obtained here corresponds to the topic described above.

  The important video segment extraction unit 15 selects an important video segment from among the video segment candidates corresponding to the segments in the clustered topic based on the importance of each keyword obtained by the processing of the topic assignment / segment update unit 13. Has a function of performing a process of extracting as a summary video.

  The video output unit 16 is based on at least one of the video segment corresponding to each cluster obtained by the processing of the segment group clustering unit 14 and the important video segment of each cluster obtained by the processing of the important video segment extraction unit 15. It has a function to output video.

  By executing the processing of each of the functional units 11 to 16 described above, it is possible to obtain a video group reconstructed for each topic and a summary video group for each topic from which important video sections are extracted as an output. .

  Each functional unit 11 to 16 can be realized by a computer having a memory and a CPU, and the processing is executed by a program.

[Processing of segment initialization unit 12]
Next, the process of the segment initialization unit 12 will be described. The segment initialization unit 12 creates a segment information management table in which information about the segment is stored for each segment by extracting keywords from text data with a time section corresponding to each video and determining the initial state of the segment. To do.

(About keyword extraction)
First, keyword extraction from a text data group with a time section will be described. Here, the keyword and the keyword frequency in the entire data (hereinafter, the keyword frequency in the entire data is also referred to as the total frequency) are extracted from the input text data with time section.

  As a method for extracting a keyword, morphological analysis of text data may be performed, and a specific phrase such as a noun phrase may be extracted as a keyword. For example, a character string having a specific rule, such as a character string in which a certain number of kanji characters continue, may be extracted as a keyword.

  At this time, a term called a stop word, which has a very high appearance frequency for any video and does not function as a keyword, is, for example, a keyword tf-idf value when text data with a time interval is regarded as one document. It is desirable to remove it beforehand by evaluating the above.

  The extracted keyword and its frequency information are stored in the data storage unit 11 in a format in which the keyword ID is associated with the keyword itself and its total frequency, for example, as shown in FIG. FIG. 4 is an example, and in addition to these elements, for example, the previously calculated tf-idf value may be included as an element.

  Examples of the morphological analysis method described above include, for example, “Yuji Matsumoto,“ Morphological Analysis System “Chaya” ”, Information Processing, Vol. 41, No. 11, November 2000, p.1208-1214,“ “Yet Another Part-of-Speech and Morphological Analyzer ”, [onlile], [searched on November 15, 2012], <URL: http://mecab.googlecode.com/svn/trunk/mecab/doc/index.html> Can be used.

(About segment initialization)
Next, the segment initial state construction processing will be described. In the present embodiment, each segment obtained by the processing of the segment initialization unit 12 is a minimum topic allocation unit.

  In the subsequent processing, adjacent segments are combined based on topic similarity, thereby improving topic segmentation accuracy and topic allocation accuracy for the segments.

  There are various methods for constructing the initial state of a segment. As a viewpoint to be considered at that time, (a) increasing the amount of information per segment, (b) one segment spans multiple topics. There are two elements: the initial segment is constructed so that it does not.

  In the topic assignment / segment update unit 13 described later, topic assignment to each segment is performed based on the frequency of keywords included in the segment or information related thereto.

  In general, the more information contained per segment, the higher the relevance of the topic assigned by the topic assignment process described later. Therefore, the viewpoint of (a) above that makes the amount of information per segment larger than a threshold is important. is there.

  On the other hand, in the segment initialization process in the topic allocation / segment update unit 13 described later, when the initial segment includes a plurality of topics, the accuracy of topic segmentation is lowered, so the viewpoint (b) is also important.

  For the above reasons, it is necessary to apply a segment initialization method that is appropriate from both viewpoints (a) and (b). Specifically, (1) segment initialization based on punctuation marks, (2) segment initialization based on the amount of information per segment, and (3) segment initialization based on video switching. Can be considered.

  The method (1) is a method of constructing an initial segment by dividing sentences on the basis of punctuation marks or reading marks. FIG. 5 shows an example in which sentences are divided for each punctuation point to constitute an initial segment.

