Progressive Video Scan Patterns for 8×4 and 4×8 Coefficient Blocks
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Solution Overview
Problem
Existing video compression techniques, such as those in Windows Media Video 8 and 9, and video codec standards like H.261, MPEG-1, H.262, H.263, and H.264, are not well-suited for common configurations of non-zero transform coefficients in 8×4 and 4×8 inter-coded blocks, leading to sub-optimal re-ordering of transform coefficients and inefficiencies in entropy coding for progressive and interlaced video.
Innovation Solution
Adopting scan patterns that bias the vertical direction for 8×4 blocks and the horizontal direction for 4×8 blocks during encoding and decoding to prioritize the ordering of lowest frequency AC coefficients, improving the efficiency of entropy coding by bunching non-zero coefficients together.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing video compression techniques are used for progressive video, then general video compression is achieved, but entropy coding efficiency deteriorates due to sub-optimal re-ordering of transform coefficients in 8×4 and 4×8 inter-coded blocks
Solution Approach 1:
The patent applies different scan patterns to different block types and video formats. Specifically, it uses distinct scan patterns for progressive video versus interlaced video, and different patterns for 8×4 versus 4×8 blocks. This local differentiation optimizes entropy coding efficiency for each specific case without requiring a completely new scanning approach for all scenarios.
Solution Approach 2:
The invention changes the scanning parameters (order and direction) of transform coefficients based on the video format and block dimensions. By adjusting the scan pattern parameters to match the specific characteristics of progressive video and different block sizes, the patent achieves optimal coefficient re-ordering that improves entropy coding efficiency while maintaining compatibility with existing video compression frameworks.
2Productivity
If standard scan patterns are used for all block types, then implementation simplicity is maintained, but compression performance deteriorates due to inefficient grouping of non-zero coefficients
Solution Approach 1:
The patent implements specialized scan patterns tailored to specific block dimensions (8×4 and 4×8) and video formats (progressive and interlaced). This local optimization ensures that non-zero coefficients are efficiently grouped for each case, improving compression performance without requiring complex adaptive algorithms that would compromise implementation simplicity.
Solution Approach 2:
The invention dynamically selects appropriate scan patterns based on the video format and block type being processed. This dynamic adaptation allows the system to achieve optimal compression performance for different scenarios while maintaining a relatively simple implementation through predefined pattern selection rather than complex real-time optimization.
Data Source
AI summary
Tools and techniques for applying scan patterns during encoding and decoding of progressive video are described. For example, a video decoder entropy decodes transform coefficients in a one-dimensional array and scans the transform coefficients into a block according to a scan pattern. The block is 8×4, and the scan pattern biases the vertical direction for at least the lowest frequency AC coefficients in the horizontal and vertical directions. Or, the block is 4×8, and the scan pattern biases the horizontal direction for at least the lowest frequency AC coefficients in the horizontal and vertical directions. A corresponding video encoder applies the scan patterns to scan transform coefficients from blocks to one-dimensional arrays.