# US 2015/0146784 A1 · Motion compensation with moving window > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0146784 A1 - Document ID: US20150146784A1 - Status: Published application - Kind: A1 - Application number: 14/089,902 - Filed: 2013-11-26 - Published: 2015-05-28 - Earliest claimed: 2013-11-26 - Assignees: ViXS Systems, Inc. - Inventors: Xinghai Li; Xin Guo - Web page: https://patentgrep.com/patent/US20150146784A1 ## CPC - H04N 19/51: Motion estimation or motion compensation - H04N 19/433: characterised by techniques for memory access - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A video encoder employs a relatively small sized cache for motion compensation. A motion search module selects an initial subset of the full reference picture and has it transferred to the cache. For a first set of blocks of a current picture, the motion search module calculates a set of motion vectors using the reference picture subset stored at the cache. Based on the set of motion vectors, the motion search module identifies an offset that indicates a predicted direction of motion. Based on the offset, the motion search module identifies another subset of the reference picture and transfers the identified subset to the cache for calculation of the next set of motion vectors. ## Claims ### Claim 1 A method implemented at a video encoder, comprising: storing a first subset of pixels of a reference picture of a video signal at a cache of the video encoder, the cache having a smaller size than the reference picture; and performing motion search for a first frame of the video signal based on a comparison of at least a portion of the first frame to the first subset of pixels stored at the cache. ### Claim 2 (depends on 1) The method of claim 1, further comprising: identifying a set of motion vectors based on a second frame of the video signal; and selecting the first subset of pixels of the reference picture based on the set of motion vectors. ### Claim 3 (depends on 2) The method of claim 2, wherein selecting the first subset of pixels of the reference picture comprises: calculating an offset value based on components of the set of motion vectors for a first direction; and selecting the first subset of pixels of the reference picture based on the offset value. ### Claim 4 (depends on 3) The method of claim 3, wherein calculating the offset value comprises averaging the components of the set of motion vectors. ### Claim 5 (depends on 3) The method of claim 3, wherein calculating the offset value comprises performing a regression analysis based on the components of the set of motion vectors. ### Claim 6 (depends on 3) The method of claim 3, wherein the first direction is a vertical direction. ### Claim 7 (depends on 3) The method of claim 3, wherein the first direction is a horizontal direction. ### Claim 8 (depends on 1) The method of claim 1, further comprising: storing a second subset of pixels of the reference picture at the cache, the second subset of pixels different from the first subset of pixels; and performing motion search for a second frame of the video signal based on a comparison of at least a portion of the second frame to the second subset of pixels stored at the cache. ### Claim 9 A method, comprising: selecting, based on a first set of motion vectors, a first subset of pixels of a reference picture; and transferring the first subset of pixels from a memory to a cache to identify a second set of motion vectors. ### Claim 10 (depends on 9) The method of claim 9, further comprising: selecting, based on the second set of motion vectors, a second subset of pixels of the reference picture; and transferring the second subset of pixels from the memory to the cache to identify a third set of motion vectors. ### Claim 11 (depends on 9) The method of claim 9, wherein selecting the first subset of pixels comprises: calculating an offset value based on components of the set of motion vectors for a first direction; and selecting the first subset of the reference picture based on the offset value. ### Claim 12 (depends on 11) The method of claim 11, wherein calculating the offset value comprises averaging the components of the set of motion vectors. ### Claim 13 (depends on 11) The method of claim 11, wherein calculating the offset value comprises performing a regression analysis based on the components of the set of motion vectors. ### Claim 14 A video encoder, comprising: a cache; and a motion search module to: store a first subset of pixels of a reference picture of a video signal at the cache of the video encoder, the cache having a smaller size than the reference picture; and perform motion search for a first frame of the video signal based on a comparison of at least a portion of the first frame to the first subset of the reference picture stored at the cache. ### Claim 15 (depends on 14) The video encoder of claim 14, wherein the motion search module is further to: identify a set of motion vectors based on a second frame of the video signal; and select the first subset of pixels based on the set of motion vectors. ### Claim 16 (depends on 15) The video encoder of claim 15, wherein the motion search module is further to select the first subset of the reference picture by: calculating an offset value based on components of the set of motion vectors for a first direction; and selecting the first subset of pixels based on the offset value. ### Claim 17 (depends on 16) The video encoder of claim 16, wherein calculating the offset value comprises averaging the components of the set of motion vectors. ### Claim 18 (depends on 16) The video encoder of claim 16, wherein calculating the offset value comprises performing a regression analysis based on the components of the set of motion vectors. ### Claim 19 (depends on 16) The video encoder of claim 16, wherein the first direction is a vertical direction. ### Claim 20 (depends on 16) The video encoder of claim 16, wherein the first direction is a horizontal direction.