  In general, it is unlikely that a sentence or phrase delimited by punctuation marks includes a plurality of topics. For this reason, the initial segment obtained by the method (1) is unlikely to have a plurality of topics, and is therefore suitable as a segment initialization method. On the other hand, for example, there is a possibility that a segment with a very small amount of information or a non-existing segment such as a segment such as “Good morning” may occur, and a segment that makes topic assignment difficult may occur.

  The method (2) is a method of performing division based on the amount of information such as the number of characters in a sentence and the number of keywords. FIG. 6 shows an example in which an initial segment is formed by dividing a sentence by a certain length. In addition, a method is also conceivable in which segments are configured so that the number of keywords obtained by keyword extraction processing is equal for each segment.

  Each initial segment obtained by this method does not generate a segment with a small amount of information and is difficult to allocate topics as in method (1), but the initial segment may span multiple topics. In this case, there is a demerit that the division accuracy of the video section by topic is lowered.

  The method (3) is a method of defining text data included in a video section defined by switching between video and audio as a segment. FIG. 7 shows an example in which an initial segment is formed by dividing sentences every time a video is switched.

  Each initial segment obtained by this method can set the size of the initial segment larger than the method (1), so that the number of iterations in the topic assignment / segment update unit 13 described later can be reduced. it can.

  Note that switching between video and audio can be detected using, for example, the methods described in JP-A-8-214210 and JP-A-11-18028. When the segment is actually initialized, an appropriate method may be selected from (1) to (3) while comparing the viewpoints (a) and (b) and the data characteristics.

(About segment information management table generation)
Based on the above processing results, the segment initialization unit 12 constructs a segment information management table as shown in FIG. The segment information management table stores the ID of the video to which the segment belongs, the start time and end time of the segment, the text of the segment, the keyword included in the segment, and its frequency.

  FIG. 8 is an example, and when other information related to video channels is given, an element of channel ID may be added to the table. When a video broadcast date and time (hereinafter referred to as a time stamp) is given, the data may be added to the table.

  Hereinafter, the keyword frequency in each segment is also referred to as intra-segment frequency. The keyword information stored in the segment information management table is a keyword ID managed in the keyword information management table, and is preferably associated with the keyword itself and the total frequency. The intra-segment frequency can be obtained by counting how many times the keyword appears in the text of each segment.

  There are various methods for setting the start time and end time of each segment. The simplest method is to define the earliest start time and the latest end time as the start time and end time of a segment in a time interval including a part of a sentence included in a segment.

[Topic assignment / segment update unit 13]
Next, the processing of the topic assignment / segment update unit 13 will be described. The topic assignment / segment update unit 13 improves the accuracy of topic segmentation and topic assignment by repeating the topic segment assignment process based on topic assignment and topic similarity to a segment a predetermined number of times.

  Specifically, as shown in FIG. 9, the segment feature amount calculation process in step S101, the topic assignment process in step S102, and the segment combination process in step S103 are performed until the segment update end determination condition in step S104 is satisfied. repeat.

  By this iterative process, the segment information management table generated by the segment initialization unit 12 is updated, and the subsequent process of the segment group clustering unit 14 is performed using the information of the finally obtained table.

(Step S101: Segment feature amount calculation process)
First, the segment feature amount calculation unit calculates the feature amount for each segment based on the keyword information management table and the segment information management table.

  As the feature amount, a histogram based on the frequency of keywords included in the segment is extracted. The histogram extracted here may use, for example, the intra-segment frequency of the keyword as it is, or consider the segment as one document, and use a score obtained by using a known technique such as tf-idf for each keyword. May be.

  Here, in calculating the feature amount of each segment, the feature amount is calculated in consideration of the information amount of the segment itself and the distance between the segments, and also the information of the surrounding segments.

  FIG. 10 is an example of segment feature amount calculation that also considers neighboring segments. In this example, the feature amount in the nth segment (“in the urban areas of western Japan and eastern Japan from last night”) is calculated in consideration of the information held by the two segments before and after this segment.

  Peripheral segment information is taken into account after being weighted 0.6 times for the segment adjacent to the nth segment and 0.2 times for the segment next to the nth segment, A value as shown on the right side of the figure is obtained as the histogram feature amount of the nth segment.

  Depending on the method used in the segment initialization unit 12, there is a possibility that a segment having a very small amount of information and difficult to assign to a topic may occur. In such a case, it is effective to calculate the feature amount in consideration of the information of the surrounding segments because the information amount of the segment can be virtually increased.

