Video Coding With Luma-Derived IBC Chroma Prediction
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Solution Overview
Problem
In video coding technologies, particularly for high-definition and ultra-high-definition video sequences with screen content types, the direct mode (DM) in intra block copy (IBC) mode leads to inaccurate chroma prediction due to inappropriate configuration of chroma prediction modes, reducing encoding efficiency.
Innovation Solution
A method is provided where, if the prediction mode of a first color component block is an IBC mode, a block vector parameter is determined for the first color component block, and a target block vector parameter for a second color component is derived based on this. IBC extension mode-based prediction is then performed on the second color component using the target block vector parameter to determine its predicted value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If IBC mode is used for luma block in direct mode, then encoding efficiency is improved, but chroma prediction accuracy deteriorates due to inappropriate chroma prediction mode configuration
Solution Approach 1:
The patent changes the chroma prediction mode parameter from a fixed default mode to a dynamically selected mode based on the luma block's prediction mode. When luma uses IBC mode, chroma prediction mode is changed to IBC extension mode, and block vector parameters are adjusted accordingly to match the luma block's block vector, thereby improving chroma prediction accuracy while maintaining encoding efficiency.
Solution Approach 2:
The patent makes the chroma prediction mechanism universal by allowing it to adapt to different luma prediction modes. The chroma prediction system can now function in multiple modes (IBC extension mode when luma uses IBC, other modes when luma uses different prediction modes), making it multi-functional rather than fixed, which resolves the contradiction between encoding efficiency and prediction accuracy.
2Device complexity
If chroma prediction mode is not configured appropriately when IBC mode is used for luma block, then device complexity is reduced, but coding performance deteriorates
Solution Approach 1:
The chroma prediction system serves itself by automatically selecting the appropriate prediction mode based on the luma block's prediction mode. When luma uses IBC mode, chroma automatically switches to IBC extension mode without requiring external configuration, thereby maintaining low device complexity while improving coding performance through appropriate mode selection.
Solution Approach 2:
The patent implements a feedback mechanism where the chroma prediction mode selection is based on the luma block's prediction mode. The system receives feedback about the luma prediction mode and adjusts the chroma prediction mode accordingly, ensuring optimal coding performance without increasing device complexity through automatic adaptation.
Data Source
AI summary
Embodiments of this application disclose a coding method, a bitstream, an encoder, a decoder, and a storage medium. The method includes: determining a first color component block of a current block; in a case that a prediction mode of the first color component block is an IBC mode, determining a first block vector parameter of the first color component block; determining a target block vector parameter of a second color component of the current block based on the first block vector parameter of the first color component block; and performing IBC extension mode-based prediction on the second color component of the current block by using the target block vector parameter, to determine a predicted value for the second color component of the current block.