Motion Vector Reuse for Video Format Conversion
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Solution Overview
Problem
Existing moving picture conversion technologies face inefficiencies when converting between different encoding standards, such as from MPEG-4/AVC to MPEG-2, due to differences in motion vector support and accuracy, leading to increased processing time.
Innovation Solution
A moving picture conversion apparatus that selects and reuses motion vectors fulfilling the conditions of the target encoding method, reducing the need for extensive motion vector searching and narrowing the search range, thereby accelerating the conversion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If motion vectors from MPEG-4/AVC are reused for MPEG-2 conversion, then processing time is reduced, but compatibility with MPEG-2 motion vector specifications cannot be guaranteed
Solution Approach 1:
The patent performs preliminary determination of motion vector reusability by checking whether MPEG-4/AVC motion vectors satisfy MPEG-2 specifications (block size, motion vector precision, reference picture constraints) before conversion. This preliminary filtering enables selective reuse of compatible motion vectors, reducing processing time while ensuring MPEG-2 compatibility for the vectors that are reused.
Solution Approach 2:
The patent transforms MPEG-4/AVC motion vectors into MPEG-2 compliant motion vectors by adjusting parameters such as motion vector precision (from quarter-pixel to half-pixel), block size mapping (from 8x8 to 16x16), and reference picture selection. This parameter transformation enables compatibility while preserving the essential motion information.
2Measurement precision
If motion vectors are re-searched at quarter-pixel precision for MPEG-2 conversion, then motion vector accuracy is improved, but processing time increases
Solution Approach 1:
The patent performs partial motion vector re-search only for those motion vectors that were determined not to be reusable in the preliminary check. Instead of re-searching all motion vectors, it selectively applies re-search to specific blocks where compatibility issues were detected, thereby reducing overall processing time while maintaining accuracy where needed.
Solution Approach 2:
The patent applies different processing strategies to different blocks based on their individual compatibility characteristics. Blocks with compatible motion vectors are processed quickly through direct reuse, while blocks with incompatible vectors undergo re-search or transformation. This localized quality adjustment optimizes the overall conversion process.
Data Source
AI summary
A moving picture conversion apparatus converts first moving image data encoded in accordance with a first motion compensated prediction method into second moving picture data that has a same format as data encoded in accordance with a second motion compensated prediction method. The moving picture conversion apparatus determines whether a relationship between a block in the second motion compensation method and an image used as a reference image with respect to the block confirms with a condition. When the relationship is determined to confirm with the condition, the moving picture conversion apparatus performs encoding using a motion vector or vectors of the first moving image data corresponding to the block.