  On the other hand, when the segment itself has a sufficient amount of information, considering the information on the surrounding topics may reduce the quality of the segment feature amount. For this reason, it is desirable that the number of segments to be considered is set to be smaller as the information amount of the segment itself is larger.

Various methods can be considered as a method of considering the information of the surrounding segments after considering the information amount of the segments themselves and the distance between the segments. For example, when the maximum value of surrounding segments to be considered when calculating the feature amount is 2N _b and the total number of keywords included in the nth segment is N _w , it is defined as σ = N _b / (N _w +1) A method is conceivable in which W calculated from the following equations (1) and (2) is used as a weight for information included in the segment B _i . | B _n −B _i | indicates the number of segments in which the n-th segment B _n is separated from the i-th B _i .

(Step S102: topic assignment processing)
Subsequently, the topic assignment unit assigns topics to each segment based on the feature values of each segment obtained by the segment feature value calculation unit.

  In the segment feature value calculation unit described above, the feature values for each segment are given as a histogram. Since the histogram is information indicating how many times a certain code c has occurred, it can be modeled as following a multinomial distribution.

  There are several well-known topic models for estimating a topic behind a variable that follows a multinomial distribution. Representative examples include “T. Hoffmann,“ Probabilistic Latent Semantic Indexing ”, SIGIR'99, 1999, p.50-57” and “DM Blei, two others,“ Latent Dirichlet Allocation ”, Journal of Machine Learning. PLSA (Probabilistic Latent Semantic Analysis) and LDA (Latent Dirichlet Allocation) described in Research 3, 2003, p.993-1022.

In the topic model, it is assumed that “each word included in a certain document is generated according to a word appearance probability distribution Φ _z unique to the topic after selecting a certain topic according to the topic ratio θ _B unique to the document”.

If the segment B _i is regarded as a document in the topic model, the topic model is expressed as a joint probability p (B _i , z) of the segment B _i and the topic zi behind it.

Since the joint probability p (B _i , z) cannot generally be calculated strictly, it is obtained using an approximation method such as Gibbs Sampling or variational Bayes approximation as necessary. What is directly obtained from these approximation methods is a document-specific topic ratio θ _b and a topic-specific word appearance probability distribution Φ _z .

The document-specific topic ratio θ _b is a vector of probability values having the same dimension as the preset number of topics _NZ . Hereinafter, this vector of probability values is referred to as a topic vector. Computing θ _bi for each segment B _i corresponds to topic assignment to the segment.

On the other hand, the topic-specific word appearance probability distribution Φ _z is a histogram of probability values having the same dimension as the total number of words N _w included in all segments, and _NZ histograms are generated. The value of each element of the word appearance probability distribution Φ _z is the appearance probability of the word w in the topic z, which can be interpreted as representing the importance of the word w in the topic z.

Using the result of the word appearance probability distribution Φ _z , a topic-word importance degree table using the topic ID and the keyword ID as keys as shown in FIG. 11 is constructed. Regarding the construction of the topic-word importance level table, a table storing importance levels for all combinations of topics and keywords may be constructed. The number of elements is (number of topics) × (number of keywords). In addition, it is possible to store only elements having a certain degree of importance or higher, or store only the top several items for each topic. The important video section extraction unit 15 described later extracts an important video section by using this topic-word importance degree table.

(Step S103: Segment combining process)
Subsequently, in the segment combination unit, segments are combined by evaluating the similarity of adjacent segments based on the topic vector of each segment obtained by the topic assignment unit.

As described in the topic assignment process, the topic vector assigned to each segment is an _NZ- dimensional probability vector. As a method for calculating the similarity between segments based on the topic vector, for example, an inner product between topic vectors or a cross-correlation may be calculated.

  Whether or not adjacent segments are to be combined is determined by setting a threshold value for the similarity obtained by this calculation. As the threshold value, various methods can be used, for example, a predetermined value is determined in advance, or the threshold value is dynamically set based on the average value of topic similarities.

  When it is determined that two adjacent segments are combined, the segment information management table is updated. FIG. 12 shows an example of updating the segment information update table. If there are keywords that appear in either of the two segments, the intra-segment frequencies are added together and stored in the table as one element.

