Picture Parameter Set Signaling for Lower-Redundancy Video Bitstreams
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Solution Overview
Problem
In the current version of the VVC draft specification, certain parameters signaled in a slice header remain constant for the entire bitstream, leading to unnecessary penalties in compression efficiency as they are redundantly signaled across all slices.
Innovation Solution
Implement a mechanism where parameter values that stay constant for a set of segments, such as slices, are signaled only once in a parameter set (e.g., the sequence parameter set) rather than in each segment, and an indicator value is used to determine whether the parameter value is included in the parameter set or each segment header.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If parameter values are signaled in each slice header, then each slice can have independent parameter values, but bit redundancy increases and compression efficiency deteriorates
Solution Approach 1:
The patent extracts parameter values from individual slice headers and relocates them to the sequence parameter set when they remain constant across all slices. This separation removes redundant information from each slice while maintaining the ability to signal different values when needed, thereby reducing bit redundancy without sacrificing adaptability.
Solution Approach 2:
The patent introduces a dynamic signaling mechanism where the location of parameter values (sequence parameter set vs. slice header) can be flexibly determined based on whether the parameters are constant or variable across slices. This dynamic approach allows the system to adapt to different scenarios, optimizing compression efficiency while preserving parameter independence when necessary.
2Adaptability or versatility
If parameter values are signaled in each slice header, then slice-specific parameter variations are supported, but the amount of data in the encoded video bitstream increases
Solution Approach 1:
The patent extracts and removes redundant parameter values from individual slice headers, relocating them to the sequence parameter set. This extraction eliminates unnecessary data repetition while preserving the capability to signal slice-specific variations when parameters actually differ, thereby reducing the total data amount without sacrificing adaptability.
Solution Approach 2:
The patent discards redundant parameter signaling in slice headers when parameters are constant across slices, recovering the parameter information from the sequence parameter set instead. This discard-and-recover mechanism eliminates unnecessary data while maintaining the ability to recover slice-specific parameter values when they differ, optimizing bitstream efficiency.
3Ease of operation
If constant parameter values are signaled in each slice header, then decoding can proceed independently per slice, but compression efficiency is penalized due to redundancy
Solution Approach 1:
The patent extracts constant parameter values from slice headers and places them in the sequence parameter set, reducing redundancy while preserving independent slice decoding capability. The decoder can still process slices independently by using the extracted parameters from the sequence parameter set, maintaining ease of operation without sacrificing compression efficiency.
Solution Approach 2:
The patent makes the sequence parameter set serve multiple functions: it stores both sequence-level parameters and constant slice-level parameters. This universal approach allows the same data structure to support both global parameter storage and local parameter optimization, improving compression efficiency while maintaining independent slice decoding through the use of extracted constant parameters.
Data Source
AI summary
A method performed by a decoder for decoding a bitstream comprising a picture parameter set, PPS, and a first set of slices. The method includes obtaining the picture parameter set. The method also includes decoding a syntax element included in the picture parameter set to obtain an indicator value. The decoder is configured such that if the indicator value is set to a first value then the decoder determines that a picture header included in the bitstream comprises a parameter value corresponding to a particular parameter, otherwise the decoder determines that each slice included in the first set of slices comprises a parameter value corresponding to the particular parameter. If the picture header comprises the parameter value corresponding to the particular parameter, then this parameter value is used to decode slice data of each slice included in the first set of slices.