Bit-Accurate Comfort Noise Addition for Video Compression Artifacts
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Solution Overview
Problem
Existing video compression techniques at low bit rates result in noticeable artifacts like blockiness and structured noise patterns, which are not effectively masked by current comfort noise methods that lack control over noise addition.
Innovation Solution
A method is introduced to generate and add temporally correlated comfort noise to video images based on supplemental information, using a Comfort Noise SEI message within the H.264 video compression standard, allowing for controlled noise addition based on expected compression artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If random noise is added to the decoded video stream to reduce compression artifacts, then the noticeability of blockiness and structured noise patterns is reduced, but large frame-to-frame differences are created that produce new noticeable artifacts
Solution Approach 1:
The patent applies preliminary action by generating comfort noise in advance based on quantization parameters before it is added to the decoded video stream. The comfort noise is generated using a deterministic algorithm that processes the quantization parameters (QP) to create noise characteristics that match the compression artifacts, ensuring the noise is ready and properly calibrated before being combined with the video data, thus preventing excessive frame-to-frame variations
Solution Approach 2:
The patent implements dynamics by making the comfort noise generation adaptive to local video characteristics. The system dynamically adjusts the noise properties based on position-dependent quantization parameters (QPY, QPB, QPC for different blocks) and spatial location (x, y coordinates). This dynamic adaptation ensures the comfort noise matches the local compression artifact characteristics while maintaining temporal consistency through the use of temporal filtering and reference frame comparison
2Object-affected harmful factors
If comfort noise addition techniques are applied to hide compression artifacts, then artifact noticeability is reduced, but control over the amount and characteristics of noise added is insufficient
Solution Approach 1:
The patent applies parameter changes by utilizing multiple quantization parameters (QPY for luminance, QPB and QPC for chrominance) that are already present in the H.264 bitstream. These parameters naturally encode the desired noise characteristics based on the compression settings. The system also uses spatial parameters (x, y positions) and temporal parameters (frame differences) to control the comfort noise properties, providing fine-grained control over the noise addition process without requiring external configuration
Solution Approach 2:
The patent implements feedback mechanisms by comparing the current frame with reference frames and using the quantization parameters that were actually applied during compression. This feedback loop ensures the comfort noise characteristics match the actual compression artifacts present in the video, providing automatic adaptation and control based on the encoding conditions
Data Source
AI summary
The addition of comfort noise to an image serves to hide compression artifacts. To facilitate comfort noise addition, supplemental information accompanying a video image contains at least one parameter that specifies an attribute regarding comfort noise. Typically, the supplemental information includes parameters that function to turn the comfort noise on and off, as well as to indicate the level of noise to add, based on the expected level of compression artifacts.