Patent Application
20100085481
A portion of the disclosure of this patent document contains material, which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office files or records, but otherwise reserves all copyright rights whatsoever.
1. Field of the Invention
This invention relates generally to video analysis systems and methods and, more particularly, to systems and methods for comparing and matching frames within video streams based upon representations of visual signatures or characteristics of the frames (referred to herein as “video content DNA” or “content DNA”).
2. Description of Related Art
Generally speaking, conventional methods of comparing and matching content within a video file include comparing each frame within a sequence of frames of the video using an image matching approach. As such, conventional frame-by-frame analysis of videos tends to be computationally intensive. Attempts have been made to reduce computational costs by comparing and matching content within a video using temporal and spatial matching of the frames of the video. However, a need remains for improving the efficiency and computational speed at which video analysis and matching is performed.
The inventors have discovered an approach that is based on the assumption that the precision of employing image matching techniques to video frames is precise enough and has low enough false positive rates to offer a reliable solution for finding matching videos. Further, the inventors have discovered that comparing and matching selected frames within subject videos provides improvements in computing efficiency and speed while permitting detection of common parts or sections of videos to allow for successful video matching.
The present invention is directed to a method for identifying a plurality of videos within a corpus of reference videos matching at least one query video. The method includes providing the corpus of reference videos and receiving an input search criteria. The criteria includes the at least one query video, a parameter representing a desired search mode and a parameter representing a desired matching mode. Once the criteria is received, the method includes indexing each video in the corpus of reference videos frame by frame and determining a visual signature for each of the reference videos based on visual signatures of at least one of all frames within the reference video or a subset of frames within the reference videos. When signatures for each of the reference videos are determined, the method includes determining a visual signature of the query video and comparing the visual signatures of each video within the corpus of reference videos to the visual signature of the at least one query video, and identifying videos within the corpus of reference videos that match the at least one query video.
In one embodiment, indexing each of the reference videos includes reading each video frame by frame, comparing one frame to a next frame, and determining subsets of frames within each of the videos including anchor frames, heart beat frames and key frames. In one embodiment, a primary visual signature determined for each of the reference videos is based on the visual signatures of all frames within the reference video. In another embodiment, a secondary visual signature determined for each of the reference videos is based on the visual signatures of at least one of the subsets of frames within the reference video. In one embodiment, the comparison of the visual signatures of each reference video to the visual signature of the query video includes first comparing the secondary visual signatures to identify matches and, if no satisfactory matching results are obtained, only then determining the primary visual signatures for each reference video and comparing the primary visual signatures to the visual signature of the query video.
The features and advantages of the present invention will be better understood when the Detailed Description of the Preferred Embodiments given below is considered in conjunction with the figures provided, wherein:
In these figures like structures are assigned like reference numerals, but may not be referenced in the description of all figures.
As illustrated in
For example,
It should be appreciated that the processor 140 includes a computer-readable medium or memory 142 having algorithms stored therein, and input-output devices for facilitating communication over a network, shown generally at 150 such as, for example, the Internet, an intranet, an extranet, or like distributed communication platform connecting computing devices over wired and/or wireless connections, to receive and process the video data 20 and 30. The processor 140 may be operatively coupled to a data store 170. The data store 170 stores information 172 used by the system 100 such as, for example, content DNA of the reference videos R1-RN and query videos Q1-QM as well as matching results. In one embodiment, the processor 140 is coupled to an output device 180 such as a display device for exhibiting the matching results. In one embodiment, the processor 140 is comprised of, for example, a standalone or networked personal computer (PC), workstation, laptop, tablet computer, personal digital assistant, pocket PC, Internet-enabled mobile radiotelephone, pager or like portable computing devices having appropriate processing power for video and image processing.
As shown in
Another one of the parameters 160 of the frame based video matching process determines whether the system 100 searches for sections (e.g., sequences of one or more frames) of the selected one of the query videos Q1-QM that match with one or more videos of the corpus 20 of reference videos R1-RN or a part thereof. When searching for sections, matching proceeds in a “sequence matching” scenario or matching mode. If the entire query video must be found in the corpus 20 of reference videos R1-RN, then the matching is done in a “global matching” scenario or matching mode. In the case of the sequence matching mode, an additional parameter represents the minimum duration (e.g., time or number of frames) of a sequence that is to be detected. This parameter is referred to as “granularity” g. Any sequence in the selected one of the query videos Q1-QM that would be present in one of the corpus 20 of reference videos R1-RN, but with duration smaller than the granularity parameter g, may not be detected. Any sequence in the selected one of the query videos Q1-QM with the same properties as one of the reference videos R1-RN but duration greater than the granularity parameter g is detected.
