HEVC Motion Vector Coding for Multiview 3D Video Compatibility
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Solution Overview
Problem
The current High Efficiency Video Coding (HEVC) design impedes the development of future extensions like multiview or 3DV, particularly in accurately identifying and scaling reference pictures for motion vector prediction, especially when reference pictures are from different views.
Innovation Solution
The techniques involve determining the type of motion vectors and setting variables to indicate the availability of candidate motion vector predictors, allowing for accurate coding and decoding of motion vectors based on type differences, and disabling scaling to prevent errors in inter-view prediction scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the current HEVC design is used for motion vector coding, then the base codec functionality is maintained, but forward compatibility with multiview or 3DV extensions is impeded
Solution Approach 1:
The motion vector prediction process is segmented by introducing a type identification mechanism that separates temporal and disparity motion vectors into distinct categories. This segmentation allows the codec to handle different motion vector types through different processing paths, enabling multiview and 3DV extensions while maintaining the original HEVC temporal prediction functionality.
Solution Approach 2:
The patent applies local quality by making the availability of candidate motion vector predictors context-dependent. Instead of a uniform approach, the system selectively determines availability based on the specific type of motion vector being coded and the type of candidate predictor, allowing optimal processing for each local context while maintaining overall system compatibility.
2Productivity
If candidate motion vector predictors from neighboring blocks are always used, then coding efficiency is improved, but errors occur when reference pictures are from different views
Solution Approach 1:
The patent implements a feedback mechanism where the type of the current motion vector is used to determine the availability of candidate predictors. The system continuously checks type compatibility and adjusts predictor availability accordingly, preventing erroneous predictions from different view references while maintaining efficient prediction when types match.
Solution Approach 2:
The availability status of candidate motion vector predictors is changed as a parameter based on type matching. When the current motion vector type differs from the candidate predictor type, the availability parameter is set to false, preventing incorrect predictions. When types match, availability remains true, allowing efficient prediction to proceed.
3Measurement precision
If motion vector scaling is applied to all reference pictures, then prediction accuracy is improved, but errors are introduced in inter-view prediction scenarios
Solution Approach 1:
The patent applies preliminary action by determining the types of both the current motion vector and candidate predictors before proceeding with scaling operations. This preliminary type checking prevents inappropriate scaling from being applied to inter-view predictions, eliminating prediction errors before they can occur while allowing accurate scaling when types are compatible.
Data Source
AI summary
In one example, a device includes a video coder (e.g., a video encoder or a video decoder) configured to determine that a block of video data is to be coded in accordance with a three-dimensional extension of High Efficiency Video Coding (HEVC), and, based the determination that the block is to be coded in accordance with the three-dimensional extension of HEVC, disable temporal motion vector prediction for coding the block. The video coder may be further configured to, when the block comprises a bi-predicted block (B-block), determine that the B-block refers to a predetermined pair of pictures in a first reference picture list and a second reference picture list, and, based on the determination that the B-block refers to the predetermined pair, equally weight contributions from the pair of pictures when calculating a predictive block for the block.