Quantization Parameter Prediction for Video Coding Efficiency
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Solution Overview
Problem
In HEVC, adjusting the quantization parameter per coding unit increases the number of quantization parameters to be encoded, leading to higher coding bits and reduced coding efficiency due to weaker correlation between quantization parameters compared to H.264.
Innovation Solution
A method is introduced to restore the differential quantization parameter of a current coding unit, generate a quantization parameter predictor using neighboring quantization parameters, and adjust the minimum size of the quantization unit per picture to reduce encoding complexity and improve coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the quantization parameter is adjusted per coding unit in HEVC, then the compression efficiency is improved, but the number of quantization parameters to be encoded increases, leading to greater coding bits and reduced coding efficiency
Solution Approach 1:
The patent merges multiple quantization parameters (left, above, and above-left neighboring QPs) into a single predicted quantization parameter through averaging. This combining approach reduces the number of separate QP values that need to be encoded while maintaining the benefits of fine-grained QP adjustment per coding unit, thereby resolving the contradiction between compression efficiency and the quantity of quantization parameters.
Solution Approach 2:
The patent introduces a quantization parameter predictor as an intermediary that derives the current coding unit's QP from neighboring QPs. This predictor acts as a mediator that reduces the direct number of QP values to be encoded while still allowing adaptive QP control, thus improving coding efficiency without sacrificing compression performance.
2Productivity
If the quantization parameter is adjusted per coding unit in HEVC, then the compression efficiency is improved, but the correlation between quantization parameters becomes weaker, requiring a new encoding method
Solution Approach 1:
The patent implements feedback by using already-encoded neighboring quantization parameters (left, above, above-left) to predict the current coding unit's QP. This feedback mechanism maintains correlation between QPs across different coding units by leveraging spatial redundancy, thus preserving stability in the QP composition while enabling fine-grained control for compression efficiency.
3Productivity
If various sizes of coding unit are introduced in HEVC, then the compression efficiency is improved, but the complexity of encoding and decoding increases
Solution Approach 1:
The patent changes the parameter approach by deriving QP values through a standardized prediction formula using neighboring QPs rather than encoding each QP independently. This parameter change reduces encoding and decoding complexity while maintaining the ability to handle various coding unit sizes, thus resolving the contradiction between compression efficiency and device complexity.
Data Source
AI summary
A method for encoding an image using intra prediction can include determining an intra prediction mode of a current block, generating a mode group indicator and a prediction mode index specifying the intra prediction mode of the current block, constructing a most probable mode (MPM) group including three intra prediction modes determined using a left and an above intra prediction mode of the current block. The method can further include generating a prediction block based on the intra prediction mode of the current block specified by the mode group indicator and the prediction mode index, generating a residual block of the current block, generating a quantization block by transforming and quantizing the residual block. The method can include scanning the quantized block using a scan pattern determined based on the intra prediction mode and the size of a transform unit, and entropy-encoding the scanned information of the quantized block.