One embodiment of an inventive frame based video matching process 200 is depicted in
At Block 260, the content DNA of the selected one of the query videos Q1-QM is compared to content DNA for each of the reference videos R1-RN. During comparison, a count is maintained of all frames that the selected query video has in common with each separate one of the reference videos R1-RN. At Block 270, the count is compared to a predetermined matching threshold. If the selected one of the query videos Q1-QM has more frames in common with a subject one of the reference videos R1-RN than the predetermined matching threshold, the subject one of the reference videos R1-RN is declared a match with the selected query video. At Block 280 the matching one of the reference videos R1-RN is tagged as matching by, for example, documenting the match in a results list, file or data set. At Block 290, the parameters 160 are evaluated to determine the matching mode of the current execution of the process 200, for example, whether the process 200 is being performed in the extensive/exhaustive matching mode or the alert detection matching mode. If the execution is being performed in the alert detection matching mode, control passes along a “Yes” path and execution ends. If the execution is being performed in the extensive/exhaustive detection matching mode, control passes along a “No” path from Block 290 and execution continues at Block 300 where a next one of the query videos Q1-QM is selected. At Block 310 if there are no more query videos Q1-QM to be selected, then control passes along a “No” path and execution ends. Otherwise, control passes from Block 310 along a “Yes” path and returns to Block 240 where execution continues by again performing the operations at Blocks 240 through Block 290.
The inventors have discovered that at least some of the perceived value of the frame based video matching process 200 of the present invention over conventional matching processes resides in the inventive process' simplicity and low complexity. For example, the inventive frame based video matching process 200 is an efficient and low false positives frame matching process.
As noted above, in one aspect of the present invention, each of the reference videos R1-RN are indexed (at Block 220) prior to generation of the video content DNA (at Block 230) for the reference videos. In one embodiment, a subset of frames within each of the reference videos R1-RN are identified during indexing and the visual signature (video content DNA) for the reference image is generated using the identified subset of frames. Accordingly, it is within the scope of the present invention to employ one or both of at least a primary content DNA (based on all frames within a subject video) and a secondary content DNA (based on a subset of frames within the subject video). For example, to illustrate the differences between the primary content DNA and the secondary content DNA it should be appreciated that content DNA as described herein is a local matching DNA as generated in accordance with the systems and methods described in the aforementioned commonly owned U.S. patent application Ser. No. 12/432,119, filed Apr. 29, 2009, wherein the content DNA is comprised of a plurality of visual descriptors and features representing visual properties of an image and objects therein. At least one effect of employing local matching DNA is that the resulting processing is CPU intensive. Thus, by reducing the number of frames evaluated, CPU processing is reduced. Moreover, the inventors have discovered that within many videos, matching frames are common and provide little help in uniquely identifying the overall video. Accordingly, the inventors have discovered an indexing process that identifies a subset of frames within a subject video that are more desirable for determining content DNA for matching processes. As should be appreciated, by generating content DNA only for the subset of frames, CPU processing is reduced.
The process 400 continues as above until the end of the video file is reached (determined at Block 500), the duration parameter is reached (determined at Block 460), or a non-matching frame is detected at Block 450. When the current frame continues to match the anchor frame and the duration expires (Block 460), control then passes along a “Yes” path from Block 460 to Block 470. At Block 470, the current frame is assigned as a heart beat frame. In one embodiment, a list, record or file 472 of heart beat frames is maintained. In one embodiment, the file 472 is stored in the memory 144 of the processor 140 or the data store 170. At Block 480, the current frame is assigned as a new instance of the anchor frame, the anchor file 432 is updated to include the current frame and control passes to Block 490 where a next frame is read, and then the operations of Block 500 are performed.
