The present disclosure relates generally to processing of video data. More particularly, the present disclosure relates to methods and systems for compressing video data to reduce the size of the video data.
A number of video recording systems store video streams that are provided by a variety of video cameras that are installed or otherwise arranged around a surveillance area such as a city, a portion of a city, a facility or a building. Recording all video streams with high video quality settings can consume substantial storage space and/or communication bandwidth of a video recording system, particularly when there are numerous video cameras. Recording all video at reduced video quality settings can save storage space and/or communication bandwidth, but the resulting video may not be of sufficient quality to meet user needs. What would be desirable are methods and systems for reducing the storage space and/or communication bandwidth requirements of video streams while maintaining sufficient video quality to meet user needs.
The present disclosure relates to processing of video data. More particularly, the present disclosure relates to methods and systems for compressing video data to reduce the size of the video data. An example may be found in a method for compressing a video stream. The illustrative method includes retrieving a plurality of frames corresponding to the video stream. For each of two or more sequential frames of the plurality of frames of the video stream, the method includes extracting Key Point Descriptors (KPDs) for the respective frame and processing the respective frame using Principle Component Analysis (PCA) followed by vector quantization, resulting in a quantized explained variance matrix for the respective frame. The quantized explained variance matrix for the respective frame is stored. The quantized explained variance matrix represents the respective frame with reduced dimensions. The KPDs for the respective frame are also stored.
Another example may be found in a method of decoding each of the two or more sequential frames of the plurality of frames. For each of two or more sequential frames, the method includes retrieving the quantized explained variance matrix for the respective frame and the KPDs for the respective frame, performing an inverse PCA transform to the quantized explained variance matrix of the respective frame to produce a respective reconstructed frame, merging the KPDs associated with the respective frame with the respective reconstructed frame, and assembling the reconstructed frames for the two or more sequential frames into a decoded video sequence.
Another example may be found in a method for compressing a video stream. The method includes receiving a video stream having a plurality of frames, wherein two or more sequential frames of the plurality of frames are associated with a Group of Pictures (GOP) that includes an I-Frame and one or more P-Frames. Key Point Descriptors (KPDs) are extracted for each of the two or more sequential frames of the GOP. A mean frame for the GOP is determined from the two or more sequential frames of the GOP. The mean frame is subtracted from each of the two or more sequential frames of the GOP, resulting in two or more mean subtracted frames (MSF) for the GOP. The method further includes, for each of the mean subtracted frames (MSF) of the GOP, processing the respective frame using Principle Component Analysis (PCA), resulting in an explained variance matrix for the respective frame, wherein the explained variance matrix represents the respective frame with reduced dimensions. The method includes storing the explained variance matrix for the respective frame and storing the KPDs for the respective frame.
Another example may be found in a method for compressing a video stream. The method includes receiving a plurality of frames corresponding to the video stream, wherein two or more sequential frames of the plurality of frames are associated with a Group of Pictures (GOP) that includes an I-Frame and one or more P-Frames. Key Point Descriptors (KPDs) are extracted for each of the two or more sequential frames of the GOP and are stored for each of the two or more sequential frames of the GOP. A mean frame for the GOP is determined from the two or more sequential frames of the GOP. The mean frame is stored. Each of the two or more sequential frames of the GOP are subtracted from the mean frame, resulting in two or more mean subtracted frames (MSF) for the GOP. For each of the mean subtracted frames of the GOP, the method includes dividing the respective frame into a plurality of blocks of pixels. For each of the blocks, the method includes processing the respective block using Principle Component Analysis (PCA), resulting in an explained variance matrix for the respective block, wherein the explained variance matrix represents the respective block with reduced dimensions, and storing the explained variance matrix for the respective block.
The preceding summary is provided to facilitate an understanding of some of the innovative features unique to the present disclosure and is not intended to be a full description. A full appreciation of the disclosure can be gained by taking the entire specification, claims, figures, and abstract as a whole.
