Automatic scene decomposition and optimization of MPEG compressed video
First Claim
1. A method for detecting a scene change in compressed video data that represent a plurality of successive video frames, comprising the steps of:
- (a) determining an interframe correlation between successive video frames of the compressed video data;
(b) determining a measure indicative of a scene change between two successive video frames as a function of the interframe correlation between the two successive video frames; and
(c) comparing the measure to a threshold value, and as a function of a difference between the measure and the threshold value, indicating whether the scene change has occurred between the two successive video frames.
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Accused Products
Abstract
Analysis of video data in an MPEG compressed format to identify scene changes to facilitate indexing to access specific video frames and to improve data compression and/or quality of the compressed video. MPEG compressed video data include I-pictures, P-pictures, and B-pictures. Scene changes are identified by analyzing P-pictures using average error power, based upon direct cosine transform components in the compressed data, and/or using an interframe correlation between a P-picture and its past reference frame. When a scene change occurs, average error power becomes large and interframe correlation between frames becomes substantially zero. Alternatively (or in addition), B-pictures in a video slot can be analyzed, in terms of interframe correlation between past and future reference frames, using either an AND analysis technique or an OR analysis technique. The AND analysis identifies a scene change when two or more B-pictures between two reference frames defining the video slot all imply a scene change, while the OR analysis indicates that a scene change has not occurred in the video slot if one B-picture implies that a scene change has not occurred. Once the scene changes have been identified, all I-pictures not occurring at a scene change are converted to P-pictures, and all P-pictures immediately following a scene change are converted to I-pictures. This step improves compression and/or quality of the compressed video, since P-pictures require less data than do I-pictures, and fewer I-pictures will be used in the compressed data following this step.
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Citations
29 Claims
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1. A method for detecting a scene change in compressed video data that represent a plurality of successive video frames, comprising the steps of:
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(a) determining an interframe correlation between successive video frames of the compressed video data; (b) determining a measure indicative of a scene change between two successive video frames as a function of the interframe correlation between the two successive video frames; and (c) comparing the measure to a threshold value, and as a function of a difference between the measure and the threshold value, indicating whether the scene change has occurred between the two successive video frames. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A system for detecting scene changes in compressed video data representing a plurality of successive video frames, comprising:
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(a) a processor that executes machine instructions embodied in software, to carry out processing of the video data so as to implement functions that are determined by the machine instructions; (b) a volatile memory that is accessible by the processor, for temporarily storing the machine instructions executed by the processor and for temporarily storing the video data; (c) a nonvolatile storage device for storing the machine instructions executed by the processor and for storing the compressed video data and output data that include a list of the scene changes detected in the compressed video data; and (d) said machine instructions causing the processor to implement the following functions; (i) determine an interframe correlation between successive video frames; (ii) determine a measure indicative of a scene change between two successive video frames as a function of the interframe correlation between the two successive video frames; (iii) compare the measure to a threshold value, and as a function of a difference between the measure and the threshold value, indicate whether the scene change has occurred between the two successive video frames; and (iv) add the scene change to the list of scene changes for the compressed video data.
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19. An article of manufacture that is adapted for use by a computer to detect a scene change in compressed video data representing a plurality of successive video frames, comprising:
a nonvolatile memory device in which are stored a plurality of machine instructions that are executable by the computer, said plurality of machine instructions comprising a computer program that causes the computer to implement the following functions; (a) determine an interframe correlation between successive video frames of the compressed video data; (b) determine a measure indicative of a scene change between two successive video frames as a function of the interframe correlation between the two successive video frames; and (c) compare the measure to a threshold value, and as a function of a difference between the measure and the threshold value, indicate whether the scene change has occurred between the two successive video frames.
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20. A method for increasing at least one of a compression and a quality of compressed video data that represent successive video frames, said compressed video data including intra-pictures (I-pictures), predicted-pictures (P-pictures), and bidirectional-predicted pictures (B-pictures), said I-pictures each being independent of any other type of picture, said P-pictures each being related to a previous I-picture or a previous P-picture, and said B-pictures each being related to the previous I-picture or the previous P-picture and to a next I-picture or a next P-picture, said method comprising the steps of:
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(a) identifying scene changes between successive video frames of the compressed video; (b) ensuring that I-pictures always immediately follow a scene change and do not occur at any other points in the compressed video data; and (c) ensuring that P-pictures do not immediately follow a scene change. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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28. A system for increasing at least one of a compression and a quality of compressed video data that represent successive video frames, said compressed video data including intra-pictures (I-pictures) and predicted-pictures (P-pictures), said I-pictures each being independent of any other type of picture, and said P-pictures each being related to a previous I-picture or a previous P-picture, said system comprising:
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(a) a processor that executes machine instructions embodied in software, to carry out processing of the video data so as to implement functions that are determined by the machine instructions; (b) a volatile memory that is accessible by the processor, for temporarily storing the machine instructions executed by the processor and for temporarily storing the compressed video data; (c) a nonvolatile storage device for storing the machine instruction executed by the processor and for storing the compressed video data; and (d) said machine instructions causing the processor to implement the following functions; (i) identify scene changes between successive video frames; (ii) ensure that the I-pictures always immediately follow a scene change and do not occur at any other points in the compressed video data; and (iii) ensure that the P-pictures do not immediately follow a scene change.
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29. An article of manufacture that is adapted for use by a computer to detect a scene change in compressed video data representing a plurality of successive video frames, said compressed video data including intra-pictures (I-pictures) and predicted-pictures (P-pictures), said I-pictures each being independent of any other type of picture and said P-pictures each being related to a previous I-picture or a previous P-picture, said article of manufacture comprising:
a nonvolatile memory device in which are stored a plurality of machine instructions that are executable by the computer, said plurality of machine instructions comprising a computer program that cause the computer to implement the following functions; (a) identify scene changes between successive video frames; (b) ensure that the I-pictures always immediately follow a scene change and do not occur at any other points in the compressed video data; and (c) ensure that the P-pictures do not immediately follow a scene change.
Specification