Video Compression Normalization for Quality Consistency
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Solution Overview
Problem
Constant bit rate compression methods in video sequences lead to sudden variations in image quality due to abrupt changes in compression factors, degrading the perceived quality of service.
Innovation Solution
A method involving a normalization step to smooth variations in the compression factor by simulating the receiver's buffer filling level and adjusting the quantization factor to maintain optimal buffer constraints, combined with local optimization techniques to minimize quality differences between images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If constant bit rate compression is used, then the bitrate is maintained constant, but the image quality varies abruptly due to sudden changes in compression factor
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant bitrate approach to a dynamic variable bitrate approach. The compression factor is adjusted frame-by-frame based on scene complexity analysis, allowing the bitrate to vary dynamically while maintaining perceptual quality consistency. This resolves the contradiction by making the system adaptive rather than rigid.
Solution Approach 2:
The patent changes the compression parameter (quantization factor) based on scene complexity metrics. By analyzing scene changes and adjusting the compression factor accordingly, the system maintains consistent perceptual quality while allowing bitrate to vary. This parameter adaptation resolves the contradiction between constant bitrate and quality consistency.
2Manufacturing precision
If variable compression factor is used to adapt to image complexity, then image quality is optimized, but bitrate varies causing buffer overflow or starvation
Solution Approach 1:
The patent implements feedback by simulating the receiver buffer behavior during the encoding process. The buffer simulation provides feedback about potential overflow or starvation conditions, which is used to adjust the compression factor and bitrate accordingly. This feedback mechanism ensures both quality optimization and buffer stability.
Solution Approach 2:
The patent performs preliminary buffer simulation during the encoding phase to predict and prevent buffer overflow or starvation before they occur. By proactively adjusting compression parameters based on simulated buffer behavior, the system ensures reliable playback while maintaining quality.
3Quantity of substance
If quantization factor is increased to reduce bitrate, then data amount is reduced, but image quality deteriorates significantly in high complexity scenes
Solution Approach 1:
The patent applies local quality by allowing different compression factors for different frames based on their complexity. Low complexity frames receive higher compression (lower quality), while high complexity frames receive lower compression (higher quality). This local adaptation optimizes the overall quality-bitrate tradeoff rather than applying uniform compression.
Solution Approach 2:
The patent dynamically changes the quantization factor based on scene complexity analysis. By adjusting this parameter adaptively rather than using a fixed value, the system achieves better quality-bitrate efficiency, reducing data amount while preserving quality where it matters most.
Data Source
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AI summary
The present invention relates to the field of video compression and, specifically, to controlling the bit rate of the generated compressed sequence. The invention relates to a method for constant bit rate compression, using a step of normalising the compression ratio. Variations in said ratio can thus be smoothed out, eliminating sudden variations in image quality in the resulting sequences. The perceived quality of service is thereby improved.