The disclosure may be more completely understood in consideration of the following description of various examples in connection with the accompanying drawings, in which:
While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the disclosure to the particular examples described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.
The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict examples that are not intended to limit the scope of the disclosure. Although examples are illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.
All numbers are herein assumed to be modified by the term “about”, unless the content clearly dictates otherwise. The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).
As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include the plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is contemplated that the feature, structure, or characteristic may be applied to other embodiments whether or not explicitly described unless clearly stated to the contrary.
The illustrative video controller 10 includes a controller 14 and a memory 16 that is operably coupled with the controller 14. In some instances, the memory 16 may be used to store at least a portion of a video stream or a video clip that the controller 14 is processing. In some instances, the memory 16 may be used to store one or more algorithms that the controller 14 may utilize when processing the input video stream 12. The controller 14 may be configured to utilize one or more algorithms that are stored within the memory 16 for processing the input video stream 12. In some instances, these algorithms may include video compression algorithms that allow the input video stream 12 or a portion thereof to be compressed such that the input video stream 12 or a portion thereof requires less storage space and/or less communication bandwidth, while retaining sufficient details regarding important parts of the input video stream 12 or a portion thereof to reproduce a representation of the original input video stream 12 or a portion thereof when decoded (e.g. uncompressed).
In the example shown, the video controller 10 is operably coupled with a video recorder 18. In some instances, the input video stream 12 may be recorded in its entirety to the video recorder 18. In some instances, a compressed version of the input video stream 12 may be recorded to the video recorder 18, where the compressed version of the input video stream 12 may be a result of the controller 14 executing one or more algorithms to create the compressed version of the input video stream 12.
In the example shown, the video controller 10 is operably coupled with a monitoring station 20. In some instances, the monitoring station 20 may include a user interface 22. The user interface 22 may be configured to display video streams for viewing by a person using the monitoring station 20, such as the input video stream 12 and/or recorded video streams. The user interface 22 may include one or more of a keyboard, a mouse, a track pad and the like that allows the person using the monitoring station 20 to enter information for use by the video controller 10. In some instances, for example, the person may enter selections for various video parameters that the controller 14 may utilize in running various video compression algorithms on the input video stream 12.
For each of two or more sequential frames of the plurality of frames of the video stream, a number of steps are carried out, as indicated at block 28. The number of steps include extracting Key Point Descriptors for the respective frame, as indicated at block 28a. In some instances, the two or more sequential frames may include a Group of Pictures (GOP) that includes an I-Frame and one or more P-Frames. In some instances, the method 24 includes extracting the Key Point Descriptors (KPDs) for each of the I-Frame and each of the P-Frames of the GOP.
In some instances, the number of steps include processing the respective frame using Principle Component Analysis (PCA) followed by vector quantization, resulting in a quantized explained variance matrix for the respective frame, as indicated at block 28b. In some instances, the method 24 may include processing each of the I-Frame and each of the P-Frames of the GOP using Principle Component Analysis (PCA) followed by vector quantization, resulting in a quantized explained variance matrix for the respective frame. In some instances, the respective frame may be processed using Principle Component Analysis (PCA) to produce an intermediate explained variance matrix, followed by processing the intermediate explained variance matrix using vector quantization to produce the quantized explained variance matrix for the frame.
The number of steps include storing the quantized explained variance matrix for the respective frame. The quantized explained variance matrix represents the respective frame with reduced dimensions, as indicated at block 28c. The number of steps include storing the KPDs for the respective frame, as indicated at block 28d.
In some instances, there may be a desire to regain the original video, or as close as possible to the original video.