(Step S104: Segment update end determination)
Finally, the segment update end determination unit performs the process end determination of the topic assignment / segment update unit 13. There are various methods for determining termination.

  For example. The end may be determined in advance when the number of repetitions of the topic assignment / segment update unit 13 exceeds a certain number. The number of newly combined segments may be used as a determination condition, and it may be determined to end when the number of combined segments is equal to or less than a certain number.

[Processing of the segment group clustering unit 14]
Next, processing of the segment group clustering unit 14 will be described. The segment group clustering unit 14 performs a process of grouping the segments using the topics of the respective segments obtained as a result of the process of the topic assignment / segment update unit 13.

  As described above, since a topic is a vector of probability values, segments can be grouped into clusters by applying a clustering process using an appropriate distance measure such as an L2 norm as shown in FIG.

  Clustering methods include k-means, “MM Yeung, 1 other,“ Time-Constrained Clustering for Segmentation of Video into Story Unites ”, International Conference on Pattern Recognition, vol.3, 1996, p.375- A known method such as Time-Constrained Clustering described in “380” can be used.

  A cluster assigned to each segment by the segment group clustering process may be stored in the data storage unit 11 by adding it to an element of the segment information management table.

[About processing of the important video section extraction unit 15]
Next, processing of the important video section extraction unit 15 will be described. The important video section extraction unit 15 extracts an important section from the video section candidates using the word importance obtained by the processing of the topic assignment / segment update unit 13.

  There are various ways of giving the video section candidates, but each candidate is defined as a partial element of the segment finally obtained by the processing of the topic assignment / segment update unit 13.

  As examples of how to give video segment candidates, for example, all elements of the input text with time segment are defined as important video segments, or initial segments obtained by the processing of the segment initialization unit 12 are selected as important video segment candidates. A way to do this is conceivable.

As a method of extracting an important section from these video section candidates, for example, the score Score of each candidate is calculated for each topic based on the following formula (3), and a candidate having a high score Score is selected as the important video section. A method such as

Here, Score (B ⁰ _j ) represents the score of the initial segment B ⁰ _j . N _bjwi is the frequency of the keyword w _i included in the segment B ⁰ _j , Φ _{zk, wi} is the importance of the keyword w _i in the topic z _k , θ _{Bj, zk} is the topic among the probability vectors assigned to the segment B ⁰ _j z represents the value of the element corresponding to _k .

Expression (3) is an expression that gives a score regarding each initial segment, but can be defined even when different sections are defined by appropriately changing the portion corresponding to the segment B ⁰ _j .

[Processing of video output unit 16]
Finally, the processing of the video output unit 16 will be described. The video output unit 16 uses the video section of each cluster obtained by the processing of the segment group clustering unit 14 and the important video section of each cluster obtained by the processing of the important video section extraction unit 15 to display a video. Output.

  There are various video output methods. As one of the simplest methods, a method of outputting each video segment group reconstructed for each cluster in the order of the time stamp of each video is conceivable. In addition, when channel information is assigned to the input video group, the video sections may be sorted for each channel, or a video player may be installed for each channel and output them at the same time.

  As a method of using each cluster obtained by the processing of the segment group clustering unit 14 and the important video section of each cluster obtained by the processing of the important video section extracting unit 15, a video viewing interface as shown in FIG. 14 is prepared. May be.

  In FIG. 14, bars corresponding to the videos included in the video group are displayed below the video playback unit 17. The length of the bar is proportional to the video length of each video, and the dot portion represents a video section included in a certain cluster obtained by the present embodiment. The important video section is displayed in the shaded area in the bar.

  By performing an operation such as clicking on an arbitrary place on the bar, seeking to the corresponding scene is performed. The interface as shown in FIG. 14 makes it possible to view a video of a scene included in an arbitrary cluster while grasping the entire image of the video group.

  Note that what is shown here is merely an example of a video output method, and any video output form may be used as long as the technology of the present invention is applicable.

  As described above, according to the present embodiment, the text data with a time section is divided into one or more segments along the time axis, and the topic according to the keyword in each segment is assigned to each segment and the topic Since the process of combining temporally adjacent segments based on the similarity is repeated and each segment after the repetition is clustered for each topic assigned to the segment, as shown in FIGS. Video groups can be automatically reconfigured into video segment groups for each topic without using any prior knowledge. Since the reconstructed video is collected for each topic, the viewer can easily grasp the content of the topic by viewing it.

