Coded Picture Buffer Sizing for Full-Frame Video Decoding
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Solution Overview
Problem
Existing video encoding and decoding systems face challenges in efficiently managing the coded picture buffer (CPB) size, leading to issues such as CPB overflow or underflow, particularly when encoding at minimum compression ratios, which can result in incomplete storage of video data.
Innovation Solution
Adjusting the maximum CPB size or removing the minimum compression ratio (MinCR) constraints to ensure the CPB can store an entire picture, even at minimum compression ratios, by implementing larger CPB sizes or modifying the MinCR scaling factor to maintain buffer integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the minimum compression ratio (MinCR) constraint is enforced, then compression efficiency is improved, but the coded picture buffer may become insufficient to store entire pictures
Solution Approach 1:
The patent changes the parameter relationship between MinCR and CPB size by introducing a scaling factor (e.g., 2.0) that adjusts the CPB size requirement based on MinCR. When MinCR is set to a value that would cause buffer insufficiency, the scaling factor automatically increases the required CPB size to ensure the buffer can store at least one complete picture, thus resolving the contradiction between compression efficiency and buffer reliability
Solution Approach 2:
The patent makes the CPB size dynamic rather than fixed by defining it as a function of MinCR and the scaling factor. This allows the buffer size to adapt automatically to different compression scenarios, ensuring that when MinCR changes, the CPB size adjusts accordingly to maintain sufficient storage capacity for complete pictures
2Reliability
If the coded picture buffer size is increased to store entire pictures, then buffer overflow is prevented, but memory usage increases
Solution Approach 1:
The patent optimizes the CPB size parameter by introducing a scaling factor that calculates the minimum required buffer size based on actual needs (MinCR and picture size). This ensures the buffer is large enough to prevent overflow while avoiding excessive allocation, thus resolving the contradiction between reliability and memory usage
3Productivity
If the minimum compression ratio is reduced to improve compression efficiency, then more video data can be compressed, but the CPB may become insufficient to buffer the encoded data
Solution Approach 1:
The patent creates a dynamic relationship where CPB capacity automatically scales with MinCR adjustments. When MinCR is reduced to improve compression efficiency, the scaling factor increases the required CPB size proportionally, ensuring buffer capacity remains sufficient to hold the increased amount of compressed data
Data Source
AI summary
An apparatus includes a video data decoder and a coded picture buffer to buffer successive portions of an input video data and provide a portion to the video data decoder for decoding. The video data decoder is responsive to parameter data associated with the input video data. The parameter data indicates, for a given input video data, an encoding level selected from a plurality of encoding levels. Each level defines at least a maximum luminance picture size, a minimum compression ratio, and a maximum value of the coded picture buffer size. For each encoding level of the plurality of encoding levels, the maximum value of the coded picture buffer size is greater than or equal to the number of bits required to represent a picture at the maximum luminance picture size when encoded according to the minimum compression ratio.