Adaptive Loop Filter for Video Bitrate Reduction

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Solution Overview

Problem

Current video compression methods face challenges in reducing bitrate while maintaining video quality, particularly due to high computational intensity and coding delay, which are critical issues in applications with strict resource constraints and real-time requirements.

Innovation Solution

The implementation of an adaptive loop filter (ALF) that selectively applies filtering to specific areas of video frames using optimized filter taps and reduced computational complexity, allowing for efficient bitrate reduction and low encoding/decoding delay by using a simplified pixel mask and quantization techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If traditional video compression methods are used to reduce bitrate, then video quality degradation occurs, but computational intensity and coding delay increase

Engineering Contradiction:
ImprovebitrateVSAvoidcomputational intensity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent changes parameters of existing filtering operations by introducing adaptive loop filters with modified tap configurations and quantization techniques. These parameter changes enable bitrate reduction while controlling computational complexity through selective application to specific video regions and optimized filter designs.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If traditional video compression methods are used to reduce bitrate, then video quality degradation occurs, but coding delay increases

Engineering Contradiction:
ImprovebitrateVSAvoidcoding delay
Core Design Contradiction:
Loss of energyVSLoss of time

Solution Approach 1:

The adaptive loop filter modifies temporal and spatial parameters of video reconstruction by applying filtering operations with adjusted tap weights and quantization levels. This enables bitrate reduction while maintaining real-time processing capability through efficient filter designs that minimize encoding and decoding delay.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If adaptive loop filtering is applied to improve video quality and reduce bitrate, then computational intensity increases, but video quality improves

Engineering Contradiction:
Improvevideo qualityVSAvoidcomputational intensity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies adaptive loop filtering selectively to specific regions of video frames based on local characteristics such as edge detection and variance thresholds. This local quality approach improves video quality where needed while reducing computational intensity in homogeneous regions, resolving the contradiction between quality and complexity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The adaptive loop filter applies filtering operations with partial intensity by using quantization techniques and selective tap application. Instead of full-precision filtering everywhere, the system uses reduced precision where appropriate, achieving acceptable video quality improvement while significantly reducing computational intensity.

Inventive Principle:
Principle #16Partial or excessive action

4Loss of energy

If adaptive loop filtering is applied to reduce bitrate, then encoding/decoding delay increases, but bitrate reduction is achieved

Engineering Contradiction:
ImprovebitrateVSAvoidencoding/decoding delay
Core Design Contradiction:
Loss of energyVSLoss of time

Solution Approach 1:

The patent optimizes the temporal parameters of the adaptive loop filter by using previously reconstructed frames and motion compensation techniques. This allows bitrate reduction through improved reconstruction accuracy while minimizing encoding and decoding delay through efficient use of available temporal information and optimized filter application timing.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9332278B2Video compression using an adaptive loop filter
Publication Date: 2016.05.03 CISCO TECHNOLOGY INC
  • US9332278B2 patent drawing
  • US9332278B2 patent drawing
  • US9332278B2 patent drawing

AI summary

A method including: obtaining video information at a video decoder apparatus, the video information including largest coding units of video data and filtering information, each of the largest coding units having a common size; obtaining, at the video decoder apparatus, an adaptive loop filter on/off indicator for each of the largest coding units, wherein each of the largest coding units includes a respective adaptive loop filter on/off indicator; and performing, by the video decoder apparatus, adaptive loop filtering to the largest coding units if the respective adaptive on/off indicators are on.