Rice Parameter Derivation With Synchronized History Updates in Video Coding
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Solution Overview
Problem
Existing video coding standards suffer from reduced coding efficiency due to the synchronization issues between the history counter and replacement variable in deriving Rice parameters, leading to suboptimal compression and computational inefficiencies.
Innovation Solution
Synchronize the updates of the history counter and replacement variable by updating the replacement variable HistValue whenever the history counter StatCoeff is updated, ensuring accurate Rice parameter derivation for transform units, thereby improving coding efficiency and enabling parallel processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the history counter and replacement variable are updated independently in existing video coding standards, then the coding process can proceed without synchronization overhead, but the Rice parameter derivation becomes inaccurate leading to reduced coding efficiency
Solution Approach 1:
The patent merges the update operations of the history counter (StatCoeff) and replacement variable (HistValue) into a single synchronized process. Both variables are updated together based on the same condition (when the first non-zero coefficient is encountered), ensuring consistency between them and improving Rice parameter derivation accuracy without requiring complex synchronization mechanisms.
Solution Approach 2:
The patent performs preliminary updates of both the history counter and replacement variable before Rice parameter calculation. By updating these variables in advance and ensuring they are synchronized, the system eliminates the need for complex runtime synchronization during the coding process, thus improving accuracy without adding complexity.
2Productivity
If the history counter is updated frequently to improve Rice parameter accuracy, then coding efficiency improves, but computational power requirements increase
Solution Approach 1:
The patent applies partial action by updating the history counter and replacement variable only when necessary - specifically, when the first non-zero coefficient is encountered in a transform unit. This selective update approach improves Rice parameter accuracy compared to using stale values, while avoiding excessive computational overhead from continuous or frequent updates.
Solution Approach 2:
The system uses the naturally occurring first non-zero coefficient in the encoding process itself to trigger the update of history variables. This self-service mechanism leverages existing data flow without requiring additional computational resources or separate update processes, thus improving accuracy without increasing power consumption.
3Measurement precision
If sequential processing is used to maintain accuracy in Rice parameter derivation, then computational precision is maintained, but processing speed decreases
Solution Approach 1:
The patent segments the processing by dividing transform units into independent coding units that can be processed in parallel. Each transform unit maintains its own synchronized history counter and replacement variable, allowing multiple units to be processed simultaneously without interfering with each other's accuracy, thus improving both speed and precision.
Solution Approach 2:
By performing all necessary updates to history variables before Rice parameter calculation within each transform unit, the patent enables subsequent parallel processing of multiple transform units. The preliminary synchronization ensures accuracy is maintained while allowing faster parallel execution across different units.
Data Source
AI summary
In some embodiments, a video decoder decodes a video from a bitstream of the video using a history-based Rice parameter derivation. The video decoder accesses a binary string representing a partition of the video and processes each coding tree unit (CTU) in the partition to generate decoded coefficient values in the CTU. The process includes updating a history counter for a color component for calculating Rice parameters and prior to calculating a next Rice parameter, updating a replacement variable based on the updated history counter. The process further includes calculating the Rice parameters for transform units (TUs) in the CTU based on the value of the replacement variable and decoding the binary string corresponding to the TUs in the CTU into coefficient values of the TUs based on the calculated Rice parameters.