Backward Compatible Video Encoding Pipeline for SDR-HDR Compatibility

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Solution Overview

Problem

Current technologies face challenges in encoding and decoding video data to support a wide variety of standard dynamic range (SDR) and high dynamic range (HDR) display devices, particularly in maintaining image fidelity and efficiency across different dynamic ranges.

Innovation Solution

The implementation of high-fidelity full reference and high-efficiency reduced reference encoding in an end-to-end single-layer backward compatible encoding pipeline, using multivariate multiple regression coefficients and dynamic 3D mapping tables to generate chroma and luma mappings, and constructing backward reshaping mappings to approximate HDR images from SDR images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional encoding pipelines are used to support both SDR and HDR displays, then device compatibility is improved, but image fidelity deteriorates due to letterbox brightening and block vanishing artifacts

Engineering Contradiction:

Improvedevice compatibilityVSAvoidimage fidelity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The encoding pipeline is segmented into separate SDR and HDR processing paths. The system determines whether to apply HDR encoding based on metadata indicating HDR capability of the display device, thereby selecting the appropriate encoding path to avoid artifacts while maintaining compatibility

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes encoding parameters dynamically based on the target display device's HDR capability. When HDR is detected, HDR-specific encoding parameters are applied; otherwise, conventional SDR parameters are used, preventing artifacts like letterbox brightening and block vanishing

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If high-fidelity HDR encoding is implemented, then image quality is improved, but computational complexity increases

Engineering Contradiction:

Improveimage qualityVSAvoidcomputational complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system applies HDR encoding only partially - specifically when the target display device supports HDR as indicated by metadata. This selective application provides high-fidelity encoding only where needed, avoiding unnecessary computational complexity in SDR-only scenarios

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The encoding system uses metadata from the source video signal to automatically determine whether HDR encoding should be applied. This self-determination mechanism eliminates the need for complex external control systems while maintaining image quality

Inventive Principle:

Principle #25Self-service

3Measurement precision

If chroma mapping is applied during HDR encoding, then color accuracy is improved, but encoding time increases

Engineering Contradiction:

Improvecolor accuracyVSAvoidencoding time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

Chroma mapping is performed as a preliminary step during the encoding process itself, rather than as a separate post-processing step. This integration allows color accuracy to be maintained while avoiding additional encoding time

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11277627B2High-fidelity full reference and high-efficiency reduced reference encoding in end-to-end single-layer backward compatible encoding pipeline

Publication Date: 2022.03.15 DOLBY LABORATORIES LICENSING CORP

AI summary

3D mapping statistics are generated for a first image of a first dynamic range and a second image of a second dynamic range different from the first dynamic range. Multivariate multiple regression (MMR) coefficients are generated by solving an optimization problem formulated using an MMR matrix built with the 3D mapping statistics without a letterbox constraint, and used to generate chroma mappings for predicting chroma codeword values of the second image. It is determined whether a letterbox exists in the images. If so, it is determined whether the chroma mappings accurately predict chroma codeword values in the second image. A reconstructed image generated by a recipient device by backward reshaping one of the images is rendered by a display device operating in conjunction with the recipient device.