Video Encoding With Selective Lossless Regions for Synthetic Content
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Solution Overview
Problem
Existing video coding standards like HEVC introduce quantization errors, which are undesirable in applications requiring lossless coding, such as automotive vision and web collaboration, where synthetic content needs to be preserved without compression artifacts.
Innovation Solution
A method for lossless coding in video encoding and decoding that allows for signaling lossless coding indicators at sequence, picture, region, LCU, and sub-LCU levels, bypassing quantization, transformation, and in-loop filtering for losslessly coded portions, using a quad-tree structure and explicit signaling of lossless coding flags.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hybrid coding scheme using block-based prediction and transform coding with quantization is used, then compression efficiency is improved, but quantization errors are introduced causing loss of information
Solution Approach 1:
The video sequence is divided into multiple picture groups, with each group containing multiple pictures. Different lossless coding modes can be applied to different picture groups, allowing selective application of lossless coding only where necessary (e.g., regions with synthetic content) while maintaining compression efficiency in other regions.
Solution Approach 2:
The patent enables different coding modes (lossless vs. lossy) to be applied to different regions or picture groups within the same video sequence. This allows synthetic content regions to be coded losslessly while natural video regions can use efficient lossy coding, optimizing both information preservation and compression efficiency locally.
2Loss of information
If lossless coding mode (I_PCM) is used, then information integrity is maintained, but compression efficiency deteriorates due to no compression being performed
Solution Approach 1:
The video sequence is segmented into multiple picture groups, allowing the system to apply lossless coding only to specific groups containing synthetic content while using efficient lossy coding for other groups, thereby maintaining information integrity where needed while preserving overall compression efficiency.
Solution Approach 2:
Instead of applying lossless coding to the entire video sequence, the patent applies lossless coding partially only to specific picture groups or regions where it is necessary (e.g., regions containing synthetic content like presentation slides or UI elements), avoiding the excessive compression overhead in regions where it is not needed.
3Loss of information
If lossless coding is applied to entire video sequence, then information integrity is maintained, but device complexity increases due to signaling requirements at multiple levels
Solution Approach 1:
The video sequence is divided into picture groups with lossless coding mode indicators signaled at the picture group level rather than individual picture level. This segmentation reduces signaling overhead while maintaining the ability to apply lossless coding selectively to groups containing synthetic content.
Solution Approach 2:
The patent signals lossless coding mode indicators only for picture groups where lossless coding is actually applied, rather than signaling for every picture in the sequence. This partial signaling approach reduces device complexity and bitstream overhead while maintaining information integrity where needed.
Data Source
AI summary
A method for coding a video sequence is provided that includes encoding a portion of a picture in the video sequence in lossless coding mode, and signaling a lossless coding indicator in a compressed bit stream, wherein the lossless coding indicator corresponds to the portion of a picture and indicates whether or not the portion of the picture is losslessly coded. A method for decoding a compressed video bit stream is provided that includes determining that lossless coding mode is enabled, decoding a lossless coding indicator from the compressed video bit stream, wherein the lossless coding indicator corresponds to a portion of a picture in the compressed video bit stream and indicates whether or not the portion of the picture is losslessly coded, and decoding the portion of the picture in lossless coding mode when the lossless coding indicator indicates the portion of the picture is losslessly coded.