  In addition, according to the present embodiment, since the important video section is extracted from the video sections corresponding to the segments in the clustered topic based on the importance of the keyword with respect to the topic after the above repetition, A summary video can be output. By viewing this summary video, the viewer can grasp the content of the topic in a shorter time.

DESCRIPTION OF SYMBOLS 1 ... Video group reconstruction / summarization apparatus 11 ... Data storage device 12 ... Segment initialization part 13 ... Topic assignment / segment update part 14 ... Segment group clustering part 15 ... Important video section extraction part 16 ... Video output part 17 ... Video reproduction | regeneration Part S101-S104 ... Step

Claims (9)

In a video group reconstruction / summarization device that reconstructs a video group composed of videos to which text data with a time interval is attached, and summarizes the video.
Segment initialization means for reading the text data with time interval from the data storage means and dividing it into one or more segments along the time axis;
Topic assignment / segment update means that repeats the process of assigning topics according to the keywords in each segment to each segment and the process of combining segments that are temporally adjacent based on the similarity of the topics;
Segment group clustering means for clustering each segment after the repetition for each topic assigned to the segment;
An important video segment extracting means for extracting an important video segment from video segments corresponding to segments in the clustered topic based on the importance of the keyword for the topic;
Video output means for outputting video based on at least one of the video section of each cluster and the important video section of each cluster;
A video group reconstruction / summarization apparatus comprising: The topic assignment / segment update means includes:
Segment feature amount calculation processing for calculating the feature amount of the segment based on the frequency of use of the keyword included in the segment, topic assignment processing for assigning a topic vector based on the feature amount to the segment, and calculation using the topic vector 2. The video group reconstruction / summarization according to claim 1, wherein, when the similarity between the determined segments is equal to or greater than a threshold, the segment combination processing for combining the adjacent segments is repeated until a predetermined end condition is satisfied. apparatus. The segment initialization means includes
3. The video group reconstruction / decoding according to claim 1, wherein the information amount per segment is larger than a threshold value, and the text data with a time interval is divided so that one segment does not span a plurality of topics. Summarization device. The topic assignment / segment update means includes:
The video group reconstruction / summarization apparatus according to claim 2, wherein the segment feature value calculation process is further performed using the feature values of the previous and / or subsequent segments in terms of time. In a video group reconstruction / summarization method that reconstructs a video group composed of videos with text data with a time interval and summarizes the video,
By computer
A segment initialization step of reading the text data with time interval from the data storage means and dividing the text data into one or more segments along the time axis;
A topic assignment / segment update step that repeats a process of assigning topics according to keywords in each segment to each segment, and a process of combining temporally adjacent segments based on the similarity of the topics;
A segment group clustering step of clustering each repeated segment for each topic assigned to the segment;
An important video segment extraction step of extracting an important video segment from video segments corresponding to segments in the clustered topic based on the importance of the keyword with respect to the topic;
A video output step of outputting video based on at least one of the video section of each cluster and the important video section of each cluster;
A video group reconstruction / summarization method characterized by comprising: The topic assignment / segment update step includes:
Segment feature amount calculation processing for calculating the feature amount of the segment based on the frequency of use of the keyword included in the segment, topic assignment processing for assigning a topic vector based on the feature amount to the segment, and calculation using the topic vector 6. The video group reconstruction / summarization according to claim 5, wherein when the similarity between the determined segments is equal to or greater than a threshold value, the segment combination processing for combining the adjacent segments is repeated until a predetermined end condition is satisfied. Method. The segment initialization step includes:
7. The video group reconstruction / construction according to claim 5 or 6, wherein the information data per segment is larger than a threshold value, and the text data with a time interval is divided so that one segment does not span a plurality of topics. Summarization method. The topic assignment / segment update step includes:
The video group reconstruction / summarization method according to claim 6, wherein the segment feature value calculation process is further performed using the feature values of the preceding and / or following segments in terms of time.   9. A video group reconstruction / summarization program that causes a computer to execute the video group reconstruction / summarization method according to claim 5.

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