Video Encoding Transform Subband Representations Blocking Artifacts

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Solution Overview

Problem

Existing video compression techniques suffer from blocking artifacts due to the use of non-overlapping region transforms, which can propagate errors and degrade image quality, especially at high compression rates.

Innovation Solution

Employing different transform/subband representations for various regions of a video frame, such as using the Lapped Orthogonal Transform (LOT) for I-frames and the Discrete Cosine Transform (DCT) for B and P-frames, or combining non-overlapping and overlapping region transforms within the same frame to reduce blocking artifacts and improve encoding efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If non-overlapping region transforms (DCT) are used for video encoding, then device complexity is reduced and ease of manufacture is improved, but blocking artifacts occur and image quality deteriorates

Engineering Contradiction:

Improveencoding simplicityVSAvoidblocking artifacts

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The video frame is divided into multiple blocks that are processed separately using DCT, which simplifies encoding. However, to reduce blocking artifacts, the patent applies overlapping block discrete cosine transform (OB-DCT) where adjacent blocks share common samples, creating a seamless transition between blocks and eliminating visible boundaries while maintaining the benefits of block-based processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines intra-frame coding and inter-frame coding within the same video sequence, allowing the encoder to switch between I-frames and P-frames based on scene complexity. This hybrid approach merges the error-resistance of intra-frame coding with the compression efficiency of inter-frame coding, reducing overall blocking artifacts while maintaining encoding simplicity.

Inventive Principle:

Principle #5Merging (Combining)

2Loss of information

If inter-frame coding is used to reduce bit rate, then loss of information is reduced, but error propagation occurs and reliability deteriorates

Engineering Contradiction:

Improvebit rate reductionVSAvoiderror propagation

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

The patent implements periodic intra-frames (I-frames) at regular intervals throughout the video sequence, creating anchor points that reset error propagation. Between these periodic I-frames, P-frames use inter-frame coding to maintain low bit rates. This periodic structure ensures that errors do not propagate indefinitely while maintaining compression efficiency for most of the video content.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies different coding strategies to different regions of the video frame based on local characteristics. In regions with high motion or complex content, intra-frame coding is used locally to prevent error propagation, while in stable regions, inter-frame coding maintains low bit rates. This local adaptation optimizes the balance between compression and reliability.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If overlapping region transforms are used to reduce blocking artifacts, then image quality is improved, but device complexity increases

Engineering Contradiction:

Improveblocking artifact reductionVSAvoidtransform complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent uses copying of sample data between overlapping blocks, where boundary samples are replicated and shared between adjacent blocks. This copying approach eliminates blocking artifacts by ensuring continuity across block boundaries while using the same DCT transform algorithm, thus improving image quality without significantly increasing device complexity.

Inventive Principle:

Principle #26Copying

4Productivity

If multiple transform representations are used for different frame types, then encoding efficiency is improved, but device complexity increases

Engineering Contradiction:

Improveencoding efficiencyVSAvoidtransform variety

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent dynamically switches between different transform representations based on the frame type and content characteristics. I-frames use one transform configuration optimized for intra-frame coding, while P-frames use another configuration optimized for predictive coding. This dynamic adaptation improves encoding efficiency by matching the transform to the coding mode, while the switching logic keeps device complexity manageable.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9479771B2Using multiple transform/subband representations for video encoding

Publication Date: 2016.10.25 MASSACHUSETTS INST OF TECH

AI summary

A method of encoding a sequence of video frames, comprising receiving a sequence of video frames, encoding at least a first portion of the sequence of frames using the first type of transform/subband representation to produce first transform/subband coefficients, encoding at least a second portion of the sequence of frames using the second type of transform/subband representation to produce second transform/subband coefficients; and providing the first and second transform/subband coefficients at an output.