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EP0794674A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Fast DCT inverse motion compensation

Assignee: HP Inc
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Filing: 1997-03-06
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Granted: —
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Expires: 2017-03-06
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Abstract

Abstract Downsampling and inverse motion compensation are performed on compressed domain representations for video. By directly manipulating the compressed domain representation instead of the spatial domain representation, computational complexity is significantly reduced. For downsampling, the compressed stream is processed in the compressed (DCT) domain without explicit decompression and spatial domain downsampling so that the resulting compressed stream corresponds to a scaled down image, ensuring that the resulting compressed stream conforms to the standard syntax of 8 x 8 DCT matrices. For typical data sets, this approach of downsampling in the compressed domain results in computation savings around 80 % compared with traditional spatial domain methods for downsampling from compressed data. For inverse motion compensation, motion compensated compressed video is converted into a sequence of DCT domain blocks corresponding to the spatial domain blocks in the current picture alone. By performing inverse motion compensation directly in the compressed domain, the reduction in computation complexity is around 68 % compared with traditional spatial domain methods for inverse motion compensation from compressed data. The techniques for downsampling and inverse motion compensation can be used in a variety of applications, such as multipoint video conferencing and video editing.

Inventors

  • 👤 Neri Merhav
  • 👤 Vasudev Bhaskaran

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 17:04
CPC Classifications
G; G11; G11B; G11B27/00; G11B27/02; G11B27/031; G11B27/034; G06; G06T; G06T3/00; G06T3/40; G06T3/4084; H; H04; H04N; H04N19/00; H04N19/40; H04N19/42; H04N19/48; H04N19/50; H04N19/503; H04N19/51; H04N19/59; H04N19/60; H04N19/61

Claims Analysis

Total Claims: 12
Claim 1
Independent Claim 134 words
A method for achieving inverse motion compensation in the compressed domain, where such information has been compressed in accordance with a discrete cosine transform (DCT) based compression scheme, the method comprising the steps of: Huffman decoding a compressed bitstream to extract a plurality of N x N DCT-based data blocks defining a picture T-1 and to extract a motion vector h,w ; processing n of said data blocks in accordance with at least one sampling matrix and with said motion vector to produce a single N x N DCT-based data block corresponding to a picture T , wherein n is used to define a region occupied by said picture T-1 , and wherein said single data block is a combination of a data block consisting of a determined average of said n data blocks.
Claim 2
Dependent Claim 68 words
The method of Claim 1, said processing step further comprising the step of: determining a DCT X of a current block from a given DCT E of a prediction error e of the current block, and DCTs X 1 ,..., X 4 of x 1 ,..., x 4 respectively, where and is a DCT of , such that is determined directly from X 1 ,..., X 4 .
Claim 3
Dependent Claim 97 words
The method of Claim 1, further comprising the step of: precomputing fixed matrices: and where Q 1 and Q 2 are N x N DCT-based matrices; where matrices U 1 = SQ 1 S -1 and K 1 = SQ 2 S -1 ; where a factorization S is represented as follows: S = DPB 1 B 2 MA 1 A 2 A 3 , where D is a fixed diagonal matrix, where P is a fixed permutation matrix; and where B 1 B 2 MA 1 A 2 A 3 are fixed N x N matrices.
Claim 4
Dependent Claim 14 words
The method of Claim 3, further comprising the step of: determining in accordance with:
Claim 5
Dependent Claim 14 words
The method of Claim 3, further comprising the step of: determining in accordance with:
Claim 6
Dependent Claim 14 words
The method of Claim 3, further comprising the step of: determining in accordance with:
Claim 7
Independent Claim 139 words
An apparatus (13) for achieving inverse motion compensation in the compressed domain, where such information has been compressed in accordance with a discrete cosine transform (DCT) based compression scheme, the apparatus comprising: a Huffman decoder (12) for decoding a compressed bitstream to produce a plurality of N x N DCT-based data blocks defining a picture T-1 and to produce a motion vector h,w ; a processor (30) processing n of said data blocks in accordance with at least one sampling matrix and with said motion vector to produce a single N x N DCT-based data block corresponding to a frame T , wherein n is used to define a region occupied by said frame T-1 , and wherein said single data block is a combination of a data block consisting of a determined average of said n data blocks.
Claim 8
Dependent Claim 65 words
The apparatus (13) of Claim 7, said processor further comprising: means (40) for determining a DCT X of a current block from a given DCT E of a prediction error e , and DCTs X 1 ,..., X 4 of x 1 ,..., x 4 respectively, where and is a DCT of , such that is determined directly from X 1 ,..., X 4 .
Claim 9
Dependent Claim 96 words
The apparatus of Claim 8, further comprising: means for precomputing fixed matrices: and where Q 1 and Q 2 are N x N DCT-based matrices; where matrices U 1 = SQ 1 S -1 and K 1 = SQ 2 S -1 ; where a factorization S is represented as follows: S = DPB 1 B 2 MA 1 A 2 A 3 , where D is a fixed diagonal matrix, where P is a fixed permutation matrix; and where B 1 B 2 MA 1 A 2 A 3 are N x N fixed matrices.
Claim 10
Dependent Claim 13 words
The apparatus of Claim 9, further comprising: means for determining in accordance with:
Claim 11
Dependent Claim 13 words
The apparatus of Claim 9, further comprising: means for determining in accordance with:
Claim 12
Dependent Claim 13 words
The apparatus of Claim 9, further comprising: means for determining in accordance with:

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