Referring again to Block 450, when the current frame is found to not match the anchor frame, control passes along a “No” path from Block 450 to Block 520. At Block 520, the current frame is assigned as a key frame. In one embodiment, a list, record or file 522 of key frames is maintained. In one embodiment, the file 522 is stored in the memory 144 of the processor 140 or the data store 170. At Block 530, the current frame is assigned as a new instance of the anchor frame, the anchor file 432 is again updated and control passes to Block 490 where a next frame is read, and then the operations of Block 500 are performed.
As noted above, the index process 400 continues until all frames of the video file (e.g., one of the reference videos R1-RN) are evaluated. At the conclusion of the index process 400 for each video file, each frame of video file has been evaluated and three subsets of the frames are determined. For example, anchor frames stored in file 432, heart beat frames stored in file 472 and key frames stored in file 522 are determined. In one embodiment, the primary DNA for a video is the local matching DNA based upon DNA determined for each frame within the video file, e.g., each frame of the subject one of the reference videos R1-RN. In one embodiment, the secondary DNA for the video is the local matching DNA based upon DNA determined for a subset of frames determined within the video file. For example, the secondary DNA is the local matching DNA based upon DNA determined for each frame within one or more of the anchor frames, the heart beat frames and key frames. It should be appreciated that if the secondary DNA is determined from the three subsets, the anchor frames, the heart beat frames and the key frames, most all consecutive duplicate or matching frames within the video file are eliminated from the DNA determination and CPU time is saved. It should also be appreciated that if the secondary DNA is determined from one subset of frames, for example, only from the key frames, even fewer frames are included in the DNA determination step so even more CPU time is saved.
Accordingly, the inventors have discovered that improved computational performance of the frame based video matching process 200 is achieved when the secondary DNA is determined at Block 230 rather than the primary DNA and when the secondary DNA is used in the matching process 200. As such, properties of the secondary DNA include: (1) being significantly faster to compute than the primary DNA; and (2) that the matching of the secondary DNA implies a match with the primary DNA.
In one embodiment, the secondary DNA is first used for detecting video frames that match between the query and reference videos. However, if a match is not found using the secondary DNA, then the computationally more complex primary DNA is computed and used in the matching step performed at Block 260. The inventors have discovered that the use of the secondary DNA improves CPU time by an average factor of about twenty (20) when indexing videos.
In one embodiment, the frame based video matching system 100 includes a kit for indexing videos made of for example, an executable program and a library reference. The program indexes a video. The program takes a video file as input, extracts its key frames and saves them into, for example, a file.
The program parameters include, for example:
The library reference is such that the program is recursively applied and all videos within the library.
In another embodiment, frame based video matching system of the present invention includes a kit for video search and matching. The kit includes, for example:
A program to match a folder that contains videos (e.g., including the aforementioned query set Q1-QM) with a reference database (e.g., including the aforementioned reference corpus R1-RN). In one embodiment, the program takes two folders as an input: one that contains files that make up the reference corpus R1-RN, and one that contains video files that make up the query set Q1-QM. Other inputs are the granularity parameter, a parameter providing an indication of the searching mode (e.g., the “extensive search” or “alert detection” mode), and a parameter providing an indication of the matching mode (e.g., the “sequence matching” or “global matching” modes). Output of the executable includes a file that contains the matches detected.
Optionally, a program is provided for precisely matching two videos and validating a match. This makes it possible to run a precise comparison of two videos using the same matching process outlined above (process 200), but where matching frames are written to a disk or other memory location so that details of what matched may be reviewed. In one embodiment, the program input includes two video files, e.g., the query set Q and the reference corpus R. In one embodiment, output of the program is a set of files and frames created in, for example, an output folder.
Optionally, a program to compute statistics with respect to the outputs of the matching process 200, based on a predetermined “ground truth.” The ground truth is a set of videos that are declared matching by the person initiating the match process 200. The statistics help in computing performance and quality on a set of videos.
Although described in the context of preferred embodiments, it should be realized that a number of modifications to these teachings may occur to one skilled in the art. Accordingly, it will be understood by those skilled in the art that changes in form and details may be made therein without departing from the scope and spirit of the invention.
This patent application claims priority benefit under 35 U.S.C. §119(e) of copending, U.S. Provisional Patent Application Ser. No. 61/082,961, filed Jul. 23, 2008, the disclosure of this U.S. patent application is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61082961 | Jul 2008 | US |
