Dictionary Block Copy for Video Coding Efficiency
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Solution Overview
Problem
Current video coding technologies, such as HEVC, face challenges in efficiently compressing screen content with high-frequency content, leading to substantial artifacts and reduced subjective quality, particularly in applications like remote desktop and cloud gaming where high-resolution video needs to be transmitted over limited bandwidth.
Innovation Solution
The introduction of a 'dictionary block copy' prediction mode, where select blocks of reconstructed samples are stored in a dictionary memory and reused for prediction, rather than traditional intra-block copy methods, to improve coding efficiency and reduce memory usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional transform-based video compression techniques are used for screen content, then the compression process is simple, but substantial artifacts are introduced which reduces the subjective quality of the decoded video data
Solution Approach 1:
The patent applies block copying by storing reconstructed blocks in a dictionary memory and reusing them for prediction. Instead of transforming and quantizing blocks, the method directly copies identical or similar blocks from the dictionary to predict current blocks, eliminating transform-based artifacts while maintaining compression efficiency.
Solution Approach 2:
The patent performs preliminary action by pre-storing reconstructed blocks in a dictionary memory before they are needed for prediction. This allows the decoder to efficiently retrieve and reuse previously decoded blocks without re-computing transforms, reducing artifacts while maintaining simple processing.
2Productivity
If a dictionary memory is introduced to store reconstructed blocks for prediction, then coding efficiency improves, but memory overhead increases
Solution Approach 1:
The patent applies local quality by storing only the most relevant reconstructed blocks in the dictionary memory rather than all blocks. The dictionary maintains a limited set of high-value blocks that are most useful for prediction, optimizing the trade-off between memory usage and coding efficiency by focusing on locally important blocks.
Solution Approach 2:
The patent changes parameters by dynamically managing the dictionary memory contents, replacing less useful blocks with more useful ones based on prediction effectiveness. This allows the system to adapt to different content types and maintain high coding efficiency while controlling memory overhead through intelligent block selection and replacement.
3Object-affected harmful factors
If high-resolution video is transmitted over limited bandwidth networks, then video quality should be maintained, but transmission efficiency decreases
Solution Approach 1:
The patent uses block copying to predict and reconstruct video blocks without transmitting full high-resolution data. By copying identical blocks from the dictionary and only transmitting differences (residuals), the method maintains high video quality while significantly reducing the amount of data that needs to be transmitted over limited bandwidth networks.
Solution Approach 2:
The patent extracts only the essential information that differs from previously transmitted blocks. Instead of transmitting complete high-resolution frames, the method extracts and transmits only the residual differences, maintaining video quality while improving transmission efficiency for bandwidth-constrained networks.
Data Source
AI summary
A method of decoding a coding unit from a video bitstream determines reconstructed samples for a first coding unit, from the video bitstream, and decodes a dictionary store flag from the video bitstream for the first coding unit. Where the dictionary store flag indicates that reconstructed samples for the first coding unit be stored, the method (i) stores the reconstructed samples for the first coding unit into a memory buffer; (ii) determines reconstructed samples for a second coding unit, the reconstructed samples for the second coding unit being copied from reconstructed samples for the first coding unit from the memory buffer, and (iii) outputs the reconstructed samples for the second coding unit. Also disclosed is a complementary method for encoding, a decoder and an encoder.