POC LSB Coding for Long-Term Reference Picture Identification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing video coding standards face challenges in efficiently signaling and decoding long-term reference pictures, leading to ambiguities and increased bit usage due to the use of exponential-Golomb coding for delta POC LSBs, which is not well-suited for the wider distribution of POC LSB values.
Innovation Solution
The proposed solution involves directly specifying the POC LSBs of long-term reference pictures using variable fixed unary codes, allowing for uniform length unsigned binary encoding, and optionally signaling most significant bits to ensure uniqueness, thereby reducing bit usage and improving decoding accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If exponential-Golomb coding is used for delta POC LSBs, then decoding flexibility is provided, but bit usage increases and decoding accuracy decreases due to wider distribution of POC LSB values
Solution Approach 1:
The patent changes the coding parameter from exponential-Golomb to fixed-length unary coding, adapting the encoding scheme to match the actual distribution characteristics of POC LSB values. This parameter change reduces the average code length while maintaining decoding flexibility through the unary coding structure.
Solution Approach 2:
The patent applies different coding strategies to different parts of the POC value: fixed-length unary coding for LSBs (which have wider distribution) and selective MSB signaling only when needed for disambiguation. This local quality approach optimizes bit usage by applying coding techniques matched to the specific statistical properties of each part.
2Quantity of substance
If only POC LSBs are signaled, then bit usage is reduced, but ambiguities arise in identifying long-term reference pictures when multiple pictures have the same LSBs
Solution Approach 1:
The patent signals only the necessary portion of POC information: fixed-length unary coded LSBs plus selective MSBs only when required for disambiguation. This partial action approach provides sufficient identification accuracy while minimizing bit usage by avoiding transmission of redundant information.
Solution Approach 2:
The patent segments the POC value into LSBs and MSBs, handling them separately with different coding strategies. LSBs are always transmitted using fixed-length unary coding, while MSBs are transmitted selectively only when needed to resolve ambiguities, achieving reliable identification with minimal bit usage.
3Quantity of substance
If variable length coding is used for POC LSBs, then average bit usage decreases, but decoding complexity increases due to non-uniform code lengths
Solution Approach 1:
The patent uses fixed-length unary coding which provides uniform code length, simplifying the decoding process. The uniform length eliminates the need for complex variable-length decoding logic while maintaining efficiency through the unary coding structure's inherent adaptability to the data distribution.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In general, techniques are described for coding picture order count values identifying long-term reference pictures. A video decoding device comprising a processor may perform the techniques. The processor may be configured to determine a number of bits used to represent least significant bits of the picture order count value that identifies a long-term reference picture to be used when decoding at least a portion of a current picture and parse the determined number of bits from a bitstream representative of the encoded video data. The parsed bits represent the least significant bits of the picture order count value. The processor retrieves the long-term reference picture from a decoded picture buffer based on the least significant bits, and decodes at least the portion of the current picture using the retrieved long-term reference picture.