Hybrid Open-Loop Closed-Loop Video Compression Prediction

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Solution Overview

Problem

There is a tension between the small block sizes required for effective prediction in video compression and the large block sizes needed for efficient transform coding, particularly at higher resolutions, which affects prediction accuracy and noise growth.

Innovation Solution

A method of compression coding that combines a closed-loop predictor capable of exact reconstruction with an open-loop predictor, using a weighted sum of their outputs to control noise growth and optimize prediction accuracy, where the weighting factor varies with picture content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If small block sizes are used for effective prediction, then prediction accuracy is improved, but transform coding gain deteriorates

Engineering Contradiction:

Improveprediction accuracyVSAvoidtransform coding gain

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent combines two prediction approaches: closed-loop prediction (using reconstructed values from the decoder) and open-loop prediction (using original input values). This merging allows the system to benefit from both small block size prediction accuracy and large block size transform coding efficiency, resolving the contradiction between the two requirements

Inventive Principle:

Principle #5Merging (Combining)

2Loss of energy

If large block sizes are used for efficient transform coding, then transform coding gain is improved, but prediction accuracy deteriorates

Engineering Contradiction:

Improvetransform coding gainVSAvoidprediction accuracy

Core Design Contradiction:

Loss of energyVSMeasurement precision

Solution Approach 1:

The patent applies different prediction strategies to different parts of the coding process. Closed-loop prediction is used where exact reconstruction is possible, while open-loop prediction is used where it is not, allowing each region to operate at its optimal block size for its specific function

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If open-loop prediction is used to improve prediction flexibility, then prediction capability is improved, but noise growth increases

Engineering Contradiction:

Improveprediction capabilityVSAvoidnoise growth

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a weighting parameter that controls the contribution of open-loop prediction to the overall prediction. By adjusting this parameter, the system can balance between the adaptability benefits of open-loop prediction and the noise growth drawbacks, optimizing performance for different picture content types

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9451272B2Hybrid open-loop/closed-loop compression of pictures

Publication Date: 2016.09.20 BRITISH BROADCASTING CORP

AI summary

In a method of video coding, in which a difference is formed between input picture values and picture prediction values and that difference is transforming with a DCT, the picture prediction is formed as: P=(1−c)Pc+CPo where Pc is a closed loop predictor which is restricted to prediction values capable of exact reconstruction in a downstream decoder and Po is a spatial predictor which is not restricted to prediction values capable of exact reconstruction. The factor can vary from zero to unity depending on a variety of parameters.