The mean frame is subtracted from each of the two or more sequential frames of the GOP, resulting in two or more mean subtracted frames (MSF) for the GOP, as indicated at block 44. For each of the mean subtracted frames (MSF) of the GOP, a number of steps are carried out, as indicated at block 46. The number of steps include processing the respective frame using Principle Component Analysis (PCA), resulting in an explained variance matrix for the respective frame, wherein the explained variance matrix represents the respective frame with reduced dimensions, as indicated at block 46a. In some instances, each of the respective frames is processed using Principle Component Analysis (PCA) to produce an intermediate explained variance matrix, followed by processing the intermediate explained variance matrix using vector quantization to produce the explained variance matrix for the frame. The number of steps include storing the explained variance matrix for the respective frame, as indicated at block 46b. The number of steps include storing the KPDs for the respective frame, as indicated at block 46c.
In some instances, the method 36 may further include decoding (e.g. uncompressing) each of the two or more sequential frames of the GOP. Decoding may include retrieving the explained variance matrix for the respective frame and the KPDs for the respective frame. Decoding may include performing an inverse PCA transform to the explained variance matrix of the respective frame to produce a respective reconstructed frame. Decoding may include adding the respective reconstructed frame to the mean frame of the GOP to result in a reconstructed original frame. Decoding may include merging the KPDs associated with the respective frame with the respective reconstructed original frame. Decoding may include assembling the reconstructed original frames into a decoded video sequence.
In some instances, the method 36 may further include transmitting the explained variance matrix and the KPDs for the respective frame to a storage device over a network. In some instances, the method may include retrieving the explained variance matrix for the respective frame and the KPDs for the respective frame from the storage device to decode the respective frame.
A mean frame for the GOP is determined from the two or more sequential frames of the GOP, as indicated at block 58. Each of the two or more sequential frames of the GOP are subtracted from the mean frame, resulting in two or more mean subtracted frames (MSF) for the GOP, as indicated at block 60.
The method 48 continues on
In some instances, the method 48 may include sequentially selecting each of the plurality of blocks in a selection order, processing the respective block using Principle Component Analysis (PCA), resulting in an explained variance matrix for the respective block, and storing the explained variance matrix for the respective block, wherein the explained variance matrix represents the respective block with reduced dimensions. In some cases, the selection order may be sequential, random or pseudo-random. In some instances, each of the respective blocks may be processed using Principle Component Analysis (PCA) to produce an intermediate explained variance matrix for the respective block, followed by processing the intermediate explained variance matrix using vector quantization to produce the explained variance matrix for the frame for the respective block.
In some instances, the method 48 may include receiving a dimension variable applicable to the GOP, wherein the Principle Component Analysis (PCA) retains a retained number of principle components for each of the respective blocks based at least in part on the dimension variable. As an example, the dimension variable may be updated by a video compression controller to control the number of principle component that are retained with the others discarded, and thus control an amount of compression that is desired for the GOP.
In some instances, the method 48 may include decoding (e.g. uncompressing) each of the two or more sequential frames of the GOP. Decoding may include retrieving the explained variance matrix for each of the blocks of the respective frame and performing an inverse PCA transform to the explained variance matrix of each of the blocks of the respective frame. Decoding may include merging the transformed explained variance matrices of the blocks of the respective frame to reconstruct the respective frame, adding the mean frame to the respective reconstructed frame to result in a reconstructed original frame, and merging the KPDs associated with the respective frame with the respective reconstructed original frame. Decoding may include assembling the reconstructed original frames into a decoded video sequence.
A Mean value is calculated, as indicated at block 84. The mean value may be generated by summing all of the pixels of all of the frames in the GOP, and dividing the total by the number of pixels of all frames in the GOP. A Mean Frame 86 is then generated. The Mean Frame 86 may correspond to a matrix that is of the same size as each of the frames in the GOP, with each element of the matrix populated with the mean value. The Mean Frame 86 is saved and is associated with the GOP 72.
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Having thus described several illustrative embodiments of the present disclosure, those of skill in the art will readily appreciate that yet other embodiments may be made and used within the scope of the claims hereto attached. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, arrangement of parts, and exclusion and order of steps, without exceeding the scope of the disclosure. The disclosure's scope is, of course, defined in the language in which the appended claims are expressed.